A Single Lateral Hinge Screw Increased Resistance to Varus Stress After Medial Opening-Wedge High Tibial Osteotomy in a Synthetic Bone Model: A Biomechanical Analysis.

PURPOSE: To determine whether use of a tibial screw placed across the lateral tibial hinge results in significantly greater failure load compared with no lateral screw after medial opening wedge high tibial osteotomy (MOWHTO).

METHODS

Twelve Sawbone tibias were used for the study. A MOWHTO was performed in each specimen using a computed tomography-based patient specific correction guide, and 6 specimens received a lateral hinge screw. Cantilever varus bending load was applied to failure, and failure load, displacement at failure, and stiffness of the osteotomy before hinge failure were recorded.

RESULTS

Failure load was statistically higher in the hinge screw group compared to the control group, 437.0 ± 82.0 N vs 336.0 ± 55.9 N, P = .046 (mean ± standard deviation). This load to failure was 30% greater in MOWHTO using a hinge screw versus the control.

CONCLUSIONS

Using a Sawbone model, the current data showed that placement of a lateral hinge screw significantly increased resistance to varus stress following MOWHTO compared with a construct having no tibial screw. Additionally, no significant difference in displacement or stiffness was observed between the hinge screw and the control groups.

CLINICAL RELEVANCE: The current biomechanical findings suggest that the use of a laterally based proximal tibial screw can potentially reduce the risk of lateral hinge fracture and its associated morbidity after MOWHTO.