Use of Calibrated Screw Technique (CAST) for complex vertebral compression fractures: retrospective evaluation of clinical outcomes and indications

BACKGROUND: Vertebral compression fractures (VCFs), characterized by middle column involvement, osteonecrotic clefts, split morphology, or pedicle fractures, pose biomechanical challenges that reduce the effectiveness of conventional vertebroplasty and kyphoplasty. We evaluated the feasibility, safety, and clinical outcomes of the Calibrated Screw Technique (CAST), a minimally invasive approach combining percutaneous pedicle screw fixation and targeted cement augmentation, in patients with complex VCFs. METHODS: We retrospectively analyzed 147 consecutive patients (155 vertebral levels; mean age 80.1 years), primarily with osteoporotic fractures (80.6%), treated using CAST. Demographic, clinical, and radiographic data were collected at baseline, and at 1 and 6 months. Pain intensity was measured by the numeric rating scale (NRS), and patient perceived outcomes were assessed using patient global impression of change (PGIC). Radiographic outcomes included refracture rates at treated vertebrae, incidence of new fractures, and kyphotic angle correction in mobile fractures. RESULTS: CAST was technically feasible in all cases without major complications. Mean NRS scores improved significantly from 7.7 before the procedure to 3.6 at 1 month and 2.7 at 6 months (P < 0.0001). At the 1 month follow-up, 55.3% of patients reported feeling 'extremely' or 'much improved' on PGIC, increasing to 69.8% at 6 months. Radiographically, only one asymptomatic refracture occurred at 1 month (0.8%) and none at 6 months. New fracture incidence decreased from 13.8% at 1 month to 4.2% at 6 months. CONCLUSIONS: In this study, CAST provided a safe, technically feasible, and durable solution for stabilization and pain relief in complex VCFs unsuitable for conventional augmentation, highlighting its value for challenging VCFs.