radiation exposure in growing rod surgery for early onset scoliosis

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Behrooz A. Akbarnia, MD

Clinical Professor, University of California, San Diego

Medical Director, San Diego Center for Spinal Disorders

La Jolla, California

Magnetically Controlled Growing Rods (MCGR)

for

Early Onset Scoliosis (EOS)

UCSF Practical Course in Advanced Spinal techniques

Las Vegas, November 8, 2013

Disclosures (Growing Spine)

Growing Spine Foundation (a)

DePuy Spine (a,b)

Ellipse Tech. (a,b)

K2M (a,b)

Kspine (b)

a. Grants/Research Support b. Consultant c. Stock/Shareholder d. Speakers’ Bureau e. Other Financial Support

Treating very young children

with progressive EOS remains challenging…

Early Onset Spinal Deformity Challenges in EOS

• Many etiologies

• Many different treatments

• High rate of complications

• Limited outcome measures

• Comparisons difficult!

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• Options between growing rods, nonoperative treatment, VEPTR, Shilla, and fusion.

• Practical variation exists (as each patient needs special consideration) but consensus exists on the utility of GR in EOS specifically about starting age, curve and etiology.

• Vitale Study

J Ped Ortho 2010

No Evidence Based (EBM) Data

OBM (Opinion Based)

Literature Review

Growing Spine Study Group Growing Spine Foundation

Growing Spine Organization Acknowledgement

GSSG Sites

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GSSG- San Diego Site

Rady Children’s Hospital EOS Program

Development and Initial Validation of a Novel Classification System in Early Onset Scoliosis

Brendan A. Williams1, MD; Hiroko Matsumoto1, MA; Daren J. McCalla1, BS; Behrooz A. Akbarnia2, MD;

Laurel C. Blakemore3, MD; Randal R. Betz4, MD; John M. Flynn5, MD; Charles E. Johnston6, MD;

Richard E. McCarthy7, MD; David P. Roye Jr.1, MD; David L. Skaggs8, MD; John T. Smith9, MD;

Brian D. Snyder10, MD, PhD; Paul D. Sponseller11, MD, MBA; Peter F. Sturm12, MD;

George H. Thompson13, MD; Muharrem Yazici14, MD; Michael G. Vitale1, MD, MPH.

Cobb Angle Etiology Congenital/Structural Neuromuscular Syndromic Idiopathic

Results Not

Useful Useful Essential CVR

Sum of Ranks

COBB 0 1 14 0.87 29

ETIOLOGY 0 3 12 0.60 27

KYPHOSIS 0 4 11 0.47 26

AGE 5 0 10 0.33 20

PROGRESSION 3 5 7 -0.07 19

CHEST WALL ABNORMALITIES 2 9 4 -0.47 17

FLEXIBILITY 4 6 5 -0.33 16

OTHER CO-MORBIDITIES 3 8 4 -0.47 16

PULMONARY FUNCTION 3 9 3 -0.60 15

AMBULATORY ABILITY 2 12 1 -0.87 14

NUTRITIONAL STATUS 5 8 2 -0.73 12

MENTAL FUNCTION 10 5 0 -1.00 5

BONE QUALITY 11 4 0 -1.00 4

Vitale et al

Etiology

Congenital/

Structural

Neuromuscular

Syndromic

Idiopathic

Cobb Angle

1: <20°

2: 21-50°

3: 51-90°

4: >90°

Kyphosis

(-): <20°

N: 21-50°

(+): >50°

APR Modifier

P0: <10°/yr

P1: 10-20°/yr

P2: >20°/yr

Classification of EOS (C-EOS)

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Validation Studies (ICEOS)

Risk by Classification: Lower Risk of Rapid Failure • Congenital (21-50& 51-90); C2, C3 • Syndromic (21-50); S2 • Idiopathic (51-90); I3 Higher Risk of Rapid Failure • Congenital (>90); C4 • Neuromuscular (>51-90); N3 • Neuromuscular (>90); N4 • Syndromic (51-90); S3

Flynn, Vitale et al.

