Contact Stress Analysis Of Tibial Components Of Prosthetic Knee Implants — Experimental And Finite Element Analysis

Abstract

Following the clinical success of total hip joint replacement in the 1960s, total knee joint replacement has become widespread. Coupled with these developments has been a concurrent development of engineering analysis of the implant to bone system. Of particular significance in total knee joint replacement have been the high levels of contact stresses which occur between the metallic femoral implant and the polymeric tibial component. These high contact stresses have led to the failure of some components and thus remain the subject of widespread research. The present paper will describe an experimental and finite element study of this contact condition. Using modelling theory and previously developed techniques, an experimental model of the femoral and tibial interface has been designed and constructed. The model made from Araldite resin (CT200) contains embedded strain gauges in the contact region which enable measurements of strains to be recorded for various loads. Stresses are subsequently evaluated for both normal loading and normal loading with sliding. In addition to experimental analysis, a Finite Element model of both the metal to CT200 interface and the metal to UHMWPE interface has been developed. The contact condition has been modelled using MARC software which has extensive capabilities for modelling contact. The FE results and the experimental results were benchmarked with known Hertzian solutions for the normal contact case for loads in the elastic range. Subsequent analysis examined the behaviour of the components in the elastic and the elastoplastic range for both normal and sliding loads and results are compared to previously published theoretical solutions.