Clinical Outcomes and Biomechanical Evaluation of the Cement-Catching Screw Technique for Osteoporotic Vertebral Fractures

Objectives: We developed a cement-catching screw (CCS) technique for pedicle screw insertion into hardened cement, connecting anterior and posterior vertebral elements during balloon kyphoplasty (BKP) for osteoporotic vertebral fractures (OVFs). This study reports the CCS technique, clinical outcomes, and biomechanical properties.
Methods: This retrospective study included 59 patients (20 men, 39 women; mean age, 77.4 ± 8.7 years) who underwent BKP with one-above-one-below posterior fixation for OVFs between 2020 and 2023. Patients were divided into CCS (−) (without intermediate screws, n = 28) and CCS (+) (with intermediate CCSs, n = 31) groups. Clinical and radiographic outcomes, including activities of daily living, vertebral wedge angle (VWA), surgical level Cobb angle (CA), anterior vertebral body height (AVBH), screw loosening, pullout, and adjacent vertebral fractures, were evaluated preoperatively, postoperatively, and at the final follow-up (≥6 months). Biomechanical pullout strength was assessed at different insertion depths (5, 10, and 15 mm) using polymethylmethacrylate cement.
Results: No significant differences were observed between groups in age, sex, follow-up duration, or blood loss; however, the operation time was significantly longer in the CCS (+) group than in the CCS (−) group (P < 0.0001). Radiographic outcomes showed no significant differences in the VWA, CA, AVBH, adjacent vertebral fracture rates, and reoperation rates. However, the incidence of adjacent pedicle screws loosening and pullout was significantly higher in the CCS (−) group than in the CCS (+) group (P = 0.046 and 0.0084, respectively). The correction loss of the CA was significantly lower in the CCS (+) group (CCS (−), 5.6° ± 4.8°; CCS (+), 3.5° ± 4.8°, P = 0.023). The biomechanical test revealed pullout strengths of 683 ± 164, 2231 ± 208, and 3477 ± 393 N for insertion depths of 5, 10, and 15 mm, respectively, with significant increases by depth (P = 0.003 and 0.009).
Conclusions: The CCS technique improves anterior-posterior vertebral body stability, enhances fixation strength, and contributes to better surgical outcomes in OVFs treatment.