Avaliação biomecânica de prótese de recapeamento da articulação coxofemoral em cães - estudo ex vivo

Abstract

The aim of this study was to evaluate a prosthesis for hip resurfacing arthroplasty (HRA) in femoral bones of dogs by biomechanical test. Twenty cadavers of adult dogs weighing between 30kg and 50kg who died from causes unrelated to orthopedic diseases were selected. In the dogs both femoral bones were removed and kept frozen for testing. In each pair of femurs obtained from the same animal, the implantation of HRA prosthesis was performed in a femur and this sample was included in group 1 - prosthesis (n=20), while the contralateral femur remained intact and this sample was included in group 2 - control (n=20). All femoral samples were submitted to the axial compression biomechanical test and the ultimate strength (US), fracture strength (FS), maximum strength deformation (MSD), fracture deformation (FD) and strain (k) variables were evaluated. After the biomechanical test, the femoral bones were radiographed to assess the failure features of the samples. The data showed normal distribution and were submitted to the independent Student t test for comparative analysis between the groups. The control group showed significantly higher values for the variables US and FS compared to the prosthesis group. However, the forces supported by the prosthetic samples were superior to the physiological forces imposed on the hip joint of a dog in vivo. Regarding to other variables analyzed, such as MSD, FD and k, no significant differences were found between the two groups. Bone samples showed similar failure features in both groups, with the occurrence of fractures in the femoral neck area. In conclusion, the HRA prosthesis showed appropriate biomechanical performance in femoral bones of dogs.