Impact of Sarcopenia on Clinical Outcomes of Minimally Invasive Lumbar Decompression Surgery

The purpose of this study was to clarify the clinical impact of sarcopenia on the outcome of minimally invasive lumbar decompression surgery. The records of 130 patients who were >65 years and underwent minimally invasive lumbar decompression surgery were retrospectively reviewed. We collected the Japanese Orthopaedic Association (JOA) score before surgery and at the final follow-up and measured appendicular muscle mass using bioimpedance analysis, hand-grip strength and gait speed. We diagnosed the patients with sarcopenia, dynapenia and normal stages using the European Working Group on Sarcopenia in Older People definition and used cutoff thresholds according to the algorithm set by the Asian Working Group for Sarcopenia. The average age of patients undergoing surgery was 76.9 years old. The JOA score improved from 12.6 points preoperatively to 24.3 points at final follow up. The prevalence of the sarcopenia, dynapenia and normal stages was 20.0, 31.6 and 43.8%. Clinical outcomes, such as JOA score, JOA score improvement ratio, visual analog scale for low back pain, leg pain and numbness, were not significantly different among each group. Multiple regression analysis showed that preoperative JOA score and low physical performance (low gait speed) were independently associated with poor clinical outcomes. The JOA score improved after minimally invasive lumbar decompression surgery even when the patients were diagnosed as being at different stages of sarcopenia. Low physical performance had the greater clinical impact on the clinical outcome of lumbar surgery than low skeletal muscle index.