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The Importance of Lumbar Lordosis

Sofitel Melbourne on Collins | 15 -17 April 201122SPINESOCIETY OFAUSTRALIA

The Spine Society of Australia 22nd Annual Scientific Meeting 2011

In conjunction with the

Australian Orthopaedic Association

Continuing Orthopaedic Education

(AOA COE) | 13 - 15 April 2011

This Conference has been awarded

16 points - Category 1,

in the Australian Orthopaedic

Association CPD program and

15 credit points - Category 4 :

Maintenance of Clinical Knowledge

and Skills in the Royal Australasian

College of Surgeons CPD Program

Handbook COVER & AD PAGES_Layout 1 4/04/11 6:23 PM

ContentsPresident’s Message 2

Proud Supporters 3

Awards 4

Program Overview 5

Conference and Exhibition Floorplans 6

Exhibition Booth Allocations 7

Invited Presidential Guest, InternationalKeynote and Symposium Speakers 8 - 9

Editorial Secretary’s Report 10

DePuy Spine Clinical Fellowship Bursary 11

Scientific Program - Friday 15 April 12 - 14

Scientific Program - Saturday 16 April 15 - 17

Scientific Program - Sunday 17 April 18 - 19

Poster Presentations List 20

Supporter Advertising 21 - 25

Session Abstracts: Free Papers Session 1 27 - 34

Free Papers Session 2 35 - 42



President’s Session 59 - 64



Symposium 2 81 - 84


Poster Abstracts 93 - 107

Annual Meetings 108 - 109

Author Disclosure Statements 110

Poster Disclosure Statements 111

Delegate List 112 - 118

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President’s MessageOn behalf of the Spine Society of Australia I extend a warm

welcome to all those attending this 22nd Annual Scientific

Meeting of the Spine Society of Australia, here in Melbourne.

The Society and I also welcome the participation of the industry,

which has supported this Society and our patients so well.

Our 2011 meeting theme: ‘The Importance of Lumbar Lordosis,

and... are you restoring lordosis when you operate on lower lumbar

segments?’ will be addressed by a wide range of International and

local speakers.

Our esteemed Presidential Guest Speaker is Professor Jean-Charles

Le Huec, Chief of the Spine Unit and Chairman of the Department

of Orthopaedic Surgery and Traumatology at the Bordeaux

University Hospital, and Director of Surgical Research at

Bordeaux University School of Medicine.

International Keynote Speakers include Dr Christopher Ames,

Associate Professor and Co-Director of Spinal Surgery at the

University of California in San Francisco, and Professor Avinash

Patwardhan from the Department of Orthopaedic Surgery and

Rehabilitation, Loyola University Stritch School of Medicine, Chicago.

We look forward to high level academic presentations with lively

debate and the sharing of knowledge and fellowship in an

atmosphere of mutual respect.

Melbourne is a warm-hearted city and we hope you have a

chance to explore its many delights. The Conference Gala

Dinner being held on Saturday evening 16 April, in the stylish

Birrarung Gallery at Melbourne Museum, promises to be a

conference highlight. On behalf of the Organising Committee,

Welcome!

A/Prof Graeme Brazenor

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Proud Supporters

TITANIUM SUPPORT

GOLD SUPPORT

SILVER SUPPORT

BRONZE SUPPORT

AV SUPPORT

BREAKFAST SESSION SUPPORT

PRESIDENTIAL SPEAKER SUPPORT

KEYNOTE SPEAKER SUPPORT

CONFERENCE SATCHEL SUPPORT

WELCOME RECEPTION SUPPORT

Awards SPINAL RESEARCH AWARD Supported by

ROB JOHNSTON AWARD Supported by

BEST PAPER AWARD Supported by

BEST POSTER AWARD Supported by

TRAVELLING FELLOWSHIP BURSARY Supported by

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Conference Program Overview

Wednesday 13 April

AOA:COEMeeting

& Thursday 14 April Friday 15 April Saturday 16 April Sunday 17 April

10.10 Morning tea 10.20 Morning tea 10.00 Morning tea

12.30pm Lunch and Exhibition 12.00noon Award Presentations and Close

3.00 Afternoon tea

12.30pm Lunch and Exhibition

2.50 Afternoon tea

7.15 - 8.15am

SSA Registration

7.15 - 8.15am

Breakfast Session: Restoring

lumbar lordosis utilising the XLIF®

technique Dr Juan Uribe

8.30 Conference Opening

8.50 FREE PAPERS

SESSION 1:

Back Pain

8.30 FREE PAPERS SESSION 4:TDR / Sagittal Balance & The History of SpineBalance AnalysisProf Jean-Charles Le Huec

8.30 SYMPOSIUM 2

Surgery and Biomechanics

of Adult Degenerative Disease

A/Prof Chris Ames

Prof Avinash Patwardhan

10.40 SYMPOSIUM 1Vertebroplasty: Does it work?A/Prof Jacqui Close Dr Ralph StanfordProf Rachelle Buchbinder Dr Peter McCombe

Session combined with Australian Orthopaedic Association Continuing Orthopaedic Education

10.50 PRESIDENT’S SESSION

Lumbar Lordosis and Sagittal

Balance: The Masters Speak

Prof Jean-Charles Le Huec A/Prof Chris AmesProf Avinash Patwardhan

10.30 FREE PAPERS SESSION 7:Spinal Cord Injury

1.30 FREE PAPERS SESSION 5:Surgical

1.30 FREE PAPERS SESSION 2:Basic Science

3.30 FREE PAPERS SESSION 3:Cervical / BMP

3.10 FREE PAPERS SESSION 6:Scoliosis

5 - 7.00pm Welcome ReceptionSupported by

7.30 SSA GALA DINNERMelbourne Museum

4.30 - 6.00pm SSA Business Meeting

7.15 - 8.15am

Breakfast Session: Oracle: A new

approach to lumbar interbody

fusion Dr Bart Conix, MD

Conference & Exhibition Floorplans

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InternetCafe

! EXHIBITION FLOORPLAN | GRAND BALLROOM | LEVEL 1, SOFITEL MELBOURNE ON COLLINS

! LEVEL 1, SOFITEL MELBOURNE ON COLLINS

Grand Ballroom

Arthur Streeton Auditorium

Fitzroy Ballroom

Exhibition Booth AllocationsBooth 1. Internet cafe

Booth 2. OrthotechBooth 3. Orthotech

Booth 4. NuVasiveBooth 5. NuVasive

Booth 6. DePuy SpineBooth 7. DePuy Spine

Booth 8. Stryker

Booth 9. AO Spine

Booth 10. Biomet AustraliaBooth 11. Biomet Australia

Booth 12. Synthes Australia

Booth 13. Wright Medical Australia

Booth 14. Medyssey Spine

Booth 15. ETHICON (Johnson & Johnson Medical)

Booth 16. Neutron

Booth 17. Global Orthopaedic Technology

Booth 18. ArthroCare

Booth 19. B.BraunBooth 20. B.Braun

Booth 21. LifeHealthCareBooth 22. LifeHealthCareBooth 23. LifeHealthCareBooth 24. LifeHealthCare

Booth 25. Med-Chem Surgical Pty Ltd

Booth 26. Signature Spine

Booth 27. Zimmer Booth 28. Zimmer

Booth 29. MedtronicBooth 30. MedtronicBooth 31. MedtronicBooth 32. Medtronic

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Presidential Guest Speaker

International Keynote Speakers

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Professor Jean-Charles Le Huec Supported by

Chairman, Orthopaedic Department

University of Bordeaux Hospital, France

Jean-Charles Le Huec became a medical doctor in 1987,

continued his studies in Biomechanics and Biomaterials and

received his physical doctorate in 1997. In 1998 he was made

Professor of Orthopaedics and Traumatology and is now

Chairman, Spine Unit, and Head of Orthopaedics, Bordeaux University Hospital.

Professor Le Huec is a member of the French College and Society of Orthopaedic Surgery;

Vice President, Spine Society of Europe; a member of ISSLS and the North American Spine

Society; World Spine Society Treasurer and Spine Arthroplasty Society Vice President.

Professor Le Huec has numerous publications and participates in many research projects

relating to spine pathologies, biomaterials and computer-assisted surgery.

Associate Professor Chris Ames Supported by

Associate Professor of Neurosurgery

University of California, San Francisco, California, USA

Dr Ames is Director of Spinal Tumor and Spinal Deformity Surgery,

a Co-Director of the Neurospinal Disorders Program, and of the

UCSF Spine Centre, and Director of the Spine Tumor & Deformity

Fellowship Program. His clinical tumor practice focuses on spinal

deformity and complex tumor resection. While at UCSF, Dr Ames developed and published

the transpedicular approach to previously unresectable cervical and cervical thoracic tumors.

Professor Avinash Patwardhan Supported by

Dept of Orthopaedic Surgery & Rehabilitation,

Loyola University Stritch School of Medicine, Chicago, Illinois, USA

Professor Patwardhan is also Director of the Musculoskeletal

Biomechanics Lab at Edward Hines Jr. VA Hospital. A dynamic

teacher and pioneer in spinal biomechanics, his ‘follower load,’

testing technique is now recognised in biomechanical labs

worldwide. He has authored 100+ articles and13 book chapters, has presented at 267 conferences

and has received many research awards including the 2005 Outstanding Paper Award for his work

on lumbar disc arthroplasty, and the 2009 North American Spine Society’s Henry Farfan Award.

Symposium Speakers

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Associate Professor Jacqui Close

Consultant Geriatrician, Prince of Wales Hospital, Sydney,

NSW, Australia

A/Prof Close runs the Orthogeriatric and Falls, Balance and

Bone Health Service at Prince of Wales Hospital and is a

Principal Research Fellow at Neuroscience Research Australia.

She is conducting studies into the risk of falls in people with

cognitive impairment, piloting interventions to prevent falls in people with dementia and looking

at alternate pathways to care for older people using the ambulance service. She has a particular

interest in getting research generated evidence into practice and sits on a number of committees

and governing bodies to facilitate policy, guideline and practice development. She is medical

chair of the NSW ACI Aged Health Network which aims to enhance orthogeriatric services

across the State.

Professor Rachelle Buchbinder

Director, Monash Department of Clinical Epidemiology, Cabrini

Hospital, Melbourne, Vic, Australia

As a rheumatologist and clinical epidemiologist, Prof Buchbinder

is currently researching the management of soft tissue disorders.

She is also interested in the risk of malignancy in rheumatic diseases,

treatment and prevention of low back pain, magnetic resonance

imaging in rheumatoid arthritis, quality of life, patient education, complementary medicine and

outcome measurement. At present she coordinates and teaches the postgraduate course in

Measurement and supervises postdoc, BMedSci, MPH and PhD students.

Editorial Secretary’s Report Dear Members and Delegates,

2011 saw a sharp rise in the number of submitted abstracts over

2010 and so with the same amount of time available for paper

presentation, more authors were disappointed this year. In total

there were 85 abstracts submitted, 45 were accepted for oral

presentation and 17 for poster presentation. Twenty were rejected

and a further three authors did not reply to correspondence. The

process of abstract review was undertaken by a group of 5 reviewers,

including myself, representing the different clinical and scientific

disciplines that make up the Society. The review, as always, was

conducted in a fully blinded manner and each reviewer worked

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independently. The essential characteristic required of an abstract is scientific clarity. All abstracts not

making ‘the cut’ were re-appraised to ensure fairness. Once a selection had been made on the basis

of content alone, the conference secretariat contacted the relevant authors, who were still unknown

to me and the review panel. In many cases further information and clarification was requested of the

authors. The identity of abstract authors was only revealed after all correspondence had ceased and

the papers had been grouped for the purpose of building the program.

This process is unbiased and I believe leads to a better quality meeting. In my view quality is about

clear presentation of relevant data in a way that allows the audience to assess the worth of that

information. I do not subscribe to the view that an abstract is just a token for a paper, if the abstract

does not make sense, then it will suffer in the face of critical appraisal. Also, an abstract will not be

selected just because it reports a novel idea or new technology; it also has to meet minimum scientific

standards. I do not mean that data has to be collected blind or allocation randomised, I believe that

substantial case series can be useful. Critical reviews of published evidence also have merit. What is

important is that the methods used are reliable and transparent and the conclusions do not go beyond

the results. Even bias is acceptable as long as it is identified. The audience can then have confidence

in where this information came from and whether or not it has relevance to their own clinical or

scientific practice.

I congratulate the Society President, A/Prof Graeme Brazenor who has worked hard to bring together

an outstanding visiting faculty to highlight the importance of sagittal balance in surgical practice and

related biomechanical principles. The Spine Society is indebted to the tireless Prof Richard Williams

for collating the conjoint session with the Australian Orthopaedic Association on Friday morning, in

particular the symposium on vertebroplasty. I thank the scientific reviewers who gave much of their

time in silent homage to the principles of science and helped make this program a success; they are

Dr Kevin Seex, Prof Mark Pearcy, Prof Rob Moore and Dr Peter Robertson. I also thank Kate Ryall of DC

Conferences for her hard work and keeping me more or less to time, which is not easy.

I promise the delegates a stimulating and relevant program.

Dr Ralph Stanford, Editorial Secretary, Spine Society of Australia

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DePuy Spine Clinical Fellowship Bursary

Supported by

The DePuy Spine Clinical Fellowship Bursary is designed to

encourage and promote the pursuit of dedicated clinical spine

fellowship training. Bursary funds are granted to assist

successful applicants with the cost of attending an overseas

fellow program. Five individual bursaries are available for 2011,

each valued at Au$15,000. To be eligible for consideration,

applicants must satisfy the following criteria :

" Written confirmation of the applicant’s acceptance into a

Spine Fellowship Program (to be in writing from

Fellowship hospital’s department head or equivalent)

" Fellowship must be clinically based

" Fellowship program must be predominantly spine focused

(greater than 75% Spine)

" Fellowship Program to be at least 6 months duration

" Fellowship Program must be based outside Australia

" Applicants must currently be on an Australian Surgical

Training Program (Orthopaedic or Neurosurgical)

" Applications must relate to a Fellowship Program that will

commence in the calendar years of 2011 or 2012

To apply please provide details that satisfy the above

application criteria and send to:

Secretary, Spine Society of Australia

Email [email protected]

All 5 Bursaries will be awarded on a first come basis.

Successful applicants will be notified in writing within 1 month of

their application submission.

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Conference Program | FRIDAY 15 APRIL 2011

8.30am CONFERENCE OPENING | Arthur Streeton Auditorium

Chair | A/Prof. Graeme Brazenor

8.50 - 10.10am FREE PAPERS SESSION 1 | BACK PAIN | Arthur Streeton Auditorium

Chair | Prof Michael Ryan

8.50am 1.1 Facet joint injections: Are they safe or effective?

Matthew Beard

8.58am 1.2 Degenerative spondylolisthesis: The role of a weakened abdominal wall

Robert Fraser

9.06am 1.3 Why do some people experience no low back pain? Comparison of a middle-aged working

population to a population-based cohort

Markus Melloh

9.14am 1.4 Predicting the transition from acute to persistent low back pain

Markus Melloh

9.22am DISCUSSION

9.42am 1.5 Patient expectations, outcomes and satisfaction: Related, relevant or redundant?

Paul Licina

9.50am 1.6 Does posterior pedicle screw supplementation without posterolateral fusion improve anterior lumbar

interbody fusion when using anterior cage and screw constructs? A radiological study

Michael McCarthy

9.58am DISCUSSION

10.10am Morning Tea | Grand Ballroom

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Conference Program | FRIDAY 15 APRIL 2011 continued

10.40am - 12.30pm SYMPOSIUM 1 | VERTEBROPLASTY: DOES IT WORK? | Arthur Streeton Auditorium

This Session is combined with the Australian Orthopaedic Association Continuing Orthopaedic Education

Chair | Prof Richard Williams

10.40am Vertebral osteoporotic fractures: Natural history and prevention A/Prof Jacqui Close

11.00am Vertebroplasty: Technique, risks and benefits Dr Ralph Stanford

11.20am Vertebroplasty: Evidence based assessment of benefit Prof Rachelle Buchbinder

11.40am Observations on evidence based medicine and application to surgical practice Dr Peter McCombe

12.00 noon QUESTIONS and PANEL DISCUSSION

12.30pm Lunch | Grand Ballroom

1.30 - 3.00pm FREE PAPERS SESSION 2 | BASIC SCIENCE | Arthur Streeton Auditorium

Chair | Prof Clayton Adam

1.30pm 2.1 Biomaterial impregnation with bone marrow aspirate: Does it live up to the promise?

Claudia Eder

1.38pm 2.2 Recombinant human BMP-2 enhances local bone formation in the lumbar spine of osteoporotic sheep

Robert Moore

1.46pm 2.3 Elemental analysis of lumbar vertebral bone in an osteoporotic sheep model

Reza Zarrinkalam

1.54pm DISCUSSION

2.09pm 2.4 Biomechanical investigation of the stabilizing effect of a novel integrated device for intra-articular atlanto-axial stabilization

Peter Robertson

2.17pm 2.5 An intervertebral joint’s centre of rotation affects the forces experienced by the zygapophysial joints

Mark Pearcy

2.25pm 2.6 Development and validation of a spinal facet joint pseudarthrosis model

Ben Goss

2.33pm 2.7 Variations in annular defect characteristics in herniated lumbar discs: An annular repair feasability study and attempt to confirm Carragee data on defect size

David Wong

2.41pm DISCUSSION

3.00pm Afternoon Tea | Grand Ballroom

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Conference Program | FRIDAY 15 APRIL 2011 continued

3.30 - 5.00pm FREE PAPERS SESSION 3 | CERVICAL / BMP | Arthur Streeton Auditorium

Chair | Dr Greg Malham

3.30pm 3.1 Anterior cervical decompression and fusion with rhBMP-2: A prospective case series of 53 patients

Matthew Scott-Young

3.38pm 3.2 A non randomised single surgeon cohort study of rhBMP-2 versus rhBMP-7 in lumbar spinal

surgery: An outcome analysis of 186 patients

Michael McCarthy

3.46pm 3.3 The efficacy of bone morpheogenic protein (BMP-7) in posterolateral lumbar fusion surgery

Ellen Frydenberg

3.54pm DISCUSSION

4.09pm 3.4 Clinical outcomes following cervical disc replacement with PCM after a minimum 1-Year follow-up

Matthew Scott-Young

4.17pm 3.5 Seven years experience with C2 translaminar screws fixation: One surgeon's experience with 52 patients

Neill Wright

4.25pm 3.6 A radiological analysis of early failure of cervical fixation for trauma in the subaxial cervical spine

Michael McCarthy

4.33pm 3.7 Medium-term outcomes of elderly patients with odontoid fractures: Is quality of life associated

with radiographic evidence of union?

Amy Nall

4.41pm DISCUSSION

5.00pm Session closes

5.00pm - 7.00pm WELCOME RECEPTION

Grand Ballroom | Sofitel Melbourne on Collins

Supported by

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Conference Program | SATURDAY 16 APRIL 2011

7.15 - 8.15am BREAKFAST SESSION | Fitzroy Ballroom

Restoring lumbar lordosis utilising the XLIF® technique

Dr Juan Uribe

8.30 - 10.20am FREE PAPERS SESSION 4 | TDR / SAGITTAL BALANCE | Arthur Streeton Auditorium

and THE HISTORY OF SPINE BALANCE ANALYSIS | Prof Jean-Charles Le Huec

Chair | Dr Rob Kuru

8.30am 4.1 Prospective 10 year follow up of AcroFlex lumbar disc replacement

Robert Fraser

8.38am 4.2 Compliant artifical lumbar disc replacement (Cadisc-L): In vivo implant stability and

osseointegration in an animal model

Brian Freeman

8.46am 4.3 Early clinical performance of the Cadisc-L total disc replacement:

A prospective non-randomized multicentre clinical trial

Brian Freeman

8.54am DISCUSSION

9.09am 4.4 Correlation of age with spino-pelvic balance in degenerative lumbo-sacral disorder

Sabarul Mokhtar

9.17am 4.5 Association of chronic low back pain with loss of lumbar lordosis and the role of pelvic morphology

Jeb McAviney

9.25am 4.6 A software simulation of spinal sagittal balance

Peter McCombe

9.33am DISCUSSION

9.48am 4.7 History of spine balance analysis: Is there a reason to miss the target?

Prof Jean-Charles Le Huec

10.15am QUESTIONS


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Conference Program | SATURDAY 16 APRIL 2011 continued

10.50am - 12.30pm PRESIDENT’S SESSION | Arthur Streeton Auditorium

LUMBAR LORDOSIS AND SAGITTAL BALANCE: THE MASTERS SPEAK

Chair | A/Prof Graeme Brazenor

10.50am Pelvic parameters and spine parameters Prof Jean-Charles Le Huec

11.15am How to correlate parameters and global balance for daily practice Prof Jean-Charles Le Huec

11.35am QUESTIONS

11.45am Reciprocal changes and osteotomy planning in sagittal balance surgery A/Prof Chris Ames

12.05pm Geometric analysis of coronal balance in idiopathic scoliosis: Are there lessons for sagittal balance?


12.20pm QUESTIONS

12.30pm Lunch | Grand Ballroom

1.30 - 2.50pm FREE PAPERS SESSION 5 | SURGICAL | Arthur Streeton Auditorium

Chair | Dr Kevin Seex

1.30pm 5.1 Outcomes after decompressive laminectomy for lumbar spinal stenosis:

Comparison between minimally invasive unilateral laminotomy / laminectomy for

bilateral decompression (ULBD) vs. open laminectomy.

Ralph Mobbs

1.38pm 5.2 Lumbar spinal synovial cysts: Associations and treatment

Michael Ryan

1.46pm 5.3 Transforaminal endoscopic lumbar disc surgery application in upper lumbar discs: Method and results

Satishchandra Gore

1.54pm 5.4 Long-term outcomes following lumbar spine fusion for adult isthmic spondylolisthesis:

A comparison of PLIF vs PLF

John Cunningham

2.02pm DISCUSSION

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Conference Program | SATURDAY 16 APRIL 2011 continued

1.30 - 2.50pm FREE PAPERS SESSION 5 (continued) | SURGICAL | Arthur Streeton Auditorium


2.22pm 5.5 Prospective computed tomography scan analysis of percutaneously inserted pedicle screws for posterior transpedicular stabilisation of the thoracic and lumbar spine: Accuracy and complication ratesDarryl Raley

2.30pm 5.6 The role of preoperative DVT prophylaxis in thromboembolic complications in spinal surgeryJohn Cunningham

2.38pm DISCUSSION

2.50pm Afternoon Tea | Grand Ballroom

3.10 - 4.30pm FREE PAPERS SESSION 6 | SCOLIOSIS | Arthur Streeton Auditorium

Chair | Dr Peter Woodland

3.10pm 6.1 The measurement of applied forces during anterior single rod correction of adolescent idiopathic scoliosis (AIS)Helen Fairhurst

3.18pm 6.2 The value of spinal cord monitoring in scoliosis surgery: A ten year experienceSusan Liew

3.26pm 6.3 Do reinfusion drains following posterior instrumented spinal fusion for adolescent idiopathic scoliosis reduce allogenic blood requirements? A prospective audit with historical controlsMichael Selby

3.34pm 6.4 Serum titanium levels following paediatric spinal arthrodesisThomas Cundy

3.42pm DISCUSSION

4.02pm 6.5 Post-operative CT assessment of interbody fusion two years after thoracoscopic scoliosis surgeryAlan Carstens

4.10pm 6.6 Minimally invasive spine surgery in adult deformity correction: A prospective case series of 37 patientsMatthew Scott-Young

4.18pm DISCUSSION Session closes at 4.30pm

4.30 - 6.00pm BUSINESS MEETING | Arthur Streeton Auditorium

7.30pm CONFERENCE GALA DINNER | Birrarung Gallery, Melbourne Museum

Coaches depart from Sofitel Melbourne on Collins at 7.00pm

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Conference Program | SUNDAY 17 APRIL 2011

7.15 - 8.15am BREAKFAST SESSION | Fitzroy Ballroom

Oracle: A new approach to lumbar interbody fusion Dr Bart Conix MD

8.30 - 10.00am SYMPOSIUM 2 | Arthur Streeton Auditorium

SURGERY AND BIOMECHANICS OF ADULT DEGENERATIVE DISEASE


8.30am Sagittal balance and surgical strategy in adult high grade spondylolisthesis A/Prof Chris Ames

8.50am Stability of the osteoligamentous spine: The Follower Load and its implications to ex-vivo testing

and in-vivo spine stability Prof Avinash Patwardhan

9.15am A novel method of assessing facet joint motion using specimen-specific CT based model


9.30am QUESTIONS


10.30 - 12noon FREE PAPERS SESSION 7 | SPINAL CORD INJURY | Arthur Streeton Auditorium

Chair | Dr Gerald Quan

10.30am 7.1 VEGF & PDGF as an immunomodulatory strategy for the reduction of secondary degeneration

after a model spinal cord injury in rats

Ben Goss

10.38am 7.2 The pressure distribution of cerebrospinal fluid responds to residual compression and decompression

in an animal model of acute spinal cord injury

Claire Jones

10.46am 7.3 Gross morphological changes of the spinal cord immediately after surgical decompression in a large

animal model of traumatic spinal cord injury

Claire Jones

10.54am DISCUSSION

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Conference Program | SUNDAY 17 APRIL 2011 continued

10.30 - 12noon FREE PAPERS SESSION 7 (continued) | SPINAL CORD INJURY | Arthur Streeton Auditorium


11.09am 7.4 The role of spinal injury units in Australia: The effects of early and direct admission in

spinal cord injured patients

Matt Schiller

11.17am 7.5 Sequential reduction protocol using vector principle for cervical fracture dislocations

Rajeshwar Srivastava

11.25am 7.6 MRI in spinal trauma: A predictor of neurological recovery

Rajeshwar Srivastava

11.33am 7.7 Traumatic central cord syndrome: Is it associated with better neurological recovery and functional

outcomes when compared to motor incomplete tetraplegia?

Joost Van Middendorp

11.41am DISCUSSION

12.00 noon AWARD PRESENTATIONS

12.30pm Conference closes

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Poster Presentations (See pages 93 - 107)

1. Dr Markus Melloh

Clinical validity of the nerve root sedimentation sign for

the diagnosis of lumbar spinal stenosis

Department of Orthopaedic Surgery, Dunedin School of

Medicine, University of Otago, Dunedin, New Zealand

2. Dr Aziza Mahomed

Flexural properties of an elastomeric total disc replacement

School of Mechanical Engineering, University of Birmingham,

Birmingham, United Kingdom

3. Dr Eugene Wong

Management of cervicothoracic junction fracture dislocations

Austin Health, Melbourne, Vic, Australia

4 Dr Eugene Wong

Surgery for cervical facet dislocations: Which approach?


5. Dr Eugene Wong

MRI changes in cervical cord injuries


6. Dr Michael McCarthy

Screw webpacs: Is pedicle sizing accurate and reproducible

on CT

Royal Devon and Exeter Foundation NHS Trust, Exeter, Devon, UK

7. Dr Ellen Frydenberg

The role of cervical cordotomy in the management of

refractory cancer pain

St Vincent's Hospital, Darlinghurst, NSW, Australia

8. Dr Kevin Seex

Initial experience with a novel internally fixed frame to

improve retraction for anterior upper cervical surgery

Macquarie University, Sydney, NSW, Australia

9. Dr John McCormick

Novel description of an all-osseous transpelvic approach to

the intervertebral space of the lumbosacral junction

University of Florida, Gainesville, Florida, United States

10. Dr Michael McCarthy

Implementation of the NICE guidelines for metastatic

spinal cord compression: Do they make a difference?

Royal Devon and Exeter Foundation NHS Trust, Exeter, Devon, UK

11. Dr GRC Howie

A simple mnemonic to reduce errors in spinal fusion

Ascot Hospital, Remuera, Auckland, New Zealand

12. Prof Rajeshwar Srivastava

SCIWORA in adults: Is C4 the soft target?

King Georges Medical College, CSM Medical University Chowk,

Lucknow, India

13. Prof Rajeshwar Srivastava

Spinal shock in spinal cord injuries: Is duration of shock

related to neurological level?

King Georges Medical College, CSM Medical University Chowk,

Lucknow, India

14. Prof Brian Freeman

In-vitro biomechanical comparison of the native

intervertebral disc and a compliant artificial lumbar disc

replacement (Cadisc-L)

University of Adelaide, Adelaide, SA, Australia

15. Dr Michael Selby

Cervical cord injury as a complication of percutaneous

cervical facet joint radiofrequency neurotomy

University of Adelaide, Adelaide, SA, Australia

16. Dr Ralph Mobbs

Prospective analysis of graft options for anterior lumbar

interbody fusion (ALIF): Fusion and complication rates

University of New South Wales, Sydney, NSW, Australia

17. Dr Roy Michael Domacena

Radiographic fusion rate of multilevel anterior cervical

discectomy and fusion using peek cages with DBM and

plate fixation: A descriptive study

St Lukes Medical Center, Quezon City, NCR, Philippines

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DePuy Ad

22

LifeHealthCare Ad

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Nuvasive Ad

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Synthes Ad

25

Zimmer Ad

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Notes & Questions page

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22 Free Papers Session 1

Back PainFriday 15 April | 8.50am - 10.10am


S e s s i o n A b s t r a c t s

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FRIDAY 15 APRIL 2011

FREE PAPERS SESSION 1

BACK PAIN | Chair | Prof Michael Ryan


8.50am | 1.1Facet joint injections: Are they safe or effective?

