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

Abstract

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.

Keywords: Compression Testing; Finite Element Analysis; High Tibial Osteotomy; Hinge Hole; Lateral Hinge Fracture; Protective K-wire.

Fig. 1

Model design, research methods, and analysis process of this study. A Reconstruct 3D model by CT image of OA Patient; b. Computer preoperative planning by the definition of hinge save zone and position of protective K-wire; c. Using 3D printing phantom models and wedge-shaped apparatus on compression testing; d. Observe the direction of the fracture and calculate the loading-gap curve; e. Using the preoperative planning and wedge model to simulate wedge opening on FEA; e. Calculate the stress on the different regions

Fig. 2

The definition of the tibial model in this study for all testing (a) the normal model, (b) the model with a hinge hole (c) the model with a protective K-wire (d) the model with the combination of the hinge hole and the protective K-wire

Fig. 3

The cancellous and cortical structures of the phantom; a. Thickness of lateral cortex in CT image; b. Tibia model with fixing seat; c. 3D printed phantom model; d. Section of the phantom model

Fig. 4

a The boundary condition of FEA and the interaction between the wedge-shaped apparatus and tibial models; (b) Dividing the mesh around the hinge into six regions. (c) Stress–strain curve for mesh convergence test in different mesh sizes

Fig. 5

Loading vs Opening gap analysis of the phantom in different situations, a. With different hinge hole diameters; b. With different Protective K-wire diameters; c. Combination of different diameters of hinge Hole and Protective K-wire; d. Compare the ultimate strength for a different condition

Fig. 6

Appearance of the model after the compression test (a) the appearance for different opening gaps (b) the fracture type for different conditions

Fig. 7

a Comparison between the compression test results and the FEA results for the loading-opening gap curve; b. The average von-Mises stresses comparison in different regions for different Tibia model