Date of Award

6-2015

Degree Name

MS in Mechanical Engineering

Department

Mechanical Engineering

Advisor

Stephen Klisch

Abstract

Obesity is a known risk factor for osteoarthritis (OA). Excess body weight generates greater joint contact forces at the knee; however, obese individuals alter their gait to decrease joint contact forces. Knee malalignment has been identified as a strong mediating factor between obesity and knee OA progression. Excess body weight acting on a varus malaligned knee would have an additive effect on cartilage stress and could cause stress levels to exceed the threshold limit for damage and loss of cartilage matrix.

A finite element (FE) model of the human tibiofemoral joint was developed and validated in order to investigate changes in cartilage pressure due to obesity and knee varus malalignment. The results of this analysis show that obese loading conditions caused greater contact pressure in both the lateral and medial tibiofemoral compartments at most phases of stance. Increased contact pressure applied cyclically during daily activities could make obese individuals more susceptible to OA. Varus malalignment increased medial contact pressure as expected, but lateral contact pressure also increased during midstance for both normal weight and obese load conditions. These results suggest that varus malaligned individuals could be susceptible to OA development in both tibiofemoral compartments due to the overall increase in joint contact pressure.

As a qualitative tool, the FE model functioned well in highlighting changes in joint contact pressure due to the addition of obesity or varus malalignment. Further work can be done to increase confidence in the quantitative outputs of the model by using more sophisticated material models for soft tissue structures and incorporating the patellofemoral joint into the FE model.

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