Three-dimensional finite element stress and strain analysis of a transfemoral osseointegration implant.

The percutaneous transfemoral osseointegration implant is an alternative technique for direct prosthetic limb attachment. In order to investigate the stress and strain in the transfemoral osseointegration implant system, finite element (FE) analyses were carried out using three-dimensional femur-implant models and the commercial FE software ABAQUS. The three-dimensional femoral model was reconstructed from presurgery CT scans of an above-knee amputee. The implant was then inserted into the femoral model using Boolean operations in CAD software. Under a typical walking load, stress and strain from the femur-implant FE model were investigated. Stress concentrations were found near to the distal and proximal regions of the femur. To study the effect of different contact ratios between femur and implant, FE analyses were carried out using different implant diameters. The results showed that there were local stress variations near the contact discontinuity areas. A comparison was also made between the results of this study and a previous study using axisymmetric FE models. The results of the two studies revealed different stress levels, but good correlation was found in the overall stress distribution.