Contributions of External, Muscle, and Ligament Forces to Tibiofemoral Contact Loads in Patients with Knee Osteoarthritis and Healthy Individuals.

This study aims to quantify the contributions of external, muscle, and ligament forces to the tibiofemoral contact loads during gait. Additionally, the relative contributions in patients with knee osteoarthritis (KOA) and healthy individuals were also compared. For this aim, twenty medial Kellgren-Lawrence (KL) 3-4 KOA patients and twenty healthy controls were recruited to perform the gait data collection experiment using a motion capture and force plate system. The relative contributions were calculated based on an improved musculoskeletal model with knee ligaments. The results showed that the contribution of muscle forces to the total compartment contact loads was greater than that of external forces for both the healthy individuals and the KOA patients. The medial compartment contact loads were contributed predominantly by external forces, and the lateral compartment contact loads were contributed negatively by external forces for both the healthy individuals and the KOA patients. For the healthy individuals, the total/lateral compartment contact loads were predominantly contributed by muscle forces. The ligament forces provide a contribution similar to muscle forces to the medial compartment contact loads. For the KOA patients, the total/lateral compartment contact loads were contributed predominantly by ligament forces. The ligament forces provide a negative contribution to the medial compartment contact loads. In conclusion, the knee ligaments provided important contributions to the tibiofemoral contact loads. Significant differences were found in the relative contributions between the KOA patients and the healthy individuals. The results of this study have significant clinical implications for further improving the current biomechanical treatments of KOA.