*Beard, MDI, Potter, GI

Royal Adelaide Hospital, Adelaide, SA, Australia

INTRODUCTION

The effective management of chronic low back pain (CLBP)

remains a 21st century challenge. Many conservative treatments

have limited efficacy despite their continued popularity. Ensuring

patient treatments are based on current clinical evidence rather

than historical practice remains challenging (Buchbinder et al

2009). Clinicians often recommend facet joint injections as the

mainstay of conservative treatment. The attraction to both

patient and clinician is an intervention with potential diagnostic

and therapeutic utility. The objective has been to establish

whether FJI is an effective treatment for patients with CLBP.

METHODS

A review of relevant literature was undertaken that focused on

English language Randomized Controlled Trials only. Data sources

included a search of MEDLINE, EMBASE and the Cochrane

Central Register of Controlled Trials (January 1990 to December

2010). The primary outcome measure examined was pain relief.

Other measures included functional improvement, return to

work and adverse outcomes.

RESULTS

Review of published trials is unable to demonstrate sustained

improvement in pain or function for this patient population

(Stall et al 2009). Few immediate adverse events are reported

with clinical trails. In contrast a recent cellular study has

highlighted potential corrosive effects of both local anaesthetic

and corticosteroid on articular cartilage. (Seshadri et al, 2009).

CONCLUSION

Current evidence would question the efficacy of FJI in the

treatment of CLBP, which may also have the potential to initiate

or hasten joint degenerative changes.

REFERENCES

1. BUCHBINDER, R. et al.

Spine 34, 1218-1226, 2009.

2. STALL, JB et al.

Cochrane Database of Systematic Reviews CD 001824, 2009.

3. SESHADRI, V.

Journal of Arthroscopic and Related Surgery 25, 337-347, 2009.

29

8.58am | 1.2Degenerative spondylolisthesis: The role of a weakened abdominal wall

Fraser, RD


INTRODUCTION

Degenerative spondylolisthesis (DS) is thought to arise from

failure in torsion with females more vulnerable due to their bony

anatomy (Farfan, 1970). The abdominal wall has been estimated

to provide 95% of resistance to torsion (Macintosh, 1993). The

anterior abdominal wall is stretched during childbearing and a

previous study found an association between DS and pregnancy

(Sanderson, 1996). The aim of the present study was to further

examine the association of weakened anterior abdominal

muscles and DS.

METHODS

This was a prospective observational study of all new patients

50 yrs of age or older presenting with LBP. Exclusions were

previous lumbar surgery, fracture, neoplasm and infection.

Details of age, height, weight, children, pregnancies and open

abdominal operations were recorded. Integrity of the linea alba

was determined by asking the supine patient to elevate his/her

head and shoulders and the presence of rectus separation and

ventral hernia were noted. CT or MRI images were examined for

DS and the displacement was graded as a percentage.

RESULTS

205 patients were enrolled over a 5 month period. Mean ages

(years) were 70.5 for DS males, 65.9 for non-DS males, 72.0

for DS females and 64.9 for non-DS females. BMI for males and

females with and without DS was similar. DS was present in 28

of 98 males and in 56 of 107 females (M:F=1:2). DS was

multilevel in 30% of females compared with 7% of males

(p=.017). There was a significant association between DS and

ventral hernia (p=.009), rectus separation (p=.024), open

abdominal surgery (p=.022) and pregnancy (p=.03). Ventral

hernia was present in 64.3% of DS males compared with 37.1%

of non-DS males. Rectus separation was detected in 71.4% of DS

males, 52.9% of non-DS males, 51.8% of DS females and 35.3%

of non-DS females. The average number of open abdominal

procedures was 0.29 for DS males, 0.32 for non-DS males, 1.5

for DS females and 0.94 for non-DS females. The average

number of pregnancies was 3.09 for DS females compared

with 2.43 for non-DS females.

CONCLUSION

DS is extremely common in patients over 50 years of age pre-

senting to a spinal surgical clinic. The associations of DS with rec-

tus divarication, previous open abdominal surgery and

childbearing support the view that a weakened anterior abdomi-

nal wall is a significant causative factor for DS. The findings have

particular relevance to prevention as well as conservative and

surgical management of DS.

REFERENCES

1. FARFAN, HV, COSSETTE, JN, ROBERTSON, GH et al.

The effects of torsion on the lumbar intervertebral joints.

JBJS 52-A; 468: 1970

2. MACINTOSH JE, PEARCY MJ, BOGDUK N.

The axial torque of the lumbar back muscles: Aust N Z J

Surg ;63: 205: 1993–

3. SANDERSON PL, FRASER RD.

Influence of pregnancy in degenerative spondylolisthesis. JBJS

78-B; 951: 1996

30


FREE PAPERS SESSION 1 (continued)



9.06am | 1.3Why do some people experience no low backpain? Comparison of a middle-aged working population to a population-based cohort

*Melloh, M,1 Rolli Salathé, C,2 Schenk, K,2 Odermatt, E,2

Lüthi, I,2 Elfering, A 2

1 Department of Orthopaedic Surgery, Dunedin School of

Medicine, University of Otago, New Zealand 2 Department of Work and Organizational Psychology,

Institute of Psychology, University of Berne, Switzerland

INTRODUCTION

With the majority of all individuals beyond 50 years of age

experiencing low back pain (LBP) at least once in their lifetime,

little is known about those persons never having had LBP

(Nachemson et al. 2000, Waddell et al. 2001). To minimize work

absenteeism and to decrease socio-economic costs, knowledge

about persons resilient to the occurrence of LBP may help to

enhance preventative behavior in personal as well as

occupational settings (Reigo et al. 2001).

METHODS

Out of 350 individuals aged between 52 and 65, a group of

32 who never had experienced LBP before was assessed for

potential factors for never having suffered from LBP and

completed a questionnaire which had been part of a nation-wide

assessment about LBP (Muller et al. 2008). Answers were

content-analyzed, questionnaires compared to a population-

based cohort (n=4,120) using percentile ranks (PR).

RESULTS

Three main categories emerged for reasons why some people

did not develop LBP:

a) Sports and hobbies;

b) Movements during activities of daily living and in work

environments;

c) Positive attitudes towards life.

Compared to the population-based group, the group of subjects

never having had LBP scored higher for the ability to achieve routine

movements (PR=65). Also, they less frequently attended physicians

(PR=13) and had more positive attitudes towards life (PR=87).

The group of individuals never having suffered from LBP coped

better with their job (PR=61) and felt treated less unfairly at work

(PR=39). For the will to achieve something or the determination

to work for success, this group was ranked with PR 65.

CONCLUSION

Individuals above 50 years of age never having experienced LBP

are more likely to be physically active during work and daily routine

activities. Opinions and motivations, such as conscious and careful

usage of one’s bodily resources and limitations or taking good

health not for granted, as well as active and proactive health

behavior and fair treatment at work, possibly help preventing

individuals from developing LBP.

REFERENCES

1. MULLER, U, TANZLER, K, BURGER, A, STAUB, L, TAMCAN, O,

ROEDER, C, JUNI, P, TRELLE, S 2008.

A pain assessment scale for population-based studies:

Development and validation of the Pain Module of the

Standard Evaluation Questionnaire. Pain, 136, 62-74.

2. NACHEMSON, AL, JONSSON, E 2000.

Neck and back pain, Philadelphia, Williams & Wilkins.

3. REIGO, T, TROPP, H, TIMPKA, T 2001.

Absence of back disorders in adults and work-related

predictive factors in a 5-year perspective.

Eur Spine J, 10, 215-20; discussion 221.

4. WADDELL, G, BURTON, AK 2001.

Occupational health guidelines for the management of low

back pain at work: evidence review.

Occup Med (Lond), 51, 124-35.

2731

9.14am | 1.4Predicting the transition from acute to persistent low back pain

*Melloh, M,1 Elfering, A,2 Egli Presland, C,2 Röder, C,3

Hendrick, P, 4 Darlow, B,4 Theis, JC 1


Medicine, University of Otago, New Zealand2 Department of Work and Organizational Psychology,

Institute of Psychology, University of Berne, Switzerland3 MEM Research Center, University of Berne, Switzerland 4 School of Physiotherapy, University of Otago, New Zealand

INTRODUCTION

Most people experience low back pain (LBP) at least once in their

lifetime. Only a minority of them go on to develop persistent LBP.

However, the socioeconomic costs of persistent LBP significantly

exceed the costs of the initial acute LBP episode. Aim of this study

was to identify factors that influence the progression of acute

LBP to the persistent state at an early stage (Hilfiker et al. 2007).

METHODS

Prospective inception cohort study of patients attending a health

practitioner for their first episode of acute LBP or recurrent LBP

after a pain free period of at least six months. Patients were

assessed at baseline addressing occupational and psychological

factors as well as pain, disability, quality of life and physical activity,

and followed up at three, six, twelve weeks and six months.

Baseline and follow-up questionnaires were based on the

recommendations of the Multinational Musculoskeletal Inception

Cohort Study (MMICS) Statement (Pincus et al. 2008). Variables

were combined to the three indices ‘working condition’, ‘depression

and maladaptive cognitions’ and ‘pain and quality of life’.

RESULTS

The index ‘depression and maladaptive cognitions’ comprising of

depression, somatisation, a resigned attitude towards the job,

fear-avoidance, catastrophizing and negative expectations on

return to work was found to be a significant baseline predictor

for persistent LBP up to six months (OR 5.1; 95%CI 1.04-25.1).

The diagnostic accuracy of the predictor model had a sensitivity

of 0.54 and a specificity of 0.90. Positive likelihood ratio was

moderate with 5.3, negative likelihood ratio 0.5. Overall

predictive accuracy of the model was 81%. The area under the

curve in receiver operating characteristic (ROC) analysis of the

index was 0.78 (CI95% 0.65-0.92), demonstrating a satisfactory

quality of discrimination.

CONCLUSION

In this study of patients with acute LBP in a primary care setting

psychological factors at baseline correlated with a progression to

persistent LBP up to six months. The benefit of including factors

such as ‘depression and maladaptive cognition’ in screening tools

is that these factors can be addressed in primary and secondary

prevention.

REFERENCES

1. HILFIKER, R, BACHMANN, LM, HEITZ, CAM, LORENZ, T,

JORONEN, H, KLIPSTEIN, A 2007.

Value of predictive instruments to determine persisting

restriction of function in patients with subacute non-specific

low back pain. Systematic review. Eur Spine J, 16, 1755-1775.

2. PINCUS, T, SANTOS, R, BREEN, A, BURTON, AK,

UNDERWOOD, M. 2008.

A review and proposal for a core set of factors for

prospective cohorts in low back pain: a consensus statement.

Arthritis Rheum, 59, 14-24.

32





9.42am | 1.5Patient expectations, outcomes and satisfaction: Related, relevant or redundant?

*Licina, P,1,2 Ewing, L,1,2 Pearcy, M 1

1 ` Queensland University of Technology, Brisbane, Qld, Australia2 Holy Spirit Northside Hospital, , Brisbane, Qld, Australia

INTRODUCTION

Meeting patient expectations and achieving patient satisfaction

are now considered at least as important as more technical

measures of outcome such as fusion rate. However these

subjective variables are difficult to evaluate and interpret

objectively. Furthermore, their relevance to clinical practice and

how to change practice to optimize them is incompletely

understood. The purpose of this study was to determine patient

expectations before lumbar surgery and outcome after surgery,

to assess whether expectations had been met and whether

patients were subjectively satisfied after surgery.

METHODS

257 patients undergoing surgery for degenerative lumbar

conditions were identified. Those undergoing revision operations,

multi-level procedures and those with incomplete data were

excluded leaving 145 patients to be prospectively studied.

Oswestry Disability Index (ODI), back visual analogue scale

(VAS) and leg VAS were assessed pre-operatively and at 6

weeks and 6 months post-surgery. Patients’ expectations were

measured pre-operatively by asking them to score the level of

pain (back and leg VAS) and disability (ODI) that would be least

acceptable for them to undergo the operation and be satisfied.

Satisfaction was assessed six weeks post-operatively with a

5-point scale. To quantify patient expectations, the difference

between actual improvement and expected improvement was

calculated in terms of ODI, back VAS and leg VAS. This value was

termed the actual benefit change (AB ). To determine whether

this change was clinically relevant, an arbitrary margin of the

minimal clinically importance difference (MCID) of ± 15 points

for ODI and ±2 for VAS was applied, and this was termed the

clinically relevant benefit change (RB ).

RESULTS

Patient expectations were achieved in the minority of patients,

although most had a clinically relevant improvement. When the

margin of clinical relevance was applied to expectations, this

more closely approximated the outcome (Table 1).

6 weeks 6 months

AB � RB � MCID AB RB � MCID

ODI 37% 66% 73% 54% 83% 82%

Back VAS 48% 76% 76% 59% 85% 80%

Leg VAS 58% 85% 77% 63% 88% 79%

Table 1: Percentage of patients that :

AB Achieved expectations

RB Had expectations within clinically relevant margin

MCID Had clinically relevant improvement

At 6 weeks most patients (74%) reported being “very satisfied”,

with 19% stating they were “satisfied” and 7% being “somewhat

satisfied”. No patients expressed being “dissatisfied” or “very

dissatisfied”. Satisfaction did not correlate with the level of

pre-operative pain or disability, or with patient expectation of

improvement. Satisfaction correlated with post-operative back

pain and to a lesser extent ODI and type of surgery. All of the

10 patients that were only “somewhat satisfied” fell into the

highest quartile of postoperative back pain (VAS).

CONCLUSION

Satisfaction correlates with a positive outcome. Patient

expectations have little bearing on final outcome and satisfaction.

Its value probably lies in identifying patients with unrealistic

expectations and counselling them as part of the consent process.

9.50am | 1.6Does posterior pedicle screw supplementationwithout posterolateral fusion improve anteriorlumbar interbody fusion when using anterior cageand screw constructs? A radiological study

*McCarthy, MJH, Ng, L, Chan, D

Royal Devon and Exeter Hospital, Exeter, UK

INTRODUCTION

Anjarwalla et al. (2006) have shown that the addition of posterior

pedicle supplementation without posterolateral fusion during an

ALIF procedure significantly increases the rate of interbody fusion

when using a carbon fibre / PEEK cage packed with autogenous

iliac crest graft. Stand alone ALIF cages which utilise screws

passing through the interbody cage and into the vertebral bodies

were designed to obviate the need for a posterior procedure by

increasing the anterior construct stability and fusion rate. The

objective of this study was to assess the effect of posterior pedicle

screw supplementation without posterolateral fusion on the fusion

rate of ALIF when using anterior cage and screw constructs.

METHODS

Between 2003 and 2008 90 patients underwent ALIF procedure

under a single surgeon for low back pain associated with

degenerative disc disease or lytic spondylolisthesis. Routine CT

was performed at around 1 to 2 years follow up to ensure union

prior to discharge. It was noted that there was a significant number

of locked pseudathroses, especially in 2 level cases, and in 2006

the surgeon started to perform simultaneous supplementary

posterior pedicle screw stabilisation without posterolateral fusion

in the majority of cases.

RESULTS

Of the 90 patients, 76 (84%) had follow up at mean 21 months

and had CT imaging. 44 patients had anterior surgery alone (25

single level and 19 two level) and 32 had front back surgery (15

single level and 17 two level). Pseudarthrosis was seen in 16

patients (36%) of the anterior alone group and 2 (6%) of the front

back group. In the anterior alone group, pseudarthosis occurred

in 6 / 25 (24%) patients with single level surgery and 10 /19

(53%) of those with two level surgery. In this last group, the

pseudarthosis occurred in the upper fusion level in five patients

and at both fusion levels in other five.

CONCLUSION

Posterior pedicle screw supplementation without posterolateral

fusion improves the fusion rate of ALIF when using anterior cage

and screw constructs. We would recommend supplementary

posterior fixation especially in cases where more than one level

is being operated.

REFERENCES

1. ANJARWALLA et al.

Spine 31, 1281-1287, 2006.

33

Notes & Questions

34

35


Basic ScienceFriday 15 April | 1.30pm - 3.00pm





BASIC SCIENCE | Chair | Prof Clayton Adam


1.30pm | 2.1Biomaterial impregnation with bone marrow aspirate: Does it live up to the promise?

*Eder, C,1 Falkner, E,2 Meissner J,1 Tuschel A,1

Becker, P,1 Ogon, M1

1 Orthopedic Hospital Vienna-Speising, Vienna, Austria2 University of Vienna, Vienna, Austria

INTRODUCTION

The limited supply of autografts for spinal fusion has prompted

extensive research on bone graft substitutes. So far, various

biomaterials have been applied either stand alone or impregnated

with blood or bone marrow aspirate to promote spinal fusion.

Bone marrow aspirate harvested from the iliac crest is known to

contain osteoprogenitor cells, which are supposed to differentiate

into osteoblasts and form new bone at the desired fusion site.

But according to literature, only 0.001% - 0.01% of bone marrow

aspirate cells are in fact osteoprogenitor cells.1 So are we really

implanting what we think we are ?

METHODS

Surplus material remaining after cage and intervertebral space

preparation for routine spinal fusion surgery was analyzed.

Three different biomaterials (demineralised bone matrix - DBX,

ChronOS® and HealOS® were impregnated according to

specifications of the supplyer. Mesenchymal stem cell density was

assessed after impregnation and the cell seeded biomaterials

were investigated after implantation into the chick

chorionallantoic membrane model.

RESULTS

Most of the cells in bone marrow aspirate were identified as

erythrocytes while only a small fraction was identified as

nucleated stem cells. After biomaterial impregnation, average

stem cell density was 1.13 cells/mm2 (ChronOS® ), 0.92

cells/mm2 (HealOS® ) and 0.008 cells/mm2 (DBX). Only the

marginal pores of the biomaterials were filled with cells (mostly

erythrocytes) after biomaterial implantation. Despite the poor

cell yield, the cell impregnated biomaterials were able to

stimulate angiogenesis in the CAM-Model.

CONCLUSION

Impregnation of biomaterials with bone marrow aspirate can

only deliver very small amounts of osteoprogenitor cells to the

implantation site. Although these constructs are able to stimulate

angiogenesis, the number of osteoprogenotor cells delivered

seems too small to have a significant effect on osteogenesis.

Increasing cell density by centrifugation or expansion in culture

might therefore be required to improve fusion results.

REFERENCE

1. PITTENYER MF. et al.

Science 1999;248:143

36

1.38pm | 2.2Recombinant human BMP-2 enhances local bone formation in the lumbar spine of osteoporotic sheep

*Moore, RJ,1,2,4 Zarrinkalam, MR,1,2, Schultz, C,3

Arden DW,1 Vernon-Roberts, B,1,2,4

1 Adelaide Centre for Spinal Research, Adelaide, SA, Australia2 Hanson Institute, SA Pathology, Adelaide, SA, Australia3 Bone Densitometry Unit, Department of Nuclear Medicine,

Royal Adelaide Hospital, Adelaide, SA, Australia 4 Discipline of Anatomy and Pathology, University of Adelaide,

Adelaide, SA, Australia

INTRODUCTION

The failure of surgical implants in osteoporotic patients is

attributed to the lack of sufficient bone for initial stabilisation but

most current treatments for osteoporosis do not address bone

regeneration. rhBMP-2 has been used to promote bone

formation under normal conditions but has not been tested in

the osteoporotic condition. The objective of this study was to

investigate the potential for localized bone formation following

direct implantation of pellets containing rhBMP-2 in osteoporotic

vertebrae.

METHODS

Osteoporosis was induced in 19 ewes using ovariectomy, low

calcium diet and weekly steroid injection. Vertebral BMD was

monitored progressively. After induction, the steroid was

withdrawn and pellets containing inert carrier alone or carrier

with rhBMP-2 in either slow or fast release formulation were

implanted into three adjacent lumbar vertebrae of each animal.

After 2, 3 and 6 months the spines were harvested for histo-

morphometric analysis. Changes in BMD and histomorphometric

parameters were examined using ANOVA with Tukey’s

post-hoc test.

RESULTS

Within six months of induction BMD was reduced by 20.4%

from its baseline values (P<0.05), but did not change significantly

after cessation of steroid treatment or for the remainder of the

study. Micro CT analysis showed after two months BV/TV and

Tb.N increased by 12.8% and 10% respectively in the vicinity of

the fast-release rhBMP-2 pellets compared to the control

(P<0.05) and this was sustained for the duration of the study.

Focal voids surrounding all implants from the earliest time point

resolved with time.

CONCLUSION

Increased trabecular bone volume adjacent to pellets containing

rhBMP-2 within 2 months of implantation suggests that it could

be used for localised treatment of osteoporosis. Further

refinement of the delivery system and supplementary treatments

to overcome the initial catabolic effect of rhBMP-2 in trabecular

bone may be indicated.

37





1.46pm | 2.3Elemental analysis of lumbar vertebral bone in anosteoporotic sheep model

*Zarrinkalam, MR,1 Mulaibrahimovic, A,1,2 Moore, RJ, 1,2,3

1 Adelaide Centre for Spinal Research, Adelaide, SA, Australia2 Hanson Institute, Institute of Medical & Veterinary Science,

Adelaide, SA, Australia3 Discipline of Pathology, University of Adelaide,

Adelaide, SA, Australia

INTRODUCTION

Hydroxyapatite is the main inorganic component that gives

strength and stiffness to bone. The purpose of this study was to

compare the elemental composition of hydroxyapatite in

trabecular bone of lumbar vertebrae from osteoporotic sheep.

METHODS

Osteoporosis was induced in 10 mature ewes (Zarrinkalam, 2009).

Five age matched sheep were used as controls. All animals were

humanely killed and the lumbar spines collected and processed

undecalcified. The surface of the specimens was polished with fine

grade abrasive paper and then carbon coated to conduct

electron probe Microanalysis (EPMA) at up to 30 random sites

using a Cameca SX51 Microprobe (beam current of 20 nA,

accelerating voltage 15 kV). Calcium, phosphorus and oxygen

content was measured as a percentage of the total bone mass.

RESULTS

Trabecular bone of osteoporotic sheep had lower percentage of

phosphorus (P) than control sheep (12.5% vs 12.8%, p<0.01) but

the calcium level was identical in each group. Consequently

trabecular bone of the osteoporotic sheep had higher Ca/P

ratio than the control sheep (2.1 vs 2.06, p<0.01).

CONCLUSION

Osteoporosis in this sheep model not only decreases the volume

and mineral content of the vertebral trabecular bone

(Zarrinkalam, 2009) but also influences its elemental composition

which may also influence its mechanical properties.

REFERENCES

1. ZARRINKALAM, MR, H. BEARD, et al.

Eur Spine J 18: 244-53, 2009.

38

2.09pm | 2.4Biomechanical investigation of the stabilizing effect of a novel integrated device for intra-articular atlanto-axial stabilization

*Robertson, PA,1 Lim, RK,2 Tsitsopoulos, PP, 3 Voronov, LI,3

Havey, RM,3 Patwardhan, AG 3

1 The Othopaedic Clinic, Auckland NZ2 Medtronic, Memphis TN, USA3 Musculoskeletal Biomechanics Laboratory,

Edward Hines, Jr. VA Hospital, Hines, Illinois, USA

INTRODUCTION

The unique function and anatomy of the C1/2 atlanto-axial joint,

combined with the vascular and neural anatomy, has made

stabilization at this level highly challenging. Early fixation to the

posterior laminae of C1 and spinous process of C2 was associated

with poor rotational and translational stability. Newer techniques

with oblique trans-articular screw fixation (Magerl) across the

lateral mass joints, or inserting segmental screw fixation at the

lateral mass complexes (Harms technique) give dramatically

improved stability. Unfortunately, both techniques may be

technically difficult or contraindicated by local vascular and

vertebral artery (VA) anatomy. A novel integrated device was

designed and developed to obtain intra-articular stabilization via

primary interference fixation within the C1/C2 lateral mass

articulation. This study characterized the extent of immediate

stabilization of C1/C2 using the integrated device in the setting

of C1/C2 instability consistent with Type 2 odontoid fracture,

with comparison to the Harms technique.

METHODS

Biomechanical testing was performed using 6 human cadaveric

cervical spines (C0-C5, mean age: 54.6 years) with load control in

Flexion/Extension (FE), Lateral Bending (LB), and Axial Rotation

(AR) under a moment of 1.5Nm. Comparison of C1-C2 Range

of Motion (ROM) was performed using optoelectronic tracking.

ROM was measured in intact state, following destabilization after

creation of a Type 2 odontoid peg fracture, after sequential stabi-

lization using the Harms technique and the integrated device.

RESULTS

F/E ROM of the intact specimens was a mean of 14.1±2.9

degrees. Destabilization increased the ROM to 31.6±4.6 degrees.

Instrumentation with the Harms technique reduced the motion

to a mean of 4.0±1.4 degrees (p=0.0001). The integrated device

reduced F/E motion to 3.6±1.8 degrees (p=0.00007). For

evaluation of lateral bending the respective mean rotations were

1.8±1.1, 14.1±5.8, 1.4±0.7 and 0.3±0.5 degrees for the intact,

destabilized, Harms technique and integrated device. For axial

rotation the respective mean values were 67.3±13.8, 74.2±16.1,

1.3±0.8 and 0.9±0.7 degrees. All comparisons between the

destabilized state and both the Harms and integrated device

were statistically significant (p<0.05). Direct comparison of the

Harms technique and the integrated device revealed no

significant difference (p>0.05).

CONCLUSIONS

The integrated device resulted in interference fixation at the

C1/2 lateral mass joint with comparable stability to the Harms

technique. Perceived advantages with the integrated device

include avoidance of fixation below the C2 lateral mass where

the VA is susceptible to injury, access to the C1 screw entry point

through the blade of the device avoiding extended dissection

superior to the C2 nerve root and its surrounding venous

plexus, the possibility of intra-articular fusion through and

around the device, and the absence of imaging difficulties when

looking at posterior interlaminar fusion. Biomechanical testing

demonstrated improved construct stiffness with removal of

articular cartilage from the lateral mass, and bi-cortical fixation

of the C1 screw in the integrated device.

39





2.17pm | 2.5An intervertebral joint’s centre of rotation affectsthe forces experienced by the zygapophysial joints

Pearcy MJ

Institute of Health and Biomedical Innovation,

Queensland University of Technology, Brisbane, Qld, Australia

INTRODUCTION

Modifying the mechanics of an intervertebral joint through,

eg discectomy or implantation of an artificial disc will cause

changes to the forces components of the joint experience during

normal activities. This study examined how the forces on the

zygapophysial joints are affected by changes in the position of the

intervertebral joint’s centre of rotation in order to assess the

potential for accelerated degeneration to occur (Pearcy, 2010).

METHODS

Polymer models of the L4 and L5 vertebrae from the ‘Visible

Human Project®’ data set were made ensuring fidelity of the

shape of the zygapophysial processes. These were than mounted

in a robotic testing machine (de Visser et al., 2007) and aligned to

represent the functional L4/5 intervertebral joint. The superior

vertebra was rotated axially ±3.5º with the axis of rotation set at

60% of the depth of the disc. The forces caused by contact between

the faces of the zygapophysial processes were measured. The

test was then repeated with the axis of rotation moved 4mm

anteriorly then posteriorly, and then 4mm anteriorly plus 4mm

to the left and then to the right.

RESULTS

The maxima of the resultant forces experienced by the L5

vertebra.

CONCLUSION

The % difference shows that moving the centre of rotation

4mm can cause an increase in the force experienced by the

zygapophysial joints of up to 31%. As this is a purely geometric

phenomenon the displacement of the centre by 1mm would

cause an increase of nearly 8%. Repeated exposure to this

increased loading might be expected to lead to early degenerative

changes. The data also show that small asymmetries in the joints

cause significant changes to the forces experienced. Because of

geometric differences some individuals will be more susceptible

to degeneration caused by changes to the centre of rotation of

the intervertebral joint if it is altered by surgery.

REFERENCES

1. DE VISSER H, ROWE C, PEARCY MJ.

Journal of Engineering in Medicine, 2007. 221:221-227.

2. PEARCY MJ.

Expert Review of Medical Devices, 2010, 7: 855-860.

40

2.25pm | 2.6Development and validation of a spinal facet joint pseudarthrosis model

*Goss, B,1 Sugiyama, S,1 Wullschleger, M, 2

Williams,R,1 Wilson, K 3

1 AOSpine Reference Centre, Institute of Health and

Biomedical Innovation, Queensland University of Technology

Brisbane, Qld, Australia2 Institute of Health and Biomedical Innovation, Queensland

University of Technology, Brisbane, Qld, Australia3 Medical Engineering Research Facility, Prince Charles

Hospital, Queensland University of Technology,

Brisbane, Qld, Australia

INTRODUCTION

Despite the routine nature of spinal fusion, pseudarthrosis is still

a common complication with non-union rates reported to be as

high as 31% in some series (Steinmann 1992). Revision of a failed

fusion carries risk of further complications related to poor

vascularity, scaring, loss of bone and alterations in alignment.

Improved animal models may help advance new treatments for

pesudarthoris. Currently the only reported animal model of

spinal pseudarthrosis is the New Zealand White Rabbit (Grauer

2004) which shows a 77% pseudarthrosis rate at one month.

The limitations of this model are both the size of the animal and

possibility of spontaneous fusion later than 1 month. This study

reports an ovine model of pseudarthrosis, and determined the

efficiency of pseudarthrosis formation at 6 months.

METHODS

The experiments were approved by The QUT Animal Ethics

Committee and conducted according to NHMRC guidelines.

Eight sheep were used. After induction of anaesthesia and dorsal

approach to T13/L1 both facet joints were prepared by curetting

out the cartilage and cortical bone in the leaving 2 mm gap

between articulating surfaces.

