ACL Frequently Asked Questions 1. What is the function of the anterior cruciate ligament (ACL)?2. How are ACL tears diagnosed?3. If my ACL is torn, should I have surgery to repair it?4. What is the success rate of the surgery?5. Are the differences in technique important?6. Is one type of reconstruction stronger than the other?7. Are there more side effects from one type of reconstruction?8 . How can I decide whether a hamstring or patella tendon reconstruction is better for me? Who will make the decision?9. Can ACL tears or recurrences be prevented?
1. What is the function of the anterior cruciate ligament (ACL)?
The ACL is the most important structure in the knee for providing stability during sporting activities which involve changing of direction while moving at speed (including football, tennis, skiing). If the knee is unstable, cartilage wear & tear occurs at a much faster rate than normal which leads to arthritis of the knee joint. An ACL tear is one of the commonest serious injuries in sport - for example, in the AFL, 12% of all matches missed due to injury are from ACL tears.
2. How are ACL tears diagnosed?
Most ACL tears can be detected by experienced examiners as the knee joint will undergo abnormal movements when stressed. There is a variation in the normal range of these tests so the amount of movement is compared to the other knee. Sometimes these tests can be inconclusive immediately after an injury, due to excessive swelling. If clinical testing is inconclusive and it is very important to know at an early stage whether the ACL is torn, an MRI (Magnetic Resonance Imaging) scan can be performed. Standard X-rays may show a fracture but not an ACL tear.
3. If my ACL is torn, should I have surgery to repair it?
As a general rule, the body cannot repair a torn ACL if the tear is complete. If surgery is needed, the surgeon will not repair the ligament directly as this has a low success rate but will instead use another tendon as a graft to reconstruct the original ligament.
The answer to whether you should have surgery depends on a combination of three factors:
1. Your future demands in multi-directional sport. For example, a professional football player would be strongly advised to have an ACL reconstruction.
2. The amount of instability in the knee. A knee that has features of ACL instability on examination or is giving way on daily activities will more likely than not require surgery.
3. Your acceptance of the costs of surgery. Although an ACL reconstruction may seem expensive initially, these costs need to be weighed up against the opportunity, financial and lifestyle costs of enduring the burden of a degenerative knee joint in the long term.
4. What is the success rate of the surgery?
Long term success of ACL reconstruction surgery can be determined by the knee's stability in sport and the lack of pain. It is difficult to gauge precise long term success rates as surgical techniques for this operation have only been developed over the last 25 years. Furthermore, no two surgeon uses the exact same technique for this operation. Most failures are actually due to re-injury to the ACL tendon graft. There are also short term surgical complications from the surgery including infection and deep venous thrombosis.
5. Are the differences in technique important?
Most doctors would agree that ACL reconstruction surgery is very technically demanding and would recommend a surgeon who has successfully returned top level athletes to their sport. The two most commonly used tendon grafts for this operation are the patella tendon and the hamstring tendon. Both types of tendon grafts have been shown in the scientific literature to provide equal strength and stability.
6. Is one type of reconstruction stronger than the other?
A review article by Beynnon et al in the Americal Journal of Sports Medicine in 2005 noted that there were similar clinical and functional outcomes when comparing ACL reconstructions performed with patella tendon with 4-strand hamstring grafts. However, the thickness of the patellar and hamstring tendons vary between individuals so this must be taken into consideration when determining choice of tendon graft.
7. Are there more side effects from one type of reconstruction?
There are side effects associated with both patella and hamstring tendon grafts. This may help determine which graft to use depending on the athlete's individual circumstances. For example, a basketball player who is prone to patellar tendonitis may be better advised to have a hamstring tendon reconstruction whereas a rugby league player who has a history of hamstring tears may be better advised to have a patellar tendon reconstruction.
8 . How can I decide whether a hamstring or patella tendon reconstruction is better for me? Who will make the decision?
Most surgeons will have a preferred technique which they will recommend based on their experience. Some surgeons are capable of performing both techniques and will recommend one over another on a case by case basis. It is usually a joint decision between the surgeon and patient after some discussion.
9. Can ACL tears or recurrences be prevented?
ACL injury is associated with multidirectional sport (ie. football, basketball, netball and skiing) so refraining from these sports is one way to prevent recurrence although this strategy is often not acceptable to amateur and professional athletes.
ACL knee braces may be useful in athletes requiring extra stability to improve their sporting confidence after an injury or reconstruction.