STRESS DISTRIBUTION IN LOWER LIMB MALALIGNMENT IN THE FRONTAL PLANE. ANALYSIS BY PHOTOELASTICITY AND FINITE ELEMENT METHODS

Abstract

The human lower limb has physiological angulations between its segments that play an important role in terms of load transmission from the pelvis to the ankle. This is axis the mechanical axis and it has a normal track that depends on the angular alignment which, in turn, if disturbed alters the stress distribution in bone and joints causing disturbance in the mechanical performance and leading to future joint degeneration. Therefore, restoration of the mechanical axis is an important part of the orthopaedic treatment as it is also important in total joint replacement.The aim of the present research is to study the repercussion of pathological alignment of the lower limbs in terms of load distribution both close to the deformity and away from it, using engineering tools such as photoelasticity and finite element method. Radiographs illustrating different angular deformities of the lower limbs will be used to produce models in photoelastic resin. These models will be submitted to an application of a standardized load to the top of the femoral head and seen under polarized filter. The bands created will be analyzed both qualitatively and quantitatively. This study will be complemented by the finite element analysis. We hope to identify the most hazardous malalignments and to characterize their repercussion not only near the deformity, but also in joints away from it. This kind of evaluation has not been done before and it may provide data for new joint prosthesis design as well as to indicate deformity correction.