108S Proceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

STUDY DESIGN/ SETTING: Prospective, nonrandomized consecutive

series of patients undergoing surgery by a single surgeon.

PATIENT SAMPLE: Forty-two consecutive patients with painful DLS age

68 years(47-85 years) underwent posterior instrumented reduction/fusion

and ALIF in 21 patients at average 4.2 levels (3-6 levels) or TLIF in 21 at av-

erage 2.7 levels (1-4 levels). The decision of ALIF vs. TLIF was surgeon

preference. ALIF group curves were larger (34� vs 27�) with less lordosis

(25� vs 45�) pre-op. Follow-up averaged 38 months (24-68 months).

OUTCOME MEASURES: Oswestry Disability Index (ODI), visual ana-

log pain scores (VAS), and pain medication use were followed. Radiograph

measurements included the main scoliosis curvature, T12-S1 lordosis, cor-

onal and sagittal spinal balance, and pelvic incidence. Fusion was defined

as bridging bone on imaging without implant loosening and !3mm motion

on flexion-extension.

METHODS: Indications for surgery included painful stenosis, rotational

listhesis, or spinal imbalance failing O6 months conservative care. Cages

and BMP-2 were used in TLIF, and structural allograft or cages and

BMP-2 in ALIF. Posterior arthrodesis was achieved with local autograft

and allograft. The deformity in both groups was corrected by a combination

of direct translation, derotation, and compression/distraction on 5.5mm ti-

tanium rods. Posterior constructs averaged 6.8 levels(4-9 levels) for both

groups. Clinical and radiographic data was collected pre-op and post-op

6 weeks, 1 year, 2 years, and latest follow-up.

RESULTS: The ALIF group had 3 nonunions, 3 adjacent level fractures, 3

revisions for adjacent level degeneration, 3 infections, and one footdrop.

Revision surgery was performed in 8/21. Medical complications in this

group included 1 each pulmonary embolus, ileus requiring temporary co-

lostomy, and stroke. The TLIF group had 1 each infection, nonunion, ad-

jacent segment degeneration, transient footdrop, and additional surgery to

adjust coronal balance, with 3/21 requiring revision surgery. VAS for both

groups were similar: TLIF 6.7 pre-op(3-10) improved to 2.9(1-8), and

ALIF 6.5pre-op(0-10) improved to 2.9(1-7). Pain medication usage de-

clined post-op for both groups. Oswestry outcomes were also similar: TLIF

46.9(18-66) pre-op improved to 25.5(18-36), and ALIF 52.0(28-82) im-

proved to 31.0(0-64). Curve correction was similar: ALIF group curves

of 34�(13-49�) pre-op correcting 70% to 10�(0-18�). TLIF group curves

of 27�(14-64�) pre-op corrected 70% to 8�(0-22�). Lordosis improvement

was similar for both groups.

CONCLUSIONS: With current deformity correction techniques, both

ALIF and TLIF are effective adjuncts in DLS surgery, with similar defor-

mity correction and fusion rates. However, the complications with poste-

rior-only surgery for DLS appear to be significantly fewer.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.255

P14. Which is the Best Fusion Approach? A Nationwide Perspective

to the Surgical Treatment of Diffuse Cervical Spondylosis

Mohammed Shamji, MD, MSc1, Chad Cook, PT, PhD, MBA2,

Ricardo Pietrobon, MD, PhD, MBA2, Sean Tackett, BS2,

Christopher Brown, MD2, Robert Isaacs, MD2; 1Duke University, Durham,

NC, USA; 2Duke University Medical Center, Durham, NC, USA

BACKGROUND CONTEXT: Cervical spine fusion is performed for

various indications in patient populations ranging from young and

healthy to aged and frail. The choice of surgical approach is affected

by disease pathoanatomy, but also by age, medical comorbidities, and

the number of involved levels. Anterior fusion is more common for sin-

gle-level pathology in relatively young, healthy patients; and posterior

fusion is typically performed on older, more comorbid patients with mul-

tilevel disease. Consequently, retrospective comparisons of surgical ap-

proaches for cervical fusion will be impacted by this bias, and the

optimal management of multilevel cervical spine pathology remains

ambiguous with surgeon preference and experience playing a significant

role in choice of procedures.

PURPOSE: To define the levels of complications and resource utilization

related to multilevel cervical spine fusion surgery, and to evaluate the im-

pact of surgical approach on these outcomes.

STUDY DESIGN/ SETTING: A retrospective nationwide database study

of inpatient perioperative complications.

PATIENT SAMPLE: All patients undergoing multilevel (four to eight

levels) cervical spine fusion for degenerative disease between 2003 and

2005 at institutions represented in the Nationwide Inpatient Sample

database.

OUTCOME MEASURES: Measures of patient periprocedural mortality,

selected specific morbidities, and resource utilization were evaluated. Re-

source utilization included length of hospitalization, inflation-adjusted

cost, and likelihood of non-routine discharge to assisted living.

