The Influence of Different Injection Hole Designs of Augmented Pedicle Screws on Bone Cement Leakage and Distribution Patterns in Osteoporotic Patients

OBJECTIVE: To compare cement distribution and leakage for 2 bone cement-augmented screws with different designs of injection holes in patients and the impact of screw locations and bone mineral density (BMD) on the results. METHODS: This study recruited 40 patients who underwent instrumentation with cement-augmented screws. Screw holes of group A were 4 holes located in the distal one third of screws, while screw holes of group B were 6 holes located in distal, middle, and proximal sites. Postoperative computed tomography images were obtained to evaluate the rate and type of cement leakage and the distribution pattern of cement. The lateral or center position of screw tip, BMD, and T-score were also analyzed for their influence on the results. RESULTS: Of 192 screws, 80 (41.7%) exhibited cement leakage on postoperative computed tomography. The incidence of cement distribution in the posterior half and type B leakage in group B was significantly higher compared with group A. In group A, the probability of cement distribution in the posterior half was significantly increased when the screw was laterally inserted. For both groups, the higher incidence of cement distribution in the posterior half was correlated with lower BMD and T-score. CONCLUSIONS: Our results showed that screws with injection holes closer to the screw tip had higher incidences of distribution in the anterior half of the body and lower incidences of type B leakage. Patients with lower BMD and T-scores should be closely monitored, and a more centered position is recommended for screw insertion.