110S Proceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

neurological compromise. Revision increased the avg no. levels fused to

6.1. One death and persistent neurologic deficit in 2 patients occurred.

There was no correlation between instrumentation position and fracture

(screw-endplate relationship). Age, female gender and multiple fusion

levels at the index OR may be risk factors.

CONCLUSIONS: Acute Adjacent Segment Fracture is a rare yet cata-

strophic complication of fusion with instrumentation for spinal stenosis.

Urgent attention to revision decompression, fusion and instrumentation

is required. Advancing age, multilevel fusions and female gender are iden-

tified risk factors. This entity deserves further study.

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

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.259

P18. Evaluation of Pelvic Fixation in Neuromuscular Scoliosis:

A Retrospective Study in 55 Patients

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

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

Korea

BACKGROUND CONTEXT: There has been always a controversy about

pelvic fixation in neuromuscular scoliosis in literature. Some authors advo-

cate pelvic fixation while others do not feel necessity of pelvic fixation. In

addition, the indications for pelvic fixation are also different.

PURPOSE: To evaluate the indications of pelvic fixation in neuromuscu-

lar scoliosis patients.

STUDY DESIGN/ SETTING: A retrospective study to measure immedi-

ate post operative and final follow-up correction in Cobb’s angle and pelvic

obliquity in neuro muscular scoliosis.

PATIENT SAMPLE: Between 2002 and 2006 fifty-five neuromuscular

scoliosis patients underwent operation for correction and fusion for scoli-

osis with pedicle screw instrumentation. None of our patients received an-

terior procedure. There were 23 patient with cerebral palsy, 17 with

Duchenne muscular dystrophy, 9 with spinal muscular atrophy and 6 pa-

tients with other (3 polio, 1 each neurofibromatosis, osteogenesis imper-

fecta and post traumatic paralysis). Mean age at the time of operation

was 19.368.2 years (range, 8–43). There were 34 male and 21 female

patients.

OUTCOME MEASURES: We have measured the change in pelvic obliq-

uity over a period of 25 months among three groups; group I with initial

pelvic obliquityO15� and pelvic fixation, group II with initial pelvic ob-

liquityO15� and without pelvic fixation and group III with initial pelvic

obliquity!15� and without pelvic fixation. All patients underwent for cor-

rection and fusion for neuromuscular scoliosis using posterior-only pedicle

screw instrumentations. We have used iliac screws for pelvic fixation in se-

lected patient group.

METHODS: We analyzed the postoperative correction in Cobb’s angle and

pelvic obliquity using paired t-test and compared the correction rate. We

have also used paired t-test to observe the maintenance of the correction in

Cobb’s angle and pelvic obliquity in each group. We have also compared

the pre operative flexibility in each group with ANOVA test to find out any

difference. To find out any difference in severity of initial curve, preoperative

Cobb’s angle among three groups was analyzed using ANOVA test.

RESULTS: Comparing the Cobb’s angle correction among all three

groups there is significant correction post operatively and at final follow-

up. There is no significant loss of correction among all three groups

(p50.26). However, when pelvic obliquity was compared all three groups

displayed significant correction post operatively (p50.31); but group II ex-

hibited significant loss of correction at final follow-up when compared

with group I and group III (p50.015). Our results indicate that group II

patients had deterioration in pelvic obliquity at follow-up though immedi-

ate post-operative correction was similar.

CONCLUSIONS: Patients who have pelvic obliquity less than 15� do not

need pelvic fixation and they can maintain the correction over a long

period; while patients who have pelvic obliquity more than 15� require pel-

vic fixation to maintain the correction and balance over a long time.

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

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.260

P19. MRI Undersestimates Cervical Spondylolisthesis Compared to

Upright Radiographs

Jesse Pandorf, MD, Christopher Chaput, MD, Juhee Song, PhD,

Jared Allred, BS, Mark Rahm, MD; Scott and White / Texas A&M Heath

Science Center, Temple, TX, USA

BACKGROUND CONTEXT: With the increasing prevalence and avail-

ability of magnetic resonance imaging (MRI), plain radiographs are often

not taken until consultation with a specialist. Recent studies in the lumbar

spine have shown that supine positioning on MRI may make the abnormal

translation diminish or even disappear, and the same issue has been seen

with supine cervical MRI’s. Missed spondylolisthesis can prevent accurate

diagnosis of a source of neck pain and cervical myelopathy. No study to

date has addressed the utility of MRI in identifying spondylolisthesis.

PURPOSE: To compare upright lateral flexion films (ULF), upright lateral

neutral films (ULN) and MRI for measuring spondylolisthesis of the cer-

vical vertebral bodies.

STUDY DESIGN/ SETTING: Retrospective radiographic review of con-

secutive patients with a universally applied standard.

PATIENT SAMPLE: 127 patients with ULF, ULN and MRI images no

longer than one year apart from each other of the cervical spine seen in

an orthopedic clinic over a two year period.

OUTCOME MEASURES: Not applicable.

METHODS: Anterior translation of the C3-4 and C4-5 vertebral bodies

was measured using the Taillard method on ULF and ULN films and the

mid sagittal view on MRI. All radiographs and MRI images were captured

digitally and viewed using Centricity Enterprise Web v 2.1 viewer (GE

Healthcare Chalfont, St. Giles, U.K) and measurements were obtained