Biomechanical analysis of detachable duet screw to resist intraoperative screw loosening.

Abstract

Purpose Pedicle screws are widely used in spinal fusion surgery, while screw loosening frequently occurs during spinal deformity correction. The aim of this study was to evaluate whether detachable duet screw can resist cutting or breach of pedicle walls under tensile test. Methods In this study, a novel duet screw was designed and developed for the purpose of spinal deformity correction. Eight spine specimens from goats were used and divided into two groups: group A (traditional insertion) and group B (combination of two detachable duet screws). Prior to biomechanical testing, the average density of the vertebrae was determined using quantitative computed tomography (QCT). To simulate the distraction or compression process during spinal deformity correction, loading was applied to the side of the screw through the rod, which was perpendicular to the pedicle screw axis. The process from initiation to the breach of the pedicle was assessed in order to determine the effectiveness of the duet screw. Results The quantitative computed tomography (QCT) analysis revealed that the average bone density of the entire goat population was 500.63 ± 37.88 mg/cm3. In group A and group B, the mean maximum failure load (MFL) was determined to be 1052.38 N and 1762.25 N, respectively. Notably, the average MFL exhibited a significant increase in group B compared to group A (P < 0.05). Conclusion The implementation of detachable duet screws exhibits the potential to enhance the resistance against screw loosening by connecting two screws under tensile force. This investigation offers valuable preclinical evidence for future clinical applications.