The Anterior Cruciate Ligament (ACL) helps to stabilise and control the knee joint. ACL injury is often accompanied by damage to the cartilage and meniscus of the knee. ACL injuries are classified according to their severity:
Grade 1: The least severe category of injury, typically involving stretching of the ligament without any major compromise of joint stability.
Grade 2: a partial tear, accompanied by excessive laxity resulting from the ACL being overstretched.
Grade 3: a complete tear, causing instability in the knee, resulting from the ligament being cut or detached from the bone.
Injury to the ACL is often accompanied by a popping sound. It can result in a deep, debilitating pain within the knee, as well as rapid swelling. It may become difficult to bend or straighten the leg.
The knee joint itself will feel unstable, while weightbearing may be painful.
ACL injuries are a product of excessive force on the ligament.
This force can be delivered to the knee by a range of movements, such as pivoting, sudden halting, or jumping. It can also result from any direct blow which forces the knee into an unnatural position, as is common in contact sport, or from overextension of the knee.
Muscular imbalance resulting in excessive strain on the joint can increase the risk of ACL injury, as can physical conditioning and muscle strength.
Non-surgical treatments are typically reserved for less significant injuries or for patients for whom surgery would likely be dangerous or ineffective. These include:
Physical therapy: targeting proximal muscle strength and improved range of motion.
Knee bracing: to provide additional support to the knee during movement.
Medication: Non-steroidal anti-inflammatory drugs (NSAIDs) can reduce pain and inflammation.
Surgical treatment options offer the best chance of recovery from severe ACL injury. They focus exclusively on repair, where possible, or more commonly, reconstruction. These include:
ACL reconstruction: involves the grafting of tissue, recovered either from another part of the patient’s body (autograft) or from a donor (allograft). Autografts may utilise tendon material from the patellar, hamstring or quadriceps. Grafting is the most common approach taken, and typically offers the best chance of good long-term recovery.
ACL repair: involves the repair or reattachment of the existing ligament.
Ligament augmentation: involves the surgical repair or reconstruction of the ligament, with the addition of an artficial internal brace (Internal brace ligament augmentation) or the use of synthetic materials to reconstruction the ligament (ligament augmentation and reconstruction).
To learn more about ACL reconstruction, and what you can expect from the procedure, visit our ACL reconstruction page.
For further inquiries, or to arrange a consultation, please contact Professor Al Muderis’ office at +61 2 88829011 or book an appointment online.
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Professor Dr Munjed Al Muderis is an orthopaedic surgeon specialising in osseointegration, hip, knee and trauma surgery. He is a clinical professor at Macquarie University and The Australian School Of Advanced Medicine, a fellow of the Royal Australasian College of Surgeons and Chairman of the Osseointegration Group.