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 thought to be associated with an unfavorable outcome of surgery for spinal stenosis. Data on the relationship between an increase in olisthesis after laminectomy for spinal stenosis and outcomes of surgery are sparse and conflicting. Methods. Radiographs were obtained before surgery and at least 6 months after surgery and coded for preoperative scoliosis and change in olisthesis after surgery. The reviewers of radiographs were blind to outcome information. Patients completed questionnaires on demographic and clinical data as well as on back pain, lower extremity pain, walking capacity, and satisfaction with surgery. Associations between radiographic data and patient-reported outcomes were examined with the Spearman rank correlation and confirmed with multiple linear 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 months after surgery. An increase in olisthesis after surgery was associated with greater improvement in lower extremity pain at 6 months and at 24 months after surgery. An increase in olisthesis also was associated with greater improvement in walking capacity at 6 months and at 24 months after surgery. In multivariable analyses that adjusted for potential confounders, a change in olisthesis was not associated significantly with greater improvement in any of the outcomes. Conclusion. The data support the widely held view that preoperative scoliosis is associated with an unfavorable outcome after decompression for degenerative lumbar spinal stenosis. Increase in olisthesis was not associated with 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 tolerated well.