Association of strength, muscle balance, and atrophy with pain and function in patients with degenerative spondylolisthesis

PURPOSE: To analyze the relationship of strength, muscular balance, and atrophy with pain and function in patients with degenerative spondylolisthesis. STUDY DESIGN: Transversal, descriptive, and observational. PATIENTS AND METHODS: Institutional review board approval was obtained for this study. Twenty six patients ages 50 years and older, with degenerative spondylolisthesis at L4-L5. Measurements included Pain Visual Analogue Scale scores (VAS), Oswestry Disability Index scores (ODI), and isokinetic trunk testing; assessment of multifidus atrophy and spinal stenosis was performed by Magnetic Resonance Imaging (MRI). STATISTICS: Statistical analysis was performed using SPSS version 17.0 software for Windows. Pearson's correlation was used to ascertain the correlation between variables. ANOVA with analysis of covariance was used to determine the correlation between the remainder variables. Significance was set at p < 0.05. RESULTS: Of the 26 patients studied, with an average age of 60.23 +/- 7.6 years, 20 had grade I spondylolisthesis and 6 were grade II. Correlation between the ODI scores and spondylolisthesis grading was significant (r = 0.576, p = 0.005); correlation between agonist/antagonist ratio in the isokinetic test (predominant extensor muscles over flexors) with the ODI scores was also significant (r = 0.446, p = 0.02), regardless of spinal stenosis. No correlation was found between functionality and pain with strength or multifidus atrophy. CONCLUSION: Muscle trunk imbalance with predominance of extensor over flexor muscles is associated with functional disability. Rehabilitation programs should be designed to improve muscle balance rather than muscle strength alone.