METHODS: Data for 8548 patients who underwent cervical fusion of

four to eight levels was collected from the Nationwide Inpatient Sample

database (2003-2005), and subjects were grouped by surgical approach

(anterior versus posterior). Descriptive statistics were used to compare

baseline characteristics, and bivariate analysis and logistic regression mod-

eling were used to evaluate the effect of surgical approach on mortality,

selected postoperative complications, length of stay, hospitalization cost,

and discharge disposition.

RESULTS: This observational study indicates that a posterior approach to

multilevel cervical fusion is associated with more respiratory complica-

tions, postoperative infections, symptomatic hematomas, and transfusions

when compared to an anterior approach. Resource utilization was nearly

double for those undergoing a posterior approach, including hospital length

of stay, inflation-adjusted cost, and likelihood of discharge to an assisted-

living facility. Not surprisingly, this study confirms that patients fused pos-

teriorly had a lower incidence of symptomatic postoperative dysphagia.

CONCLUSIONS: This nationwide study defines the incidence of mortal-

ity and the frequency of inpatient complications encountered during mul-

tilevel cervical fusion. The results suggest that immediate morbidity from

anterior approaches is less than those undergoing posterior fusion. Pro-

spective analysis is required to evaluate if these findings remain significant

in a randomized study population. Further, these results represent only

perioperative complications. However, based on the data presented herein,

when confronted with the patient requiring a four-level cervical fusion, the

anterior approach may offer an less risky and less costly option.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.256

P15. Unilateral Pedicle Screw Instrumentation in Minimally Invasive

Lumbar Fusion

Graham Hall, BS1, Jean-Pierre Mobasser, MD2; 1Indiana University,

Indianapolis, IN, USA; 2Indianapolis Neurosurgical Group, Indianapolis,

IN, USA

BACKGROUND CONTEXT: Bilateral pedicle screw instrumentation

has become a widely accepted technique for stabilization during single

level lumbar fusion. There is very little scientific data assessing whether

unilateral instrumentation could provide adequate stability for the inter-

body fusion process to occur.

PURPOSE: The purpose of this study is to assess whether unilateral screw

placement has an equivalent efficacy to bilateral screw placement in allow-

ing bone fusion to occur. If unilateral screw placement is proven to be

equivalent, then using this approach will: reduce patient morbidity, reduce

blood loss, decrease operative times, reduce cost, and result in less post-

operative pain.

STUDY DESIGN/ SETTING: This is a retrospective review looking at

follow up computed tomography scans 6–12 months after a minimally

109SProceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

invasive transforminal lumbar interbody fusion with unilateral percutaneous

pedicle screw instrumentation. Off-label use of rhBMP-2 was performed in

the interbody space in all cases.

PATIENT SAMPLE: 21 patients with unilateral instrumentation have had

follow up computed tomography scans in the 6–12 month post-operative

period to assess fusion.

OUTCOME MEASURES: This is a purely radiographic analysis to as-

sess interbody fusion with unilateral instrumentation. Independent neurora-

diologists reviewed all computed tomography scans and analyzed the

interbody fusion.

METHODS: All post-operative ct scans were performed at the same hos-

pital and 1mm slices with reformatted images were utilized to assess

fusion.

RESULTS: All 21 patients showed radiographic evidence of fusion be-

tween 6–12 months post-operatively. There were no non-unions observed

in this group of patients.

CONCLUSIONS: Unilateral pedicle screw instrumentation provides ade-

quate stability for the interbody fusion to occur.

FDA DEVICE/DRUG STATUS: Pedicle screw device: Approved for this

indication; rhBMP-2: Not approved for this indication.

doi:10.1016/j.spinee.2008.06.257

P16. Multi-level Posterior Vertebral Osteotomy for Correction of

Severe and Rigid Neuromuscular Scoliosis: A Preliminary Study

Hitesh Modi, MS, Seung-Woo Suh, MD, PhD, Yang Jae-Hyuk, MD;

Scoliosis Research Institute, Korea University Guro Hospital, Seoul, South

Korea

BACKGROUND CONTEXT: For correction of severe and rigid scoli-

otic curve, anterior-posterior combined or posterior vertebral column re-

section procedures are used. Anterior release is a burden for patient

with already compromised pulmonary functions and posterior column re-

section carries a high risk of neurologic damage as well as massive intra-

operative bleeding. Therefore, authors developed a new technique, which

avoids the both.

PURPOSE: It is a prospective study of 13 neuromuscular scoliosis pa-

tients with severe and rigid curves to determine the effectiveness and

amount of correction with this technique without anterior release.

STUDY DESIGN/ SETTING: Thirteen neuromuscular scoliosis patients

(7 CP, 2 DMD and 4 SMA) who had rigid curve more than 100 degrees

were selected for the study prospectively. All patients were operated with

posterior-only approach using pedicle screw construct.

