Reduction of stress distribution in dysplastic hip joint by varying the femoral anteversion angle

Abstract

Residual hip dysplasia is the biggest cause of osteoarthrosis and its treatment in young people and adults often requires surgery. We propose a customized virtual surgery scenario to estimate the stress distribution on the hip joint, considering the planned operative procedure, and different articular rotations to change the femoral anteversion angle. We simulated the stance phase of a gait cycle using finite elements analysis on a three dimensional model constructed from computerized tomography images of a patient with residual dysplasia. The maximum effective stress post-operative over the femoral head was reduced by 20.2% and the contact pressure over the femoral articular cartilage by 42% at the point of greatest load in the gait cycle. We rotated the femoral anteversion angle from 40o to 10o, finding a better biomechanical response between 12o and 16o. The results indicated an excessive load over the pathological joint and an important reduction of the maximum stress over the post-operative model as an outcome of the joint relocation.