Questions to be addressed:

• Why children with EOS need treatment?

• What are the goals of treatment?

• What are the treatment options including growth friendly options?

• What are the expected outcomes?

• Can we minimize complications?

• What to expect in the future?




• What are the options?

• Non-fusion options


• What is the expected outcomes?


Natural History Untreated Scoliosis

•Infantile: 0 to 3 years

•Juvenile: 4 to 9 years

•Adolescent: 10 to 16 years

Pehrsson, Larssson, Oden & Nachemson, Spine,

1992

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Thoracic Insufficiency Syndrome

The Inability of the Thorax to Support

Normal Respiration

Or

Lung Growth

Campbell, Smith, et al.

J BJS Mar, 2003

J BJS Aug, 2004

Thoracic Insufficiency Syndrome Poor Quality of Life

• Among the

lowest

observed in

pediatrics

– Asthma

– JRA

– Heart

transplant

QOL in Pediatrics

53

7569

63

85

0

20

40

60

80

100

TIS Asthma JRA Heart X Norms

Vitale, JPO, 2008









Treatment Goals

Deformity Correction ( spine and chest )

and maintenance of correction

Improve pulmonary and spinal function

Normalize the spinal growth and avoid

early fusion (maintain mobility)

Minimize complications

Improve quality of life and the care of the

patient

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Fusing scoliosis early may contribute to

shortening of the thoracic spine, TIS, and

respiratory insufficiency

• 28 pts, early thoracic fusion before the age 9 years,

– evaluated by pulmonary function testing at a minimum of 5 years f/u

– compared to age matched controls

• Average age at surgery was 3.3 yrs and at follow up was 14.6 yrs.

• Thoracic spinal height FVC < 50%

< 18 cm 63% pts

18 to 22 cm 25% pts

22 cm to normal† 0% pts

† normal 28 cm males, 26 cm females

Karol, et al., JBJS 2008, 90: 1272-1281.

Deceased

13 cm









Treatment Options

• Non-operative treatment (cast, Brace, traction)

• Spine based growing rods

• Rib-based distraction

• Hybrid?

• Growth modulation

• Guided growth

• Early fusion

History

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Casting and Bracing is well tolerated Questions to be addressed:








Growth Friendly Implant Classification

1. Distraction based – Growing Rods

– VEPTR

– MCGR

2. Guided Growth – Luque-Trolley

– Shilla

3. Tension Based – Tether

– Staple

>age 8

Non-congenital

< age 8 ? All etiologies

< age 9 ?

All etiologies

< age 9 ?

All etiologies

Skaggs

ONLY VEPTR IS APPROVED in USA

Indications for Growth-Friendly Surgery

• Progressive curves not controlled or amenable to bracing or casting

• Curves where growth preservation would be beneficial

• Curves that require management of both the chest wall and the scoliosis

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Absent Ribs: Expansion Thoracoplasty by Multiple Devices

Shilla

3 level fusion

compression

distraction

derotation

Open Screws – no fusion

no bone exposed

allow rod to slide

multiaxial

Richard McCarthy

Preop Postop 1 year Postop

Newton

Single Rod Techniques

Growing Rods

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Growing Rods Distraction Based – Rib Anchors

+/- thorocotomy

Comparison of spine and Rib anchors

• All specimens eventually failed at the bone-anchor interface. No failures were observed in the instrumentation utilized.

• Young’s Modulus was calculated for each construct type and no statistically significant difference was determined.

