Ligaments are strips or sheets of thick fibrous tissue that connect two or more bones in the joint area. The main components of ligaments are collagen and elastin, so they are strong and flexible. The main function of ligaments is to maintain the stability of the joint, and each ligament has its own inherent role in preventing hyperextension, hyperflexion, and inversion of the joint during movement. The major ligaments in the human body are the anterior and posterior cruciate ligaments of the knee, the medial and lateral collateral ligaments of the knee, the medial and lateral collateral ligaments of the ankle, and the rostral collateral ligaments of the shoulder. When a ligament injury occurs, the affected limb needs to be braked and prevented from moving to prevent the injury from getting worse. If the ligament injury is severe, surgical treatment is needed to repair or reconstruct the ligament to restore the stability of the joint.