Into the defects in each facet joint a piece of oxidised cellulose

cloth (Surgicel; Ethicon Inc. NJ. USA) was placed. A loose spinous

process wire was applied to prevent massive translation but

enable small movements of the spine. The wound was closed

and local anaesthetic was applied. Each sheep was released back

to the holding yard after recovery from anaesthesia.

Sheep were sacrificed 26 weeks after surgery by an overdose

of penthobartitone sodium. The spines were harvested and

examined by micro CT, histology and mechanical testing.

RESULTS

Micro CT imaging showed that 5 of 8 animals had a discontinuity

through the facet joint 26 weeks after surgery indicating a

pseudarthrosis rate of 62.5%. When examined by histology this

region was shown to contain fibrous tissue and bear the hallmarks

traditionally seen in other non-unions. There was limited amount

of ostoid tissue, which indicated that the joint would not

spontaneously fuse if more time was given.

The mean tensile strength of the pseudarthosed joints was joint

was 782.8 +/- 235 N compared with a mean tensile strength of

936.1 +/- 280 N for the fused joints. This difference was not

statistically significant (p=0.15) but this may reflect the

unidirectional nature of the measurement.

CONCLUSION

This study reports the development of a reasonably reliable large

animal model of spinal facet joint pseudarthrosis. This will be

beneficial in the further study of the applicability of new

osteogenic technologies in the treatment of non-union.

REFERENCES

1. GRAUER, JN et al

Spine 29 (13), 1405–1412, 2004.

2. STEINMANN JC. et al,

Clin Orthop 284 80 –90 1992

41





2.33pm | 2.7Variations in anular defect characteristics in herniated lumbar discs: An anular repair feasability study and attempt to confirm Carragee data on defect size

*Wong, DA, Mauter, L, Murdock, V, Wong, CJ

Presbyterian St Luke’s Medical Center and Denver Spine,

Denver, Colorado, USA

INTRODUCTION

Carragee has studied the effect of defect size on the rate of

recurrent herniated disc and revision surgery. However,

Carragee’s paper did not report other characteristics such as

defect location (mid annulus vs. adjacent to the inferior or

superior end plate) nor tissue quality (intact / frayed / calcified).

These additional characteristics (along with defect size)

determine the feasibility of anular repair. Suturing (technically

easiest/cheapest-and already on the market) applies only where

the anular tear is mid substance with good adjacent tissue.

Defects adjacent to bone require a bone anchor for the suture

(just entering the market). Large anular holes necessitate a

technically challenging, expensive barrier reconstruction

(technology limited to clinical trials).

This study had two primary research questions:

1. What is the incidence of characteristics determining the

percentage of HNP patients who are candidates for anular

repair / reconstruction

2. Does our cohort confirm the Carragee population

distribution regarding anular defect size

METHODS

A 100 consecutive patient surgical cohort for single level, primary

HNP were prospectively studied. Size and location of the anular

defect (midsubstance/adjacent to superior or inferior end plate),

tissue quality and Carragee Type (fragment / fissure, fragment /

defect, fragment / contained, no fragment/contained) were noted.

RESULTS

• 68 males/ 32 females (higher risk for males p=0.0003),

average age 47.

• 55 right herniations/ 45 left.

• 64% mid substance defects/good adjacent tissues (suture

applicable). Defect adjacent inferior end plate (21%), adjacent

to superior end plate (8%) - bone anchor potentially

applicable (29%). Total potential repair patients (93%).

• Repair not feasible 7% due to disc calcification.

• Carragee categories (% ours/Carragee), Fragment Fissure

(33/49), Fragment Defect (11/18), Fragment Contained

(45/23), No Fragment Contained (11/8). Significant difference

between our cohort vs. Carragee all categories (chi-square

test p<0.0001).

• Using available anular suturing technology, 64% of the

patients in this study would be candidates for anular repair.

With a bone anchor, an additional 29% of patients would be

candidates for reconstruction.

• The primary reason for inability to repair was a calcified disc.

No patients had thinning or shredding of the annulus to a

degree that would prohibit anular reconstruction.

• The statistically significant variation in all Carragee defect

categories was a surprise. Carragee population data on

defect size was not confirmed. The true population incidence

remains uncertain.

CONCLUSIONS

With suturing technology and availability of a suture bone anchor

93% of patients in our cohort were potential candidates for

anular repair. Additional studies of Carragee defect categories

will be necessary to more accurately define the population

incidence of various types of anular failure. Determining reliable

population incidence is key for accurately calculating the cost

effectiveness of anular repair technologies.

REFERENCES

1. CARRAGEE E et al.

Clinical Outcomes After Lumbar Discectomy for Sciatica:

The Effects of Fragment Type and Anular Competence. J

Bone Joint Surg Am. 2003;85:102-108.

42

43


Cervical / BMPFriday 15 April | 3.30pm - 5.00pm





CERVICAL / BMP | Chair | Dr Greg Malham


3.30pm | 3.1Anterior cervical decompression and fusion withrhBMP-2: A prospective case series of 53 patients*Scott-Young, MN,1 Magno, C,2 Nielsen, D,2

Mitchell, E,2 Blanch, N 2

1 Bond University, Gold Coast, Qld, Australia 2 Gold Coast Spine, Gold Coast, Qld, Australia

INTRODUCTION

Anterior cervical decompression and fusion (ACDF) is a widely

accepted method for cervical spinal stabilization. A variety of

grafting techniques have been used to facilitate arthrodesis.

Autografts and allografts have been the standard with complications

including donor graft morbidity and non-union. Biological

innovations such as recombinant human bone morphogenetic

protein – 2 (rhBMP-2) have been studied extensively in the

lumbar spine to accelerate arthrodesis. rhBMP-2 in the cervical

spine has been complicated by insufficient knowledge of optimal

dosages. This study evaluates the safety, efficacy, clinical and

radiological outcomes of ACDF with rhBMP-2.

METHODS

This is a prospective study of 53 patients having a diagnosis of

cervical spondylotic radicular myelopathy and treated with ACDF

with local bone and rhBMP-2. The technique utilised a cage

and/or plate for stability following the decompression. The cage

was filled with local bone obtained during the decompression

mixed with rhBMP-2. It is recommended that 15% of a small

rhBMP-2 mixed with local bone should be used per level.

Management in the post operative period consists of ice to the

wound, IV dexamethasone, and patient education.

Clinical outcomes were measured using NDI, VAS (neck and

arm), SF-36 and radiological assessment. Patients were assessed

preoperatively and at 3, 6 and 12 months. Radiological assessment

consisted of AP lateral flexion/extension standing films and fine

cut CT. Mean, median, 95% confidence levels, and categorical data

have been measured.

RESULTS

Fifty-three patients had a total of 123 levels fused with an average

follow-up of 17.34 months (range 6-39 months). Thirty patients

were male and 23 patients female, with an average age of

59.92yrs (range=19-80 yrs). The average operation duration

was 72.69mins (range 50-100mins).

Results at latest follow-up versus baseline were compared using a

one-tailed paired t-test (p<0.05): mean reduction in mean back

VAS neck scores reduced by 59.7%; mean right VAS arm score

reduced by 58.3%, while left VAS arm scores reduced by 69.0%.

Mean NDI reduced by 50.4%. SF-36 PCS increased by 19.7% and

SF-36 MCS increased by 13.3%. All results were statistically

significant (p<0.05). No significant differences were noted in

functional scores between 3 and 6 months or 6 and 12 month

post-operative periods. Radiological evaluation by an independent

radiologist and the primary surgeon showed a 100% union rate

has been achieved with this technique. Post operatively one

patient (1.9%) required ICU admission for respiratory arrest

possibly related to BMP dose; one patient (1.9%) had post-

operative atrial fibrillation; and one patient (1.9%) had post-

operative dysphagia due to the inherent surgical approach of

treating multilevel spine disease.

CONCLUSION

The use of rhBMP-2 in the correct dosage, when mixed with

local bone, placed within a cage will result in a fusion. This negates

donor morbidity from autograft and non-union seen with other

bone substitutes. Correct dosage, combined with appropriate

post-operative care and education, effectively minimises the

post-operative affects of rhBMP-2 in ACDF.

44

3.38pm | 3.2A non randomised single surgeon cohort study of rhBMP-2 versus rhBMP-7 in lumbar spinal surgery: An outcome analysis of 186 patients

*McCarthy, MJH, Stanojevic,S, Goss, B, Williams,R

Queensland University of Technology, Brisbane Private Hospital

and Princess Alexandra Hospital, Brisbane, Qld, Australia

INTRODUCTION

Bone Morphogenic Proteins (BMP) have been used for several

years to improve the rates of spinal fusion. Complications of their

use include osteolysis, heterotropic bone formation and radiculitis

(Glassman et al. 2010). The aims of this study were to compare

the clinical and radiological outcomes and complication rates of

their use in lumbar spinal surgery.

METHODS

Between 2003 and 2009 all patients having spinal surgery under

a single Consultant Spinal Surgeon were identified using the

operative database and sales records of BMP. The surgeon used

rhBMP-7 routinely between 2003 and 2007 changing to rhBMP-2 in

2007 primarily because of its handling properties. A retrospective

review of the medical charts was performed and patients

selected using strict inclusion and exclusion criteria. Stage two of

the study involved a postal then telephone questionnaire and

radiological review. The primary end point was revision surgery

with secondary end points of:

1. Complications and

2. Other intervention including radiological procedures such as

root block, epidural and facet injections. The study received

Human Research Ethics Committee approval.

RESULTS

One hundred and eighty six patients matched the selection

criteria (80 rhBMP-2 and 106 rhBMP-7). There were no significant

differences between the groups for age, sex, employment,

preoperative walking distance, number of levels operated and

preoperative neurological deficits. 70% of each group had

decompression fusion surgery for spondylolisthesis. Preoperative

Oswestry Disability Index (ODI) was 41.8 (95% CI 38-46 range

8-70) in the rhBMP-2 group and 39.5 (95% CI 37-42 range 10-75)

in the rhBMP-7 group (p=0.32). The average follow up was 1 year.

At a mean of 1 year follow up, there was no significant difference

in postoperative ODI (rhBMP-2 = 15.7, 95% CI 9-22 and rhBMP-7

= 17.2, 95% CI 13-21 p=0.69) and postoperative walking distance

(p=0.37). In both groups the walking distance had doubled

compared to the preoperative distance. There was no difference

in the fusion rates between the two groups (p=0.42). Revision

surgery was required in ten rhBMP-2 patients (13%) and eighteen

rhBMP-7 patients (17%) (p=0.48). Six rhBMP-2 patients and

seven OP-1 patients required revision surgery directly related to

the index procedure. Symptomatic adjacent segment disease was

seen in four rhBMP-2 patients (5%), all of whom had surgery, and

fourteen rhBMP-7 patients (13%), eleven of whom had surgery.

This approached statistical significance (p=0.053). Post operative

non surgical interventional procedures were required in ten of the

rhBMP-2 group and twenty three of the rhBMP-7 group (p=0.23).

CONCLUSION

In our cohort, there does not appear to be a difference in

outcome between rhBMP-2 and rhBMP-7. The complication and

reintervention rates appear to be similar and match those in the

published literature.

REFERENCE

1. GLASSMAN et al.

Spine 35, 1621-1628, 2010.

Inclusion Criteria:

17 to 80 years of age, up to and including 3 level surgery, primary

lumbar surgery with use of INFUSE or OP-1 (low back fusion),

degenerative conditions only (including long term non dysplastic

spondylolysis), instrumented and uninstrumented cases with or

without canal decompression, ALIF with posterior instrumentation

and posterior BMP, TLIF, PLIF and PLF.

Exclusion criteria

any revision procedure, ALIF alone, greater than 3 level surgery,

degenerative spondylolisthesis greater than grade 2, non

degenerative conditions (such as trauma, tumour and infection)

and deformity surgery (scoliosis and kyphosis).

45





3.46pm | 3.3The efficacy of bone morpheogenic protein (BMP-7)

in posterolateral lumbar fusion surgery

Frydenberg, E St Vincent's Hospital, Darlinghurst, NSW, Australia

INTRODUCTION

Osteoinductive agents, such as Bone Morpheogenic Proteins

(BMP) have attracted considerable interest, and have become

common in spine surgery. So far there has been limited evidence

of their efficacy.

3 randomized controlled studies of the use of BMP-7 in lumbar

spine fusion have been published.

Only one study involved instrumented posterolateral lumbar

spine fusion surgery. 9 patients had OP-1 graft and 10 patients

had a combination of autograft and TCP (Kanayama et al, 2006).

Fusion was inspected and assessed at instrumentation removal

15 months post operatively. There was a higher fusion rate in the

autograft group (78% vs. 57%) (Kanayama et al., 2006).

2 studies involving non-instrumented lumbar fusion using either

autograft or BMP-7 graft material have been published. No

difference in outcome was found.

Our study is the first performed using BMP-7 that attempts to

quantify the efficacy of BMP-7 on the quality of bone formation.

A randomized controlled study of the efficacy of BMP-7,

(Osteogenic Protein-1 (OP-1 Stryker)) in posterolateral lumbar

fusion surgery was performed.

METHODS

20 patients undergoing single-level posterolateral lumbar fusion

for symptomatic degenerative spondylolisthesis were enrolled.

Surgery involved decompressive laminectomy, insertion of

pedicle screws and on-lay of bone graft with 5ml tri-calcium

phospate (TCP) bone substitute on each side. On one side 1 vial

of OP-1 was added to the graft material. The senior surgeon (TS)

was blinded to the side of BMP-7. Three months after surgery a

volumetric CT scan was obtained allowing volume and density of

the bonegraft material to be measured and compared.

In our study, by using both autograft and TCP, with BMP-7 on only

one side, each patient acted as their own control. Statistical

analysis, including Mann-Whitney U test was used.

RESULTS

9 of 20 patients had higher volume of new bone on the side

where BMP-7 had been added. 3 patients had more bone on the

contralateral side to the BMP-7. 6 patients had equal volume of

graft material. 2 patients did not have sufficient graft material for

analysis. There was not a statistically significant difference in bone

volume and density 3 months postoperatively.

CONCLUSION

We found no evidence that BMP-7 had any effect in posterolateral

spine fusion surgery at 3 months postoperatively.

REFERENCE

1. KANAYAMA, M, HASHIMOTO, T, SIHGENOBU, K, YAMANE, S,

BAUER, T, TOGAWA, D 2006.

A Prospective Randomized Study of Posterolateral Lumbar

Fusion Using Osteogenic Protein -1 (OP-1) Versus Local

Autograft with Ceramic Bone Substitute. Spine, 31, 8.

46

4.09pm | 3.4Clinical outcomes following cervical disc replacement

with PCM® after a minimum 1-year follow-up

*Scott-Young, MN,1 Magno, C,2 Nielsen, D,2

Mitchell, E,2 Blanch, N 2


INTRODUCTION

Randomised controlled trials comparing cervical total disc

replacement (CTDR) with anterior cervical discectomy and fusion

(ACDF) have been published. These trials show CTDR at one

level is an option for treatment of cervical myelopathy and

radiculopathy. An evaluation of the use of the PCM® cervical

disc system (PCM®) (NuVasive®, San Diego, CA) in patients

diagnosed with myelopathy (CSM), radiculopathy (CSR), and

adjacent motion segment degeneration (AMSD) was undertaken.

Clinical outcomes of a consecutive 73 patient cohort, treated by

a single surgeon were assessed and compared.

METHODS

Patients were divided into 3 groups - CSM, CSR, and AMSD.

Surgical sub-categories included single-level and multi-level

CTDR. Clinical outcomes were measured using Visual Analogue

Score (VAS) neck and arm, Neck Disability Index (NDI), and

SF-36 data at 3, 6, and 12 months, and annually thereafter. A

one-sided paired student t-test was used to assess improvements

at each postoperative date compared to preoperative baseline.

RESULTS

Average follow-up of the 73 patients was 39.74 months (range

13-61 months). Forty patients were male and 33 patients female,

with an average age of 54.7yrs (range=32-79 yrs). Preoperative

diagnosis included CSR in 50 patients, CSM in 16, and AMSD in

7. Seventeen patients underwent single-level CTDR, while 56

patients underwent multi-level CTDR. ACDF was also performed

in 11 patients. Three patients required additional surgery. One

patient was involved in a motor-vehicle accident postoperatively

and subluxation occurred in two patients prior to the introduction

of the V-teeth model of the PCM®.

Statistically significant clinical improvements from baseline were

observed in VAS, NDI, and SF-36 (PCS and MCS) outcomes

scores from 3 months to 48 months (p<0.05). VAS neck scores

decreased from 63.50±30.62 preoperatively to 19.21±23.43

(-70%) at latest follow-up. VAS arm scores decreased from

61.13±31.85 to 12.06±19.22 (-80%). NDI scores decreased by

59%, while SF-36 PCS increased by 33% and SF-36 MCS

increased by 24%. Patient satisfaction surveys indicated that

91.9% patients rated their satisfaction with the surgery as

“excellent” or “good” 1-year following their operation.

An analysis was undertaken in relation to the preoperative

diagnosis and clinical outcomes. Preoperative, VAS neck scores

decreased by 64% for AMSD, 72% for CSM and 70% for CSR

groups. VAS arm scores decreased by 87% for AMSD, 75% for

CSM and 81% for CSR groups. NDI scores were reduced by

56% for AMSD, 68% for CSM, and 57% for CSR groups.

One-level CTDR was compared with multi-level CTDR. In the

one-level group, VAS neck improved by 67% versus 70% for the

multi-level group. VAS arm scores for the one-level group

improved by 84% compared to 79% for the multi-level group

CONCLUSION

CSM, AMSD, and CSR can be treated with single or multi-level

CTDR. This study suggests that significant improvements in VAS

and SF-36 functional scores can be expected notwithstanding

differences in preoperative diagnosis or number of levels treated.

47





4.17pm | 3.5Seven years experience with C2 translaminar screws

fixation: One surgeon’s experience with 52 patients

*Wright, NM, Dorward, IG

Department of Neurosurgery, Washington University

School of Medicine, St. Louis, Missouri, USA

INTRODUCTION

C2 translaminar screws offer similar biomechanical stability as

other C2 fixation methods, but with greater technical ease and

minimal risk to neural and vascular structures. To advance the

understanding of C2 translaminar screw fixation, we review the

literature relating to the technique and report our experience

since developing the technique in 2002.

METHODS

52 consecutive adult patients with cervical disorders requiring

axis stabilization were treated with C2 translaminar screws by a

single surgeon between 2002 and 2009. All patients underwent

preoperative plain radiographs and CT scans to confirm feasibility

of screw placement. Patients were followed with serial flexion /

extension radiographs and/or CT scans to assess fusion; indicators

of fusion included absence of motion on dynamic radiography

and evidence of bony bridging across instrumented levels.

RESULTS

Average age at surgery was 58.1 years (range 15.8-90.8). Surgical

indications included trauma (63%), degenerative (17.3%), congenital

(7.8%), inflammatory (5.8%), and other (5.8%). A total of 103 C2

translaminar screws were placed (average length 28.9 mm,

diameter 3.5 or 4 mm). No vascular or neurologic injuries occurred.

Ventral cortical disruption occurred with in two patients, without

CSF leak or neurological injury, and was managed by placing

shorter (20mm) screws. Arthrodesis was accomplished with

structural grafts (19 patients), bone morphogenetic protein

(21 patients), or synthetic (12 patients). 40 patients had sufficient

follow-up (average 13.3 months) to evaluate fusion; 1 likely

pseudoarthrosis was identified in a patient with fractured C1

screws, though imaging indicated successful bony fusion and no

revision was required. Other surgical complications included one

durotomy and one C2 distribution dysesthesia. 5 patients

(average age 78.7 years) died within 2 months of surgery from

complications related to medical comorbidities.

CONCLUSION

This study reports on 103 C2 translaminar screws, the largest

single-surgeon series to date. The findings suggest that C2

translaminar screws are a technically feasible, low-risk, robust

option for C2 fixation, with at least 97.5% fusion rate in this series.

REFERENCES

1. CASSINELLI, E, LEE, M, SKALAK, A, AHN, N, WRIGHT, NM

Spine 31(24):2767-2771, 2006.

2. LEONARD, JJ, WRIGHT, NM

Journal of Neurosurgery: Pediatrics 104(1):59-63, 2006

[cover article].

3. WRIGHT, NM

Journal of Neurosurgery: Spine 3:409-14, 2005.

4. WRIGHT, NM

Journal of Spinal Disorders and Techniques 17(2):158-162,2004.

48

4.25pm | 3.6A radiological analysis of early failure of cervicalfixation for trauma in the subaxial cervical spine

*McCarthy, MJH, Jenkins,O, Williams, R

Princess Alexandra Hospital, Brisbane, Qld, Australia

INTRODUCTION

A previous study by Johnson et al. (2004) identified a 13% loss of

postoperative alignment in patients with single level cervical facet

fracture subluxations treated with single segment anterior surgery.

The aim of the study was to define the rate of early loss of fixation

in fusion for cervical trauma and to identify potential failure modes.

METHODS

Patients treated operatively over the last 5 years for subaxial

cervical trauma were identified using the Spinal Surgery Operative

Database and the Spinal Injury Unit Database. All injuries from

C3 to C7/T1 treated operatively were included by decompression

and stabilisation. A radiological analysis of pre-, intra- and post-

operative imaging was performed. Early failure was defined as loss

of position in the postoperative follow up period as determined

by change in angular kyphosis. The following parameters were

measured: age, sex, diagnosis, preoperative presence of endplate

and facet fractures, treatment modality, immediate and follow up

reduction and alignment, time to follow up, Bridwell fusion grade,

screw pullout / lucency and pseudarthrosis.

RESULTS

We identified one hundred and four cases of which eighty four

had a minimum 8 week radiological follow available (81%). The

mean age was 38 years with 70% males. The mean follow up was

30 weeks. There were 33 bifacet fracture dislocations, 13 unifacet

fracture dislocations, 27 vertebral body fractures with or without

dislocation, 5 chalkstick fractures and 6 other miscellaneous types

of injury. 46% of cases had facet fractures and 49% had endplate

fractures. Using strict criteria, 13 cases (15%) showed early

implant failure but only 6 of these required reoperation (7%).

A further 6 patients underwent an additional procedure during

the first 2 post operative weeks. Increasing age was associated

with the requirement of an additional post operative procedure

(p<0.05). As an index procedure, 40 patients had an Anterior

Cervical Discectomy and Fusion (ACDF) and 22 had an anterior

corpectomy. ACDF alone as a primary procedure was deemed

inadequate in 25% (10/40 cases). Patients with significant endplate

fractures tended not to have ACDF as a sole intervention. In

our series the presence of a facet fracture was not statistically

associated with failure of ACDF, however, when it was present

one third of those cases required a further intervention. None

of the corpectomy patients required an additional procedure.

CONCLUSION

Our results are comparable to those in the published literature.

Patients undergoing ACDF as a sole treatment for subaxial cervical

trauma should be followed up closely and should be warned

preoperatively of the possible need for more than one operation.

REFERENCE

1. JOHNSON et al.

Spine, 29, 2815-2820, 2004.

49





4.33pm | 3.7Medium-term outcomes of elderly patients withodontoid fractures: Is quality of life associatedwith radiographic evidence of union?*Nall, A, Easton, J, Mercuri, D, Hall, J, Martinelli, B, Wilde, P

Department of Orthopaedics, Austin Hospital,

Heidelberg, Vic, Australia

INTRODUCTION

Odontoid fractures are a common injury in elderly patients.

Traditional treatment has involved halo thoracic device

application with the aim of achieving a solid fusion but this may

not equate to a better clinical outcome.

We therefore ask: Is stable non-union of an odontoid fracture

associated with poor quality of life in patients over 65?

METHODS

Ethics approval was obtained. A retrospective cohort study was

undertaken. All patients over the age of 65 who presented to

our orthopaedic spinal unit between 2003 and 2008 with a C2

odontoid fracture were included. Patients who were suitable for

the study underwent a CT scan and cervical spine radiographs.

Patients or their carers were asked to complete a Neck Disability

Index (NDI) and Quality of Life - Arthritis Version III (QOL)

surveys. Patients were divided into two groups: evidence of union

and evidence of non-union. A pre-study power calculation

suggested that to detect a 5% difference within each survey

domain with a certainty of 80% (power = 0.8) and level of error

of 5% (alpha = 0.05) 42 patients would be required with a

minimum of 21 patients in each group.

RESULTS

48 patients presented to the Austin Hospital within the previous

5 years who met the inclusion criteria. 20 patients were deceased,

5 declined to participate due to transport difficulties and 3

patients did not consent to participation. 2 patients died within

6 weeks of their fracture from general complications without

discharge from our hospital. 7 patients passed away from causes

unrelated to their spinal fracture. Cause of death was unknown in

11 patients, however they all lived greater than six months post

injury and most greater than twelve months.

The average age of the patient cohort was 77. 12 patients

displayed radiographic evidence of non union, and 8 patients

demonstrated union. All patients who underwent halo fixation

united. Patients in the non-union group had a combination of

halo, hard collar and soft collar fixation.

We found no statistically significant difference between the two

groups in either NDI or QOL scores (p=0.171 for NDI and

p=0.243 for QOL index).

We recognise there were insufficient numbers to meet the

pre-study power calculations, which reduces the validity of our

findings. Currently ethics applications are in process to expand

the study to other institutions.

CONCLUSION

We conclude that there is no difference between quality of life

or neck disability scores between the two groups. We suggest

that internal fixation or application of a halo brace may be

over-treating this cohort of patients and propose that cervical

collar immobilisation for pain control may be more appropriate.

50

51


TDR / Sagittal BalanceSaturday 16 April | 8.30am - 10.20am



SATURDAY 16 APRIL 2011


TDR / SAGITTAL BALANCE

Chair | Dr Rob Kuru


8.30am | 4.1Prospective 10 year follow up of AcroFlex lumbar disc replacement

*Fraser, RD,1,2, Freeman, BJC,1 Meir, AR,1 Fowler, S 1

1 St Andrew’s Hospital, Adelaide SA, Australia2 Royal Adelaide Hospital, Adelaide SA, Australia

INTRODUCTION

The AcroFlex device consists of two titanium end plates bound

together by a hexane-based polyolefin rubber core. Extensive

biomechanical testing predicted at least 10 years of in-vivo use

(Serhan 2001).

Significant improvements in ODI and LBOS were observed in

a pilot study of AcroFlex (Fraser 2004), but a high rate of early

mechanical failure caused its removal from clinical use. This study

aimed to assess long-term clinical and radiological outcome and

causes of implant failure.

METHODS

28 subjects (14 male, mean age 41years) with chronic discogenic

LBP were enrolled into a prospective non-randomized trial of

the AcroFlex device. VAS for LBP, ODI, LBOS and SF36 were

administered pre-operatively at 2 years and 10 years (for 23

subjects) after the index procedure. All subjects were invited to

undergo lumbar MRI and those with the device in-situ a CT scan.

Kaplan-Meier survival analysis was performed with revision

surgery as the end point.

RESULTS

At a mean of 9 years and 8 months (range 8.67-11.47 yrs), the

cumulative rate of survival for implants was 60.7%. Indications for

revision included device failure in 7 and disabling pain in 4. Mean

time to revision was 3 years 10 months (range 23 months to 8

years 4 months). Eleven of 28 patients (39.3%) had a total of 14

revision procedures; 9 of the 11 were converted to ALIF

supplemented with pedicle screw fixation.

Mean ODI for non-revision cases was 27.5 (+/-17.6) compared to

41.8 (+/-26) for revision cases. Mean improvement in ODI for non

revision cases was 17.9 (+/-16.9) compared to 12 (+/-16.1) for

revisions. Similar trends were observed in LBOS and SF-36 scores.

Radiographic findings in revision group included mid-substance

rubber tears, osteolysis, and implant displacement. CT findings in

11 of 17 survivors included heterotopic bone formation (85%),

osteolysis (50%) and subsidence (14%). MRI in 14 of 23

demonstrated adjacent level disc degeneration in 68% of those

with AcroFlex in situ and 40% of those converted to fusion.

Skip degeneration was present in 44% of those with AcroFlex

in situ and 20% of those converted to fusion.

CONCLUSION

A revision rate of 39.3% for lumbar disc replacement is

unacceptable. The aetiology of implant failure included failure of

osseointegration, mid-subtance rubber tears and osteolysis. The

mean time to revision was 3 years and 10 months (range 23

months to 8 yrs 4 months). Guyer (2009) reported 7.7% revision

rate following Charite TDR at 5 years. Long term follow up of these

devices is clearly indicated. The incidence of adjacent level disc

degeneration for AcroFlex is comparable to that observed above

spinal fusions. Salvage procedures involving conversion to spinal

fusion are technically demanding, but appear to improve outcomes.

REFERENCES

1. SERHAN H.

Podium presentation, ISSLS, Edinburgh, June 19-23, 2001.

2. FRASER RD.

The Spine Journal: 4, 245S-251S, 2004

3. GUYER RD.

The Spine Journal: 9, 374-386, 2009

52

8.38am | 4.2Compliant artifical lumbar disc replacement(Cadisc-L): In vivo implant stability and osseointegration in an animal model

*Freeman, BJC,1 Steffen, T, 2 Aebi, M 3

1 University of Adelaide, Adelaide, SA, Australia2 McGill University, Montreal, Quebec, Canada3 University of Bern, Bern, Switzerland

INTRODUCTION

Early migration and / or expulsion of Total Disc Replacements

(TDR) are recognized complications that are mitigated by the

incorporation of primary fixation features. Longer term secondary

implant fixation can be enhanced by the use of hydroxyapatite

or similar osseo-conductive coatings. The elastomeric TDR,

Cadisc™-L has been designed with primary and secondary

fixation features applied to both polymeric end-plates. These

endplates conform to the topography of the adjacent vertebrae

for optimized load sharing. The aim of this in vivo study was to

investigate the Cadisc™-L implant stability and subsequent

osseointegration over a period of six months in an animal model.

