Purpose: To prospectively investigate the long-term clinical outcomes of microendoscopic laminotomy (MEL) in patients with lumbar spinal stenosis (LSS) with and without degenerative spondylolisthesis (DS).
Methods: In total, 159 patients (mean age, 68 years) who had undergone MEL for single-level LSS at L4/5 at our institute were recruited and followed-up for 5 years. Patients with and without DS were assigned to the DS (n = 71) and control (n = 88) groups, respectively. In addition to slippage rate, Japanese orthopedic association (JOA), recovery rate, short-form 36 (SF-36), and Roland-Morris disability questionnaire (RDQ) values were evaluated preoperatively and 5 years postoperatively. All parameters were analyzed by Student's t test, with p < 0.05 considered statistically significant.
Results: Of 159 patients, 12 were lost to follow-up (follow-up rate, 92.5%); moreover, 15 patients were excluded because of death, cerebral infarction, dementia, or terminal cancer. Thus, 132 patients (DS group: 61, control group: 71) were finally examined. No significant differences were found in preoperative JOA, JOA recovery rate, RDQ, and SF-36 values between groups. The slippage rate in the DS group was 18.1% preoperatively and 16.8% at 5 years postoperatively (p > 0.05). There was no significant increase in instability in those with DS following MEL. Progressive spinal instability was noted in six patients (9.8%) and five patients (7.0 %) in the DS and control groups, respectively (p > 0.05). Moreover, the success rate of MEL was good/excellent in 70%, fair in 20%, and poor in 10 % of patients in both groups.
Conclusion: MEL showed similar outcomes in patients with DS and in those without DS.