ASSOCIATIONS BETWEEN SPINAL DEFORMITY AND OUTCOMES AFTER DECOMPRESSION FOR SPINAL STENOSIS

Study Design. Prospective observational study. Objectives. To examine associations between radiographic parameters (scoliosis and olisthesis ) and outcomes of surgery for degenerative spinal stenosis. Summary of Background Data, Preoperative degenerative scoliosis generally is tho ught to be associated with an unfavorable outcome of surgery for spina l stenosis. Data on the relationship between an increase in olisthesis after laminectomy for spinal stenosis and outcomes of surgery are spa rse and conflicting. Methods. Radiographs were obtained before surgery and at least 6 months after surgery and coded for preoperative scolio sis and change in olisthesis after surgery. The reviewers of radiograp hs were blind to outcome information. Patients completed questionnaire s on demographic and clinical data as well as on back pain, lower extr emity pain, walking capacity, and satisfaction with surgery. Associati ons between radiographic data and patient-reported outcomes were exami ned with the Spearman rank correlation and confirmed with multiple lin ear regression models that adjusted for potential confounders. Results . Ninety patients met eligibility criteria. Preoperative scoliosis was associated with less improvement in back pain at 6 months and at 24 m onths after surgery. An increase in olisthesis after surgery was assoc iated with greater improvement in lower extremity pain at 6 months and at 24 months after surgery. An increase in olisthesis also was associ ated with greater improvement in walking capacity at 6 months and at 2 4 months after surgery. In multivariable analyses that adjusted for po tential confounders, a change in olisthesis was not associated signifi cantly with greater improvement in any of the outcomes. Conclusion. Th e data support the widely held view that preoperative scoliosis is ass ociated with an unfavorable outcome after decompression for degenerati ve lumbar spinal stenosis. Increase in olisthesis was not associated w ith unfavorable results. In fact, there was a weak trend toward better outcomes with greater slip. These data indicate that minor increases in olisthesis after surgery for spinal stenosis generally are tolerate d well.