104S Proceedings of the NASS 26th Annual Meeting / The Spine Journal 11 (2011) 1S–173S

JOA recovery rate, Oswestry-Disability Index (ODI), Roland-Morris

Questionarre (RMQ).

RESULTS: The ODI and RMQ score rapidly decreased at initial two

weeks postoperatively in MIS-PLF group, and consistently maintained

lower values than those in open-PLF group at 3, 6, 12 and 24 months post-

operatively. The %Area4/5 and %Area5/S1 in open-PLF group demon-

strated the average values of 96% and 86%, resepectively, which were

consistently lower than those in MIS-PLF (101%, 90%). However, there

were no significant differences between two groups. %Density4/5 was

98% in both groups, however, %Density5/S1 was significantly lower in

open-PLF (81%) than that in MIS-PLF (94%). The correlation coeficients

between %Density5/S1 and age, JOA recovery rate, and RMQ score were

0.61, 0.60, and -0.80, respectively.

CONCLUSIONS: The minimally invasive lumbar posterolateral fusion

with percutaneous pedicle screw system successfully improved the residual

low back pain and patients’ QOL even after two-year postoperatively. Ac-

cording to the MRI evaluation of multifidus muscle, conventional open-

PLF led to the increase of T2 signal intensity in multifidus muscle at

L5/S1 level, when compared to MIS-PLF group. This change can be ex-

plained by the increased invasiveness to the multifidus muscle and poste-

rior ramus, reflecting the degeneration and denervation of the muscle

tissue. Importantly, this muscle density parameter correlated with JOA re-

covery rate and RMQ score, suggesting a possible reason for the residual

low back pain in conventional PLF. The minimally invasive PLF serves as

the useful surgical modality in decreasing the invasiveness to the back

muscle and residual back pain.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2011.08.257

200. Retrolisthesis and Lumbar Disc Herniation: A Postoperative

Assessment of Patient Function

Kevin Kang, MD1, Michael Shen, MD2, Wenyan Zhao3, Jon D. Lurie, MD4,

Afshin Razi, MD5; 1Brooklyn, NY, USA; 2Broomfield, CO, USA; 3Hanover,

NH, USA; 4Dartmouth College, Lebanon, NH, USA; 5Rego Park, NY, USA

BACKGROUND CONTEXT: The presence of retrolisthesis has been as-

sociated with degenerative changes of the lumbar spine. However, retrolis-

thesis in patients with L5-S1 disc herniation has not been shown to have

a significant relationship with worse baseline pain or function. Whether

it can affect outcomes following discectomy has yet to be established.

PURPOSE: The purpose of this study was to determine the relation be-

tween retrolisthesis (alone or in combination with other degenerative con-

ditions) and postoperative low back pain, physical function, and quality of

life. This study was intended to be a follow-up to a previous investigation

that looked at preoperative assessment of patient function in those with ret-

rolisthesis and lumbar disc herniation.

STUDY DESIGN/SETTING: Cross-sectional study.

PATIENT SAMPLE: Patients enrolled in the SPORT (Spine Patient Out-

comes Research Trial) study who underwent L5-S1 discectomy and who

had a complete MRI scan available for review (n5125). Individuals with

anterolisthesis were excluded.

OUTCOME MEASURES: Time weighted averages over 4 years for the

SF-36 Bodily pain scale, SF-36 Physical function scale, Oswestry Disabil-

ity Index (ODI), and Sciatica Bothersomeness Index (SBI).

METHODS: Retrolisthesis was defined as posterior subluxation of 8% or

more. Disc degeneration was defined as any loss of disc signal on T2 im-

aging. Modic changes were graded 1–3 and collectively classified as ver-

tebral endplate degenerative changes. The presence of facet arthropathy

and ligamentum flavum hypertrophy was classified jointly as posterior de-

generative changes. Longitudinal regression models were used to compare

the time-weighted outcomes over 4 years.

