The effect of lateral hinge fracture with hinge hole and protective K-wire for medial opening-wedge high tibial osteotomy by compression testing and finite element analysis.

BACKGROUND

Medial open-wedge high tibial osteotomy (MOWHTO) is effective for treating medial-compartment knee osteoarthritis but carries a risk of lateral hinge fractures (LHF), compromising stability and outcomes. Hinge holes and protective K-wires reduce LHF by lowering stress and enhancing lateral support. However, their combined effect has not been evaluated. This study investigates whether using both techniques together can more effectively reduce lateral cortical bone stress and prevent LHF during MOWHTO.

METHODS

This study combined finite element analysis (FEA) and in-vitro compression testing to evaluate stress distribution and fracture behavior during MOWHTO. Three-dimensional models reconstructed from osteoarthritic CT images were used, with consistent definitions of wedge, hinge, and protective K-wire placement. Compression testing models were 3D-printed for cost efficiency and repeatability.

RESULTS

FEA simulated stress during wedge opening, while compression testing measured load-gap curves, fracture load, and fracture patterns. Hinge holes alone reduced hinge stress by 14.4% and maximum loading by 34%. Protective K-wires improved maximum load capacity by 48-60%, increasing lateral hinge resistance. However, K-wires alone raised the risk of Type III fractures, especially in corrections > 10 mm. The combined use of hinge holes and K-wires reduced lateral cortical stress by 22% and significantly lowered the incidence of Type III LHF to 11.1%, compared with 16.7% for hinge holes alone and 77.8% for K-wires alone.

CONCLUSION

Combining hinge holes and protective K-wires provides superior mechanical support and reduces the risk of Type II and III lateral hinge fractures, offering a promising strategy to improve MOWHTO outcomes.