An injury to the anterior cruciate ligament can be a debilitating musculoskeletal injury to the knee, seen most often in athletes.
Non-contact tears and ruptures are the most common causes of ACL injury.
The anterior cruciate ligament or ACL (see diagram) is an important ligament for proper movement.
ACL injury more commonly causes knee instability than does injury to other knee ligaments. Injuries of the ACL range from mild such as small tears to severe when the ligament is completely torn (see photo). There are many ways the ACL can be torn; the most prevalent is when the knee is bent too much toward the back and when it goes too far to the side. Tears in the anterior cruciate ligament often take place when the knee receives a direct impact from the front while the leg is in a stable position, for example a standing football player is tackled sideways when his feet are firmly planted. Torn ACL’s are most often related to high impact sports or when the knee is forced to make sharp changes in movement and during abrupt stops from high speed. Research has shown that women involved in sports are more likely to have ACL injuries than men. Indeed, women are 5 times more likely to suffer from ACL injuries in general. An ACL tear can be determined by an individual if a popping sound is heard after impact, swelling after a couple of hours, severe pain when bending the knee, and when the knee buckles or locks during movement or gives way while standing still with weight on the affected knee.
Symptoms of an ACL injury include hearing a sudden popping sound, swelling, and instability of the knee (i.e., a "wobbly" feeling). Pain is also a major symptom and can range from moderate to severe. Continued athletic activity on a knee with an ACL injury can have devastating consequences, resulting in massive cartilage damage, leading to an increased risk of developing osteoarthritis later in life.
ACL injuries occur when an athlete rapidly decelerates, followed by a sharp or sudden change in direction (cutting). ACL failure has been linked to heavy or stiff-legged landing directing the forces directly up the tibia into the knee; as well as twisting or turning the knee while landing, especially when the knee is in the valgus (knock-knee) position.
The pivot-shift test, anterior drawer test and the Lachman test are commonly used during manual clinical examination of suspected ACL injury. The ACL can also be visualized using a magnetic resonance imaging scan (MRI scan).
These tests can be explained by your Doctor or Physio as can the various treatments and rehabilitation techniques.