Photoelastic evaluation of pathological axis deviation of the femur in the frontal plane

Abstract

The objective of this study is to evaluate the repercussions of the pathological deviation of the coxa brevis, femur, and tibia without the pathological deviation of the axis in the femoral or tibial frontal plane. The stress distribution in the proximal and distal joints was evaluated in relation to the deviations using transmission photoelasticity. Two-dimensional femur and tibia models were developed from frontal panoramic radiographs, which were later used to fabricate molds and photoelastic models. A force of 8 N was applied to the top of the femoral head. For the deviation of the coxa brevis and for the femur and tibia without pathological deviation, the stresses were more critical in the calcar region of the proximal femur. In the distal femur and proximal and distal tibia, the stress distributions were in accordance with the models, the proposed fixation conditions, and the long bone geometries. The most important conclusion of this investigation was that joint deviation also alters the stress on all primary joints of the lower extremities. From this study, it will be possible to develop better correction criteria for angular deviations and discharges of bone and joint forces of the lower extremities and to provide refinements to prostheses.