METHODS

Institutional animal care and use committee (IACUC) approval

was obtained prior to commencement of this project. A total

of six skeletally mature male baboons (Papio annubis) were

included and followed for a period of 6 months. Under general

anaesthesia (GA), using a transperitoneal exposure, a custom

made Cadisc™-L device was implanted into the disc space one

level above the lumbo-sacral junction in all 6 subjects.

Antero-posterior (AP) and lateral radiographs of the lumbar spine

were performed under GA prior to surgery, and post-operatively

under GA at intervals up to 6 months. Systematic examination of

these radiographs was carried out by an independent radiologist

looking specifically at disc height, and for any evidence for

subsidence or implant migration. Flourochrome markers (which

contain molecules that bind to mineralization fronts) were

injected at specified intervals in order to investigate bone

remodeling with time.

Animals were humanely euthanized six months after index

surgery. Both test and control specimens were retrieved, fixed

and subjected to histological processing to assess the

bone-implant-bone interface. Fluorescence microscopy and

confocal scanning laser microscopy were utilized in combination

with BioQuant image analysis to determine the bone mineral

apposition rates and gross morphology.

RESULTS

Systematic radiographic evaluation revealed no loss of disc

height at the level of surgery or adjacent levels. No evidence of

subsidence or significant migration of the implant up to 6 months

following surgery was observed. Heterotopic ossification (HO)

was observed to varying degrees at the operated level.

Histology revealed that the primary fixation features of the

implant were embedded within the adjacent vertebral endplates.

Flourochrome distribution revealed active bone remodeling

occurring adjacent to the polymeric end-plate with no evidence

of adverse biological responses. Mineral apposition rates at the

implant surface of between 0.7 - 1.7 microns / day are in keeping

with literature values for hydroxyapatite coated implants in

cancellous sites of various species.

CONCLUSIONS

Radiographic assessment demonstrates that the Cadisc™-L

implant remains stable in vivo with no evidence of subsidence or

significant migration. Histological analysis suggests the primary

fixation features are engaged, and in close apposition with the

adjacent vertebral bone. Flourochrome markers provide

evidence of a positive bone remodelling response in the

presence of the implant.

53




Chair | Dr Rob Kuru


8.46am | 4.3Early clinical performance of the Cadisc-L totaldisc replacement: A prospective non-randomizedmulticentre clinical trial

*Freeman, BJC,1 Quirk, I,1 Bertagnoli, R,2 Conix, B,2 Hes, R,3

McConichie, A,5 Zeilstra, D,6

1 Ranier Technology, Cambridge,UK2 ProSpine Clinics, Straubing / Bogen, Germany3 ZNA Middelheim, Antwerp, Belgium4 University of Adelaide, Adelaide, SA, Australia5 University of Glasgow, Glasgow, Scotland6 Isala klinieken, locatie Sophia, The Netherlands

INTRODUCTIONThe Cadisc™-L is a compliant polyurethane-polycarbonate

graduated modulus compliant total disc replacement (TDR)

designed to mimic the biomechanical properties of the natural

lumbar disc. In vitro biomechanical studies of this elastomeric

device have demonstrated very similar biomechanical behaviour

to the native L4/5 intervertebral disc. In vivo studies, in an animal

model, have shown the device to be stable, with no evidence of

subsidence or migration and excellent osseointegration, six months

after insertion. This paper reports the early clinical performance of

Cadisc™-L in a prospective non-randomized multicentre clinical

trial treating subjects with debilitating chronic low back pain (LBP).

METHODSTwenty-eight subjects with chronic LBP (>6 months), unresponsive

to conservative treatment, with an Oswestry Disability Index

(ODI) of >30 points, aged between 25-65 years with single level

degenerative disc disease between L3 and S1 were recruited

from three European centres. Clinical success was defined as a

minimum of 15 points improvement in ODI. Visual Analogue

Scores (VAS,1-100) for back and leg pain, EQ-5D and SF-36

scores were compared to data obtained from published literature

using improvement ratio analyses. Clinical outcomes were

independently monitored and statistical analysis carried out

independently. The study follow-up period will run for 5 years.

RESULTS

The mean follow-up for 28 subjects to date is 6 months (range

1.5 to 12 months). There was one non-device related serious

adverse event requiring revision in an osteopenic patient with a

degree of spinal instability. The percentage of subjects achieving

an ODI reduction of 15 points or more was 52% (95% CI:

31.3%, 72.2%), 70% (95%CI: 47.1%, 86.8%) and 83% at 6 weeks,

3 months and 6 months respectively. ODI reduction ratio over

time is presented in the figure below, with comparisons to

published results for the Charite, Prodisc and Maverick TDR.

Charite: (Data from FDA) , Prodisc: (Data from FDA)i, Maverick: (Le Huec, 2005)

Mean VAS (back) reduced over time (30.7 units, p<0.001; 30.3

units, p=0.001; 52.0 units, p=0.013) at 6 weeks, 3 months and 6

months respectively. Mean VAS (leg pain) were lower than baseline

over time (by 11.8, 17.5 and 27.2 units, p=0.041) at 6 weeks, 3

months and 6 months respectively. EQ-5D data demonstrated

significant increases in quality of life (0.31, p<0.001; 0.64, p<0.001;

0.57, p=0.036) at 6 weeks, 3 months and 6 months respectively

and demonstrated an increase of 0.14 QALYs in the first 3 months.

CONCLUSION

The Cadisc™-L appears safe and effective for the treatment

of debilitating chronic LBP in this study, however the authors

acknowledge the short follow-up. There have been no device

related adverse events to date. The clinical results are superior

to those previously reported in other TDR cohorts.

REFERENCES

1. www.accessdata.fda.gov/cdrh_docs/pdf4/P040006b.pdf

2. LE HUEC JC Orthop Clin North Am. 36 (3): 315-22; 2005

54

9.09am | 4.4Correlation of age with spino-pelvic balance in degenerative lumbo-sacral disorder

*Mokhtar, SA,1 White, G 2 Sears,WR 2

1 Australian School of Advanced Medicine, Macquarie

University, Sydney, NSW, Australia2 Dalcross Adventist Hospital, Sydney, NSW, Australia

INTRODUCTION

Several measures of spinal sagittal alignment have been found to

vary between those found in normal, volunteer subjects and

those in patients with certain degenerative spinal conditions.

Measures of sacro-pelvic alignment, such as Pelvic Incidence, are

believed to reflect developmental morphology and to remain

constant over time.

There is little data in the literature regarding the effect of age on

changes in spinal sagittal alignment. The purpose of this study

was to determine whether univariate correlations exist between

age and changes in measures of spino-pelvic alignment, in a series

of patients with degenerative lumbo-sacral spinal disorders.

METHODS

A cross-sectional, observational study was undertaken of 674

patients with degenerative lumbo-sacral disorders (416 females,

258 males, mean age 66 ± 13 years) who underwent surgery

between September 2000 and September 2010. Patients who

had undergone previous lumbar fusion surgery were excluded.

Pre-operative measures of spinal sagittal alignment were made

using the pelvic radius (PR) technique of Jackson. Parameters

measured were: overall lumbar lordosis (OA lordosis), total

lumbopelvic lordosis (PRT12), sacro-pelvic morphology (PRS1),

pelvic angulation (PA) and distances of sagittal plumb lines from

the hip axis (HAS1, HAT4 and HASP).

Univariate relationships between the measured parameters and

age were assessed by Spearman rank order correlation for all

patients and for the subgroups: degenerative spondylolisthesis

(DS), lytic spondylolisthesis(LS), degenerative scoliosis(DSc) and

nil deformity(NIL). Significance was set at p < 0.05.

RESULTS

The mean values (± standard deviations) were: -50° ± 15° for

OA lordosis, 81° ± 14° for PRT12, 26° ± 12° for PRS1 and 27°

± 8° for PA, The sagittal plumb line from HA were: -60 ± 22 mm

for HAS1, -72 ± 36 mm for HAT4 and -31 ± 18 mm for HASP.

Significant correlations were found between age and: OA lumbar

lordosis (r =0.17), PRT12 (r =0.21), PA (r=0.24), HAS1 (r = 0.18 ),

HAT4 (r=0.15) and HASP (r = 0.16 ). No correlations were

found between age and PRS1.

Subgroup analysis was done for DS(N=297, mean age 69±10

years), LS(N=85.mean age 54±17 years), DSc(N=136,mean age

70±9 years) and NIL(N=129,mean age 64±15 years). Significant

correlation were found in subgroup DS between age and PA

(r=0.16), subgroup LS between age and:

PRT12(r=0.37),PA(r=0.36),HAS1(r=0.34) and HASP(r=0.32),

subgroup DSc between age and HAT4(r=0.36). No correlation

were found between age and measured sagittal parameter in

subgroup NIL.

CONCLUSION

Age was found to correlate with changes in several measures

of spino-pelvic alignment, in patients with degenerative spinal

disorder. As expected, sacro-pelvic morphology, as measured by

PRS1, did not vary with age. Further studies are required to

assess the effects of confounding variables such as hip flexibility,

which change with age and are likely to affect standing spinal

sagittal alignment.

REFERENCES

1. JACKSON, RP et al.

Congruent Spinopelvic Alignment on Standing Lateral

Radiographs of Adult Volunteers. Spine 25(21), 2808-2815,

2000

2. JACKSON, RP et al.

Pelvic lordosis and alignment in spondylolisthesis.

Spine 28:151–160, 2003.

55




Chair | Dr Rob Kuru


9.17am | 4.5Association of chronic low back pain with loss oflumbar lordosis and the role of pelvic morphology

*McAviney, J,2 Harrison, DE,1 Harrison, DD,3 Janik, JJ, 4

Cailliet, R, 5 Holland, B 6

1 Sydney Scoliosis Clinic, Sydney, NSW, Australia2 Private Practice, Elko, Nevada, USA3 Universite du Quebec a Trois Rivieres, Quebec, Canada4 CompMath Research, Alabama, USA5 Department of Rehabilitative Medicine, University of Southern

California School of Medicine, Los Angeles, California, USA6 Department of Statistics, Temple University,

Philadelphia, Pennsylvania, USA

INTRODUCTION

Measures of lumbar lordosis and elliptical modelling have been

shown to discriminate between normal and chronic low back

pain subjects (Harrison 1998). Pelvic morphology influences an

individual’s lumbar lordosis (Vaz 2002). However, few studies

have systematically looked at the interdependence of pelvic

morphology and lumbar lordosis in normal and pain groups.

The purpose of this study was to investigate the sensitivity and

specificity of sagittal plane radiographic alignment and modelling

variables to discriminate between controls and chronic low back

pain subjects. Also to determine if group variations in pelvic

morphology explain possible differences in elliptical modelling

and angular measurements of lumbar lordosis or angle of pelvic

incidence (API) in controls versus low back pain subjects.

METHODSFifty healthy control subjects were attained from a pre-employmentphysical examination. 29 men and 21 women (mean age of 27years) with no history of low back pain, a normal spinal examination,and no radiographic evidence of pathologies, anomalies, and instability. From the same clinic files, 50 chronic low back painsubjects were randomly chosen from a population that matchedthe control group characteristics. Inclusion criteria required noabnormalities on lumbar spine radiographs. Computer analysis ofdigitised vertebral body corners and sacral segments on laterallumbar sacral radiographs was undertaken. Radiographic variablesincluded L1-L5 lordosis, T12-S1 lordosis using Cobb’s and Posteriortangent Average Rotation Angle (ARA) methods, b/a ellipticalratio, sacral base angle (SBA), and sacral tilt to vertical using posterior tangent S1 (PTS1). Two measures of pelvic morphologywere determined for each subject: API and posterior tangent pelvicincidence angle (PTPIA). Descriptive statistics and correlationsamong the primary variables were determined. Receiver OperatingCharacteristic curves (ROC curves) for primary variables wereanalysed for diagnostic comparisons between groups.

RESULTSThe mean values of lumbar lordosis (ARA L1-L5, ARA T12-S1,Cobb T12-S1) were statistically different between the normal andchronic low back pain groups (p < 0.001) indicating a hypo-lordosislumbar spine for the chronic group. The mean b/a ratio was statistically less in the chronic pain group (p = 0.0066). Pelvicmorphology variables were similar between the groups (p > .05).The API had stronger correlation to the SBA and Cobb T12-S1than did PTPIA, while PTPIA had stronger correlation to S1 tangentand ARA T12-S1 than did API. ROC curve analyses identified thatlordosis T12-S1 (69°), L1-L5 (36°), sacral tilt (46°), and b/a, hadgood discrimination between groups (AUC= .83, .78, .75, and .72).

CONCLUSIONSBased on this study, it was found that chronic low back pain subjects have an abnormal decreased lumbar lordosis, not relatedto their pelvic morphology.

REFERENCES1. HARRISON et al,

Journal of Spinal Disorders. 11(5):430-439, October 1998.2. VAZ et al

European Spine Journal, Volume 11, Number 1, 80-87,February 2002

56

9.25am | 4.6

A software simulation of spinal sagittal balance

McCombe, PF

St Andrews War Memorial Hospital and Royal Brisbane

Hospital, Brisbane, Qld, Australia

INTRODUCTION

There is significant variation in normal sagittal alignment. This

causes difficulty in determining if a particular spinal shape is due

to normal variation or pathology. A fundamental problem is the

inability to simply geometrically construct a spinal shape and to

modify it in a way that allows compensatory changes to be

resolved after proposed corrective surgery.

Pelvic morphology, defined by pelvic incidence (PI), primarily

determines spinal shape. The lumbar lordosis (LL) and thoracic

kyphosis (TK) correlate directly or indirectly with PI. The

parameters of PRT12 (pelvic radius-T12 angle), spinal tilt angle

(STA) and spinosacral angle (SSA) (Roussouly 2006) are

relatively constant. Despite these observations, a unified model

of spinal balance remains elusive. Simulation software that allows

user input may therefore be clinically useful.

METHODS

A digitized normal lateral erect radiograph was used to create an

articulated graphical model in software (MATLAB) that could be

modified by user input. Angles of motion segments, LL, TK, PI and

pelvic tilt (PT) were modifiable. The distribution of segmental

changes for global changes in LL and TK could be specified. Angle

changes could either reset neutral segmental angles or produce

offsets from neutral values. Motion segment flexibility curves

were modeled by fitting third degree polynomial functions to

published normative data (Busscher 2009). The polynomial

constants for each level could be modified to change neutral

zone stiffness and range of motion. An arbitrary centre of mass

of the trunk was defined anterior to the T10 vertebral body in

line with the femoral heads. Perturbation of the model caused

recalculation of the segmental and total spinal moments required

to overcome segmental stiffness and to resist flexion by the

gravity load. An attempt was made to create reasonable facsimiles

of published different normal sagittal profiles by modifying PI and

then variables to maintain the published values of STA at

approximately 95 degrees and SSA at approximately 0.9*SS + 99

(Roussouly 2006). The simulator also was used to model obvious

cases of sagittal malaligment.

RESULTS

Variations in PI between 25 and 65 degrees were modeled.

Iterative changes to LL, TK and SS could be performed rapidly

in 3-4 cycles to produce close approximation to SSA and STA

targets. The final shapes reasonably approximated the normal

sagittal types described by Roussouly(2005), though was

improved by fine tuning the distribution of lumbar lordosis.

Appropriate values for LL were slightly higher than PI and TK was

slightly lower than PI. A series of 5 cases with significant sagittal

disturbance could be quickly modeled by entering only 4 basic

parameters (PI,SS,LL,TK). It was relatively easy to simulate corrective

surgery and to be guided by the avoidance of potentially painful

large changes in the segmental and total moments.

CONCLUSION

Software simulation of sagittal spinal alignment may be of clinical

use.

REFERENCES

1. ROUSSOULY, P.

Spine, 31, E320-E325, 2006.

2. ROUSSOULY, P.

Spine, 30, 346-353, 2005.

3. BUSSCHER, I.

Spine, 34, 2858-2864, 2009.

57




Chair | Dr Rob Kuru


9.48am | 4.7History of spine balance analysis: Is there a reason to miss the target?


Orthopaedic Department, University of Bordeaux Hospital,

Bordeaux, France

58

59

22 President’s Session

Lumbar Lordosis and Sagittal Balance: The Masters SpeakSaturday 16 April | 10.50am - 12.30pm




PRESIDENT’S SESSION

LUMBAR LORDOSIS AND SAGITTAL BALANCE:

THE MASTERS SPEAK



10.50am Pelvic parameters and spine parameters



Bordeaux, France

PELVIC PARAMETERS

The adoption by humans of an upright position resulted in

broadening and verticalisation of the pelvis together with the

appearance of characteristic spinal curves, has profoundly

modified the structure of the muscles supporting the spine.

In order to characterise the sagittal balance of the pelvis, it is

necessary to define parameters based on notable biomechanical

forces involved in the transmission of constraints. The angle of

incidence was constructed to enable reproducible analysis of the

anatomical characteristics of the pelvis in the sagittal plane. The

angle of incidence is the algebraic sum of two complementary

angles: pelvic tilt (PT) and sacral slope (SS). Since the value of

incidence is fixed for any given patient, the sum of pelvic tilt and

sacral slope is a constant value: when one increases, the other

necessarily decreases. The position of the lumbar spine, attached

to the sacral plateau, is thus affected by the pelvic tilt and by the

sacral slope. Consequently, the pelvic parameters affect the entire

underlying sagittal spinal profile. Global spinal balance involves

harmonisation of lumbar lordosis and thoracic kyphosis taking

into account the pelvic parameters.

SPINE PARAMETERS

According to the anatomical segmentation, spine curves are the

sacral kyphosis (sacrum), lumbar lordosis (L1 to L5), thoracic

kyphosis (T1 to T12) and cervical lordosis (C1 to C7). From

the morphological point of view the vertebrae of a curve are

not identical: from cranial to caudal and vice-versa there is a

progressive anatomical modification. Both curves of the thoraco-

lumbar spine may be divided at the Inflexion Point where lordosis

turns into kyphosis. A geometrical construct of each curve by

two tangent arcs of circle allows understanding the reciprocal

changes between both curves. Lumbar Lordosis is mainly

dependent on SS orientation, and the top of thoracic curve on

C7 is very stable over the sacrum. Thoracic curve is dependent

on lumbar lordosis orientation and C7 positioning. On a reverse

effect, structural changing of thoracic kyphosis may affect the

shape of the lumbar lordosis and the orientation of the pelvis.

60

11.15amHow to correlate parameters and global balance for daily practice



Bordeaux, France

Standing erected position is a human property. The pelvis anatomy

and position defined by the Pelvis Incidence, interacts with the

spinal organisation in shape and position to regulate the sagittal

balance between both spine and pelvis. Sagittal balance of the

human body may be defined by a setting of different parameters:

1. Pelvic parameters: Pelvic Incidence (PI), Pelvic Tilt (PT) and

Sacral Slope (SS)

2. C7 positioning: Spino Pelvic Angle (SSA) and C7plumb line

3. Shape of the spine: lumbar lordosis

In case of pathological kyphosis, different mechanical compensations

may be activated. When the spine remains flexible, the hyper

extension of the spine below or above compensates the kyphosis.

When the spine is rigid the only way is rotating backward the

pelvis (retroversion). This mechanism is limited by the value of PI.

Hip extension is a limitation factor of big retroversion when PI is

high. Knees flexion may occur when hip extension is overpassed.

The quantity of global kyphosis may be calculated by the SSA.

The more SSA decreases, the more the severity of kyphosis

increases. We used Roussouly’s classification of lumbar lordosis in

four types to define the shape of the spine. The forces acting on

a spinal unit are combined in a Contact Force (CF). CF is the

addition of gravity and muscle forces. In case of unbalance, CF is

tremendously increased. Distribution of CF depends on vertebral

plate orientation. In an average tilt (45°) the two resultants,

parallel to the plate (sliding force) or perpendicular (pressure),

are equivalent. If the tilt increases, the sliding force is predominant.

On the contrary, with a horizontal plate, the pressure increases.

Importance of curvature is another factor of CF distribution. In a

flat or kyphosis spine, CF is acting more on the vertebral bodies

and disc. In case of important extension curvature, it is on the

posterior elements that CF is playing more.

According to the shape of the spine we may expect different

degenerative evolution:

1. Type 1 is a long thoraco lumbar kyphosis and a short hyper

lordosis: Discopathies in TL area, arthritis of the posterior

facets in the distal lumbar spine. In younger patients L4 S1

hyper extension may induce a nut cracker L5 spondylolysis.

2. Type 2 is a flat lordosis: Stress is at its maximum on the discs

with a high risk of early disc herniation then lately with multi

level discopathies.

3. Type 3 has an average shape without characteristics for a

specific degeneration of the spine.

4. Type 4 is a long and curved lumbar spine: This is the spine

for L5 isthmic lysis by shear forces.

When the patient keeps the lordosis curvature, a posterior arthritis

may occur and lately a degenerative L4L5 spondylolisthesis. In

older patients, they may lose the lordosis curvature, SSA decreases

and pelvis tilt increases. A widely retroverted pelvis with a high

pelvic incidence is certainly a previous Type 4 and a restoration

of a big lordosis is needed in case of arthrodesis

CONCLUSION

The genuine shape of the spine is probably one of the main

mechanical factors of degenerative evolution. This shape is

oriented by a shape pelvis parameter, the pelvis incidence.

In case of pathology, this constant parameter is the only signature

to determine the original spine shape we have to restore to

balance the patient.

61


PRESIDENT’S SESSION (continued)

LUMBAR LORDOSIS AND SAGITTAL BALANCE:

THE MASTERS SPEAK



11.45am Reciprocal changes and osteotomy planning in sagittal balance surgery

A/Prof Chris Ames

Neurosurgery Department, University of California,

San Francisco, California, USA

Current strategies to optimize post operative sagittal balance

will be explained. Recent analyses of cervical, thoracic and pelvic

reciprocal changes will be presented and ways to incorporate

these expected changes in treatment planning will be described.

62

12.05pm Geometric analysis of coronal balance in idiopathic scoliosis: Are there lessons for sagittal balance?


Department of Orthopaedic Surgery and Rehabilitation,

Loyola University Stritch School of Medicine,

Chicago, Illinois, USA

This review will cover a discussion of the author’s original work

on geometric analysis of coronal balance, followed by a review of

current findings regarding sagittal balance.

Coronal decompensation or imbalance is a possible complication

in the management of idiopathic scoliosis when selective correction

and fusion of the thoracic curve is performed. Previous studies

have suggested that overcorrection of the primary thoracic curve

may be the principal cause of coronal decompensation. The

objective of the authors study was to determine if a balanced

spinal configuration is possible when the lumbar curve is larger

than the thoracic curve, and to determine the limits on the relative

curve magnitudes beyond which a spinal configuration with

acceptable balance cannot be achieved. The underlying premise of

this study is that spinal configuration cannot be uniquely defined by

the thoracic and lumbar curve magnitudes alone. There may be

multiple configurations that have the same thoracic and lumbar

curve magnitudes but different magnitudes of decompensation.

The take home finding of this work is that decompensation in

coronal plane does not appear to be caused by the relative

magnitudes of the thoracic and lumbar curve, but is a result of

inadequate relative distance between the thoracic and lumbar

apical vertebrae and the tilts of the junctional and end vertebrae

of the thoracic and lumbar curves.

The review of sagittal balance literature will highlight the findings

concerning the compensatory mechanisms that distinguish the

issues of sagittal balance from coronal balance.

63

Notes & Questions

64

65


SurgicalSaturday 16 April | 1.30pm - 2.50pm





SURGICAL



1.30pm | 5.1

Outcomes after decompressive laminectomy

for lumbar spinal stenosis: Comparison

between minimally invasive unilateral

laminotomy / laminectomy for bilateral

decompression (ULBD) vs. open laminectomy

*Mobbs, RJ,1,2 Li, J,1 Sivabalam, P 1

1 University of New South Wales, Sydney, NSW, Australia2 Prince of Wales Hospital, Spinal Unit, Sydney, NSW, Australia

INTRODUCTION

To compare outcomes following minimally-invasive unilateral

laminectomy / laminotomy for bilateral decompression (ULBD)

or open laminectomy for degenerative lumbar spine stenosis (LSS).

METHOD

We conducted an analysis of 54 patients who underwent a

ULBD (27 patients) or open laminectomy (27 patients) for

degenerative LSS between 2007 and 2009. Patient demographics

and post-operative course outcomes (ie duration of

post-operative stay, time-to-mobilise, post-operative analgesic

consumption, complication / re-operation rates) were collected

from medical records. A standardised questionnaire obtained

clinical outcomes using pre-operative and post-operative

Oswestry Disability Index (ODI) scores, Visual Analogue Scale

(VAS) scores, Patient Satisfaction Index scores and post-operative

Short-Form 12 (SF-12) scores.

RESULTS

The conventionally-treated group had a significantly longer period

of follow-up (30.22 months versus 12.83 months; p<0.0001).

MIS-treated patients were significantly older at the time of

operation (71.55 years versus 64.64 years; p=0.0471). There

were significant improvements in mean pre-operative to

post-operative ODI and VAS scores within each group

(MIS-treated group: p<0.0001 and p<0.0001 respectively;

conventionally-treated group: p=0.0004 and p<0.0001

respectively), however no significant difference in improvement

between groups (mean ODI improvement: p=0.0630; mean VAS

improvement: p=0.0767). MIS-treated patients had a significantly

shorter length of post-operative hospital stay (55.08 hours

versus 120.9 hours; p=0.0031), time-to-mobilise (15.59 hours

versus 33.27 hours; p<0.0001) and were more likely to not use

opioids for post-operative pain (55.55% versus 14.8%; p=0.0038).

CONCLUSION

Based on short-term follow-up, microscopic ULBD is equally

effective as open decompressions in improving function and

decreasing leg/back pain, with the additional benefits of a

significantly shorter post-operative hospital recovery time and

time-to-mobilise, less post-operative pain and opioid use.

REFERENCES

1. SASAI, K, UMEDA, M, MARUYAMA, T, WAKABAYASHI, E,

LIDA H

Microsurgical bilateral decompression via a unilateral approach

for lumbar spinal canal stenosis including degenerative

spondylolisthesis. J Neurosurg Spine. 2008; 9:554-559

2. KHOO, LT, FESSLER, RG.

Microendoscopic decompressive laminotomy for the

treatment of lumbar stenosis.

Neurosurgery. 2002; 51 (5 Suppl):S146-154.

3. COSTA, F, SASSI, M, CARDIA, A, ORTOLINA, A, DE SANTIS, A,

LUCCARELL, G, FORNARI, M.

Degenerative lumbar spinal stenosis: Analysis of results in a

series of 374 patients treated with unilateral laminotomy for

bilateral microdecompression. Journal of Neurosurgery

Spine. 2007; 7(6):579-586.

66

1.38pm | 5.2Lumbar spinal synovial cysts: Associations and treatmentRyan, MD

Notre Dame University, Sydney, NSW, Australia

and RNS, NPR and Mater Hospitals, Sydney, NSW, Australia

INTRODUCTION

The cause, natural history and appropriate management of

symptomatic synovial cysts remain elusive. Regimens are largely

based on dogma. Pathological interpretation is purely descriptive

with little which allows the formulation for a scientific study of

causation.

METHODS

A retrospective review of 96 consecutive patients presenting to a

solo private practice was performed. Those managed operatively

and non-operatively were included. A comparison was made

between the outcomes of those who were managed by surgical

decompression alone, and those managed by decompression and

spinal fusion. Possible biomechanical precipitants for synovial cyst

formation were identified

RESULTS

Of the 96 subjects, 57 were female (59%). The average age at

presentation was 69 years (range: 46-89 years).

• Cysts occurred at L2/3 (2%), L3/4 (15%), L4/5 (67%), and

L5/S1 (15%)

• 52% were right-sided

• 34 were managed non-operatively, 36 underwent

decompression alone and 26 underwent decompression

and spinal fusion

• Comorbidities in patients managed conservatively were

cardio-vascular disease 26%, arthritis 24 %, prior malignant

disease 9%, diabetes, thyroid dysfunction & asthma, 6% each.

• Comorbidities in patients managed operavatively were

cardio-vascular disease 52%, Arthritis 35 %, prior malignant

disease 18%, diabetes and thyroid dysfunction 8% each, and

asthma, 5%.

• Those managed non-operatively had minimal symptoms and

no evidence of neurological deficit.

• In those managed surgically, there was no mortality,

neurological complication or infection.

• Of the 36 who underwent decompression alone, 10 (27%)

are comfortable, unrestricted, and need only occasional

analgesics. 6 have back pain that requires regular analgesics.

11 have had recurrence of back and leg pain, and 8 (22%)

have undergone further surgery.

• Of the 26 treated by decompression and spinal fusion, 17

(65%) are comfortable and unrestricted. 7 need regular pain

relief for low back pain. One required a revision of spinal

fusion after falling down a stairs, and another has trochanteric

bursitis.

• If the ‘comfortable’ and ‘occasional analgesics only’ groups

above are deemed acceptable, then only 44% of the

decompression group achieved that status, whereas 92% of

the decompression and fusion group were deemed acceptable.

CONCLUSION

The results suggest that decompression and fusion is the best

option for management of a synovial cyst that must be excised.

Recurrences of synovial cyst formation occurred in the decom-

pression only group. In those who under went fusion, synovial

cysts occurred at adjacent levels. This observation suggests that

clinically significant synovial cysts require movement and stress

concentration for their development.

