Effect of Lateral Meniscus Tears and Partial Meniscectomy on Stress Concentrations in Knee Joint During Walking

INTRODUCTION: Load distribution and shock absorption are the primary functions of menisci in the knee joint [1]. Therefore, maintenance of intact menisci is important for prevention of osteoarthritis. Radial tears are common injury types in menisci [2, 3]. Partial meniscectomy is generally used for treatment of radial tears [4]. In this operation, a small part of the meniscal tissue is removed. Finite element (FE) method can be used to simulate knee joint stresses and strains, and the effects of meniscal injuries and meniscectomy. Earlier models on meniscal tears or partial meniscectomies, including the whole knee joint geometry, do not consider realistically knee joint movement [5, 6]. Therefore, they exhibit limited prediction accuracy, in terms of location and time dependence. Furthermore, earlier models do not include realistic depth-dependent collagen fibril orientations and split-lines in the models. The aim of this study was to evaluate the influence of different meniscal tears and partial meniscectomy on the cartilage and meniscus stresses by implementing a fibril reinforced poroviscoelastic (FRPVE) material and realistic gait cycle loading into a FE model. MATERIALS AND METHODS: Three dimensional geometry of an intact knee joint was constructed from magnetic resonance images using Mimics v12.3 (Materialise, Leuven, Belgium). Then, the geometry was imported into the FE analysis package Abaqus v6.10 (Dassault Systèmes, Providence, RI, USA), where the FE mesh and model were created. Femoral and tibial cartilages were modeled as FRPVE materials [7] and menisci were considered as transversely isotropic materials [8]. In cartilage layers, collagen fibrils had realistic depth-dependent arcadeline orientations and cartilage surfaces exhibited typical split-line patterns [9, 10]. Four different models of the knee joint were constructed with different geometries for lateral meniscus: healthy, intact menisci; radial tear in the middle lateral meniscus; radial tear in the posterior lateral meniscus; partial meniscectomy, indicating the surgical operation for the middle lateral tear (Fig 1). For the boundary conditions of the models, realistic time-dependent gait cycle data including 2 rotations and 2 translations, as well as loading force, were obtained from the literature [11, 12, 13] and implemented into the models.