RESULTS: Patients with retrolisthesis did significantly worse in regard to

bodily pain and physical function over 4 years. However, there was no

All referenced figures and tables will be available at the Annual Mee

significant difference in terms of ODI or SBI. Similarly, retrolisthesis

was not a significant factor in operative time, blood loss, length of stay,

complications, rate of additional spine surgeries, or recurrent disc hernia-

tions. Disc degeneration, modic changes, and posterior degenerative

changes did not affect outcomes.

CONCLUSIONS: Although retrolisthesis in patients with L5-S1 disc her-

niation did not affect baseline pain or function, postoperative outcomes ap-

peared to be somewhat worse. It is possible that the contribution of pain or

dysfunction related to retrolisthesis became more evident after removal of

the disc herniation.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2011.08.258

201. Direct Versus Indirect Decompression and Stabilization:

A Comparison of Clinical Outcomes with Coflex� Interlaminar

Stabilization, Laminectomy and Spinal Fusion, and X-STOP to Treat

Spinal Stenosis and Low-Grade Degenerative Spondylolisthesis

Joshua Auerbach, MD1, Reginald Davis, MD, FACS2; 1Brooklyn, NY, USA;2Greater Baltimore Neurosurgical Assoc., Baltimore, MD, USA

BACKGROUND CONTEXT: Interspinous process device technologies

have been developed to complement conservative care, laminectomy,

and laminectomy with or without spinal fusion as treatment options for

spinal stenosis and low grade degenerative spondylolisthesis. While the

X STOP interspinous implant relies upon indirect decompression and fix-

ation to the spinous processes, the coflex� interlaminar stabilization de-

vice is implanted following a direct neurologic decompression, and is

fixated to the stronger laminar bone.

PURPOSE: To compare 2-year functional outcomes in patients treated

with X STOP, coflex� interlaminar stabilization device, or spinal fusion

in the treatment of spinal stenosis with up to Grade 1 spondylolisthesis.

STUDY DESIGN/SETTING: Comparative analysis of the results of two

separate, independent, randomized, prospective, multicenter Food and

Drug Administration Investigational Device Exemption trials comparing:

1) conservative care with X STOP, and 2) direct decompression and

coflex� interlaminar stabilization with decompression and fusion.

PATIENT SAMPLE: In the coflex� IDE trial, a total of 219 patients

(146 coflex� and 73 fusion controls) were randomized and treated from

21 US sites to receive direct decompression and coflex� interlaminar sta-

bilization or laminectomy and posterolateral spinal fusion with spinal in-

strumentation in a 2:1 ratio. In the X STOP IDE trial, a total of 191

patients (100 X STOP and 91 controls) were randomized and treated from

9 US sites to receive X STOP or to continue with conservative treatment.

OUTCOME MEASURES: The primary outcome measure was Zurich

Claudication Questionnaire, a patient-reported validated functional out-

comes instrument for spinal stenosis and neurogenic claudication. Compos-

ite success criteria required a 0.5 point improvement in ZCQ-Physical

Function and ZCQ-Symptom Severity, and !2.5 in ZCQ-Patient

Satisfaction.

METHODS: In both IDE trials, patients were eligible for enrollment if

they had spinal stenosis and up to Grade 1 spondylolisthesis at 1-2 levels.

Data were evaluated at baseline and at the 24 month time points.

RESULTS: At 2 years, Composite ZCQ success was achieved in 75.7% of

coflex� patients, compared with 68.3% of fusion controls, and 48.4% of

X STOP patients (Table). The proportion of patients achieving success

was significantly higher in the coflex� cohort than in the X STOP cohort

(p5.02). There were no significant differences between the coflex� and

fusion cohorts (p5.30), nor in the fusion and X STOP cohorts (p5.31).

CONCLUSIONS: coflex� interlaminar stabilization following direct de-

compression facilitated superior ZCQcomposite success at 2 years compared

with X STOP to treat spinal stenosis and degenerative spondylolisthesis, and

nonsignificant improvements over laminectomy with spinal fusion. Our data

suggests that there are clear benefits of direct neurologic decompression that

ting and will be included with the post-meeting online content.