REFERENCES

1. WILBY MJ et al.,

Spine 34, 2518-24, 2009.

2. RISHENG XU et al.,

Spine 35, 1044-53, 2010.

67



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1.46pm | 5.3Transforaminal endoscopic lumbar disc surgery application in upper lumbar discs: Method and results

Gore, S

Consultant Spine Endoscopist, Ratna Memorial Hospital,

Pune, India

INTRODUCTION

Lumbar disc herniation is commonest at L4/5 and L5/S1 levels.

Higher lumbar discs are comparatively less common.(Wei et al.,

1989) Endoscopic surgery at high lumbar levels is safe and

precise and can be done and is done in awake aware patients.

(Ahn et al., 2009)The safety and precision makes it a natural

choice in high level nuclear herniation. Morbidity and risks of

open surgery are well known. Instability is common after open

surgery. (Cui and Zhang, 2008) An oblique paraspinal approach

has been described for accessing upper lumbar herniation with

excellent results.(Kim et al., 2009) This study was to apply

technique of transforaminal endoscopic lumbar disc surgery to

D12/L1 and L1/L2 and L2/L3 levels.

METHODS

14 cases of L1/2 D12//L1 and L2/3 herniation were operated

by transforaminal surgery under local anesthesia with laser

assistance during jan 2002 and December 2007. Average follow

up is 48 months or more. The main clinical presentation of

anterior thigh pain was noted. The patient is awake and aware

and herniated fragment is accessed under C arm and then

removed under direct visualization under local anesthesia.

Clinical results were assessed using VAS and ODI scale.

RESULTS

The relief of pain was noted within 24 hours in all cases. In case

of neurological recovery it took 7 months to recover. Targeted

removal of herniated fragment resulted in relief of symptoms of

front thigh pain. Surgical time was average 35 minutes. Blood loss

was about 5 cc. Hospital stay average was 20 hrs. All surgeries

were under local anesthesia and in awake and aware state. There

were no complications. One patient did not have full recovery

of neuro status. One patient needed a fusion later due to

progressive deformity. Due to non invasive nature of the surgery

there was less morbidity and very rapid return to work. There

were no instabilities or recurrence. There was recovery on VAS

from 7/8 to 2 over 3 weeks. Significant improvement in ODI was

seen in 4 weeks, and then maximum 8 weeks.

CONCLUSION

Transforaminal endoscopic targeted removal of herniation of

upper lumbar disc is not morbid, results in rapid return to work.

It is associated with no complications and is safe even in patients

with medical co morbidities. Relief of pain and neurological

symptoms were rapid and near full. Our results have been

comparable with recent series with similar approach.

(Ahn et al., 2009)

REFERENCES

1. AHN, Y, LEE, SH, LEE, JH, KIM, JU, LIU, WC 2009.

Acta Neurochir (Wien), 151, 199-206.

2. CUI, ZJ, ZHANG, XL 2008.

Zhonghua Yi Xue Za Zhi, 88, 619-21.

3. KIM, JS, LEE, SH, MOON, KH, LEE, HY 2009.

Neurosurgery, 65, 95-9; discussion 99.

4. WEI, CP, CHENG, WC, CHANG, CN, LEE, ST, LUI, TN,

WANG, AD 1989.

Changgeng Yi Xue Za Zhi, 12, 193-9.

68

1.54pm | 5.4Long-term outcomes following lumbar spine fusion for adult isthmic spondylolisthesis: A comparison of PLIF vs PLF

*Cunningham, JE, Robertson, PA

Auckland City Hospital, Auckland, New Zealand

INTRODUCTION

Posterior lumber interbody fusion (PLIF) has the theoretical

advantage of optimising foraminal decompression, improving

sagittal alignment and providing a more consistent fusion mass

in adult patients with isthmic spondylolisthesis (IS) compared to

posterolateral fusion (PLF). Studies to date though have not

shown a clinical difference, with follow-up to two years.

METHOD

An observation cohort study was performed of a single

surgeon’s patients with IS over a ten year period, treated by

either PLF or PLIF. Preoperative and 12-month data were

collected prospectively, and long-term follow-up was by mailed

questionnaire. Preoperative patient characteristics between the

two groups were not significantly different. Average follow-up

was 7 years, 10 months, and 81% of questionnaires were

returned. Outcome measures were Roland Morris Disability

Questionnaire (RMDQ), Low Back Outcome Score (LBOS),

SF-12v2 and SF-6D R2. The SF-6D R2 is a “whole of health”

measure.

RESULTS

PLIF provided better short- and long-term results than PLF. The

PLIF group had significantly better LBOS scores in the long term,

and non-significantly better RMDQ scores in the long term. As

measured by RMDQ MCID short term set at 4, RMDQ MCID

set at 8, the LBOS MCID set at 7.5 points and by SF-12v2

physical component score (PCS), PLIF patients performed better

than PLF patients. When analysing single level fusions alone, the

difference is more pronounced, with PCS, mental component

scores and SF-6D R2 all being significantly better in the PLIF

group rather than the PLF group.

CONCLUSION

This paper strongly supports the use of PLIF to obtain equivalent

or superior clinical outcomes than PLF for spinal fusion for lumbar

isthmic spondylolisthesis. Although there are considerable issues

when commenting on the results of observational studies, the

results of this study are the first to report to such a long-term

time point, and further larger long-term randomised studies are

suggested.

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2.22pm | 5.5Prospective computed tomography scan analysisof percutaneously inserted pedicle screws for posterior transpedicular stabilisation of the thoracic and lumbar spine: Accuracy and complication rates

*Raley, D,1 Mobbs, RJ 1,2

1 Prince of Wales Hospital, Sydney, NSW, Australia2 Sydney Spine Clinic, Sydney, NSW, Australia

INTRODUCTION

Percutaneous insertion of cannulated pedicle screws has been

developed as a minimally invasive alternative to the open

technique during instrumented fusion procedures of the thoraco-

lumbar spine. Given the reported rate of screw misplacement

using open techniques (up to 40%), and the paucity of data on

the exact failure rate of the percutaneous technique, we

considered a study important to analyse the misplacement rate

and related clinical complications of this relatively new and

evolving technique.

METHODS

A total of 424 percutaneously inserted pedicle screws from 2007

- 2009 were analysed in 88 patients, from a single surgeon series

(RJM). Axial and sagittal reformatted computer tomography

images were examined by two independent observers and

individual and consensus interpretation was obtained for each

screw position. A simple grading system was used for assessment

of screw accuracy:

Grade 0: screw within cortex of pedicle;

Grade 1: screw thread breach of wall of pedicle >2mm;

Grade 2: significant breach >2mm with no neurological

compromise;

Grade 3: complication including pedicle fracture, anterior

breach with neuro-vascular compromise lateral or

medial breach with neurological sequelae.

RESULTS

The indications for percutaneous pedicle screw insertion include:

degenerative (78%), trauma (13%), tumour (8%) and infection

(1%). 381 out of 424 screws (90%) were placed in the cortical

shell of the pedicle (Grade 0). 43 screws (10%) were misplaced

from T4 to S1. Of these, the majority were Grade 1 pedicle

violations (25 screws; 6%), with 16 Grade 2 violations (4%) and 2

Grade 3 violations (<1%). Of the two Grade 3 pedicle violations,

both were pedicle fractures but only one had associated

neurological deficit (L4 radiculopathy post-op). Both pedicle

violations could be attributed, in part, to incorrect angulation

of screw insertion.

CONCLUSION

This study has shown that percutaneous insertion of cannulated

pedicle screws in the thoracic and lumbar spine is an acceptable

technique with a low complication rate in experienced hands.

The overall rate of perforation is below the higher rates

reported in the literature for the open technique. Complication

rates including pedicle fracture was low. It remains a technically

demanding technique and should be performed with appropriate

training and attention to detail.

REFERENCE

1. RINGEL, F, STOFFEL, M, STÜER, C, MEYER, B

Minimally invasive transmuscular pedicle screw fixation of the

thoracic and lumbar spine. Neurosurgery. Oct; 59, 2006.

70

2.30pm | 5.6The role of preoperative DVT prophylaxis inthromboembolic complications in spinal surgery*Cunningham, JE, Swamy, G, Thomas, K

University of Calgary, Calgary, Alberta, Canada

INTRODUCTION

The American College of Chest Physicians recommends only the

use of postoperative pharmaceutical deep venous thrombosis

(DVT) prophylaxis in spine surgery. The effects of preoperative

DVT prophylaxis, specifically with respect to DVT, pulmonary

embolism (PE) and spinal epidural haematoma (SEH) rates

remain unknown.

METHOD

A 5-year retrospective review of all elective spine operations at

one major institution was carried out. Patients were separated

into 2 groups, based on the presence or absence of preoperative

DVT prophylaxis. The DVT, PE and SEH rates were compared

between the two groups. The study was adequately powered to

detect a halving of the DVT rate.

RESULTS

Of the 3870 elective spinal operations conducted between

2004 and 2008, 37% of patients received preoperative DVT

prophylaxis as either 5,000 units of unfractionated heparin or

40mg of enoxaparin. Preoperative DVT prophylaxis administration

was not found to have a significant effect on DVT or PE rates

(relative risk 0.91, 95% CI 0.37 – 2.23, p=1.00). There was no

apparent significant effect on SEH rates, although the overall

incidence of SEH was very low at 0.4% (RR 1.33, CI 0.50 – 3.56,

p=0.61). The timing of presentation of SEH was usually within

three days of surgery, but there were also several cases that

presented out to 20 days.

CONCLUSION

Administration of preoperative DVT prophylaxis does not

influence the rate of clinically relevant postoperative DVT or

PE, and probably does not affect SEH rates. Given the cost and

human resource burden of its administration, the use of

preoperative DVT prophylaxis is not recommended. In light of

the continued drive for early discharge, physicians need to be

cognizant that late presentation of SEH is possible, and that a

vigilance mechanism is required. Patients need to be informed

of the signs and symptoms of SEH, and counselled to present

immediately should they arise.

71

Notes & Questions

72

73


ScoliosisSaturday 16 April | 3.10pm - 4.30pm





SCOLIOSIS



3.10pm | 6.1The measurement of applied forces during anterior single rod correction of adolescent idiopathic scoliosis (AIS)

*Fairhurst, H, Little, JP, Adam, CJ

Queensland University of Technology, Brisbane, Qld, Australia

INTRODUCTION

Following anterior thoracoscopic instrumentation and fusion for

the treatment of thoracic AIS, implant related complications have

been reported as high as 20.8% (Reddi, 2008). Currently the

magnitudes of the forces applied to the spine during anterior

scoliosis surgery are unknown. The aim of this study was to

measure the segmental compressive forces applied during

anterior single rod instrumentation in a series of AIS patients.

METHODS

A force transducer was designed, constructed and retrofitted

to a surgical cable compression tool, routinely used to apply

segmental compression during anterior scoliosis correction.

Transducer output was continuously logged during the compression

of each spinal joint, the output at completion converted to an

applied compression force using calibration data. The angle

between adjacent vertebral body screws was also measured

on intra-operative frontal plane fluoroscope images taken both

before and after each joint compression. The difference in angle

between the two images was calculated as an estimate for the

achieved correction at each spinal joint.

RESULTS

Force measurements were obtained for 15 AIS patients (Ages

11-19 years) with single thoracic curves (Cobb angles 47˚- 67˚).

In total, 95 spinal joints were instrumented. The average force

applied for a single joint was 540 N (± 229 N) ranging between

88 N and 1018 N. Experimental error in the force measurement,

determined from transducer calibration was ± 43 N. A trend for

higher forces applied at joints close to the apex of the scoliosis

was observed. The average joint correction angle measured by

fluoroscope imaging was 4.8˚ (±2.6˚, range 0˚-12.6˚).

CONCLUSION

This study has quantified in-vivo, the intra-operative correction

forces applied by the surgeon during anterior single rod

instrumentation. This data provides a useful contribution towards

an improved understanding of the biomechanics of scoliosis

correction. In particular, this data will be used as input for

developing patient-specific finite element simulations of scoliosis

correction surgery.

REFERENCE

1. REDDI, V.

Spine 33(18), 1986-1994, 2008.

74

3.18pm | 6.2The value of spinal cord monitoring in scoliosissurgery: A ten year experience *Liew, SM, Torode, IP, Nattrass GR, Johnson, MB,

Dickens, DRV, Watson, S, Simons, M

Royal Children’s Hospital, Melbourne, Vic, Australia

INTRODUCTION

Spinal cord monitoring in posterior scoliosis surgery is a standard

of care. At the Royal Children’s Hospital in Melbourne, we have

routinely monitored the somato-sensory potential (SEP) and

motor evoked potential (MEP) in all such procedures on ambulant

patients. We report on and discuss alterations in the spinal cord

monitor signal occurring in 33 of 374 consecutive patients.

METHODS

A retrospective review was undertaken of all patients who

underwent spinal cord monitoring during their procedure for

scoliosis +/- kyphosis correction and fusion. Data collection

included details on demographics, diagnosis, intraoperative course

including changes in potential, postoperative course, and

outpatient follow-up.

RESULTS

There were 374 ambulant patients who underwent spinal cord

monitoring during their posterior instrumented procedures

between 1999 and 2009. Surgery was performed by paired

combinations of five of the authors. In 33 cases there was a

change in one or both signals during the procedure. Seven signal

changes were directly related to changes in blood pressure, three

changes attributed to other anaesthesia-related issues, and the

rest thought to be implant or correction associated.

Fifteen patients had a post-operative neurological deficit, two of

whom had an intra-operative cardiac arrest. In these 15 cases,

five had complete loss of both the SEP and MEP signals, three

had more than 50% loss of both signals, three had complete loss

of the MEP signal only, and four had more than 50% loss of the

SEP signal only. Twelve patients had complete neurological

recovery within nine months but three patients continue to have

a residual neurological deficit.

Eighteen patients did not have a post-operative neurological

deficit. Of these patients, six had more than 50% loss of the SEP

signal only, four had complete loss of the MEP signal with one of

these four also having a <50% loss of SEP, and eight had <50%

loss of MEP.

CONCLUSION

On review of the management and outcome of these cases, we

conclude that profound hypotension will alter the SEP and may

herald a catastrophic cardiovascular or neurological event.

Continuous spinal cord monitoring can provide specificity in the

diagnosis of an actual or impending neurological insult and allow

for appropriate and timely intervention. We believe spinal cord

monitoring in the posterior approach for spinal deformity is an

invaluable tool and is in fact mandatory for all idiopathic, and

ambulant non-idiopathic spinal deformity surgery.

75



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3.26pm | 6.3Do reinfusion drains following posterior instrumented spinal fusion for adolescent idiopathic scoliosis reduce allogenic blood requirements? A prospective audit with historical controls

*Selby, MD,1,3 Rehn, J,2 Sutherland, LM,2

Freeman, BJC,1,2,3 Cundy, PJ 1,2

1 University of Adelaide, Adelaide, SA, Australia2 Department of Orthopaedics, The Women’s and

Children’s Hospital, Adelaide, SA, Australia3 Spinal Injuries Unit,The Royal Adelaide Hospital, SA, Australia

INTRODUCTION

The management of blood loss in posterior instrumented spinal

fusion for the correction of Adolescent Idiopathic Scoliosis

remains a significant challenge. Allogenic blood transfusion carries

a risk of complications in addition to high costs and ongoing

availability issues (Shander, 2007). Many techniques are available

to reduce allogenic blood requirements but controversy remains

over the effectiveness of these interventions (Bowen, 2010).

This study aimed to confirm the effectiveness, safety and clinical

utility of reinfusion drains in this patient population.

METHODS

A prospective audit was undertaken of 18 consecutive patients

undergoing posterior instrumented spinal fusion for correction

of Adolescent Idiopathic Scoliosis in which a reinfusion drain was

used. This group was compared to a historical control group of

12 consecutive patients operated on by the same surgical team

in which no drain was used. Complete data was available for all

patients and statistical analysis performed.

RESULTS

There was a significant difference in the use of post-operative

allogenic blood transfusion between the two groups (p = 0.02),

with no patient requiring post-operative allogenic blood transfusion

in the reinfusion drain group. Post-operatively, a mean of 0.5 units

of allogenic blood was transfused in the no drain group (range

0-2). Autologous units were under-utilized in both groups with a

mean of 0.5 units transfused (range 0-2) and 1.17 units collected

(range 0-3) in the drain group, and a mean of 0.85 units transfused

(range 0-3) and 1.08 units (range 0-3) collected in the no drain

group. There were no other significant differences between the

two groups, including surgical time and number of levels fused.

There were no complications related to the use of a reinfusion

drain. Each drain costs $211 AUD and a unit of allogenic blood

is estimated to cost $690 AUD. Based on the mean usage of

allogenic blood, reinfusion drains were found to be cost-effective,

with an estimated saving of $41 AUD per patient.

CONCLUSION

We have shown that reinfusion drains in posterior instrumented

spinal fusion reduce the requirement for post-operative allogenic

blood transfusion in this patient population. Reducing allogenic

blood transfusion decreases risks of infection and other transfusion

related complications. Additionally, an increased rate of delayed

infection and wound complications has been reported where

wound drainage is not used in similar patient populations (Ho,

2007 and Blank, 2003). There have been concerns about the

cost-effectiveness and safety of reinfusion drains in total joint

arthroplasty (de Jong, 2007), however, we found the use of

reinfusion drains to be both safe and cost-effective.

REFERENCES

1. SHANDER et al.

Best Practice Research Clincal Anaesthesiology 2007;21:271-289

2. BOWEN et al.

Spine 2010;15:246-251

3. HO et al.

Spine 2007;15:2272-2277

4. BLANK et al.

J Spinal Disord Tech 2003;16:508-512

5. DE JONG

Clin Orthop Relat Res 2007;456:238-242

76

3.34pm | 6.4Serum titanium levels following paediatric spinal arthrodesis

*Cundy, TP, 1,2 Sutherland, LM,1,2 Antoniou, G, 3

Freeman, BJ, 2,4 Cundy, PJ 1,2

1 Department of Paediatrics, Faculty of Health Sciences,

University of Adelaide, Adelaide, SA, Australia2 Department of Orthopaedic Surgery, Women’s and

Children’s Hospital, Adelaide, SA, Australia3 Public Health Research Unit, Women’s and Children’s

Hospital, Adelaide, Adelaide,SA, Australia 4 Department of Orthopaedics and Trauma,


INTRODUCTION

Instrumented spinal arthrodesis is a common procedure to

correct scoliosis. Titanium-based instrumentation is becoming

increasingly favoured due to enhanced biomechanical properties,

but concerns have arisen regarding metal debris release and the

potential for local and systemic complications. The objectives of

this study were

1. To determine serum titanium, niobium and aluminium levels

at specific time points in paediatric patients following

instrumented spinal arthrodesis, and

2. To investigate predictive factors for the determination of

such serum metal concentrations including specific implant

characteristics.

METHODS

A prospective cohort study was designed to evaluate the pattern

of systemic metal release over time by comparing serum metal

levels at specific intervals: pre-operatively and at one-week,

one-month, six-months and one-year post-operatively. Serum

metal levels were measured using high-resolution inductively

coupled plasma mass spectrometry. Instrumentation for each

patient was catalogued and total construct surface area, total

exposed metal surface area and total metal-on-metal interface

surface area determined.

RESULTS

Twenty patients were included in the study group. Mean age

at surgery was 14.8 years. A significant difference between

pre-operative and post-operative concentrations was determined

for titanium and niobium (p=0.0001). Median post-operative

concentrations of titanium and niobium were elevated 2.5- and

6.0-fold above the normal range respectively with 98-99% of

samples elevated post-operatively. The critical period of metal

release was within the first week post-operatively. Significant

positive correlation was determined with metal levels and a

number of predictors. Multivariable linear regression analysis

revealed the number of screws to be the strongest predictor

of titanium and niobium levels (p<0.0001).

CONCLUSION

This study is the first prospective, longitudinal study measuring

serum metal levels at sequential time intervals in patients with

spinal implants. We report abnormally elevated serum titanium

and niobium levels in patients with titanium-based spinal

instrumentation and identify predictors of metal levels.

Previous studies of spinal arthrodesis cohorts have not sampled

patients for serum metal analysis within the first six-months

post-operatively. This may reveal why the critical chronological

period of surge in systemic debris release within the first week

post-operatively has not been captured before. The long-term

systemic consequences of debris generated by wear and

corrosion of spinal instrumentation is unclear but concerning,

particularly as these implants inserted into the paediatric

population may remain in-situ for beyond six decades.

77



SCOLIOSIS



4.02pm | 6.5Post-operative CT assessment of interbody fusiontwo years after thoracoscopic scoliosis surgery

*Carstens, A, Adam, C, Izatt, M, Labrom, R, Askin, GN

Paediatric Spine Research Group, Queensland University of

Technology and Mater Children’s Hospital, Brisbane, Qld, Australia

INTRODUCTION

The relationship between radiologic union and clinical outcome

in thoracoscopic scoliosis surgery is not clear, as apparent

non-union of a spinal fusion does not always correspond to a

poor clinical result. The aim of this study was to evaluate CT

fusion rates 2yrs after thoracoscopic surgery, and to explore the

relationship between fusion scores and;

1. rod diameter,

2. graft type,

3. fusion level,

4. implant failure, and

5. lateral position in the disc space.

METHOD

Between 2000 and 2006 a cohort of 44 patients had thoracoscopic

scoliosis correction. Discectomies were performed at instrumented

levels and defect was packed with either autograft (n=14), or

allograft (n=30). Instrumentation consisted of either 4.5mm

(n=24) or 5.5mm (n=20) single titanium anterior rod and vertebral

body screws (Medtronic). Fusion quality and implant integrity

were evaluated 2yr following surgery using low-dose CT. At each

disc space, left, right and mid-sagittal CT reconstructions were

generated and graded (ImageJ software, NIH, USA) using the

Sucato 4-point scale (Sucato, 2004) which is based on calculated

percentage of fusion across disc space.

RESULTS

Fusion scores were measured for 259 disc spaces in 44 patients.

Rod diameter had a strong effect on fusion score, with a mean

score of 2.12±0.74 for 4.5mm Ti rod, decreasing to 1.41+0.55

for 5.5mm Ti rod, and to 1.09+0.36 for 5.5mm Ti-alloy rod. Mean

fusion scores for autograft and allograft subgroups were 2.13±0.72

and 2.14±0.74 respectively. Fusion scores were highest in the

middle of implant construct, dropping off by 20-30% toward the

upper and lower ends. Fusion scores adjacent to the rod

(2.19±0.72) were significantly higher than on the contralateral

side of the disc space (1.24±0.85). Levels where rod fracture

occurred (n=11) had lower fusion scores than those without

fracture (1.09±0.67 vs 1.76±0.80). Levels where top screw

pullout occurred (n=6) had lower CT fusion scores than those

without (1.25±0.60 vs 1.83±0.76).

DISCUSSION

This is the first detailed investigation of CT fusion scores after

thoracoscopic scoliosis surgery. Rod diameter (larger), intervertebral

level (proximal or distal), lateral position in disc space (further

from rod) and rod fracture or top screw pullout all reduce fusion

scores, while graft type (autograft or allograft) does not affect

scores. However, the assumed link between higher fusion score

and better clinical outcome must be treated with caution, because

in this study rod fractures did not necessarily occur in patients

with lower fusion scores. It is possible that with a stiffer 5.5mm

rod, less bony fusion mass is required for a stable construct. We

propose that moderate fusion scores on the Sucato scale secure

successful clinical outcomes in thoracoscopic scoliosis surgery.

REFERENCE

1. SUCATO et al.

Recombinant human bone morphogenic protein-2 enhances

anterior spinal fusion in a thoracoscopically instrumented

animal model. JBJS (Am) April 2004; 86-A (4): 752-62

78

4.10pm | 6.6Minimally invasive spine surgery in adult deformitycorrection: A prospective case series of 37 patients

*Scott-Young, MN, 1 Magno, C,2 Nielsen, D,2

Mitchell, E, 2 Blanch, N 2


INTRODUCTION

Adult spinal deformity is a complex musculoskeletal problem in

the aged patient. One of the drawbacks of an open technique is

the morbidity associated with the extensive soft tissue dissection

that is associated with traditional deformity correction. Minimally

invasive spinal surgery (MISS) techniques can be employed in

conjunction with modern surgical solutions to restore sagittal

balance and spinal alignment in degenerative spinal deformity.

This study evaluates the safety, efficacy, and outcomes of MISS

for complex de novo degenerative scoliosis.

METHODS

A prospective study including 37 patients with degenerative

spinal deformity were treated by MISS techniques. The patients

received MISS anterior lumbar interbody fusion (ALIF), direct

lateral interbody fusion (DLIF) and percutaneous and minimal

access technology with biological solutions, being recombinant

human bone morphogenetic protein – 2 (rhBMP-2). Diagnosis

was based on history, examination, MRI, CT discography, AP

lateral whole spine, and electrophysiological studies. The minimum

follow-up was 12 months. Ten patients were male and 27 patients

female, with an average age group of 66.51years (range = 44-82

yrs). The average operation duration was 146.73mins (range

75-300mins) with an average blood loss of 338.0mls (range

0-910.0mls).

Clinical outcomes were measured using Oswestry Disability Index

(ODI), Visual Analogue Score (VAS) back and leg, Roland Morris

Disability Questionnaire (RMDQ) and SF-36 questionnaires.

Patients were assessed preoperatively and at 3, 6 and 12 months.

Radiological assessment consisted of AP lateral whole spine,

flexion/extension standing films and a fine cut CT at 6 months.

Cobb analysis of sagittal and coronal balance was performed.

RESULTS

Analysis of results at latest follow-up vs. baseline were: mean

reduction in mean back VAS back scores reduced from

77.08±17.85 to 22.11±20.79 (-71.3%); mean right VAS leg score

reduced from 44.0±32.50 to 16.84±22.13 (-61.7%), while left

VAS leg scores reduced from 41.73±32.89 to 27.32±27.76

(-34.5%). Mean RMDQ reduced from 16.50±4.23 to 7.44±5.59

(-54.9%). ODI reduced from 46.54±17.08 to 25.46±17.89

(-45.3%); SF-36 PCS increased from 29.47±5.56 to 39.26±8.58

(+24.9%) and SF-36 MCS increased from 40.13±11.38 to

48.19±13.12 (+16.7%). Patient satisfaction surveys indicated that

77.78% patients rated their satisfaction with the surgery as

“excellent” or “good” 3-months following their operation. All

patients had greater than 50% correction of the preoperative

coronal and sagittal Cobb angles. Complications included one

vascular injury, one reoperation, and one L4 nerve root dysfunction.

No infections occurred, no blood transfusions were performed,

and there was no pseudoarthrosis.

CONCLUSION

Technological advances innovations appear to enhance the safety

and efficacy of MISS in elderly patients with adult spinal deformity.

This study has shown comparable clinical and functional outcomes

with traditional open techniques, as well as reduced complications.

Improvement in pre to post operative sagittal and coronal

balanced was achieved. The results of this preliminary study

suggest there is a role for MISS in the care of degenerative spinal

deformity. Confirmation through a controlled randomised

prospective study would be desirable.

79

Notes & Questions

80

81

22 Symposium 2

Surgery and Biomechanicsof Adult Degenerative DiseaseSunday 17 April | 8.30am - 10.00am



SUNDAY 17 APRIL 2011

SYMPOSIUM 2

SURGERY AND BIOMECHANICS

OF ADULT DEGENERATIVE DISEASE



8.30am Sagittal balance and surgical strategy in adult high grade spondylolisthesis

A/Prof Chris Ames

Neurosurgery Department, University of California,

San Francisco, California, USA

High grade spondylolisthesis is in large part a disorder of spinal

pelvic alignment and global sagittal balance. Strategies to classify

and treat based upon this principal will be described in detail.

82

8.50am Stability of the osteoligamentous spine: The Follower Load and its implications to ex-vivo

testing and in-vivo spine stability





Muscle forces stabilize the osteoligamentous spine in vivo and

enable it to sustain bending moments as well as large compressive

preloads induced during activities of daily living (ADL). In the

absence of muscle forces, the multi-segment osteoligamentous

spine supports less than one-tenth of the compressive load

experienced during ADL. However, simulation of muscle forces in

experiments on the osteoligamentous spine has not been feasible

due to the large number of muscles and the uncertainty in load

sharing among the various muscles during different activities. As

a result, multi-segment specimens have been tested under pure

moments without a physiologic compressive preload. Since

biomechanical testing is an essential part of understanding spine

instability and developing appropriate treatment methods, ignoring

the effect of physiologic preload may lead to erroneous conclusions.

We reasoned that co-activation of trunk muscles could alter the

direction of the internal compressive force vector such that its

path followed the lordotic or kyphotic curve of the spine, passing

close to the instantaneous centers of rotation of each segment.

This would minimize the segmental bending moments and shear

forces induced by the compressive load, thereby allowing the

osteoligamentous spine to support loads that would otherwise

cause buckling of the column or tissue damage. The compressive

load vector described above is called a “follower load.”

This presentation will summarize our work leading to the

development of:

1. An experimental methodology to test multi-segment

osteoligamentous spines under loads of in vivo magnitude, &

2. A new hypothesis for the mechanism by which muscles

provide stability to the spine in vivo.

83


SYMPOSIUM 2 (continued)

SURGERY AND BIOMECHANICS

OF ADULT DEGENERATIVE DISEASE



9.15am A novel method of assessing facet joint motionusing specimen-specific CT based model





Recent clinical studies have shown accelerated degeneration of

facet joints at the index level after total disc replacement in the

lumbar and cervical spine. These changes may be due to a

mismatch between the kinematics of the native anatomy and the

prosthesis, leading to abnormal facet motions and loading. Our

goal was to develop a tool to assess facet joint motions without

making any assumptions regarding the host anatomy, tissue

properties, or the performance of the prosthesis implanted in a

motion segment.

