What is the ACL?
The anterior cruciate ligament (ACL) is a 38mm long band of fibrous tissue that connects the femur (thigh bone) to the tibia (shin bone). Its function is to control stability when performing twisting actions and it is essential in controlling the rotation forces developed during side stepping, pivoting and landing from a jump. It is usually not required for normal daily living activities.
What causes ACL tears?
The ACL is commonly injured whilst playing ball sports or skiing. The actions of attempting a pivot, side step or land from a jump are usually implicated and the knee gives way. When skiing, the ACL is injured when the binding fails to release as the ski twists the leg. Patients frequently hear or feel a snap, or crack accompanied by pain.
What are the Symptoms?
Swelling commonly occurs within the hour. Pain is felt on the outer aspect of the knee. The medial ligament of the knee joint may also be disrupted resulting in severe pain and swelling about the inner side of the joint. If not treated patients may experience recurrent episodes of instability when pivoting.
How are ACL tears diagnosed?
ACL tears are often diagnosed on the basis of how the injury was sustained and the clinical examination. An MRI examination is usually performed to confirm the diagnosis but more importantly to allow assessment of the other structures of the knee which may have also been injured.
Can ACL ruptures be treated without surgery?
The aim of treatment of an injured knee is to return the patient to their desired level of activity without risk of further injury to the joint. Those patients who have a ruptured ACL and are content with activities that require little in the way of side stepping (running in straight lines, cycling and swimming) may opt for treatment without an operation.
Conservative treatment includes physiotherapy to reduce swelling, restore the range of motion of the knee joint and rehabilitate to full muscle power. Proprioceptive training to develop essential protective reflexes are required to protect the joint for normal daily living activities. Patients who choose conservative treatment need to ensure that any physical activity or exercise involves straight line activity only. Social (non-competitive) sport may still be possible without instability as long as one does not change direction suddenly.
What operation may be beneficial?
Patients who wish to pursue competitive ball sports, or who are involved in an occupation that demands a stable knee are at risk of repeated injury without surgery. Repeated injuries may result in tears to the menisci and damage to the articular surface leading to degenerative arthritis and further disability. In these patients, surgical reconstruction is recommended. The best time for surgery is when the knee is pain free and with a full range of motion.
All reconstructive procedures for the ACL require a graft. Most commonly, segments of the hamstring tendons are used as grafts. Specially designed screws allow secure and immediate fixation of the tendon within the joint allowing for a rapid rehabilitation. Stabilising the joint in this way protects the menisci and reduces the risk of osteoarthritis later.
Can ACL injury be prevented?
The PEP program (Prevent injury and Enhance Performance Program) has been shown to decrease both first time ACL injuries and ACL injuries after reconstruction. It is a highly specific training program that replaces the traditional warm up and includes stretching, strengthening, plyometrics, and sport specific agility training. For best results, it should be performed at least 2-3 times per week during the sporting season. More information will be provided if required.