65. Indirect decompression for the treatment of degenerative lumbar stenosis: clinical outcome in a consecutive series of 568 patients

Abstract

BACKGROUND CONTEXT Surgical treatment of symptomatic lumbar stenosis has traditionally included laminectomy for direct decompression. With expanding options for lumbar interbody fusion, interest has been increasing in indirect decompression to treat degenerative stenosis. Segmental distraction afforded by these interbody techniques is thought to increase foraminal height and reduce ligamentous infolding, thereby indirectly decompressing neural elements. PURPOSE The primary purpose of this study was to determine whether indirect decompression via anterior lumbar interbody fusion (ALIF) can provide symptomatic relief in patients with lumbar spinal stenosis. Secondary purposes were to: (1) determine if risk factors for failure of indirect decompression could be identified, and (2) compare outcomes between patients undergoing stand-alone ALIF vs those with supplemental posterior fixation (ALIF+PF). STUDY DESIGN/SETTING This was a retrospective chart review study. PATIENT SAMPLE The study was based on a consecutive series of 568 patients undergoing single-level ALIF without posterior decompression to treat degenerative stenosis during a 5-year period. OUTCOME MEASURES Data recorded included general demographics, symptom type, Oswestry Disability Index (ODI) scores, visual analog scale (VAS) data separately assessing back and leg pain, and re-operations. METHODS Failure of indirect decompression was defined as return to the operating room for direct decompression. Patients who failed indirect decompression were compared to those who did not to determine whether differences between groups could be identified. An additional subgroup analysis was performed to compare outcomes of patients who underwent stand-alone ALIF (n=247) vs those in whom supplemental posterior fixation was used (ALIF+PF; n=321). RESULTS Re-operation due to failure of indirect decompression occurred in 4.0% (23/568) of patients. The only factor found to be related to failure was age. Patients greater than 60 years of age were more likely to fail indirect decompression than were younger patients (7.0% vs 3.1%, p 0.50). For example, prior to surgery, ODI scores were 44.0 and 43.8 in the ALIF and ALIF+PS groups, respectively. These improved significantly to 27.3 and 27.5 after surgery. The percentage of patients in the 2 groups undergoing re-operation for direct decompression was not significantly different (ALIF 4.9% vs. ALIF+PS 3.4%; p>0.05). CONCLUSIONS Indirect decompression via ALIF was effective in treating appropriately-selected patients with degenerative lumbar spinal stenosis. Significant improvements on ODI and pain scores were observed. Only 4% of patients underwent subsequent direct decompression. Increased age was the only identified risk factor for failure of indirect decompression. This may be related to increased osseous stenosis in older individuals, which may be less amenable to indirect decompression. There were no significant differences in clinical outcomes or re-operation rates when comparing ALIF vs ALIF+PF, suggesting that posterior instrumentation may be omitted without sacrificing the effectiveness of indirect decompression unless there is a well-defined indication for it. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.