Effect of Total Elbow Arthroplasty in Varus-Valgus Laxity and Stress Distribution of Elbow Joint

Nowadays, there are vast number of studies, which concentrate on the elbow joint problems and total elbow arthroplasty (TEA). Mostly, these studies focus on the complications and failures of the implants. In this thesis the main objective is to understand how the varus-valgus laxity and stresses change when elbow joint is implanted as these may lead the failure and future problems of artificial joints. In this study varus-valgus laxity and Von Mises stress tests are performed. Varus-valgus laxity is measured during 140° of flexion motion with 15N and 50N loads for both anatomic and artificial elbow joint. Von Mises stress test is performed with a 15N load on the ulna of the anatomic elbow joint and ulnar part of the implant in artificial elbow joint. In this thesis a 3D model of elbow joint implant has been designed and also 3D models of the ulna and humerus are used. These 3D models are assembled in order to create finite element (FE) models of anatomic and artificial elbow joints. Ligaments are neglected in order to decrease the time of the process. Once the varus-valgus laxity and the Von Mises stress measurement tests are performed for the anatomic elbow joint, the same analyses are performed for implanted elbow joint. Obtained results from the FE model of anatomic and artificial elbow joints are compared with each other in order to understand the efficiency of the TEA and probable limitations, which may occur after total elbow replacement. As written in the literature review the implantation increases the varus-valgus laxity almost 20% in 140° of flexion motion. The maximum Von Mises stress of the implanted elbow joint is much higher than this value in normal elbow joint. The increase of the varus-valgus laxity is a cause of failure of the implants in TEA. Moreover, the increase in Von Mises stress leads to wear of the polyethylene part and finally failure of the implants. Keywords: Total Elbow Arthroplasty, Range of Motion, Varus-Valgus Laxity, Von Mises Stress, Finite Element Analysis