Knee Brace control for Reduction of Medial Compartment Load

Abstract

Medial unloader braces are often developed to achieve pain elimination of the knee medial compartment. However, traditional braces cause medial unloading along with lateral overloading. Neglecting this phenomenon, unwarranted rotation from adduction to abduction oblige the knee to confront the overloading of the lateral compartment, and subsequently, the risk of damage is dictated to the lateral compartment exceedingly. In order to prevent this phenomenon, the new embedded mechanism is designed for unloader braces based on a novel computational procedure for the first time. We use the procedure that calculates the cartilage penetration depth and knee abduction-adduction angle simultaneously which are the surrogate parameter for determining pain in knee osteoarthritis. Therefore, the new unloader brace corrects the abduction angle via the embedded mechanism and applies unloader force along with attention to the contact point and cartilage penetration depth. Hence, 1.4° change in femur rotation from adduction to abduction in the frontal plane reduces the medial contact force to 752 N leading 853 N lateral compartment overloading for knee osteoarthritis with 0.5 mm cartilage thickness. Moreover, we calculate the required torque for tracking desired adduction angle. Finally, the result shows that our design is requisite to prevent excessive overloading of the lateral compartment while it unloads the medial compartment sufficiently.