A validated finite element study of stress shielding in a novel hybrid knee implant

Abstract

This study (1) proposes a hybrid knee implant design to improve stress transfer to bone tissue in the distal femur by modifying a conventional femoral implant to include a layer of carbon fibre reinforced polyamide 12, and (2) develops a finite element model of the prosthetic knee joint, validated by comparison with a parallel experimental study. The Duracon knee system was used in the experimental study, and its geometry was modelled using CAD software. Synthetic bone replicas were used instead of cadaveric specimens in the experiments. The strains generated on the femur and implant surfaces were measured under axial compressive loads of 2000 N and 3000 N. A mesh of 105795 nodes was needed to obtain sufficient accuracy in the finite element model, which reproduced the experimental reading within 10-23% in six of the eight test locations. The model of the proposed hybrid design showed considerable improvements in stress transfer to the bone tissue at three test flexion angles of 0°, 20°, and 60°.