The effect of high tibial osteotomy on stress in the tibio-femoral joint: a computer simulation study

Osteoarthritis (OA) is a degenerative disease of all of the tissues within the diarthrodial joint and one of the leading causes of disability. Knee OA is often caused by lower limb malalignment, high body mass index, and injury to the surrounding soft tissues, resulting in a cyclic degradation of the joint. High tibial osteotomy (HTO) is a realignment surgery to restore knee function and minimise excessive loading. However, the link between malalignment and stress in the knee is not well understood and surgical outcomes by HTO have been unpredictable. Therefore the overarching goal is to develop a three-dimensional virtual surgery finite element (FE) model that integrates subject specific imaging and computational biomechanics to predict the effects of different realignment techniques on knee joint contact stress. FE models of a cadaveric knee joint were created from magnetic resonance images, using Mimics v14 (Materialise, Belgium). Following non-manifold assembly, these 3D models were exported to Abaqus 6.11 to determine the stress distribution within the medial-lateral compartments of the well-aligned knee. A 10° open wedge HTO was performed to simulate the malaligned knee. Boundary conditions of 300N axial load and 12 Nm bending moment were applied to simulate posture in the well aligned and malaligned knee. Peak compressive stress in the malaligned knee was 60% higher than that of the well-aligned knee. This excessive stress is considered a primary factor for the onset and progression of OA. These results highlight the importance of understanding the effects of HTO on the knee joint contact stresses in order to delay OA progression.