ACL Rupture

Australia is responsible for the largest frequency of ACL rupture in the world, as well as ACL reconstructive surgery.

This is a traumatic condition characterised by rupture of the anterior cruciate ligament in the centre of the knee. It is typically due to a twisting, pivoting movement in the knee, and is often associated with a multi-ligamentous or meniscal injury. While particular populations are at higher risk of ACL rupture, it is seen in both the weekend-warrior as well as high level athletes.

The knee initially swells up with blood and can be terribly painful in the acute phase. It is important to control this with ice and compression, as the bleeding will slow and be reabsorbed. The intense pain felt from an ACL rupture should completely dissipate with enough time icing and compressing the knee.

Movement remains critical in the knee despite ACL rupture. In the absence of other injury, once the intense bleeding and swelling has dissipated, the knee should move freely and completely. This is a prerequisite for ACL reconstruction, hence the value in “prehabilitation”. Bracing the knee in a fixed position for an isolated ACL injury is without merit and causes more problems if stiffness sets in.

After the acute phase of painful injury, ACL rupture is characterised by knee instability: the knee gives way when pivoting on that knee. This is usually very uncomfortable.

Due to certain factors, namely poor blood supply, the ACL has a poor healing potential. It will indeed scar down, but in an elongated form, not in its anatomic footprint where it can reproduce its function. This does not necessitate surgery; in an isolated ACL rupture without other injury, many patients can have a well-functioning ACL deficient knee. Physical therapy is the cornerstone of non-operative treatment, where stabilising muscles around the knee can prevent symptomatic instability for most activities of daily living. Returning to a high-level of pivoting activity is usually not possible, but there are exceptions.

While ACL repair has been performed, it pales in comparison to the success rate of reconstructive surgery. This is partly due to the elongated and injured ACL, which cannot compete with the strength of modern graft techniques in reconstruction. In Mr O’Bryan’s view, the indication for ACL repair is in tibial spine avulsion fractures of a young patient and repair in an open multi-ligament injury with very select injury patterns. There is evidence that patients over 40 can have an equivalent outcome with ACL repair compared to reconstruction. Often this patient population does best without surgery, but this population can also have an equivalent outcome with a donor graft reconstruction.

ACL reconstruction is the surgical option of choice for those who have persistent knee instability despite physical therapy, or young patients who are returning to pivoting sports, or in those with certain multi-ligamentous and meniscal injuries.