Modified Marmot Operation Versus Spinous Process Transverse Cutting Laminectomy for Lumbar Spinal Stenosis

Study Design. Retrospective comparative cohort study. Objective. To compare clinical outcomes for lumbar spinal stenosis (>= 3 levels) treated with posterior decompression without exposing the paravertebral muscles (PVM) with outcomes from surgery with PVM exposure. Summary of Background Data. Exposure of the PVM can cause muscle injury and denervation, which may induce failed back syndrome. However, it is unknown whether lumbar spinal stenosis is more likely to lead to clinical improvement after PVM preservation than the procedure involving exposure of the PVM. Methods. Fifty-three patients with lumbar spinal stenosis were divided on the basis of the timing of the surgery into 2 groups: modified split-spinous process laminotomy (Marmot operation) (MM) group (26 patients) and spinous process transverse cutting laminectomy through a unilateral approach (control) group (27 patients). The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, visual analogue scale score of low back pain, and patients' satisfaction were assessed preoperatively and 1 year postoperatively. Operation time, blood loss, and creatine phosphokinase and C-reactive protein levels were measured 7 days postoperatively. Magnetic resonance imaging changes in the PVM were evaluated at the follow-up. Results. The preoperative visual analogue scale and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire scores did not differ between groups. The operation time did not differ between groups, but blood loss was less in the MM group than in the control group (129 vs. 205 mL) (P < 0.05). C-reactive protein (1.1 vs. 2.8 mg/dL) and creatine phosphokinase (68 vs. 253 IU/L) levels were lower in the MM group (P < 0.05). The visual analogue scale score for low back pain and patient satisfaction did not differ between groups. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire scores for pain-related disorders, gait disturbance, and social life disturbance improved significantly in the MM group compared with the control group (P < 0.05). Nine patients in the control group showed positive changes in the PVM. Conclusion. The MM operation was less invasive and produced superior clinical outcomes compared with laminectomy involving exposure of the PVM.