Knee Medial and Lateral Contact Forces Computed Along Subject-Specific Contact Point Trajectories of Healthy Volunteers and Osteoarthritic Patients

Abstract

Tibiofemoral medial and lateral contact forces, analysed on healthy volunteers, seem to depend on the trajectories of the contact points. Contact point trajectories in OA patients are shifted in the medial direction and contact forces are generally reported to be slightly reduced. The present study compares medial and lateral contact forces between OA patients and healthy volunteers. The forces are estimated during gait using a musculoskeletal model with subject-specific contact point trajectories obtained from biplane X-ray images at different flexion angles. Large inter-subject variability was found in the contact point trajectories and the contact forces. Significant but weak correlations were found between the positions of the contact points in the medial-lateral direction and the peaks of medial contact forces for both healthy volunteers and OA patients: the more medial the contact points the lower the forces. In the literature, when computing the contact forces considering a frontal equilibrium only, the correlation is obviously strong. Relationship between the positions of the contact points and the contact forces is more controversial in studies using deformable knee models. The interactions between altered contact points and contact forces should be further investigated with subject-specific musculoskeletal models.