The main functions of the medial collateral ligament of the knee include maintaining knee stability and protecting the meniscus. 1. Maintaining knee stability: The medial collateral ligament connects the medial distal femur to the medial proximal tibia to maintain medial tension, which prevents the knee from over-turning, thus ensuring a normal joint line of force and joint stability. 2. Protect meniscus: The medial collateral ligament is connected to the medial meniscus, this special anatomical structure can make the stress of meniscus and medial collateral ligament to be dispersed, reduce the damage of tissues and structures, and play the role of mutual protection. The medial collateral ligament of the knee is an important structure of the human body, once abnormalities are detected, you should go to the hospital in time, under the guidance of a professional doctor for diagnosis and treatment.