Relationship between Lumbar Extensor Muscle Degeneration Classification and Osteoporotic Vertebral Compression Fracture

ABSTRACT

STUDY DESIGN: Retrospective study. OBJECTIVES: To investigate the reliability of the lumbar extensor muscle degeneration classification as an indicator of potential risk for osteoporotic vertebral compression fractures (OVCF). SUMMARY OF LITERATURE REVIEW Fatty degeneration of lumbar extensor muscles has attracted increased interest in the literature as a risk factor for OVCF. MATERIALS AND METHODS: Ninety-one patients with OVCF (group 1) and 60 patients without OVCF (group 2) were investigated. Magnetic resonance imaging was used to measure and to analyze the muscle mass and fatty degeneration of the lumbar extensor muscle. The degree of fatty degeneration of the lumbar extensor muscle was classified into 4 stages less than 10%, 10%–25%, 25%–50%, and more than 50%. RESULTS: Fatty degeneration of the lumbar extensor muscle and the bone mineral density T-score were 29.66%±12.28% and −3.56±1.13 in group 1 and 24.04%±13.29% and −2.27±1.46 in group 2, which were statistically significant differences (p < 0.05). Logistic regression analysis revealed that as the fatty degeneration of the lumbar extensor muscle increased, the risk of OVCF increased (odds ratio [OR]=1.21; p=0.01). The risk of OVCF increased as the lumbar extensor muscle degeneration classification scores increased (OR=13.53; p=0.02). Furthermore, as the muscle mass of the multifidus decreased, lumbar lordosis and sacral inclination decreased (β=0.33; p=0.01 and β=0.25; p=0.04, respectively). However, no factor affected thoracic kyphosis. CONCLUSIONS: Fatty degeneration of the lumbar extensor muscle was correlated with OVCF. A lumbar extensor muscle degeneration classification higher than stage 3 should be considered a risk factor of OVCF.