Ligament injuries that affect joint stability require surgery, and different locations necessitate different surgical methods. Generally, for ligaments within a joint, such as the anterior cruciate ligament or the posterior cruciate ligament of the knee, reconstruction is performed using either autografts, allografts, or synthetic tendons to replace the original damaged ligaments. For ligaments outside of a joint, such as the medial collateral ligament, lateral collateral ligament of the knee, or the anterior talofibular ligament of the ankle, if the joint stability is compromised, suturing is generally performed during the acute phase. For chronic, long-standing injuries that affect joint stability, reconstruction is usually necessary, also using autografts, allografts, or synthetic tendons to substitute their function.