Construct Type Maximum load for failure (Mean & Standard Deviation)

(Screw-Screw) SS 349 89 N

(Laminar Hook-Hook) HH 283 48 N

(Rib Hook-Hook) RR 429 133 N

(Transverse Process-Laminar Hook-Hook) TPL 236 60 N

Rib to Spine

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• EOSQ being collected prospectively

Quality of Life Outcomes

RESULTS (cont’d)

GROUP Cobb Angle (Pre-Initial to

Post Final)

%

Correction

Increase in

T1-S1

Length

Single with

apical

85° → 65 ° 23% 6.4cm

Single w/o

apical

61° → 39 °

36% 7.6cm

Dual w/o

apical

92° → 26°

71% 11.8cm

Growth per Year (cm)

• Total Group 1.21

• Under 5 years 1.19

• 5-10 year 1.13

• Under treatment 1.01

• Post final fusion group 1.66

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250

270

290

310

330

350

370

390

410

Apr

-98

Dec

-98

Oct-9

9

Oct-9

9

Sep

-00

May

-01

Oct-0

1

Sep

-01

May

-03

Feb-

04

Jan-

05

Dec

-06

0

10

20

30

40

50

60

70

80

90

100

T1-S1 Length

Length of Implant

Cobb Angle

Age 3 +11 Age 12 + 7

3 + 10 Year Old Girl With Marfan’s 7 + 8 yrs Follow Up

Final Fusion

13 cm

RESULTS

mm

.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

Change in T1-T12 (Pre-op to Latest Follow-up)

∆ in T1-T12 was greater in the 4-6 and ≥7 groups (p<0.001)

3 (n=17)

4-6 (n=19)

>7 (n=15)

Number of Spinal Distractions

Mean # of distractions = 5.4 (Range: 3–11)

Early onset scoliosis treated with Growing Rods has more growth and better Cobb correction but

more surgeries compared to Shilla

• 37 GR 37 Shilla

• Same FU (4.1 vs 4.6)

• T1-S1 ( 8.5 vs 6.4)

• Cobb angle Change ( 36 vs 23)

• Number of surgeries (7 vs 2.8)

Lindsay M. Andras, MD1; Elizabeth R. A. Joiner, BS1; Richard E. McCarthy, MD2; Scott J. Luhmann, MD3; Paul D. Sponseller, MD4; John B. Emans5, MD; David L. Skaggs, MD1 and Growing Spine Study Group

ICEOS 2012

Progression

86° 103

33

128

134

2+6

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No Trach. Normal activity









Adequate or Classic

Inadequate

Supra-laminar

Infra-laminar

Cross link

ANCHORS

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Significance of sagittal alignment

• Syndromic patients with early onset scoliosis

with thoracic kyphosis over 40 degrees who

undergo growing rod treatment should be

monitored very closely for complications,

particularly for implant failure

Final outcome at final FU

GR treatment abandoned in 11 out of 42 patients (26%)









Magnetically Controlled

Growing Rod

(MCGR)

Phenix MAGEC

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• The use of remotely controlled

lengthening devices has been

previously reported. (Takaso

et al., Soubeiran et al.)

• Goal of MCGR: To reduce

frequency of surgeries while

still providing distraction

Introduction

• The complication risk increased by 24% for each additional

surgical procedure.

• Growth-guided procedures, may reduce the number of

procedures, but do not provide any distraction.

December 2010

Growth modulation with current Growing Rod (GR)

techniques require frequent surgical lengthening and has a high risk of complications

Introduction

2012 • Magentically controlled growing rods (MCGR) were

developed to allow for non-invasive lengthening

• Pre-clinical studies has shown promising results

INTRODUCTION

Spine 2012

• 7-9 levels were un-instrumented between cephalad and caudal foundations

• 7 mm of remote distraction was performed weekly for 7 weeks in EG under sedation

• Implants were removed at week #7

• Animals were sacrificed 3 weeks after implant removal

METHODS

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• MCGR was shown to be safe and effective in this study

• No complication resulted directly from distraction

• MCGR distinguishes itself by:

• Distraction accuracy / prediction

• Ability to shorten

CONCLUSIONS

--------------------------------------

-

MCGR Technology

Implantable spinal rod

with magnetic actuator

External remote controller

non-invasive adjustment

Example of current

physician directed

adjustable rod.

