• Akihito Minamide, Munehito Yoshida, Hiroshi Yamada, Yukihiro Nakagawa, Hiroshi Hashizume, Hiroshi Iwasaki, and Shunji Tsutsui.
• Department of Orthopaedic Surgery, Wakayama Medical University, 811-1 Kimiidera, Wakayama City, Wakayama, 641-8510, Japan, minamide@wakayama-med.ac.jp.
• Eur Spine J. 2015 Feb 1; 24 (2): 396-403.

PurposeTo prospectively investigate the long-term clinical outcomes of microendoscopic laminotomy (MEL) in patients with lumbar spinal stenosis (LSS) with and without degenerative spondylolisthesis (DS).MethodsIn 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.ResultsOf 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.ConclusionMEL showed similar outcomes in patients with DS and in those without DS.

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