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.