Requires surgical

intervention for

adjustment

MAGEC

• This study was designed to evaluate the

safety and efficacy of the MCGR technique in

patients with early onset scoliosis

• 33 MCGR patients in 4 centers (Hong

Kong, London, Cairo and Ankara)

• 14 patients met the inclusion criteria

(1) EOS of any etiology

(2) Minimum of 3 distractions

• T1-T12, T1-S1 and height of

instrumented spine was measured

Materials and Methods

Instru

men

ted h

eight o

f the

spin

e

Actu

ator exp

ansio

n

T1-T1

2

T1-S1

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• 14 patients:(7 M, 7 F)

• Mean age: 8 y+10 m

(3 y+6 m to 12 y+7 m)

• 14 initial surgeries

• 68 distractions

Materials and Methods

36%

29%

14%

14% 7%

Etiology

Idiopathic Neuromuscular

Congenital Syndromic

NF

• 5 single rod (SR) and 9 dual rod (DR)

• Average of 10 months follow up (6-18).

• An average of 4.9 distractions per patient

• Mean interval between index MCGR and the

first distraction was 66 days

• Mean interval between two subsequent

distractions was 43 days

Results

• Initial and final Cobb correction were significant in each group.

• Curve correction from initial post-op to final was maintained in both SR

and DR groups.

Results (Height)

T1-T12 (mm) T1-S1 (mm)

Pre

in

dex

Po

st

ind

ex

Fin

al

To

tal G

row

th*

Mo

nth

ly G

row

th

P v

alu

e

Pre

in

dex

Po

st

ind

ex

Fin

al

To

tal G

row

th*

Mo

nth

ly G

row

th

P v

alu

e

Total 177.9 197.7 208.2 10.5 1.65 <0.05 292.4 322 338 16 2.44 <0.05

Single 177.8 196.4 204 7.6 1.09 <0.05 295 322 331 9 1.27 <0.05

Dual 178 198.4 210.5 12.1 1.97 <0.05 290.6 322 342.2 20.2 3.09 <0.05

P > 0.05 P < 0.05

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1.27 mm

3.09 mm

2 mm

1.2 mm 1.22 mm

Mean Monthly T1-S1 Height Change (mm/mo)

MCGR Single Rod MCGR Dual Rod Dimeglio 0-5 years

Dimeglio 5-10 years Original GR (Akbarnia)

N=9 N=5 N=23

Results - Mean Monthly T1-S1 Height Change

P<0.05

Case one: 5.5 y/o Female (NM)

T1-T12: 176 mm

T1-S1: 251 mm

T1-T12: 181 mm

T1-S1: 261 mm

45° 21°

Pre Index Post Index

∆T1-T12: 5 mm

∆T1-S1:10 mm

Case one: A 5.5 y/o NM female

Post Index Latest Follow up

21°

9°

T1-T12: 181 mm

T1-S1: 261 mm

T1-T12: 193 mm

T1-S1: 292 mm ∆T1-T12: 11 mm

∆T1-S1: 31 mm

Comparison Data

Pre-operative Most recent Result

GSSG Data (average follow up 28 months)

Cobb Angle (°) 77.6 ± 16.7 41.3 ± 16.6 47% deformity

correction

Thoracic Spine

Height (mm) 165.6 ± 22.1 203.5 ± 27.5

23% Increased

thoracic spine height

MAGEC Data (average follow up 7.6 months)

Cobb Angle (°) 58.8 ± 12.3 31.4 ± 9.3 47% deformity

correction

Thoracic Spine

Height (mm) 186 ± 28 212 ± 28

14% Increased

thoracic spine height

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MCGR Cheung, Cheung, Samartzis, Mak, Wong, Cheung,

Akbarnia, Luk (Lancet April 19,2012)

• Five patients , 2 with over 24 months follow

up

• Monthly distractions

• Scoliosis from 67 to 29 at 2 years

• 1.9 mm increase per distraction

• No Anesthesia, No pain

• No complications

Scoliosis

Spinal Length MCGR (Case 1)

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MCGR (Case 1) MCGR (Case 2)

Pre Op AP Post Op AP

MCGR- Case 2

12.3 mm

14.5 mm

Post Distraction June 2010

Courtesy of Ken Cheung, MD, University of Hong Kong, HK

B. A. Akbarnia, K. Cheung, G. Demirkiran, H. Elsebaie J. Emans, C. Johnston, G. Mundis, H. Noordeen, J. Pawelek M. Shaw, D. Skaggs, P. Sponseller, G. Thompson, M. Yazici,

