Purpose: The goal of laminectomy is to relieve spinal stenosis and improve radiculopathy. Back pain related to poor trunk muscular conditioning may negatively affect post-operative outcomes. A better understanding of this relationship is important to improve the selection of appropriate surgical candidates. The purpose of this study was to assess the association between cross-sectional lumbar paraspinal muscle area as measured by CT or MRI and outcomes following laminectomy.

Method: Prospective observational study of 23 patients undergoing primary elective lumbar laminectomy without fusion who were assessed with pre-operative CT scans. Clinical outcomes were measured with Numerical Pain Scale (NPS) for back and leg pain and the Oswestry Low Back Disability Index (ODI) at baseline and follow-up at a minimum of one year. Lumbar paraspinal muscle cross-sectional area was measured using digital imaging software and adjusted for percent fat infiltration; CT scans evaluations were blinded to clinical outcomes.

Results: There were significant improvements in clinical outcomes following laminectomy. ODI decreased from 53.9±11.8 (mean±standard deviation) at baseline to 27.3±20.6 after a follow-up of 15.2±3.5 months. A strong correlation existed between cross-sectional lumbar paraspinal muscle area after adjusting for infiltrating fat content an improvement in ODI (r=0.51, p< 0.02) or back pain NPS (r=0.55, p< 0.02). These relationships remained statistically significant after adjusting for age and body mass index. No significant associations were identified for improvements in leg pain NPS.

Conclusion: This study suggests a possible relationship between cross-sectional lumbar paraspinal muscle area and outcomes following laminectomy. This raises important questions regarding the role of trunk muscular conditioning in the etiology of back pain and success of surgery. Further research is required to refine this measurement as a tool to improve patient selection for surgery.