Lumbar and cervical spine specimens were instrumented with

radiopaque markers on each vertebra. A 3-D specimen-specific

anatomical model of each specimen was reconstructed using

fine-slice axial CT scans. A digital link was established between

the radiopaque markers in the CT reconstruction and the

motion sensors attached to each vertebra by digitizing the

marker location relative to the motion sensors. Next, the

specimen’s kinematic response was measured in response to

flexion-extension, lateral bending, and axial rotation moments.

Three-dimensional motion of each vertebral body was tracked

using an optoelectronic motion measurement system. The motion

data obtained during the flexibility test was used to drive the

anatomical model. As a result, motion of anatomic landmarks on

the specimen could be assessed in response to the loads applied

to the specimen during flexibility tests.

The model was validated by comparing model-predicted motions

of anatomical points on each vertebra to those measured using

sensor data not used in the model development. The model

predicted motions were reliable within ±0.3mm of measured

motions. The model was used to visualize and quantify facet

kinematics in terms of facet overlap area, facet gapping, and

capsular strains in flexion-extension, lateral bending and axial

rotation.

This model couples an individual specimen’s 3-D CT-reconstruction

with its own kinematic data collected in the laboratory in order

to assess facet kinematics. This approach differs from the

traditional finite element models in that there are no assumptions

made regarding material properties, host anatomy or in situ

implant response. In addition to assessing the motion of facet

joints, the specimen-specific model can be also used to make

quantitative measurements of intervertebral foraminal and spinal

canal areas, and ligament stretches in the specimen’s intact state and

after a surgical procedure, at both the index and adjacent levels.

84

85


Spinal Cord InjurySunday 17 April | 10.30am - 12.00noon





SPINAL CORD INJURY



10.30am | 7.1VEGF and PDGF as an immunomodulatory strategy for the reduction of secondary degenerationafter a model spinal cord injury in rats

*Goss, B,3 Young, WY, 1, 2 Lutton, C,1 Williams, R,2

Meedeniya, ACB,3 Mackay-Sim, A,3

1 Institute of Health and Biomedical Innovation, Queensland

University of Technology, Brisbane, Australia 2 AOSpine Reference Centre, Institute of Health and

Biomedical Innovation, Queensland University of Technology,

Brisbane, Qld, Australia3 National Centre for Adult Stem Cell Research,

Griffith University, Brisbane, Qld, Australia

INTRODUCTION

Inflammation in most tissues is initially a protective attempt to

facilitate the removal of damaged tissue which ultimately transitions

to an anti-inflammatory nature thereby initiating a healing response.

However, after spinal cord injury (SCI), the inflammatory response

is prolonged and the anti-inflammatory response delayed, leading

to secondary degeneration and glial scarring. Here, we investigate

the potential of sustained delivery of vascular endothelial growth

factor (VEGF) and platelet derived growth factor (PDGF) to

increase early inflammatory events and promote inflammatory

resolution in both hemisection and contusion injury models of SCI.

METHODS

Animal ethics approval was obtained from the Queensland

University of Technology. Adult Wistar-Kyoto rats (12-16 weeks

old) were subjected to laminectomies and T10 hemisections or

150 kDyne T10 contusion with an infinite horizions impactor.

Animals were then randomised to low dose treatment

(implantation of osmotic pump (Alzet) loaded with 5ug VEGF &

5 g PDGF) high dose treatment (implantation of osmotic pump

(Alzet) loaded with 15ug VEGF & 15 g PDGF) or control

groups (lesion control or lesion plus pump delivering PBS).

Rats were sacrificed at one month and the spinal cords were

harvested and examined by immunohistology, using anti-

neurofilament-200(NF200) and anti- ionized calcium binding

adapter molecule 1 (Iba1) and the chondroitin sulphate

proteoglycan NG2. Behaviour was assessed using open field and

digigait analysis. One way ANOVA was used for statistic analysis.

RESULTS

At 1 month, both high and low dose active pump-treated cords

showed a high level of axonal filament throughout the defects.

The mean lesion size, as measured by NF200, was 0.53+/-0.12

mm2 for the lesion control, 0.39+/-0.10mm2 for the vehicle

control and 0.10+/- 0.03mm2 for the low dose active pump

group and 0.001+/-0.001 mm2 for the high dose pump

(p<0.001). Animals undergoing a contusion injury showed that

the lesion area was reduced to 5% of the control animals. Iba-1

and NG2 co-staining also showed significant differences in the

post-injury inflammatory response and indicated the presence of

a regenerative phenotype of inflammatory cells.

CONCLUSION

We have shown that delivery of VEGF/PDGF from the time of

spinal cord injury reduces or eliminates secondary degeneration.

In these experiments, the high dose growth factors eliminated

the lesion cavity at 1 month. These experiments were based on

the hypothesis that secondary degeneration would be reduced if

inflammation could be resolved at the injury site, and that VEGF

and PDGF would do this by stimulating the initial availability and

activation of macrophages early in the inflammatory process and

accelerate inflammatory resolution.

86

10.38am | 7.2The pressure distribution of cerebrospinal fluid responds to residual compression and decompression in an animal model of acute spinal cord injury

*Jones, CF,1,2,3 Newell, RS,1,2,3 Lee, JHT, 1 Cripton, PA,1,2,3

Kwon, BK,1,3

1 International Collaboration on Repair Discoveries

University of British Columbia, Vancouver, Canada 2 Department of Mechanical Engineering

University of British Columbia, Vancouver, Canada3 Department of Orthopaedics

University of British Columbia, Vancouver, Canada

INTRODUCTION

Lowering intrathecal pressure via the drainage of cerebrospinal

fluid (CSF) through a lumbar intrathecal catheter is currently

instituted to prevent ischemia-induced spinal cord injury (SCI)

during aortic aneurysm surgery (Estrera, 2005). This was recently

investigated as a potential intervention for patients with acute

traumatic SCI (Kwon, 2009). However, in such patients, persistent

extradural compression can occlude the subarachnoid space,

either partially or completely. This may generate differential CSF

pressures across the injury site, which cannot be fully appreciated

in the clinical setting because the lumbar intrathecal catheter

resides caudal to the injury. The purpose of this study was to

measure CSF pressure (CSFP) and pulse pressure amplitude

(CSFPPA) cranial and caudal to the injury site, and to assess

changes that occur with extradural compression, subarachnoid

occlusion, and decompression.

METHODS

Fourteen pigs received a moderate or severe acute contusive

SCI at T11 (N=6 each) or sham surgery (N=2), followed by

eight hours of sustained compression at the injury site. Pressure

transducers in the subarachnoid space cranial and caudal to the

injury site measured CSF pressure during compression and for

six hours post-decompression.

RESULTS

A linear mixed model indicated that the CSFP differential (cranial

- caudal) increased at 0.39 mmHg/hr, predominantly due to

increased cranial CSFP. Cranial CSFP decreased on average

by -1.16 mmHg and caudal CSFP increased by 0.65 mmHg in

immediate response to decompression. The CSFP differential did

not change significantly in the post-decompression period. At the

time of decompression the caudal CSFPPA increased in some

but not all animals; the mean change was not significant

(-0.01±0.1 mmHg, p=0.63).

CONCLUSION

While extradural compression remains on the site of SCI, the

CSF pressure measured caudally may not be an accurate indicator

of CSF pressure cranial to the injury. Decompression may provide

immediate, though perhaps partial, resolution of the pressure

differential. Pulse pressure amplitude was not a consistent indicator

of successful decompression in this animal model. These findings

extend our observations of CSF pressure changes that occur

after human SCI, and may have implications for future clinical

protocols in which CSF pressures are monitored after acute SCI.

REFERENCES

1. ESTRERA, AL et al.

Ann Thorac Surg. 80(4) 1290-6, 2005.

2. KWON, BK., et al.

J Neurosurg Spine. 10(3) 181-93, 2009.

87



SPINAL CORD INJURY



10.46am | 7.3Gross morphological changes of the spinal cordimmediately after surgical decompression in alarge animal model of traumatic spinal cord injury

*Jones, CF,1,2,3 Kwon, BK,1,3 Cripton, PA,1,2,3

1 International Collaboration on Repair Discoveries

University of British Columbia, Vancouver, Canada 2 Department of Mechanical Engineering

University of British Columbia, Vancouver, Canada3 Department of Orthopaedics


INTRODUCTION

The role of surgical decompression for traumatic spinal cord injury

(SCI) is controversial (Furlan, 2010). Intra-operatively, surgeons

can typically confirm the adequacy of their decompression

(Lerch, 2002). However, postoperative imaging often reveals the

cord has swollen to fill the subarachnoid space. The objective of this

study was to use ultrasound in a large animal model of traumatic

SCI to study morphologic changes of the spinal cord and dura

during six hours immediately following surgical decompression.

METHODS

Anaesthetised Yucatan miniature pigs (~20 kg) were subjected to

a moderate (N=6, 20 g, 2.3 m/s) or high (N=6, 20 g, 4.7 m/s)

severity weight drop SCI at T11, with a 100g weight providing

ongoing compression afterwards; one animal received sham

surgery. At 8 hr post-injury the weight was removed to simulate

surgical decompression. Prior to injury and for 6 hours post-

decompression, mid-sagittal ultrasound images were taken to

measure cord and thecal sac diameters.

RESULTS

We identified three main patterns of cord response:

1. residual deformation followed by swelling;

2. gradual swelling leading to thecal occlusion; and,

3. rapid swelling and interruption of the anterior pia / spinal cord

Moderate injury severity animals exhibited residual cord

deformation of up to 0.64 mm within 10 mins of decompression,

which tended to resolve over six hours. High severity injuries

exhibited substantial swelling immediately after decompression,

resulting in occlusion of the subarachnoid space in all animals,

while this occurred for only 50% of the moderate injury group.

CONCLUSION

Swelling of the spinal cord can occur very quickly after surgical

decompression, and may occlude the subarachnoid space within

hours. The pressure that the dura may exert upon the swollen

cord may attenuate the benefits of surgical decompression. These

observations suggest that it may be important to reduce cord

swelling in order to optimize the clinical outcome after acute

traumatic SCI.

REFERENCES

1. FURLAN, JC et al.,

J Neurotrauma. 27, 2010.

2. LERCH, K, et al.

Ultrasound Med Biol, 28(1), 27-32, 2002.

88

11.09am | 7.4

The role of spinal injury units in Australia:

The effects of early and direct admission in

spinal cord injured patients

*Schiller, MD,1 Mobbs, RJ,1,2 Lee, BB,1,2 Stanford, RE,1,2 Marial, O2

1 University of New South Wales, Sydney, NSW, Australia2 Prince of Wales Hospital, Sydney, NSW, Australia

INTRODUCTION

The importance of specialised multidisciplinary care at a spinal

injury unit (SIU) in the early management of acute traumaticspinal

cord injury (ATSCI) is not clearly established or differentiated

from care provided at general trauma centres. This study compared

the outcomes of spinal cord injured patients presenting at a SIU

early vs. late, and those referred directly vs. indirectly, in order to

determine the benefit or otherwise of care provided at SIUs.

METHODS

A prospective cohort study was conducted on ATSCI patients

admitted to a Sydney SIU between 2001 and 2009, using the

New South Wales Spinal Cord Injury Database. 296 persons

were identified. Patients were divided into those admitted within

24 hours of injury or later, and also into those who were admitted

directly or indirectly to the SIU hospital. Groups were analysed for

potential differences in ASIA Grade at admission, neurological level

of injury at admission, and Injury Severity Score. Main outcome

measures were complications during stay, length of stay, and cost of

stay. Logistic regression was used to control for differences in age.

RESULTS

There were no significant differences between either sets of

groups in any of the potential confounders except age. Compared

to delayed admission, admission within 24 hours led to significantly

decreased number of pressure ulcers, UTIs, and total number of

complication types (out of five), as well as decreased length and

cost of stay. Compared to indirect admissions, direct admission

led to significantly decreased numbers of pressure ulcers, as well

as decreased length and cost of stay.

CONCLUSION

Early management of ATSCI at a SIU may improve patient

outcomes by reducing the rate of major complications, as well as

length and cost of hospitalisation. We believe that wherever it is

safe and feasible, ATSCI patients should be admitted directly into

a SIU, or transferred to a SIU within 24 hours from injury.

89

Variable Timing of admission Type of admission

Early (!24 hours) Late (>24 hours) Significance Direct Indirect Significance

n 184 112 - 81 215 -

Age (years) Mn: 34.9 SD: 14.9 Mn: 44.3 SD: 19.0 p<0.001* Mn: 34.9 SD: 16.5 Mn: 39.9 SD: 17.3 p=0.025*

Neurological level of injury Md: C6 R: C2-S3 Md: C7/C8 R: C2-L3 p=0.234 Md: C6 R: C2-L5 Md: C6 R: C2-S3 p=0.847

ASIA Grade Md: C R: A-D Md: C R: A-D p=0.922 Md: 3 R: A-D Md: 3 R: A-D p=0.669

ISS† Mn: 23.8 SD: 8.5 Mn: 26.2 SD: 10.4 p=0.056 Mn: 23.0 SD: 7.8 Mn: 25.3 SD: 9.7 p=0.076

Pressure ulcers (number) Md: 0 R: 0-9 Md: 1 R: 0-10 p=0.007* Md: 0 R: 0-9 Md: 1 R: 0-10 p=0.002*

UTIs (number) Md: 0.5 R: 0-6 Md: 1 R: 0-9 p=0.035* Md: 1 R: 0-5 Md: 1 R: 0-9 p=0.502

DVT (number) Md: 0 R: 0-2 Md: 0 R: 0-2 p=0.837 Md: 0 R: 0-2 Md: 0 R: 0-2 p=0.057

PE (number) Md: 0 R: 0-2 Md: 0 R: 0-2 p=0.094 Md: 0 R: 0-2 Md: 0 R: 0-2 p=0.478

Pneumonia (number) Md: 0 R: 0-4 Md: 0 R: 0-10 p=0.503 Md: 0 R: 0-3 Md: 0 R: 0-10 p=0.906

Complication types (number) Md: 1 R: 0-5 Md: 2 R: 0-5 p=0.023* Md: 1 R: 0-5 Md: 2 R: 0-5 p=0.240

Total LOS (days) Md: 129 R: 1-791 Md: 170 R: 9-837 p=0.005* Md: 125 R: 1-434 Md: 151 R: 2-837 p=0.026*

Cost of stay (AU$) Md: 151k R: 3-1065k Md: 192k R: 14-1398k p=0.023* Md: 138k R: 3-514k Md: 174k R: 3-1398k p=0.049*

n = no. of patients

Mn = mean

SD = standard deviation

Md = median

R = range

* Statistically

significant (p<0.05)

† n = 170 for early,

n = 77 for late;

n = 76 for direct,

n = 171 for indirect.

DemographicsOutcomes



SPINAL CORD INJURY



11.17am | 7.5Sequential reduction protocol using vector principle for cervical fracture dislocations Srivastava, RN

KG Medical College, CSM Medical University, Lucknow, India

INTRODUCTION

Management of cervical fracture-dislocation by skull-tongs is the

best & safest method for reduction of the skeletal injury and

decompression of the spinal cord. Controversial is the upper

limits of weight recommended. As per Sabiston,CP et al.

(J.Trauma. 1988 Jun; 28(6):832-5) traction up to 70% body weight

and Star AA et al. (Spine 1990 Oct; 15(10):1068-72) up to 100

lbs is safe.

This study was undertaken to evaluate:

1. A step wise reduction protocol for safe & effective reduction in

traumatic quadriplegia by judicious application of traction vector

2. Upper limit of weight required for reduction by skeletal traction

METHODS

A sequential protocol was followed in treatment of all the cases.

Skeletal traction was applied by Crutchfield tongs on the day of

admission and by judicious application of traction in following

steps. Bricks of standard size weighing 6.14 lbs each were used as

traction weights. To begin with 18.42 pounds, traction vector was

kept in flexion by elevating the horizontal bar supporting the

traction cord and placing bolsters beneath one or both the

shoulder blades. After 6-8 hours, maintaining traction, vector

angle was brought to neutral position by lowering the horizontal

bar and removing the bolsters. By gentle palpation of spinous

processes, realignment was judged and X-rays were taken to

confirm the reduction. If reduction was achieved it was

maintained in extension by further lowering the horizontal bar

and placing the bolsters or neck rolls beneath the neck at the site

of the lesion. If reduction was not achieved, then weights were

added in 6.14 pound increments at 6 hourly interval and the

sequential steps of traction in flexion, neutral and then extension

were repeated. Traction vector was easily altered with the help of

bolsters under shoulders or neck and proper placement/level of

the horizontal rod supporting the traction cord.

RESULTS

Reduction was achieved in 41 of 47 cases (87.22%) within 48

hours. Maximum weight needed was 36.84 pounds. Six irreducible

dislocations showed symptoms of cord stretching when more

than 36.84 pounds weight were applied, and needed open

reduction. Manipulation under anaesthesia was also tried in 4 of

these 6 patients but reduction could not be achieved and were

taken up for open reduction thereafter.

CONCLUSION

Cervical fracture-dislocations can be reduced without the need

of heavy traction of 100lbs or 70% body weight, if traction is

applied on vector principles. The sequential reduction protocol

suggested here is safe, effective and easily monitored. If traction

vector is altered as described only 36.84 lbs is sufficient for

reduction and recovery. The proposed protocol requires much

less weights than recommended.

90

11.25am | 7.6MRI in spinal trauma: A predictor of neurological recovery Srivastava, RN


INTRODUCTION

Use of Magnetic Resonance Imaging appears to be of great help

in diagnosing spinal trauma because of better contrast resolution,

absence of bony artifacts, multiplanar imaging and choice of pulse

sequences. In cases of spinal cord ischemia, hemorrhage, edema,

and contusion, MRI findings may serve as prognostic indicators.

Aims and Objective

To compare and correlate the MRI findings with those of patients

clinical profile and neurological outcome to assess prognostic and

clinical value of MRI in patients with acute spinal cord injury.

METHODS

We performed this prospective study on sixty two patients of

acute spinal trauma. We evaluated the epidemiology of spinal

trauma & various traumatic findings by MRI. Then the MRI findings

were correlated with clinical findings at admission & discharge

according to ASIA impairment scale. Four types of MR signal

patterns were seen in association with spinal cord injury - cord

edema / non haemmorhagic cord contusion (CC), severe cord

compression (SCC), cord hemorrhage (CH) and epidural

hematoma (EH). Isolated lesion of cord contusion was found in

40%. All other MR signal patterns were found to be in combination.

In cord contusion we further subdivided the group into contusion

of size < 3 cm and contusion of size > 3 cm to evaluate any

significance of length of cord contusion. In cord haemmorhage

involving >1cm of the cord, focus was said to be sizable.

RESULTS

On bivariate analysis, there was a definitive correlation of cord

contusion (CC) involving <3cm & > 3cm of cord with sensory

outcome. In >3cm, chances of improvement was 5.75 times

lesser than in patients with CC involving <3cm of cord (odds

ratio = 5.75 (95% CI: 0.95, 36), Fisher’s exact p = 0.0427 (p<.05).

In severe cord compression (SCC) the risk of poor outcome was

more (odds ratio 4.3 and p=0.149) however was not statistically

significant. It was noted that the patients in which epidural

hematoma (EH) was present, no improvement was seen,

however, by statistical analysis it was not a risk factor and was

not related with the outcome (odds ratio – 0.5 and p = 0.22).

Presence of cord oedema / non haemorrhagic contusion was not

associated with poor outcome (odds ratio 0.25 and p=0.178).

On multiple logistic regression / multivariate analysis for estimating

prognosis, sizable focus of haemorrhage was most consistently

associated with poor outcome (odds ratio -6.73 and p= 0.32)

however it was not statistically significant. The risk of retaining a

complete cord injury at the time of follow up for patients who

initially had significant haemorrhage in cord was more than 6 fold

with patients without initial haemorrhage (odds ratio 6.97 and

p= .0047).

CONCLUSION

Besides being helpful in diagnosis, MRI findings may serve as a

prognostic indicator for clinical, neurological and functional

outcome in acute spinal trauma patients.

8791



SPINAL CORD INJURY



11.33am | 7.7Traumatic central cord syndrome: Is it associated with better neurological recoveryand functional outcomes when compared tomotor incomplete tetraplegia?

*Van Middendorp, JJ,1 Pouw, MH,1 Hosman, AJF,1

Van de Meent, H,1 Curt, A,2

1 Spine Unit, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands

2 Spinal Cord Injury Center, University Hospital Balgrist, Zürich, Switzerland.

INTRODUCTION

The traumatic central cord syndrome (TCCS) is a clinical diagnosis

which is characterized by the following:

1. A disproportionate impairment (weakness & reduced function)

of the upper limbs compared with the lower limbs,

2. Neurogenic bladder dysfunction and

3. Varying degrees of sensory loss at and below the level of

lesion. In a prospective European multicenter cohort study,

we compared the neurological recovery and functional

outcomes between TCCS patients and motor incomplete

tetraplegic patients.

METHODS

In 248 traumatic motor incomplete tetraplegics, initial phase

(0 -15 days) American Spinal Injury Association (ASIA) impairment

grading, upper and lower extremity motor scores (UEMS & LEMS),

upper and lower sensory scores and chronic phase (6 or12 mths)

neurological outcomes were analyzed. In addition, chronic phase

self-care and indoor mobility Spinal Cord Independence Measure

(SCIM) items were studied. Tetraplegics were subdivided into

three groups:

1. Non-TCCS group (UEMS"LEMS),

2. Intermediate-TCCS group (UEMS=(1–9 points)<LEMS) and

3. TCCS group (UEMS=("10 points)<LEMS). Student’s t-tests

and 2-tests were applied.

RESULTS

A total of 89 non-TCCS subjects (AIS D, n=28), 62 int-TCCS

(AIS D, n=43) and 97 TCCS (AIS D, n=80) subjects were analyzed.

Although minimal significant differences in chronic phase LEMS

and UEMS outcomes were identified between TCCS and

non-TCCS patients after stratification by the AIS grade, our data

showed no significant differences in functional upper and lower

extremity outcomes at 6 or 12 months post-injury.

CONCLUSION

The AIS grading system, and not the diagnosis TCCS, continues to

be the best available prognostic parameter for neurological and

functional outcomes in motor incomplete tetraplegics. We

recommend that for future outcome studies in motor incomplete

tetraplegia, patients should not be selected based on, or stratified

by, the diagnosis TCCS.

REFERENCES

1. POUW, MH, VAN MIDDENDORP, JJ, VAN KAMPEN, A,

HIRSCHFELD, S, VETH, RP

EM-SCI study group, Curt A, Hosman AJ, van de Meent H.

Diagnostic criteria of traumatic central cord syndrome,

Part 1: A systematic review of clinical descriptors and scores.

Spinal Cord. 48(9), 652-56, 2010

2. VAN MIDDENDORP, JJ, POUW, MH, HAYES, KC, WILLIAMS, R,

CHHABRA, HS, PUTZ, C, VETH, RPH, GEURTS, ACH, AITO, S,

KRIZ, J, MCKINLEY, W, VAN ASBECK, FWA, CURT A,

FEHLINGS, MG, VAN DE MEENT, H, HOSMAN, AJ.

Diagnostic criteria of traumatic central cord syndrome,

Part 2: A questionnaire survey among spine specialists.

Spinal Cord. 48(9), 657-63, 2010.

3. POUW, MH,* VAN MIDDENDORP, JJ,* VAN KAMPEN, A,

CURT, A, VAN DE MEENT, H, HOSMAN, AJ for the EM-SCI

study group. Diagnostic criteria of traumatic central cord

syndrome. Part 3: Descriptive analyses of neurological and

functional outcomes in a prospective cohort of traumatic

motor incomplete tetraplegics. Spinal Cord. 2010. [Epub

ahead of print] *: Both authors contributed equally.

92

93

22 Poster Presentations


POSTER PRESENTAT IONS

1. Clinical validity of the nerve root sedimentation sign for the diagnosis of lumbar spinal stenosis

*Melloh, M,1 Barz, T, 2 Staub, LP, 3 Lord, SJ,3,4 Merk, HR,5 Theis, JC1


Medicine, University of Otago, New Zealand2 Department of Orthopaedic Surgery, Asklepios Klinikum

Uckermark, Germany3 NHMRC Clinical Trials Centre, University of Sydney,

Sydney, NSW Australia4 The Screening and Test Evaluation Program, University of

Sydney, Sydney, NSW Australia5 Department of Orthopaedic Surgery, University of Greifswald,

Germany

INTRODUCTION

The Nerve Root Sedimentation Sign in transverse magnetic

resonance imaging has been shown to discriminate well between

selected patients with and without lumbar spinal stenosis (LSS),

but the performance of this new test, when used in a broad

patient population, is not yet known (Barz et al. 2010).

METHODS

We conducted a retrospective study of consecutive patients with

suspected LSS from 2004-2006, before the sign had been described,

to assess its association with health outcomes. Based on clinical

and radiological diagnostics, patients had been treated with

decompression surgery or conservative treatment (physical therapy,

oral pain medication).Changes in the Oswestry Disability Index(ODI)

from baseline to 24 month follow-up were compared between

Sedimentation Sign positives and negatives in both treatment arms.

RESULTS

Of the 146 included patients (52% female, mean age 59 yrs), 71

underwent surgery. Baseline ODI in this treatment arm was 52%,

the sign was positive in 44 patients (mean ODI improvement 25

points) & negative in 27 (ODI improvement 24), with no significant

difference between groups. In the 75 patients of the conservative

treatment arm, baseline ODI was 44%, the sign was negative in

45 (ODI improvement 17), and positive in 30 (ODI improvement

5). Here a positive sign was associated with a smaller ODI

improvement compared with sign negatives (t-test, p=0.003).

CONCLUSION

This study allowed an unbiased clinical validation of the

Sedimentation Sign by avoiding it influencing treatment selection.

In patients commonly treated with decompression surgery, the

Sedimentation Sign does not appear to predict surgical outcomes.

Patients with beginning LSS due to spondylolisthesis or scoliosis

were also included here, which explains the sign negatives. In the

conservative treatment arm a positive sign appears to identify a

group of patients who are less likely to benefit. In these cases,

surgery might be effective; however, this needs confirmation in

prospective studies.

REFERENCES

1. BARZ, T, MELLOH, M, STAUB, LP, LORD, SJ, LANGE, J,

RODER, CP, THEIS, JC, MERK, HR 2010

Nerve root sedimentation sign: Evaluation of a new

radiological sign in lumbar spinal stenosis. Spine, 35, 892-7.

2. Flexural properties of an elastomeric total disc replacement

*Mahomed, A,1 Moghadas, PM,1 Shepherd, DET, 1

Hukins, DWL,1 Roome, A,2 Johnson, S 2

1 University of Birmingham, UK2 Ranier Technology Limited, Cambridge, UK

INTRODUCTION

Elastomeric Total Disc Replacements (TDR) have been developed,

whose aim is to provide motion properties resembling those of

the natural disc. Unlike articulating TDRs, elastomeric devices

attempt to restore axial stiffness and flexural stiffness. It is not

clear how the flexural properties of elastomeric implants may

alter with varying axial compressive loads and flexural rates. The

flexural stiffness of the natural spine increases as the applied axial

load increases (Stokes et al., 1999; Patwardhan et al., 2003; Janevic

et al., 1991). It was anticipated that elastomeric TDR would

94

exhibit similar characteristics. The aim of this study was to

quantify the change in flexural properties of an elastomeric TDR

(Cadisc™-L) when subjected to increasing magnitudes of axial

load and at different flexural rates.

METHOD

Six CadiscTM-L lumbar devices (MC-10mm-12° size, Ranier

Technology Ltd, Cambridge, CB5 8AA, UK), were tested using a

BoseTM spinal disc testing machine (Bose Corporation,

ElectroForce Systems Group, Minnesota, USA.) in Ringer’s

solution at 37 °C. A fixed static load of (1000 N, 1500 N or

2000 N) was applied to a device and it was then subjected to

motions of 0° to 6° to 0° (flexion) and 0° to -3° to 0° (extension)

at rates of 0.5 °/s, 1.0 °/s and 2.0 °/s as recommended by BS ISO

18192-1:2008 and previous literature (de Visser et al., 2007).

Results were compared statistically using a Student’s t-test.

RESULTS

Figure 1 shows the variation of torque with flexion and extension

angle at different compressive loads and flexural rates. Torque

increases linearly with flexion and extension angles at all flexural

rates (results shown for 1500 N and 2000 N to make graphs

clearer). Figure 2 shows the change in implant stiffness at different

flexural rates at 1000 N, 1500 N and 2000 N; the flexural

stiffness of the implant increases with increasing load in both

flexion and extension motions.

FIGURE 1: Change in implant torque response (expressed as a % of the total torque) at the different load

FIGURE 2: Change in implant flexural stiffness in response to increasing load

CONCLUSION

Elastomeric TDRs are intended to provide mechanical and motion

properties that resemble those of the natural disc. Natural discs

loaded under a pure bending moment between 3-10 N.m

achieved flexion angles between 5-15° (Wilke et al.,1997); the

results presented show the Cadisc™-L to be within this range.

In this investigation, flexural stiffness increases with load which is in

agreement with changes observed within the natural lumbar spine

(Patwardhan et al., 2003; Stokes et al., 2003; Janevic et al., 1991).

