Risk factors for progressive collapse in osteoporotic vertebral compression fractures treated conservatively using a body cast

Purpose Studies on the risk factors affecting progressive vertebral body collapse are scarce. This study aimed to investigate the clinical and radiological factors related to progressive vertebral collapse following osteoporotic vertebral fracture under consistent conservative treatment using a body cast. Methods A total of 202 vertebrae (male, 164; female, 38) in 168 patients with acute osteoporotic vertebral fractures were examined. The association between the difference in compression rate between the first and final follow-up visits (> 6 months) and clinical and radiological factors, including abnormal signal on magnetic resonance imaging, fracture of the anterior or posterior cortical wall, and intravertebral cleft on computed tomography (CT), was analysed. Results The mean compression rate increased markedly by 6.9% during follow-up. Strong correlations were evident among radiological factors, and multiple linear regression models indicated that the intravertebral cleft (p < 0.001) was the only factor predicting progressive vertebral body collapse. Conclusion An intravertebral cleft ≥ 1 mm on CT was the only independent risk factor for progressive collapse during the 6-month follow-up of conservative treatment using a robust body cast for acute osteoporotic vertebral fractures. The results demonstrate the usefulness of CT scans in predicting the progression of vertebral collapse during the initial treatment phase and provide a basis for selecting subsequent treatment strategies.