The anterior cruciate ligament (ACL) is one of 4 strong stabilising ligaments of the knee. It acts to prevent excessive movement of the tibia (shin bone) on the femur (thigh bone). ACL tears are most often associated with high impact sports, where the knee is forced to make sudden changes of direction or contact sports where the knee is hit with the foot planted on the ground. Severity of injury ranges from a strain or tear to part of the ligament to a full rupture. Women are more susceptible to ACL tears than men.
Symptoms experienced will depend on the degree of damage to the ACL but often included:
- A popping sound is often heard at the time of injury.
- Pain and swelling may vary from moderate to severe.
- A feeling of instability or that the knee will give way with weight bearing.
- Inability to fully bend or straighten the knee.
Diagnosis of the injury can usually be made quite well by your physio through a number of tests to the ligament. In the presence of significant damage or ambiguous test results, a referral to an orthopaedic surgeon is generally made. An MRI scan may be conducted to confirm diagnosis and to assess the degree of damage to other structures in the knee.
A torn or ruptured ACL does not necessarily have to be surgically repaired. Depending on the degree of damage, age and activity levels of the injured party, conservative management may be suggested. This will generally involve a period of relative rest to allow the damaged tissue to settle followed by a prolonged period of rehabilitation with your physio to improve the muscle control and train the muscles of the leg to take over some of the role of the damaged ligament.
Surgical repair and subsequent rehabilitation time has improved so much with modern surgical techniques that in the presence of significant damage, surgery will normally be recommended. This relates particularly to the young age and activity levels of most people who sustain an ACL injury. Following surgery, a period of progressively more difficult rehabilitation exercises to restore muscle function to optimal levels is undertaken. Typical return to sport time is now around 6 months.