REFERENCES

1. STOKES, IAF, et al

J. Electromyo. .Kinesiol.13, 397-402, 2003

2. PATWARDHAN, AG, et al

J. Orthop. Res. 21, 540-546, 2003

3. JANEVIC, J, et al

J. Orthop. Res. 9; 228-236. 1991

4. DE VISSER, H, et al

Proc. Inst. Mech. Eng. [H], 221, 221-227, 2007

5. WILKE, HJ, et al

Spine, 22, 2365-2374, 1997

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3. Management of cervicothoracic junction fracture dislocations

*Wong, E,1 De La Harpe, D,2 Ton, L, 2 Rogers, M,2 Wilde, P 2

1 Emory University, Decatur, Georgia, USA2 Vertebral Column Surgical Group and Victorian Spinal Cord

Injury Service, Austin Health, Heidelberg, Vic, Australia

INTRODUCTION

Unstable fractures at the cervicothoracic junction is a rare injury

with a variation of injury patterns and poor neurological outcome.

Diagnosis of these injuries require good imaging and fixation is

biomechanically challenging. The aim of this study was to evaluate

the surgical experience in treating traumatic fractures at the

cervicothoracic junction.

METHODS

There were 11 patients who underwent surgery for unstable

fractures / dislocation at the cervicothoracic junction between

2006 to 2008. Clinical outcome was evaluated using ASIA scoring

and radiological outcomes using CT scans and plain radiographs.

Follow-up periods ranged from 11 to 48 months, with an average

of 18 months.

RESULTS

9 patients sustained complete neurologic deficits with no recovery

ASIA A with the remaining in ASIA B. Neurologic deficit was

related to the degree of anterior displacement of C7 on T1.

8 patients sustained a C7 burst fracture and 3 had a C7 T1 fracture

dislocation. Anterior corpectomy and fusion was performed in 8

patients. Posterior reduction and rod - screw fixation was done in

1 patient while a combined approach and fixation was performed

for 2 patients. There was a complication of misplaced upper

cervical plate screws with tilting of the mesh cage inferiorly. No

subsequent displacement of the implant was noted on follow-up.

CONCLUSIONS

Fracture-dislocation at the cervicothoracic junction is a rare

injury with a poor neurologic outcome. The anatomic and

biomechanical features of the cervicothoracic junction require

the selection of suitable approach and implants. The anterior

approach is valuable in treating burst fractures at C7. Facet

dislocations at the cervicothoracic junction are best treated with

a posterior lateral mass and pedicle screw fixation or with a

combined approach.

4. Surgery for cervical facet dislocations: Which approach?

*Wong, E,1 De La Harpe, D,2 Ton, L, 2 Rogers, M,2 Wilde, P 2


Injury Service, Austin Health, Heidelberg, Vic, Australia

INTRODUCTION

The surgical treatment of traumatic cervical facet dislocations is

highly variable. There is lack of consensus on the surgical approach

and the variables that influence it in these patients. The aim of this

study is to determine the fracture patterns involving unilateral or

bilateral facet fractures and analyse optimum management

strategies and approaches for these injuries.

METHODS

This is a retrospective study of patients with cervical facet

dislocations surgically treated at a spinal trauma and cord injury

referral center. All 36 consecutive cases of surgically treated

unilateral and bifacetal fracture dislocations were included in this

study. No preoperative reduction was performed in all cases.

Presenting history, neurologic examination (ASIA grading),

imaging findings and type of surgery were recorded. All patients

had CT and MRI scans of their cervical spine prior to surgery.

Injury patterns were characterized using the Subaxial Cervical

Spine Injury Classification System (SLIC) classification.

RESULTS

Between 2004 - 2008, there were 21 cases with bilateral facet

dislocation, of which 9 were associated with a vertebral burst

fracture. Unifacetal dislocation was found in 15 cases (right n=9

and left n= 6). All fractures had 6 - 9 points on the SLIC scale. All

fractures had distraction or distraction with translational type

96

morphology. 50% of the cases in the bifacetal group had a

combined anterior and posterior approach and fixation compared

to 20% in the unifacetal group (p <0.05). The average follow-up

was 24 months. There were three complications in the bifacetal

dislocation group. One patient developed kyphosis at the level of

injury while another had inadequate cord decompression and a

misplaced lateral mass screw.

CONCLUSIONS

Cervical bilateral facet fractures are associated with higher

complication rates and more severe injury patterns often with

disruption of all discoligamentous complexes. The integrity of the

discoligamentous structure and surgeon preference were the

significant factors influencing the surgical approach in treating

these fractures.

5. MRI changes in cervical cord injuries

*Wong, E,1 Calver, N,3 De La Harpe, D,2 Ton, L, 2 Rogers, M,2

Wilde, P 2


Injury Service, Austin Health, Heidelberg, Vic, Australia3 Department of Radiology, Austin Health, Heidelberg,

Vic, Australia

INTRODUCTION

There is lack of data in the literature regarding the extent of

discoligamentous injuries, cord and canal changes which occur in

patients with bifacetal and burst fractures with complete

neurologic injury. The aim of this study was to compare the findings

in both the groups and determine if there was any correlation

between the cord compression, canal changes and space available

for the spinal cord.

METHODS

Clinical data and radiologic studies of patients with cervical spinal

cord injury (SCI) involving the subaxial spine (C3-T1) were

included in the study. The neurologic status of each patient was

classified according to the standardized American Spinal Injury

Association (ASIA). Imaging performed included lateral radiographs,

(CT) scans and sagittal T1- and T2-weighted magnetic resonance

images (MRI). Data obtained from the CT scan was the Maximum

Canal Compromise (MCC). MRI imaging provided data on the

status of the discoligamentous injuries and changes within the

spinal cord. The amount of Maximum Spinal Cord Compression

(MSCC) was calculated from midsagittal T2 scans. The SAC data

was compared the various injury levels with data from normal

patients.

RESULTS

There were 9 patients with cervical bifacetal fracture and 9 with

burst fractures included in the study. 5 patients with normal MRI

findings were used as controls with cord and canal measure-

ments done at C3-C7 levels. All patients had ASIA A neurologic

grading and were all surgically stabilized. In the bifacetal dislocation

group MSCC was 19.28% and MCC 28.44%. The mean

discoligamentous score (MDLS) was 8.33.

Cord signal changes and haematoma was found in 88.9% and

33.3% respectively. Cord to canal ratio at the level of injury was

0.63 with the mean SAC of 2.88mm. In the burst fracture group

MSCC was 13.4% and MCC 32.05%. The MDLS was 5.78. Cord

signal changes and haematoma was found in 88.9% and 77.8 %

respectively. Cord to canal ratio at the level of injury was 0.73

with the mean SAC of 2.56mm.

There was significantly higher MDLS in the bifacetal dislocation

group and greater haematoma formation in the cervical burst

group. There was no correlation between canal compromise and

cord compression. SAC was significantly smaller in both the cervi-

cal bifacetal fracture 2.88mm and burst fracture groups 2.56mm

when compared to the normal group at all levels 6.44mm.

CONCLUSIONS

In this study group of neurologically complete patients there

were extensive discoligamentous changes. A significant number

had cord signal changes and haematoma. The amount of cord

and canal changes did not reflect final neurologic outcome.

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6. Screw webpacs: Is pedicle sizing accurate andreproducible on CT

*McCarthy, MJH,2 Bucher, TA,1 Redfern, A,1 Hutton, MJ1

1 Peninsula Spinal Unit, Princess Elizabeth Orthopaedic

Centre, Royal Devon and Exeter Foundation NHS Trust,

Exeter, UK2 The Princess Alexandra Hospital, Brisbane, Qld, Australia

INTRODUCTION

Crawford et al. (2009) showed that the WEBPACS angulation

tool was accurate and reproducible when measuring spinal

angulation. Preoperative CT scans can be used to plan spinal

instrumentation, in particular, the accurate sizing of pedicles in

order to assess their suitability for screw insertion. We could find

no studies validating the WEBPACS ruler tool. The objectives of

this study were:

1. To determine whether the ruler tool on WEBPACS is accurate

2. To determine whether measuring pedicle size on CT is

accurate and reproducible

METHODS

Study Design: Radiologial analysis.

Subject: A human cadaveric spine along with 5 geometrical

shapes were scanned using a multislice spiral CT scanner with

1mm cuts. The objects were measured independently using the

WEBPACS ruler tool by a spinal consultant (Observer 1) and a

spinal fellow (Observer 2). The pedicle diameters for lumbar and

thoracic vertebrae in the axial plane were then measured. The

measurements were then repeated a week later. The geometrical

shapes and pedicle size on the skeleton were then measured

using Vernier callipers by an independent observer and again

repeated a week later. All measurements were taken to the

nearest 0.1mm.

Outcome Measures: Reproducibility of the measurements was

assessed using Bland and Altman plots. Accuracy was assessed

using the Vernier calliper measurements as the gold standard and

comparing the plots.

RESULTS

The independent observer achieved perfect reproducibility when

measuring the geometric objects with the Vernier callipers (all

measurements were exactly the same). The error of the

measurement associated when measuring the pedicles was

0.5mm. The error of the measurement for the geometric objects

for observers 1 and 2 was 0.5 and 0.6mm respectively, and for

the pedicles it was 1.0 and 0.6mm respectively.

CONCLUSION

The WEBPACS ruler on a CT scan is accurate to within 0.5-0.6mm

of the true size of an object. The error for pedicle measurements is

marginally higher (0.6-1.0mm) and this may reflect the fact that

they are ill defined geometric shapes. Measuring pedicle size on

CT for surgical planning may have implications for small pedicles

when sizing them up for a pedicle screw.

7. The role of cervical cordotomy in the management of refractory cancer pain

*Frydenberg, EM, Steel, TR

St Vincent’s Hospital, Darlinghurst, NSW, Australia

INTRODUCTION

Over the last two decades the administration of intrathecal

morphine has improved and simplified pain management for

many malignant processes. The reduced number of patients being

referred for cordotomy in recent years have led to fewer surgeons

developing the necessary expertise to perform cordotomy with

the ease and precision previously reported (Steel & Burchiel, 2002).

Infusion pumps have been successful in controlling pain in more

than 90% of patients in whom pain is unrelieved by standard

opioid regimens. However there may still be a role for destructive

surgical approaches.

We report two cases of open cervical cordotomy for treatment

of refractory cancer-related pain.

98

METHODS AND RESULTS

Case 1: 78-year-old man with invasive SCC of chest wall, left

axilla and brachial plexus causing severe arm pain that could not

be controlled with maximum medical therapy and local anaesthetic

infusion. The patient was hospitalised for analgesia pre-operatively

and still reported severe arm pain. A right open C2/3 cordotomy

was performed. The left arm pain was completely alleviated by

the surgery. He was pain free independent at home 6 weeks

after surgery.

Case 2: 16-year-old girl with pelvic malignancy, incapacitated from

severe pelvic and lower extremity pain. Cervical cordotomy was

performed with complete relief of symptoms. She was able to travel

overseas without analgesia for a period of 12 months after surgery.

CONCLUSION

Cordotomies were first performed in 1912. For several decades

after cordotomy remained one of the most successful procedures

for the management of chronic pain from malignant processes.

There have been few recent surgical series presented or published

as open cordotomy is a procedure that is only rarely performed

today. Jones et al published a series of 9 open cordotomies

performed over a period of 10 years for patients with intractable

cancer-related pain(Jones et al., 2003). They found that all patients

experienced near complete pain relief from the pre-operative

pain with reduction in analgesia use (Jones et al., 2003).

While 90% of patients with cancer-related pain obtain relief with

oral analgesia or intrathecal opioids there is a small group of

patients where pain control remains difficult and neuro-ablative

procedures should be considered.

We report the successful use in 2 patients with intractable

malignant pain who were able to discontinue all opioid analgesia

following their surgery.

REFERENCES

1. JONES, B, FINLAY, I, RAY, A, SIMPSON, B 2003.

Is there still a role for open cordotomy in cancer pain

management? Journal of pain & Symptom management, 25, 6.

2. STEEL, T, BURCHIEL, K 2002.

Ablative Neurosurgical Techniques in the Treatment of

Chronic Pain: Overview. In: BURCHIEL, K. (ed.) Surgical

Management of Pain. Thieme.

8. Initial experience with a novel internally fixedframe to improve retraction for anterior uppercervical surgery

*Seex, KA,1 Koustais, S,1 Macdonald, M 2

1 Macquarie University, Sydney, NSW, Australia2 Royal Adelaide Hospital, Adelaide, SA, Australia

INTRODUCTIONAnterior upper cervical surgery is made more difficult because

conventional self retaining retractors are poorly designed for use

in this area and handheld retractors lack stability. Except for

transoral surgery all approaches to this area create asymmetrical

wounds which produces unequal tissue forces that work against

retractors stability. This is further complicated because such

approaches work under the overhang of the jaw and its tissues.

Such surgery is commonly associated with post operative

swallowing and airway complications most likely due to retraction

injury indicating that efforts to improve retraction are worthwhile

and may benefit patients as well as address surgeons frustrations.

METHODSA novel retractor was developed for this indication and cadaveric

tests confirmed its feasibility prior to clinical use. A small

radiolucent rectangular frame is fixed to spine beneath the

prevertebral fascia. Radiolucent retractor blades are clipped to

the sides of the frame. The blades may rotate in 3 planes, medial,

lateral and cranial, with the fixed frame providing a stable axis for

rotation. The design allows for easy intermittent retraction.

Depending on the geometry of the blades, blades can provide

retraction at right angles to the frame or obliquely in the line of

the wound. Surgery is carried out within the frame. We present

this novel device and show its use in its first 3 cases of upper

cervical spine surgery.

RESULTS2 cases of Type 2 odontoid fracture anterior fixation and one

case of partial c2 and c3 4 corpectomy for tumour. The frame

was secured with 2 small screws into C4 vertebrae for odontoid

screw fixations and C5 for the vertebrectomy. The radiolucent

cranial retraction blade could be held by an elastic band and a

hook. This improved stability, ease of imaging and assistants

radiation exposure. No retraction complications were observed

post operatively.

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POSTER PRESENTAT IONS(Poster 8 continued)

CONCLUSION

The design principle of bone fixation with rotation were recently

described (Seex, 2010. Pattavilokam, 2010.) however this fixed

frame with retractor blade rotation in the cranial plane and

angled blades have not been previously described. This frame

made the tissue retraction much easier in these difficult operations

without causing injury. Inventors (KAS) regularly misjudge the

value of their inventions. One of the authors (MM) has no bias.

Some ideas immediately seem sensible and require more

independent appraisal.

REFERENCES

1. SEEX, KA

J Neurosurg Spine 12:547-551,2010

2. PATTAVILOKAM, A, SEEX, KA

J Neurosurg Spine 12:552-559,2010

9. Novel description of an all-osseous transpelvic approach to the intervertebral spaceof the lumbosacral junction

*McCormick, J, Macmillan, M, Rice, JW

University of Florida, Gainesville, Florida, USA

INTRODUCTION

The position of the lumbosacral junction within the pelvis and

the surrounding structures can complicate the access to the

lumbosacral disc. This has resulted in different techniques

described to obtain entry into the disc to perform a fusion.

The development of minimally invasive instruments and computer

navigation has enabled techniques that were not previously

feasible. We describe a trans-pelvic technique to access the

intervertebral space of the L5/S1 junction, through an all-osseous

tunnel. Our hypothesis was that with the use of computer

guidance the disc space could be reliably accessed. The purpose

of this study was to anatomically describe this pathway.

METHODS

Three cadaveric specimens were obtained and soft tissue was

removed from the specimen. Under direct visualization, a

transosseous portal was created from the iliac crest through the

sacrospinous space into the sacral ala before accessing the L5/S1

intervertebral disc space. This was performed from each iliac

crest allowing us to evaluate six transosseous portals. The

integrity of the portals and the preparation of the disc space was

evaluated grossly and with computer tomographic scans within

the sagittal, coronal and axial planes. Measurements were then

obtained to determine the length of the portals, the location of

the isthmus in all planes, endplate diameters, and angles necessary

to access the space.

RESULTS

A transosseous portal was successfully created in all specimens

from the right and left iliac crest. The computer tomographic

scans and the anatomic evaluations confirmed that the portal

was bound by cortical bone at all times until it entered the L5/S1

disc space. Upon sectioning the specimens it was determined

that the isthmus of the approach is within the sacral ala. The

sacral ala was not breached when entering the L5/S1 disc space.

The narrowest point was found within the axial and sagittal plane

of all specimens within the sacral ala. The average angle of the

approach was 45 degrees superior within axial plane with the

pelvis in a prone position and 25 degrees caudally in the coronal

plane for the pelvis. The average length of the transosseous por-

tal was 69mm. The average angle between the L5/S1 endplates

was 15 degrees.

CONCLUSION

A transosseous approach to the lumbosacral junction is feasible

with computer tomography and navigation. Further studies will be

required to determine optimal surgical instrumentation, optimal

implantation devices and the biomechanical stability of the

approach.

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10. Implementation of the NICE guidelines for metastatic spinal cord compression: Do they make a difference ?

*McCarthy, MJH, 2 Berry, CL,1 Cumming, D,1 Hutton, MJ 1

1 Peninsula Spinal Unit, Princess Elizabeth Orthopaedic

Centre, Royal Devon and Exeter Foundation NHS

Trust, Exeter, UK2 The Princess Alexandra Hospital, Brisbane, Qld, Australia

INTRODUCTION

Historically, the main treatment for Metastatic spinal cord

compression (MSCC) was radiotherapy. Very few patients

were referred to the spinal team and even less went on to

have surgery. We have conducted a comparative audit to

assess whether the introduction of the UK NICE guidelines in

2008 have changed our practices.

METHOD

Single site study comparing a retrospective audit of patients

diagnosed with MSCC in 1999-2000 to a prospective audit of

patients diagnosed with MSCC in 2009-2010. During this study

specific outcomes were monitored, time from referral to MRI,

percentage of patients with spinal stability documented,

percentage of patients referred for a spinal opinion and

definitive management of patients presenting with MSCC.

RESULTS

In 1999-2000 over a 16 month period there were 38 patients

diagnosed with MSCC. Diagnosis was reached by MRI in 27 (71%)

of patients. MRI scan was performed at a mean of 42 hours. The

referral rate to a spinal surgeon was 8 (21%) patients. All patients

were treated with radiotherapy. Spinal stability was documented

in only one case. The average time on bed rest was 5.5 days.

In 2009-10 over a 12 month period 56 patients were diagnosed

with MSCC. All patients with neurological deficits had MRI within

a mean of 6 hours from presentation. All patients were referred

to the spinal team, 14 (25%) had surgery, 35 (63%) radiotherapy,

3 chemotherapy, 2 other form of therapy and 2 patients passed

away prior to any treatment. Spinal stability was documented in

all cases. The average time on bed rest was 2 days.

CONCLUSION

These results suggest that the introduction of the NICE guidelines

(2008) have resulted in a significant improvement in the care

pathway of patients with MSCC and in the time to imaging, and an

increase in patients receiving surgery for the treatment of their

MSCC. It is uncertain whether these results are attributed to the

introduction of the NICE guidelines or wider knowledge of the

condition.

REFERENCE

1. UK NICE Guidelines 2008.

11. A simple mnemonic to reduce errors in spinal fusion

Howie, GRC

Ascot Hospital, Remuera, Auckland, New Zealand

INTRODUCTION AND METHOD

Pre-operative check lists have reduced the incidence of “surgical”

errors such as wrong patient, wrong operation and wrong side /

level problems but errors of omission can still occur. These may

result in re-operation or affect outcome.

By using a simple mnemonic (ABCDEFG), occasional errors have

been corrected.

A is for X-rAy

B is for Bone graft

C is for Cage

D is for Drain

E is for Epidural and Epidural space

F is for Fixation

G is for Go home when the count is correct

Examples:

A. at the conclusion of spinal fusion the radiographs should be

checked Again for level and positioning of implants (cages,

screws, &c). This should be confirmed with Another doctor.

B. Has all the Bone graft or substitute been placed appropriately?

C. Is the Cage optimally positioned?

D. Is the Drain placed properly (not sutured to the fascia)?

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E. Will an Epidural be required for post-op analgesia?

Have you checked the nerve roots to ensure there are no

bone fragments or other compression.

F. Is the Fixation satisfactory (two views are better)?

Have all the nuts been tightened?

Are the rods too long?

Do you need a cross-link?

G. Count correct, all suture needles, swabs and instruments

accounted for? Well done

Constant use of this aide memoire at the end of every spinal

fusion has reduced the incidence of “return to theatre”. Problems

with each of these seven categories have occurred and have

been rectified prior to the end of surgery.

CONCLUSION

This simple mnemonic can be used at the completion of every

spinal fusion.

12. SCIWORA in adults: Is C4 the soft target?Srivastava, RN

King Georges Medical College, CSM Medical University,

Lucknow, India

INTRODUCTION

First described by Rang & Wilberger, SCIWORA was initially

defined as a syndrome of traumatic myelopathy without vertebral

column disruption as visualized on plain spine films, flexion-

extension films, myelography or CT. The mean incidence was

reported to be around 40% with majority ( two thirds) in young

child less than 8 to 10 years of age, less commonly in adolescents

and rare in adults. With improved imaging capability and increased

use of MRI the true incidence is likely to be 15 - 20%. We initiated

a study to evaluate the incidence, prevalence and outcome of

SCIWORA in adults. In literature, spinal cord injury without

radiological abnormality is rare in adults. We present seven adult

patients with SCIWORA seen over two years.

METHODS

A study was undertaken to evaluate the incidence, prevalence

and outcome of SCIWORA in adults. 5180 patients were admitted

in the Department of Orthopaedic Surgery at our institution.

708 of these (13.66%) were spinal cord injuries. 7 cases of adult

SCIWORA were diagnosed in these two years. A case by case

analysis was done and evaluated systematically. Following trauma,

these patients had quadriparesis. Conventional radiographs were

within normal limits. MRI showed lesions only in four and three

had absence of any abnormal cord signal.

RESULTS

The incidence of SCIWORA in adults was < 1% of SCI ( 7/708),

The mean age was 33.28 years, and male/female ratio was 6:1.

The mode of injury was FFH in 4/7 (AK, MK, RV & S), RTA in 2/7

(KS & RB) and SOG in 1/7 (SK). Associated injuries were found

in 3/7 (AK, KS & MK).

Clinical presentation at admission was ASIA A in 2/7 (AK & RV),

ASIA C in 2/7 (KS & RB) and ASIA D in 3/7 (MK, SK & S). ASIA

A remained A and C & D recovered to ASIA E within 6 weeks.

Neurological level was C4 in 6/7 (AK, KS, MK, RB, RV & SK), and

T2 in 1/7 (S). Motor level was C4 in 6/7 and T1 in 1/7. Sensory

level was C4 in 4/7 (AK, KS, RB & RV), and normal sensations in

3/7 (MK, SK & S).

At MRI, isolated cord contusion was found in 3/7 (RB, RV & S),

combined contusion with hemorrhage in 1/7 (AK) and absence

of abnormal cord signal in 3/7 (KS,MK&SK).

CONCLUSION

SCIWORA is no more an injury of children. In our series a rare

presentation is neurological level of C4 in all but one case. MRI

findings for the cord are highly correlated with the prognosis -

hemorrhage with poor outcome, contusion with moderate to

good recovery and absence of abnormal cord signal with

complete recovery. Management is essentially conservative and

prognosis is better than that seen in patients with fracture or

dislocation of cervical spine.

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13. Spinal shock in spinal cord injuries: Is duration of shock related to neurological level?*Srivastava, RN, Arya, S


INTRODUCTION

The definition and etiology of spinal shock remain controversial.

The factors influencing this duration and its clinical significance

are not well studied. A study was undertaken to study the

duration and the factors influencing spinal shock. An arithmetical

relationship was seen to exist between the duration of spinal

shock and the segmental level of spinal cord injury.

A study was done to determine the duration of spinal shock in

spinal cord injury (SCI), the first reflex to return while recovering

from spinal shock & the factors influencing duration of spinal shock.

METHODS

116 patients in spinal shock following SCI were included. A

detailed neurological examination of sensory, motor and reflex

activity was done everyday till the patients were out of spinal

shock. The duration of spinal shock by appearance of any reflex,

the first reflex to return & the influence of variable factors on

duration of spinal shock were studied

RESULTS

In 76 patients (85.4%) anal wink (AW) was the first reflex to

return either alone or simultaneous with BC / DPR.In 7 patients

cremastric reflex, in 3 pathological reflexes & in 2 deep tendon

reflexes ( ankle) were the first to return.

Mean duration of spinal shock (MD of SS) was shorter in

children, shorter in malnourished, shorter in untrained / laborers,

shorter in patients admitted early and shorter in patients without

any complications. "MD of SS" was not influenced by sex of patient,

associated injuries and by different modalities of treatment.

CONCLUSION

On statistical analysis of duration of spinal shock with neurological

level as a variable "MD of SS "was 1.7 days in cervical cord lesions,

8.2 days in upper thoracic, 15 days in lower thoracic and 17 days

in lumbar cord lesions. Such an arithmetical progression was also

found at each segmental level i.e. the duration of spinal shock

progressively increased at every segmental level. "MD of SS" was

1.36days at C4, 1.60 at C5, 1.72 at C6, 8.1 at T6, 12.4 at T8, 13.1

at T10, 15.3 at T12 & 21.6 at L2.

An arithmetical relationship exist between the duration of spinal

shock and the segmental level of spinal cord injury - the duration

of spinal shock was directly proportional to level of injury. Higher

or proximal the lesion, shorter is the duration. We do not have

the answer of this important observation. Does the duration of

spinal shock dependant on the cord length / neuronal mass

involved / spared?

14. In-vitro biomechanical comparison of the native inter-vertebral disc and a compliant artificial lumbar disc replacement (Cadisc-L)

*Freeman, BJC,2 Naylor, J,1 McNally, DS1

1 University of Nottingham, UK 2 University of Adelaide, Adelaide, SA, Australia

INTRODUCTION

The majority of lumbar Total Disc Replacements (TDR)

currently available are low friction devices with designs based

on ball-and-socket articulate bearings. Whilst these devices allow

motion, they possess no shock absorbing capacity. The Cadisc™-L

is a polyurethane-polycarbonate graduated modulus compliant

TDR designed to restore the elastomeric properties of the disc,

including normal shock absorption and physiological centres of

rotation (CoR).

This study aims to assess the in-vitro biomechanical behaviour

of the native intervertebral disc and that observed following

implantation of the Cadisc™-L Specifically, the effects of

implantation on the location of the CoR, the compressive stiffness

and the bending moment vs. bending angle characteristics, will be

studied. The hypothesis to be tested is that implantation of the

Cadisc™-L will not significantly change the biomechanical

behaviour of the cadaveric motion segment.

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METHODS

Ten L4-5 fresh frozen cadaveric motion segments were dissected

to remove all non-osteoligamentous tissues. This number was

determined using a power analysis (p=0.05, =0.8) to detect

differences greater than the sample standard deviation. Care was

taken to preserve specimen hydration. The L4-5 motion segments

were mounted in loading cups using the low melting point alloy.

Testing was performed in an environmental chamber at 37°C

with 80-90% humidity. Specimens were pre-conditioned with a

1kN load for 30 minutes to restore physiological disc hydration.

The location of the static CoR was determined by adjusting the

anterior/posterior position of a single loading roller until no

flexion / extension was produced on application of a small test load.

Compressive stiffness of the specimen was determined on the

5th of a series of 6 loading cycles to 1kN (0.5Hz). The bending

stiffness of the specimen was determined by a physiologically

relevant combination of bending moment, compressive load and

forward shear. The position of the roller was offset to 15mm

anterior to the static CoR producing a bending moment that

increased to approximately 15Nm at 1kN applied load. Bending

angle, measured using an electronic inclinometer, was used to

calculate the bending moment from the applied load and roller

offset geometry. Data was captured on the 5th of 6 cycles.

Following testing of the intact motion segment, the L4/5

intervertebral disc was removed and a medium-sized CAdisc™-L

implant inserted. The location of the new CoR was determined

and the mechanical testing protocol repeated. Data from the

intact and implanted conditions were then compared using

paired students ‘t’ tests.

RESULTS

Compressive stiffness and bending stiffness were reduced by 50%

and 20.5% respectively following implantation of the CAdisc-L. The

instantaneous axis of rotation locus maintained its characteristics

with a centrode displaced 4.1 mm at 3° flexion.

CONCLUSION

The results of this study support the hypothesis that implanting

the elastomeric TDR, Cadisc™-L, produces very similar in-vitro

biomechanical behaviour to that observed when studying the

native L4/5 intervertebral disc.

104

15. Cervical cord injury as a complication of percutaneous cervical facet joint radiofrequencyneurotomy

*Selby, MD,1,2 Clark, SR,2 McDonald, M,2,3 Marshall, R,1,2

Freeman, BJC 1,2

1 The University of Adelaide, Adeleaide, SA, Australia2 Spinal Injuries Unit, Royal Adelaide Hospital, SA, Australia 3 Department of Neurosurgery, Flinders Medical Centre,

Flinders University, Bedford Park, SA, Australia

INTRODUCTION

Cervical facet joint radiofrequency neurotomy, also know as

cervical facet rhyzolysis, is a procedure for addressing chronic

axial neck pain in patients with a previous response to diagnostic

blocks (Lord 1996). While the application of this procedure

remains controversial, it is commonly employed by surgeons, pain

physicians and radiologists as the benefits are thought to clearly

outweigh potential risk (Falco 2009). We report the first case, to

our knowledge, of cervical cord injury as a result of incorrect

probe placement during radiofrequency neurotomy.

