Effectiveness and Safety of Vertebral Body Stenting for Acute Spinal Compression Fractures due to Primary Osteoporosis: A Multicenter Prospective Clinical Study

Introduction: Segmental spinal deformity results from vertebral compression fracture (VCF) and progressive collapse of the fractured vertebral body (VB). The VB stenting (VBS) system^® comprises a balloon-assisted, expandable, intrasomatic, metal stent that helps maintain the restored VB during balloon removal and cement injection, which minimizes cement leakage. We performed a prospective, multicenter, clinical trial of the VBS system in Japanese patients with acute VCF owing to primary osteoporosis. Methods: Herein, 88 patients, 25 men and 63 women aged 77.4±8.3 years, with low back pain, numerical rating scale (NRS) score of !4, and mean VB compression percentage (VBCP) of <60% were enrolled. The primary endpoints were the VBCP restoration rate and reduction in low back pain 1 month and 7 days after VBS surgery, respectively. Secondary endpoints included changes in VBCP, NRS pain score, Beck index, kyphosis angle, and quality of life according to the short form 36 (v2) score. Safety was assessed as adverse events, device malfunctions, and new vertebral fractures. Results: Overall, 70 patients completed the study. VBS surgery increased the restoration rates of anterior and midline VBCP by 31.7%±26.5% (lower 95% confidence intervals (CI): 26.8) and 31.8%±24.6% (lower 95% CI: 27.2), respectively, and the reduction in NRS pain score was −4.5±2.4 (upper 95% CI: −4.0). As these changes were greater than the predetermined primary endpoint values (20% for VBCP and −2 for NRS score), they were judged clinically significant; these changes were maintained throughout the 12-month follow-up (p<0.001). Likewise, significant improvement was observed in the Beck index, kyphosis angle, and quality of life score, which were maintained throughout the follow-up. There were three serious adverse events. New fractures occurred in 12 patients-all in the adjacent VB. Conclusions: VBS surgery effectively restored the collapsed VB, relieved low back pain, and was tolerable in patients with acute osteoporotic VB fracture.