The Effect of High Tibial Osteotomy Correction Angle on Cartilage and Meniscus Loading Using Finite Element Analysis

Abstract

Medial opening wedge high tibial osteotomy (MOWHTO) is a popular clinical method for curing the osteoarthritis (OA) caused by varus deformity. However, the ideal alignment to maximize osteotomy successful rate and post-operative knee function remains controversial to date. Moreover, the between-patient variability of knee joint biomechanics, particularly during functional tasks, signifies critical importance of conducting patient-specific planning. For this reason, this study introduces a subject-specific modeling procedure to determine the biomechanical effects of simulated different alignments of MOWHTO on tibiofemoral cartilage stress distribution. A 3D finite element (FE) knee model was developed from MRI images of a healthy living subject and used to simulate different alignments following MOWHTO (i.e. 0.2°, 2.7°, 3.9° and 6.6° valgus). Loading and boundary conditions were assigned based on the subject-specific kinematic and kinetic data recorded during gait tests. The compressive and shear stress distributions in the femoral cartilage and tibia cartilage were quantified. It was found that when the loading axis shifted laterally, the peak stresses in the medial compartment decreased, but increased in the lateral compartment. The findings suggest that equal loading between two compartments can be successfully achieved by performing MOWHTO with a HKA angle around 3.9 to 6.6° valgus. More importantly, this patient-specific non-invasive analysis of stress distribution that provided a quantitative insight to evaluate the mechanical responses of the soft tissue within knee joint as a result of adjusting the loading axis, may be used as a preoperative assessment tool to predict the consequential mechanical loading information for surgeon to decide the patient specific optimal angle.