Anatomy/Symptoms
There are two cruciate (crossing) ligaments in the middle of the human knee, anterior (front) and posterior (back).
The anterior cruciate ligament (ACL) coordinates knee function and controls rotation function, i.e. allows change of direction or “side step” function.
The posterior cruciate ligament (PCL) is the lynch pin about which the knee rotates, and prevents backwards movement of the tibia (shin) or the femur (thigh).
Rupture of the anterior cruciate ligament seriously affects knee function in the majority of cases. Most people suffer serious functional loss with insecurity, giving way, and loss of the ability to function in field sports and activities of daily living. Because no muscle can substitute for the anterior cruciate ligament, its loss cannot be overcome by rehabilitation, it does not heal, and knee function usually deteriorates over time with repeated episodes of giving way. In young, athletic adults, continued use of the cruciate-deficient knee results in the onset of knee arthritis within a 10 to 15 year period. In a few people, the effect is not as severe.
Non-operative Treatment
If the functional loss of the knee is small, bike riding and swimming are good exercises to help maintain adequate strength and function. This is more appropriate for older patients, however age is no contraindication to operative treatment.
Operative Treatment - Arthroscopic/Open ACL Reconstruction
Surgical treatment of the ACL involves reconstruction of the ligament using either the patella (kneecap) tendon or the hamstring tendon as a graft material. This tendon graft is placed through tunnels made in the femur and tibia to accurately replace the ruptured ligament, and is securely fixed in the tunnel with screws.
Both methods give predictably good results – feel free to discuss the subtle differences with Dr Mansfield.
An ACL reconstruction also involves an arthroscopy of the knee joint, where a small telescope is used to view the inside of the joint. Any damage to the cartilage or meniscus of the knee can be diagnosed and repaired or trimmed as appropriate.
Post-operative Treatment
The majority of ACL reconstructions are performed as day surgery under general anaesthetic. Wound drains are used, and these are removed the day after surgery. A waterproof dressing is then applied to the wounds – these can stay in place for about 10 days. You should expect some fluid to gather under the dressings – this is normal and is part of the healing process.
You will have a splint on your leg and will need crutches to help you mobilise for about two weeks. You may be advised to see the physio to use a Continuous Passive Movement (CPM) machine to help maintain your knee range of motion. After approximately two weeks, bike riding is recommended to help knee movement and strength. Further exercises will be discussed with you at follow-up visits with Dr Mansfield. Recovery time after surgery is usually 6-8 weeks to manual work; recovery for sporting activities is usually 6-8 months.
Risks/Complications
Complications that can occur with ACL reconstruction include: