Anterior Cruciate Ligament

Anterior Cruciate Ligament is the most commonly injured ligament of the knee. The major cause of injury to the ACL is sports related. This injury occurs when the knee is forcefully twisted or hyperextended. Many patients recall hearing a loud pop when the ligament tears, and feel the knee give away. Remember that the ACL controls how far forward the tibia moves in relation to the femur. If the tibia moves too far the ACL can rupture. This tearing of the ligament results in the loud pop and the feeling of instability in the knee. The ACL may not be the only ligament injured when the knee is twisted violently, such as in a clipping injury in football. It is not uncommon to see both the Medial Collateral Ligament and the ACL injured.

The symptoms following a tear of the ACL are variable. Usually there is swelling of the knee within a short time following the injury due to bleeding into the knee joint from torn blood vessels in the ligament. The instability caused by the torn ligament leads to a feeling of insecurity and giving way of the knee, especially when trying to change direction on the knee. The pain and swelling from the initial injury will usually resolve after 2 to 4 weeks, but the instability remains. The symptom of instability, and the inability for the patient to trust the knee for support is what requires treatment. Also important in the decisions about treatment is the growing realization by Orthopedic Surgeons that long term instability leads to early arthritis of the knee..