What Is the Effect of Spino-Pelvic Sagittal Parameters and Back Muscles on Osteoporotic Vertebral Fracture?

STUDY DESIGN: Case control study. PURPOSE: To examine the effect of spino-pelvic sagittal parameters and back muscles on osteoporotic vertebral fracture. OVERVIEW OF LITERATURE: Low bone mass is not the only important component of the risk on osteoporotic vertebral fracture; many other risk factors also contribute to skeletal fragility. METHODS: Seventy-two patients who had a lateral radiograph of the whole spine, magnetic resonance imaging of the lumbar spine, and bone densitometry, were enrolled. The spino-pelvic sagittal parameters (pelvic incidence, pelvic tilt [PT], sacral slope, thoracic kyphosis, lumbar lordosis), age, lumbar bone mineral density, and amount of back muscle around the lumbar spine were analyzed. RESULTS: There was higher sagittal imbalance of the spine in the vertebral fracture group (p=0.011). In spinopelvic parameters, the average of PT was 22.13° in vertebral fracture group and 13.70° in the non-fracture group (p=0.002). The amount of lower back extensor muscle in the vertebral fracture group was 2,170 mm(2), which was lower than the non-fracture group (3,040 mm(2), p=0.001). Multiple logistic regression analysis for the risk of osteoporotic vertebral fracture was significant in lumbar bone mineral density (odds ratio [OR], 0.313; 95% confidence interval [CI], 0.139-0.706, p=0.005) and the muscle ratio of extensor back muscle (OR, 0.902; 95% CI, 0.826-0.984; p=0.020). CONCLUSIONS: These results suggest that osteoporotic vertebral fracture could be developed easily by weakness of extensor back muscle in sagittal imbalance of the spine with high pelvic tilt.