Knee medial and lateral contact forces in a musculoskeletal model with subject-specific contact point trajectories

Abstract

Contact point (CP) trajectory is a crucial parameter in estimating medial/lateral tibio-femoral contact forces from the musculoskeletal (MSK) models. The objective of the present study was to develop a method to incorporate the subject-specific CP trajectories into the MSK model. Ten healthy subjects performed 45 s treadmill gait trials. The subject-specific CP trajectories were constructed on the tibia and femur as a function of extension-flexion using low-dose bi-plane X-ray images during a quasi-static squat. At each extension-flexion position, the tibia and femur CPs were superimposed in the three directions on the medial side, and in the anterior-posterior and proximal-distal directions on the lateral side to form the five kinematic constraints of the knee joint. The Lagrange multipliers associated to these constraints directly yielded the medial/lateral contact forces. The results from the personalized CP trajectory model were compared against the linear CP trajectory and sphere-on-plane CP trajectory models which were adapted from the commonly used MSK models. Changing the CP trajectory had a remarkable impact on the knee kinematics and changed the medial and lateral contact forces by 1.03 BW and 0.65 BW respectively, in certain subjects. The direction and magnitude of the medial/lateral contact force were highly variable among the subjects and the medial-lateral shift of the CPs alone could not determine the increase/decrease pattern of the contact forces. The suggested kinematic constraints are adaptable to the CP trajectories derived from a variety of joint models and those experimentally measured from the 3D imaging techniques.

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

“…The subject-specific contact point trajectories were approximated using a weighted centre of the bone-to-bone distances [4] and were expressed as a function of the knee flexion angle. These subject-specific contact point trajectories were introduced as kinematic constraints into the musculoskeletal model [3]. The corresponding Lagrange multipliers were the medial and lateral contact forces computed simultaneously with the musculo-tendon forces.…”

“…Considering a tri-dimensional (3D) equilibrium of the tibiofemoral joint (i.e. with flexion-extension, adduction-abduction, and internal-external rotation moments) and computing the musculo-tendon forces and contact forces simultaneously somewhat mitigate the dependence of the medial and lateral contact forces on the position of the contact points [3]. This was reported for subject-specific contact point trajectories of healthy volunteers which remain aligned with the medial and lateral plateau centrelines.…”

“…Tibiofemoral medial and lateral contact forces estimated from musculoskeletal modelling depend on the trajectories of the contact points [1][2][3]. The partition of the total contact forces is generally based on the adduction-adduction moment, the resultant of the musculo-tendon forces spanning the joint, and the position of the contact points in the frontal plane of the tibia.…”

Fluoroscopy-based subject-specific knee joint constraints for the estimation of prosthesis kinematics and contact velocities during gait

“…A solution can be to perform a multibody kinematics optimisation but the model-derived kinematics is very sensitive to the kinematic constraints. Subject-specific kinematic constraints based on contact point trajectories (obtained by a series of static biplane X-rays on healthy subjects) have been recently implemented in a musculoskeletal model (Zeighami et al 2018). Such constraints based on fluoroscopic data have never been obtained nor assessed yet.…”

Accuracy of the tibiofemoral contact forces estimated by a subject-specific musculoskeletal model with fluoroscopy-based contact point trajectories

“…The measured tibiofemoral kinematics was directly applied to the model (Zheng et al, 2014) or translated into spline functions coupling the joint degrees of freedom (DoFs) (Gerus et al, 2013). To estimate the medial and lateral contact forces in addition to the total tibiofemoral contact forces, the contact point trajectories are also required and appear to be sensitive parameters (Lerner et al, 2015;Saliba et al, 2017;Zeighami et al, 2018). These contact point trajectories, translated into kinematic constraints, have been recently personalised using biplane radiography acquired during quasi-static squat movements (Zeighami et al, 2018), but not using fluoroscopy acquired during dynamic tasks.…”