Summary

For both the OWHTO and OWDTO models, a transverse cut perpendicular to the tibial axis is preferable for the stresses on the plate and tibial hinge area.

Abstract

Background

In recent years, the number of medial open wedge high tibial osteotomy (OWHTO) and open wedge distal tuberosity osteotomy (OWDTO) procedures for medial knee osteoarthritis (OA) has increased. However, there is no consensus on the optimal sagittal plane angle for the transverse cut.

Objective

This study aims to determine whether performing the transverse cut parallel to the posterior tibial slope (PTS) or perpendicular to the tibial axis is more biomechanically suitable in OWHTO and OWDTO using finite element analysis.

Methods

Finite element analysis was conducted using MECHANICAL FINDER®. 3D models of OWHTO and OWDTO were created using CT data from a 64-year-old female patient with medial knee OA (PTS 6°) and CAD data of locking plates and screws. Models were created with transverse cuts made either parallel to the PTS or perpendicular to the tibial axis at 35 mm from the tibial joint surface. These models were expanded by 10 mm at the transverse cut, with artificial bone insertion. A 600N vertical load was applied to the tibial joint surface while the distal tibia was fixed.

Results

In both OWHTO and OWDTO models, the models with transverse cuts perpendicular to the tibial axis showed less stress concentration at the tibial hinge and plate center. Similarly, the number of damaged tibial elements was lower in models with cuts perpendicular to the tibial axis.

Discussion

These results suggest that making the transverse cut perpendicular to the tibial axis is more appropriate.