METHODS

A single case of this devastating injury is reported, following

repeat left sided cervical facet radiofrequency neurotomy at the

C4/5 level. The procedure was performed by a pain physician

with extensive experience with this technique.

RESULTS

We present the clinical and radiographic outcome of this case

at 6 months following injury. The patient presented with an

incomplete cervical cord injury defined as C4, ASIA D, with

predominantly dorsal column involvement. Initial treatment was

non-surgical and intravenous high dose dexamethsone was

commenced. The patient made a slow and as yet incomplete

neurological recovery. Serial MRI demonstrates the progression

of a focal cord lesion at C4/5 two hours post injury to diffuse

cord oedema from C2 to T1 level at one week.

We review the potential reasons for this technical error and

discuss the various available techniques for performing this

procedure.

CONCLUSION

Despite controversy over the efficacy of cervical facet radio-

frequency neurotomy, it has previously been thought to be a low

risk procedure. We report this case as a serious potential

complication that patients should be informed about prior to

treatment.

REFERENCES

1. LORD et al.

N Engl J Med 1996;335:1721-1726

2. FALCO et al.

Pain Physician 2009;12:323-244

16. Prospective analysis of graft options for anterior lumbar interbody fusion (ALIF): Fusion and complication rates

Mobbs, RJ

University of New South Wales and Sydney Spine Clinic,

Sydney, NSW, Australia

INTRODUCTION

Anterior Lumbar Interbody Fusion (ALIF) is an acceptable

technique for a variety of indications including the management

of Degenerative Disc Disease, Spondylolisthesis, foraminal

stenosis and symptomatic non-union of posterior fusion. There

are a variety of graft options avaliable to the surgeon including

Autograft, BMPs, allografts and a variety of synthetic based bone

graft substitutes. This study aims to compare early fusion rates

and complication rates of a variety of avaliable graft options.

METHODS

Over an 18 month time period, the data from 35 consecutive

ALIF's has been prospectively collected; including 10 autograft

(Iliac crest), 10 Infuse (rhBMP-2) and 15 i-Factor (P-15) patients.

Patients were reviewed at 2, 6, 12 and 24 weeks postoperatively.

(Clinical outcomes are the subject of a separate study.) Early

radiological outcomes based on fine cut coronal CT assessment,

and graft associated complications were prospectively recorded.

105


RESULTS

Early fusion rates were positive throughout all patient groups.

By 3 months, there was bridging bone on coronal CT in 4/10

patients in the autograft group, 7/10 in the Infuse group and 11/15

in the iFactor group. By 12 months there was one non-union in

the autograft group (smoker / diabetic) and no non-union in the

Infuse group. The average followup in the i-Factor group is only 5

months, however fusion rates at time of reporting were 13/15 in

the i-Factor group. Complication rates at the 3 month mark

include; 3/10 patients suffering from significant graft site pain in

the autograft group, 1/10 patients suffering a severe Infuse

related radiculitis, and no complications in the i-Factor group.

CONCLUSION

From this early data analysis with regards to fusion and

complications, all groups demonstrated excellent early fusion

rates. Bone bridging appears to develop faster in the Infuse and

iFactor group based on the 3 month data. The major graft related

complication is from residual graft.site harvest pain, followed by a

severe Infuse radiculitis in one patient. Issues of cost and graft

related complications will require longer term follow-up and

larger patient cohorts to define more accurately. No firm

conclusions can be made in terms of the most suitable bone

graft option for ALIF based on this early data analysis.

REFERENCES

1. CHAU, AM, MOBBS, RJ.

Bone graft substitutes in anterior cervical discectomy and

fusion. Eur Spine J. Apr;18(4):449-64. 2009

2. FOLDAGER, C, BENDTSEN, M, NYGAARD, JV, ZOU X,

BÜNGER, C.

Differences in early osteogenesis and bone micro-architecture

in anterior lumbar interbody fusion with rhBMP-2, equine bone

protein extract, and autograft. Bone. Aug;45(2):267-73. 2009

17. Radiographic fusion rate of multilevel anterior cervical discectomy and fusion usingpeek cages with DBM and plate fixation: A descriptive study

*Domacena, RM, Ver, M

St Luke’s Medical Center, Quezon City, NCR, Philippines

INTRODUCTION

Background: The issue in the management of multilevel cervical

spondylotic radiculopathy/ myelopathy continues to be debated

in the literature. One controversy is the high non union rate of

multilevel fusion and the use of allograft instead of autologous

bone. Spinal surgery using autogenous bone graft is currently the

standard method of fusion and is a common procedure for spinal

pathology. Despite being the optimal graft solution, autogenous

graft is associated with a certain rate of pseudoarthrosis, and the

potential complications and morbidity from the donor site

(Park HW et al, Spine 2009)

Objective: The purpose of this study was to assess the

radiographic fusion rate of patients treated for cervical

radiculopathy / myelopathy with multiple anterior decompression

and spinal fusion (ADSF) using PEEK cages with DBM and

cervical plate fixation.

METHODS

Radiographs of 12 patients, non randomized, surgically treated by

a single surgeon was reviewed. The anterior Smith-Robinson

technique was performed for all patients with adjunct cervical

plate instrumentation. Postoperative radiographs of 38 cervical

levels of all cases were reviewed by 2 orthopedic surgeons and a

radiologist who were not involved in the care of the patients.

Radiographic fusion criteria is based on the presence trabecular

bridging between the PEEK cages and the vertebral bodies

RESULTS

A solid fusion was obtained in 37 out of 38 cervical levels in all

patients (97%) as observed by the orthopedic surgeons and

100% fusion as observed by a radiologist with a high concordance

rate (92%) and a fair interobserver agreement ( coefficient

0.22) among the evaluators. Average time to fuse was 3 months.

106

CONCLUSIONS

This study demonstrates that a high fusion rate may be achieved

with the use of PEEK cages and DBM in managing multilevel

cervical pathology without the morbidity of harvesting IBG.

REFERENCES

1. BOHLMAN, HH, EMERY, SE, GOODFELLOW, DB

J Bone Joint Surg Am. 1993;75:1298-1307.

2. BOLESTRA, MJ, et al

Spine. 2000 Aug 15;25(16):2040-4.

3. PARK, HW, LEE, JK, MOON, SJ, SEO, SK, LEE, JH, KIM, SH

Spine (Phila Pa 1976). 2009 Aug 1;34(17):E591-5.

4. ROBINSON, RA, WALKER, AE, FERLIC, DC, WIECKING, DK

J Bone Joint Surg. 1962; 44-A: 1569-1587

5. VACARRO, AR, MADIGAN, L., LIM, R

J Am Acad Orthop Surg, 2007 May Vol 15, No 5, 274-280.

107

108

Annual Meetings

Year President Date / Site / Guest(s)

1990 Prof Robert Fraser 14 - 15 JULY | Royal North Shore Hospital, Sydney, NSWGuest: Dr Henry Bohlman

Dept of Orthopedic Surgery, Case Western Reserve University, Cleveland, Ohio, USA

1991 Prof Robert Fraser 4 - 5 JUNE Australian Academy of Sciences, Canberra, ACT

1992 Prof Robert Fraser 8 - 9 AUGUST | Adelaide Festival Centre, Adelaide, SAGuests: Dr Daniel Chopin

Centre d’Etude et de Traitement des Affections du Rachis, Institut Calot, Berck-sur-mer, France

Dr John O’BrienDept of Spinal Disorders, Robert Jones & Agnes Hunt Orthopaedic Hospital, Oswestry, Shropshire,UK

Dr Arthur SteffeeDivision of Orthopaedics, Cleveland Spine & Arthritis Center,Lutheran Medical Center, Cleveland Medical Center, Cleveland, Ohio, USA

1993 Prof Michael Ryan 26 - 27 JUNE | Hyatt Hotel, Coolum, QldGuests: Dr Stephen Esses

Dept of Orthopedic Surgery Baylor College of Medicine, Houston, Texas, USADr James WeinsteinDept of Orthopedic Surgery, University of Iowa, Iowa City, Iowa, USA

1994 Prof Michael Ryan 14 - 15 MAY | RACS, Melbourne, VICGuest: Dr Gunnar Andersson

Dept. of Orthopedic Surgery, Rush-Presbyterian-St Luke’s Medical Center, Chicago, Illinois, USA

1995 Assoc Prof Bruce McPhee 18 - 22 SEPTEMBER | Combined SSA/NSA Meeting | Cable Beach Resort, Broome, WA

Guest: Dr Tom ZdeblickDept of Orthopaedic Surgery, University of Wisconsin, Madison, Wisconsin, USA

1996 Assoc Prof Bruce McPhee 13 - 15 SEPTEMBER | Cairns Convention Centre, Cairns, QldGuest: Dr Iain McCall

Dept of Radiology Robert Jones and Agnes Hunt Orthopaedic Hospital Oswestry, Shropshire, UK

1997 Dr Richard Vaughan SEPTEMBER | Sanctuary Cove, Gold Coast, Qld

1998 Dr Richard Vaughan SEPTEMBER | Queenstown, NZGuest: Prof H. Alan Crockard

The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK

1999 Dr Richard Vaughan SEPTEMBER | Coffs Harbour

2000 Dr Ian Torode Adelaide Festival Centre, Adelaide, SAGuest: Dr Howard An

Dept of Orthopdeic Surgery, Rush-Presbyterian-St Luke’s Medical Center, Chicago, Illinois, USA

109

Annual Meetings

Year President Date / Site / Guest(s)

2001 Dr Barrie Slinger 27 - 29 APRIL | The Esplanade Hotel, Fremantle, WAGuest: Dr Frank Eismont

Dept of Orthopedics and Rehabilitation, University of Miami School of Medicine, Miami, Florida, USA

2002 Dr Barrie Slinger 26 - 28 APRIL | Hilton Hotel, Melbourne, VICGuest: Dr Randy Davis John Hopkins University Baltimore, Maryland, USA

2003 Prof Nigel Jones 25 - 27 APRIL | Canberra Hyatt, Canberra, ACTGuest: Prof Bernard George Dept of Neurosurgery Dublin, Eire

2004 Prof Nigel Jones 16 - 18 APRIL | Hyatt Hotel, Coolum, QLDGuests: Prof Ciaran Bloger National Centre of Neurosurgery, Dublin, Eire

Prof Robert Gunzburg Free University of Brussels, Antwerp, Belgium

2005 Dr Ian Farey 14 - 17 APRIL | Auckland Hilton Hotel, Auckland, NZGuest: Dr John Hellier Emory Spine Center, Dept of Orthopaedic Surgery

Emory University School of Medicine, Atlanta, Georgia, USA

2006 Dr Ian Farey 28 - 30 APRIL | Sofitel Wentworth Hotel, Sydney NSWGuest: Dr Alexander Vaccaro Dept of Othopaedic Surgery, Rothman Institute,

Thomas Jefferson University, Philadelphia, Pennsylvania, USA

2007 Dr Roy Carey 20 - 22 APRIL | Hotel Grand Chancellor, Hobart, Tas.Guest: Prof Eugene Carragee

Dept of Orthopaedic Surgery, Stanford University School of Medicine, California, USA

2008 Dr Roy Carey 18 - 20 APRIL | Hilton Adelaide, Adelaide, SAGuests: Prof Dieter Grob

Dept of Spinal Surgery, Stanford University School of Medicine, California, USA

2009 Dr Peter McCombe 17 - 19 APRIL | Sofitel Hotel, Brisbane, QldGuests: Dr Marcel Dvorak, Dr Charles Fisher, Dr Tom Oxland


2010 Dr Peter McCombe 9 - 11 APRIL | Christchurch Convention Centre, Christchurch, NZGuests: Prof Paul Anderson Dept of Orthopaedics, University of Wisconsin-Madison

Dr Adam La Caze School of Pharmacy, University of Queensland, Brisbane, Qld Prof Kerrie Mengersen Dept of Statistics, QUT, Brisbane, Qld Dr Paul Mernagh Health Economics Manager, Health Technology Analysts, Sydney, NSW

2011 Assoc Prof Graeme Brazenor 15 - 17 APRIL | Sofitel Melbourne on Collins, Melbourne, Vic, AustraliaGuests: Prof Jean-Charles Le Huec Orthopaedic Dept University of Bordeaux Hospital, France

Assoc Prof Chris Ames Neurosurgery Dept, University of California, San Francisco, USAProf Avinash Patwardhan Dept of Orthopaedic Surgery & Rehabilitation, Loyola University

Stritch School of Medicine, Chicago, Illinois, USAAssoc Prof Jacqui Close Geriatrician, Prince of Wales Hospital, Sydney, NSW, AustraliaProf Rachelle Buchbinder Monash Clinical Epidemiology Dept, Cabrini Hospital, Melbourne, Vic

110

Author Disclosures

Free Papers Session 1

1.5 QUT Research Assistant position (second author) is

funded by the Queensland Orthopaedic Research Trust

which receives funding from Synthes.


2.1 Consultancy: TeTec

Research grant: FFG / Generation Innovation

2.2 Research grant from Medtronic

2.4 Peter Robertson is a Consultant to Medtronic and De Puy,

and has a Royalty agreement with Medtronic unrelated to

this presentation.

Roy Lim is an employee of Medtronic, Memphis, TN, USA

2.6 Support from Synthes, Stryker and Medtronic

2.7 Royalties: Lippincott, Williams and Wilkins

Stock: Neurotech, Colorado Orthopaedic and Surgical

Hospital, Greenwood Ambulatory Surgery Center,

Denver Integrated Imaging

Consultant: Stryker, Synthes, United Healthcare, Allos


3.3 The presenting author's position as a spine research fellow

is funded by donations from Stryker to St Vincent's Hospital.

Stryker is not involved in the selection of candidates for the

position.

3.5 Nuvasive (consultant, royalities); Orthovita (speakers

bureau); Ulrich Medical GER (consultant)

3.7 Medtronic Australia provided funding for costs associated

with radiographic studies performed outside of Austin

Health, licensing fees associated with the use of quality of

life measures eg SF36 and transportation of patients.


4.1 DePuy Spine: consultancy, research grant and travel support

4.2 Professors Freeman, Steffen and Aebi are members of the

Scientific Advisory Board for Ranier Technology and all have

an option agreement relating to shares with Ranier

Technology Limited

4.3 BJC Freeman serves on the Scientific Advisory Board for

Ranier Technology Limited and hold an option agreement

relating to shares in Ranier Technology Limited

4.4 Dr William Sears and Gavin White are consultants for

Medtronic.

4.5 CBP Non Profit

4.6 Consultant Medtronic, Royalties Medtronic


5.1 1. Stocks in Medtronic and Johnson & Johnson.

2. Travel support from Stryker and Synthes

5.3 Dr Gore is consultant to KARL STORZ endoscopy and

receives travel support and royalties on his designs

5.4 Peter Robertson is a consultant for Medtronic.


6.1 This research was supported by a Mater Children's Hospital

Golden Casket Research Grant (Beginner) of amount

$12,549. Medtronic kindly loaned the surgical tool

required for the completion of this research.

6.3 Dr Michael Selby received financial support from Synthes

in 2009 to attend the Spine Society instructional course

and meeting as an Orthopaedic registrar. No financial

support has been received this year.

6.4 Non-commercial funds were received for this study from

the Bone Growth Foundation Inc, Women’s and Children’s

Hospital Foundation and Florey Medical Research Fund.


7.1 Support from Synthes, Stryker and Medtronic

7.2 / 7.3 Implants for the injury device were donated by Medtronic

111

Poster Disclosures

Poster Number 2

This project and the equipment used was funded by the

Engineering and Physical Sciences Research Council, UK

(grant reference EP/F014562/1).

Support from Ranier Technology Limited, Cambridge, UK

Poster Number 7

The presenting author fills a position as a spine fellow at

St Vincent's Hospital, Sydney. This position is funded by donations

from Stryker Spine to St Vincent's Hospital.

Poster Number 8

Dr Seex has patents pending in regard to this device and its

principles. Synthes provided a research grant

Poster Number 14

BJC Freeman and DS McNally serve on the scientific advisory

board of Ranier Techniology Limited and both hold stock options

relating to shares in Ranier Technology Limited.

Poster Number 15

Dr Michael Selby received financial support from Synthes

in 2009 to attend the Spine Society instructional course and

meeting as an Orthopaedic registrar. No financial support has

been received this year.

Poster Number 16

Stocks in Medtronic and Johnson & Johnson.

Travel support with Synthes and Stryker.

Research grant with Cerapedics.

Research grants with the University of New South Wales.

112

Mrs Kathleen Adams

Mr Lloyd Adams

Mr Tom Afzal

Mr Stephen Alfrich

Mr Michael Allan

A/Prof Christopher Ames

Dr Geoffrey Andrews

Dr Richard Appleyard

Dr Bryan Ashman

Dr Geoffrey Askin

Mrs Helen Bale

Ms Lisa Barry

Mr Gary Bateman

Mr Matthew Beard

Miss Kylie Beddoes

Mr Graeme Bond

Dr Janusz Bonkowski

A/Prof Graeme Brazenor

Dr Michael Brighton-Knight

Ms Kirstin Brown

Mr Paul Buhle

Mr Andrew Burne

Mr Roy Carey

Dr Alan Carstens

Mr Marcel Challita

Ms Tina Clark

Mr Damian Clarke-Bruce

Mrs Jill Conlin

Mr Lyndon Crossley

Dr Thomas Cundy

Mr John Cunningham

Ms Helen Cunningham

Dr Chris Daly

Dr Gordon Dandie

Ms Pip Daniell

A/Prof Gregory Day

Mr Greg Desmond

Miss Stephanie DeVreker

Delegate List

Global Orthopaedic Technology

LifeHealthcare

Spinal Kinetics

Medtronic

Medtronic

University of California

Ranier Technology Ltd

Australian School of Medicine

Bryan Ashman

Askin Spine

DePuy Spine (Johnson & Johnson Medical)

Medtronic

GB Orthopaedics Australia Pty Ltd

Spinal Unit Orthopaedics Royal Adelaide

Medtronic

B. Braun Australia Pty Ltd

Neurosurgical Medical Services Trust

Zimmer


Zimmer

Paediatric Spine Research Group Mater

Medtronic

LifeHealthcare

Zimmer

DePuy Spine (Johnson & Johsnon Medical)


Women's and Children's Hospital

Royal Melbourne Hospital

Queensland University of Technology

Gold Coast Hospital

Westmead Hospital

Stryker

Gold Coast Spine Service

Medtronic

NuVasive Aust/NZ Pty Ltd

NSW

NSW

NSW

NSW

NSW

ACT

QLD

VIC

SA

QLD

SA

NSW

NSW

VIC

VIC

VIC

NSW

VIC

QLD

NSW

NSW

NSW

VIC

NSW

SA

VIC

QLD

QLD

NSW

NSW

QLD

VIC

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

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[email protected]

Delegate Organisation Country Email AddressState or

This list includes only those delegates who have given permission for their details to be included and is correct at time of printing - 4/4/2011.

United Kingdom

United States

New Zealand

New Zealand

New Zealand

New Zealand

113

Mr Jonathan Dewey

Mr Robert Dickens

Mr Angus Dixon

Dr Roy Michael Domacena

Mr David Edis

Mr Albert Erasmus

Mrs Allison Erp

Mr Michael Falkenberg

Dr Ian Farey

Dr Wendy Findlay

Ms Emma Fitzgerald

Mr Nathan Foote

Ms Sussan Frame

Prof Robert Fraser

Prof Brian Freeman

Mr David French

Dr Ellen Frydenberg

Mrs Elisha Gaddes

Dr Matthew Giblin

Dr Satishchandra Gore

Dr Ben Goss

Mr Rob Gourlay

Mr Angus Graham

Mr Tobin Grantley

Dr Angus Gray

Dr Paul Graziotti

Mr Brenden Grib

Dr Michael Gross

Mr Simon Hadlow

Dr Alastair Hadlow

Mr David Hamilton

Mr Brian Hansen

Mr Tony Harrington

Mrs Jacqueline Hart

Dr Dennis Hartig

Mr Louise Higginson

Mr Daniel Hill

Mr Terence Hillier

Delegate List

Medtronic

Stryker

St. Luke's Medical Center

Tasmanspine

Royal Hobart Hospital

Medtronic Spinal Tap Surgical

Royal Brisbane Hospital

Zimmer

LifeHealthcare

Johnson & Johnson Medical

St Andrews & Royal Adelaide Hospitals

Royal Adelaide Hospital

Biomet QLD

St Vincent's Private Hospital

Medtronic

Ratna Memorial Hospital

AOSpine Reference Centre

Stryker

LifeHealthcare

Zimmer

Sydney Children's Hospital

Cambridge Pain Management Centre


Taranaki Base Hospital

Auckland City Hospital

Medtronic

Medtronic

Biomet Australia

Medtronic


LifeHealthcare

Stryker

Alpine Orthosport

NSW

VIC

NSW

TAS

TAS

VIC

VIC

NSW

QLD

VIC

NSW

VIC

SA

SA

QLD

NSW

NSW

NSW

India

QLD

NSW

NSW

NSW

NSW

WA

VIC

NSW

NSW

WA

NSW

NSW

QLD

NSW

NSW

NSW

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

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[email protected]

[email protected]



Philippines

New Zealand

New Zealand

114

Mr Shane Hodder

Dr Chris Hoffman

Mr Shannon Holdsworth

Dr GRC Howie

Miss Nicola Hunter

Ms Jenny Huntley

Mr David Jennings

Dr Rondhir Jithoo

Miss Christine Joe

Mr Michael Johnson

Ms Claire Jones

Mr Richard Jones

Mr Michael Jordan

Dr Andrew Kam

Mr Kenneth Kher

Mr Merv Kiley

Mr Shawn Kim

Dr Emily Kong

Mr Matt Kostiainen

Mr Jarek Kowalczyk

Dr Rob Kuru

Mr Dominic Langford


Dr Paul Licina

Dr John Liddell

A/Prof Susan Liew

Mr Roy Lim

Dr Ferraby Ling

Dr Andreas Loefler

Mr Justin Lousfel

A/Prof Peter Lowthian

Mr Alex Lukianov

Dr Kris Lundine

Mr Christopher Lyons

Mr Ross Lyte-Mason

Mr Peter Mackie

Dr Aziza Mahomed

Dr Greg Malham

Delegate List


Wellington Hospital


Howie LTD


Zimmer

Medtronic

Neurological Surgery Victoria

Medtronic

Adelaide Centre for Spinal Research

Signature Spine + Joint

Zimmer

B. Braun Australia Pty Lyd


Meddyssey Co. Ltd.

Australian Orthopaedic Association

Biomet Australia

DePuy Spine (Johnson & Johsnon Medical)

Synthes

University of Bordeaux Hospital

Medtronic

North West Regional Hospital

K2M

Cabrini Institute

NuVasive Inc

Austin Hospital



Medtronic

University of Birmingham

VIC

VIC

VIC

NSW

NSW

VIC

VIC

SA

NSW

QLD

NSW

NSW

VIC

VIC

NSW

VIC

NSW

NSW

France

QLD

WA

VIC

TAS

NSW

NSW

VIC

VIC

VIC

VIC

VIC

NSW

VIC

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

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South Korea

New Zealand

New Zealand

United States

United States

United Kingdom

115

Mr Justin Maynard

Mr Eamonn Mc Closkey

Mr Steve McAdoo

Dr Jeb McAviney

Dr Michael McCarthy

Dr Peter McCombe

Mrs Sue McCombe

Dr John McCormick

Ms Lisa McDonald

Mr Rob McPhee

Mrs Amanada McPhee

A/Prof Ian Bruce McPhee

Dr Markus Melloh

Ms Christine Migliore

Mr Chris Miller

Mr Jon Mills

Dr Bruce Mitchell

Mr Matthew Mitchell

Miss Marzena Mizgalska

Dr Ralph Mobbs

Dr Milan Mody

Dr Sabarul Mokhtar

Dr Peter Moloney

Mr Rob Montauti

Mr Alexander Montgomery

Prof Robert Moore

Dr Andrew Morokoff

Mr Paul Mullert

Mr Matt Muscio

Dr Amy Nall

Dr Naveen Narayanasamy

Dr Pierce Nunley

Mr Paul O'Brien

Mr Peter Oatey

Mr Ertan Ozer

Mr Andrew Parker

Mr Alpesh Patel

Mr Chris Patterson

Delegate List


St John of God

Cerapedics Inc

Sydney Scoliosis Clinic

AO Spine Centre Brisbane

Brisbane Spine Centre

University of Florida

Zimmer

LifeHealthcare


Dunedin School of Medicine

Medtronic

Medtronic

Medtronic

Metro Spinal Clinic

Medtronic Spinal Tap Surgical

Med-Chem Surgical

Prince of Wales Hospital

Louisiana State University

The Australian School of Advanced Medicine

Stryker

Auckland City Hospital

The Adelaide Centre for Spinal Research

Medtronic


Austin Health

NW Regional Hospital Burnie & Alfred Health

K2M

Synthes


Medtronic Spine + Biologics

Middlemore Hospital

Medtronic

NSW

WA

NSW

QLD

QLD

QLD

VIC

NSW

NSW

QLD

NSW

NSW

QLD

VIC

VIC

NSW

NSW

NSW

NSW

NSW

SA

VIC

NSW

VIC

VIC

TAS

NSW

NSW

SA

NSW

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

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United States

New Zealand

United States

New Zealand

New Zealand

New Zealand

United States

116


Dr Ronjon Paul

Prof Mark Pearcy

Mr Travis Perera

Mr Paul Petherbridge

Dr Justin Pik

Mrs Debbie Pohl

Mr George Potter

Ms Dianne Price

Mr Markus Priede

Mr Michael Pullar

Dr Gerald Quan

Dr Darryl Raley

Mr Jeff Reid

Mr Ben Reynolds

Dr Risantoso Tjuk Risantoso

Ms Amy Ritson

Dr Peter Robertson

Mr Daniel Robinson

Mr Jon Rogers

Mr Glen Ross

Dr William Edmond Ryan

Prof Michael D. Ryan

Dr Alan Sacks

Dr Davor Saravanja

Mr Matt Schiller

Mr Stan Schofield

Ms Sharon Scott

A/Prof Matthew Scott-Young

Mr Paul Seddon

Dr Kevin Seex

Dr Michael Selby

Mr Cameron Short

Ms Peta Sitcheff

Ms Helen Smith

Mr Michael Son

Mr Brett Spence

Dr Ralph Stanford

Delegate List

Loyola University Stritch School of Medicine

Queensland University of Technology

T.S.Perera Pty Ltd

LifeHealthcare

ACT Neurospine Clinic

Medtronic SA

Adelaide Spine Clinic

ArthroCare


Monash Medical Centre

Austin Health

St George Hospital

LifeHealthcare

LifeHealthcare

Indonesian Orthopaedic Association (IOA)

Medtronic/National Surgical

The Orthopaedic Clinic Mercy Specialist Centre

Medtronic

Synthes

LifeHealthcare

W.E. Ryan Medical Pty Ltd

University of Notre Dame (Sydney)

Centre for Minimally Invasive Neurosurgery

Highfield Park Specialist Centre

Medtronic

Gold Coast Spine

Synthes

Spinal Injuries Unit Royal Adelaide Hospital

Medtronic/National Surgical

Stryker

Signature Spine + Joint

Medyssey Co.Ltd.


Prince of Wales Hospital

VIC

QLD

VIC

NSW

ACT

SA

SA

NSW

VIC

VIC

VIC

NSW

NSW

NSW

East Java

QLD

WA

NSW

NSW

QLD

NSW

NSW

NSW

NSW

VIC

NSW

QLD

NSW

NSW

SA

QLD

NSW

NSW

VIC

NSW

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[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

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United States

New Zealand

United States

117

Dr Ellison Stephenson

Mr Anthony Strbik

Mrs Autumn Sutterland

Mr Anthony Swoboda

Mr Takakki Tanaka

Mr Max Tawadrous

Prof Thomas Taylor

Mrs Kathryn Temby

Dr Clayton Thomas

Mr Alex Thompson

Mrs Erica Tieu

Mr Lu Ton

Mr Emerik Trinajstic

Dr Peter Turner

Dr Juan Uribe

Dr Jacob Van Der Westhuizen

Ms Chantal Van Geel

Dr Joost Van Middendorp

Dr Richard Vaughan

Dr Paul Verrills

Ms Michelle Walkden

Mr Yi Yuen Wang

Mr Tom Wells-Quinn

Mrs Katherine Westland

Mrs Belinda Wiemers

Dr Peter Wilde

Ms Lucy Williams

Dr David Wong

Dr Peter Woodland

Ms Susan Wordsworth

Prof Neill Wright

Dr Steven Yang

Dr Reza Zarrinkalam

Delegate List

Synthes

K2M

Medtronic

NuVasive Inc

Medtronic

University of Sydney

LifeHealthcare

Synthes


Melbourne Orthopaedic Spine

Mater Hospital

Medtronic

QUT IHBI

RJV P/L-ML Consulting

Metro Spinal Clinic

Tasman Spine

Stryker


Johnson & Johnson

Austin Health & Epworth Hospital

AOSpine

Presbyterian St. Luke's Medical Center


Washington University School of Medicine


ACSR-IMVS

QLD

NSW

NSW

NSW

VIC

NSW

NSW

NSW

VIC

NSW

VIC

VIC

WA

VIC

VIC

QLD

NSW

QLD

WA

VIC

TAS

VIC

NSW

VIC

QLD

VIC

NSW

WA

VIC

QLD

SA

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

[email protected]

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[email protected]

[email protected]

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[email protected]

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United States

United States

Notes & Questions

118

the spine society 22spinesociety.org.au/sites/default/files/1__ssahandbook_final_lowres_0.pdf ·...

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