Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Collaborative Specialization

Engineering in Medicine

Supervisor

Willing, Ryan T.

Abstract

Knee Osteoarthritis (KOA) is a degenerative joint disease and a leading cause of disability worldwide. Lower limb malalignment was a risky factor leading to KOA, altering the load distributions. This study aimed to study the influence of knee deformities on knee contact mechanics and knee kinematics during squatting. A full-leg squat FE model was developed based on general open-source models and validated with in vivo studies to investigate the outputs under frontal malalignment (valgus 8° to varus 8°) and axial malalignment (miserable malalignment 30°). As a result, Varus-aligned and miserable aligned models increased medial tibiofemoral force and lateral patellar contact pressures, while the valgus-aligned model increased lateral tibiofemoral force medial patellar contact pressures with no effects on total contact loads. The Model with a higher medial force ratio (medial force/total force) induced a higher internal tibial rotation. In conclusion, we recommended that patients with knee malalignment be taken care of alignments in both frontal and axial planes.

Summary for Lay Audience

Knee Osteoarthritis (KOA) is a degenerative joint disease and a leading cause of disability around the world. Lower limb malalignments in the frontal and axial planes were risky factors leading to KOA, as it altered the force and stress distributions. To date, the influence of malalignment on load and stress distributions has not been investigated in both joints: tibiofemoral and patellofemoral joints using computational studies.

This study aimed to study the influence of knee malalignment in the frontal plane and axial plane on knee contact mechanics in tibiofemoral and patellofemoral joints and knee kinematics during a typical daily activity—squatting. To achieve this, a full-leg squat FE model was developed based on an open-source FE model and a general musculoskeletal model and validated with in vivo studies using parametric studies. Then, the model was used to investigate the outputs under frontal malalignment ranging from valgus 8° to varus 8°and axial malalignment with combined 30° femoral anteversion and 30° external tibial torsion (miserable malalignment). As a result, varus-aligned and miserable aligned models increased medial force while the valgus-aligned model decreased medial force. In contrast, malalignments showed no effects on total contact force. In addition, the model with a greater Q-angle (quadriceps angle) increased the lateral patellar contact pressures, while the model with a lower Q-angle increased the medial patellar contact pressures. According to rotational kinematics in results, models with a higher medial force ratio (medial force/total force) induced higher internal tibial rotations. In conclusion, we recommended that patients with knee malalignment be taken care of alignments in both frontal and axial planes.

Download

Share

COinS