Anterior Cruciate Ligament (ACL) Injury
The Anterior Cruciate Ligament (ACL) is one of the main ligaments within the knee and is responsible for resisting excessive forward rotational instability of the tibia (shin bone) in relation to the femur (thigh bone) and is crucial for stabilising the knee when turning or planting the foot. An ACL tear may be acute or chronic in nature.
An acute tear often occurs when over-extension or medial translation of the knee occurs, usually accompanied by a “popping” sound, and is followed by sudden pain and swelling of the knee. A chronic tear injury occurs when there is a past history of an acute ACL tear, which healed slowly with a gradual decrease in pain and joint swelling. A chronic ACL tear presents with knee instability and occasional non-traumatic joint line swelling.