Systematic review of the effect of insertion torque on locking screw performance.

Purpose: Locking plates are well established as a powerful plating concept, especially in low-density bone. Construct strength is dependent on the fixation between the screw head and the plate; however, the influence of variations in the torque used to engage the screw head into the plate hole is unclear. The aim of this study was to systematically review the effect of insertion torque on the performance of locking screws. Methods: A systematic review was performed with electronic searches of four databases using free and MeSH search terms. Systematic evaluation and data extraction was performed up to 2 April 2025. The principal outcome was the difference in failure load for the locking plate construct following variation of the insertion torque. Results: The initial search identified 894 potentially relevant studies, of which six were eligible for inclusion. All were in vitro, biomechanical studies. Both stainless steel and titanium plates were tested. The former material showed no consistent performance increase with increased insertion torque in either pushout or cantilever testing. Titanium plates showed an increased pushout force and cantilever strength with more torque for some, but not all designs. Once screw head engagement in the plate hole was achieved, further torque was not clearly beneficial. Conclusion: Increased insertion torque, beyond that required to seat the screw head, did not consistently show performance benefits. Most studies were underpowered and may not be representative of clinical failures. Further work to define optimum torque ranges for locking plate systems is required.