Growing Spine Study Group

Traditional Growing Rods Versus Magnetically Controlled Growing Rods in Early Onset Scoliosis:

A Case-Matched Two Year Study

48th Annual Meeting of Scoliosis Research Society September 18-21, 2013 – Lyon, France

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2012-13 • Early clinical results of MCGR:

- Safe and effective - Significant reduction in the number of surgical procedures

INTRODUCTION

• The purpose of this study was to perform a case-matched comparison of MCGR and TGR patients with 2 years of follow-up

INTRODUCTION

MCGR TGR

NOT FDA APPROVED FOR USE IN U.S.

• Retrospective review of MCGR patients who met the following criteria: - < 10 years old

- Major curve >30º

- No previous spine surgery

- > 2-year follow-up

• 17 MCGR patients met the inclusion criteria

• 12 of 17 patients had complete data available for

analysis

METHODS

• Each MCGR patient was matched to a TGR patient by: - Etiology - Gender - Single vs. dual rods - Pre-op age (+/-10 months) - Pre-op major curve (+/- 20º)

• Etiologies were classified per C-EOS (Vitale): - Idiopathic - Congenital/Structural - Neuromuscular - Syndromic

• One male MCGR patient was matched to a female TGR

patient since a male-male match could not be found

METHODS

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Spinal growth calculation: “Annual T1-S1 Growth”

METHODS

Δ in T1-S1 from post index to latest F/U

Length of follow-up

Annual T1-S1 Growth (mm/year)

=

• MCGR patients: - Mean age = 6.8 years - Mean follow-up = 2.5 years

• Follow-up was greater for TGR patients by 1.6 years

• Distribution of etiologies:

- 4 Neuromuscular - 4 Syndromic - 3 Idiopathic - 1 Congenital

RESULTS

Pre-op

(mean)

Post-op

(mean)

>2 Yr Post-op

(mean)

Overall

Change

Major Curve

MCGR 59° 32° 38°

TGR 60° 31° 41°

T1-S1 Spinal Length

MCGR 270 mm 295 mm 307 mm

TGR 264 mm 311 mm 347 mm

RESULTS

35%

32%

38 mm

77 mm

p=0.01

RESULTS

• Overall curve correction – Similar between groups throughout treatment (p>0.1)

• Overall increase in T1-S1

– Greater in TGR compared to MCGR (p=0.01) – Possibly due to additional follow up of TGR patients (1.6

years)

• Annual T1-S1 growth

– 7 mm/year for MCGR – 11 mm/year for TGR patients – This difference did not reach statistical significance due to

sample size (minimum 10 mm/year to show significance)

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Total Open Surgeries

Total Lengthenings

MCGR 16 137 (non-invasive)

TGR 78 49

RESULTS (Procedures) RESULTS (Procedures)

Implant Complications

Wound Complications

Medical Complications

Number of Revisions

MCGR 10 1 3 4

TGR 15 3 5 23

• MCGR revisions included: anchor pull out, prominent implants and

collapse of device (all cases were generation 1 devices)

• TGR revisions included: anchor pull out, rod breakage, prominent

implants, planned surgery to exchange connector

Compassionate Use in U.S.

8+11 year old boy with Idiopathic EOS

top

right left


8+11 year old boy with Idiopathic EOS

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top

right left


8+11 year old boy with Idiopathic EOS • Major curve correction was similar between MCGR and

TGR patients throughout treatment

• Overall gain in T1-S1 was greater in TGR compared to MCGR, however, TGR had longer follow-up

• MCGR patients had 62 fewer surgical procedures than TGR patients and more non-invasive lengthenings

• Need to build consensus and develop practice guidelines for non-invasive lengthenings to reduce surgeon variability and improve reproducibility

Summary MCGR

THANK YOU

radiation exposure in growing rod surgery for early onset scoliosis

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