PATIENT SAMPLE: There were seven males and six females with an av-

erage age of 21 years (range, 13–32 years). There were nine thoraco-lum-

bar curves, three lumbar curves and one thoracic curve. Average

preoperative Cobb’s angle in coronal plane was 118.2� (range, 100�-150�) with flexibility of 20.3% (average 24.1�, range 10�-36�) on bending

radiograms.

OUTCOME MEASURES: The correction in Cobb’s angle, pelvic obliq-

uity and apical axial derotation were compared with paired t-test. For fur-

ther evaluation, we divided our patients in two groups: spastic and

paralytic groups and we evaluated our results between these two groups

using unpaired t-test. P value of less than 0.05 was considered significant

for all the statistical calculations.

METHODS: To achieve desired correction, multilevel vertebral osteoto-

mies were executed at three to five levels (apex and one or two level above

and below the apex) through laminectomy sites connecting from concave

to convex side. Once osteotomies were finished, repeated corrective ma-

nipulation was applied over temporary short segment fixation, above and

below the apex, on convex side. On concave side, the rod was fixed with

screws with manipulation followed by derotation maneuver. Finally, short

segment fixation removed and rod-screw construct fixed on convex side,

which was followed by posterior fusion. Intraoperative MEP monitoring

was applied for all patients.

RESULTS: Average follow-up was 25 months. Average preoperative

Cobb’s angle, pelvic obliquity and apical rotation were 118.2�, 16.7�

and 57� respectively. Average postoperative Cobb’s angle, pelvic obliquity

and apical rotation were 48.8�, 8� and 43� respectively showing 59.4%,

46.1% and 24.5% correction, which were significant statistically. Average

number of osteotomy level was 4.2 and average blood loss was 33566884

milliliters. Mean operation time was 330646 minutes and none of the pa-

tient required postoperative ventilator support. None of the patient dis-

played any signs of neurological or vascular injuries during or after the

operation.

CONCLUSIONS: We recommend multiple posterior vertebral osteoto-

mies for severe and rigid scoliosis because of following advantages: 1) it

provides release of anterior column under direct vision of cord; 2) it facil-

itates creep relaxation to the anterior as well as posterior structures and 3)

prevents need of anterior procedure, and reduces massive bleeding and

chances of neurological damage.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.258

P17. Acute Fracture of the End or Adjacent Level after Posterior

Lumbar Spine Fusion and Instrumentation

Edward Abraham, MD, Neil Manson, MD; Atlantic Health Sciences

Corporation, Saint John, New Brunswick, Canada

BACKGROUND CONTEXT: The incidence of Adjacent Segment

Degeneration after spinal fusion is variable with a third of cases requiring

revision surgery. Acute Adjacent Segment Fracture (AASF) of the end or

adjacent, proximal or distal vertebrae is not well recognized and sparsely

reported on. Associated neurological compromise and instability necessi-

tates urgent major revision surgery and subsequent potential morbidity

in this population.Identifying risk factors to prevent these catastrophies

from taking place is important.

PURPOSE: The purpose of this study was to determine the incidence of

AASF and to identify risk factors associated with its occurrance.

STUDY DESIGN/ SETTING: Acute fracture post spinal fusion was de-

fined as those presenting within 4 months.321 instrumented thoracolumbar

fusions were performed between 2005–07 and 13 cases of AASF were

identified. These patients were analyzed clinically and radiologically to

look at possible risk factors. The clinical presentation and treatment of

AASF was studied. This was a retrospective review of a prospective data

bank in one institution.

PATIENT SAMPLE: 13 cases of AASF were studied over the 2 yr time

period 2005–2007. These were decompression, fusion and instrumentation

surgeries performed at the index operation for spinal stenosis. 1 pt was a 2-

level and 12 were for O2 levels, all surgery performed in the same institu-

tion by the authors.

OUTCOME MEASURES: Patient demographics, fusion levels at index

operation, radiological analysis (sagittal, coronal axes; pre-fracture pedicle

screw instrumentation position, type of fracture), type of revision surgery

necessary and SF-36, ODI evaluations were outcome measures in this

study.

METHODS: 321 instrumented spinal fusions were reviewed between

2005–2007. 13 cases of AASF were identified presenting before 4 mos

post op and are the subject of this study. Type of fracture, neurological pic-

ture, radiological assessments and clinical evaluations were carried out.

Type of revision surgery and response were assessed.Incidence and risk

factors were identified.

RESULTS: The incidence of AASF in this group was 4%(13/321). The

overall incidence of Adjacent Segment Degeneration of all types was

25%, 8% requiring surgery. There were 12 females and 1 male in the

AASF grp, avg age 75, avg no. levels fused:3.5 at the index OR.9/13

had proximal and 5/13 had distal fractures. 2 pts required surgery for re-

peat fractures. 12/13 required surgery to address instability and