• Mamoru Kawakami, Shin-ichi Nakao, Daisuke Fukui, Yasunori Kadosaka, Toshiko Matsuoka, and Hiroshi Yamada.
• *Spine Care Center, Wakayama Medical University Kihoku Hospital, Wakayama, Japan †Department of Orthopaedic Surgery, Wakayama Rosai Hospital, Wakayama, Japan; and ‡Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan.
• Spine. 2013 Nov 1;38(23):E1461-8.

Study DesignRetrospective comparative cohort study.ObjectiveTo 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 DataExposure 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.MethodsFifty-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.ResultsThe 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.ConclusionThe MM operation was less invasive and produced superior clinical outcomes compared with laminectomy involving exposure of the PVM.

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