The anterior cruciate ligament (ACL) is an important ligament inside the knee, which prevents the knee from feeling unstable. Patients who tear this ligament will describe that the knee feels unstable, wobbly, and that they can’t trust it. This may occur when they play sport, perform any twisting activities, or even when getting in and out of a car, or stepping up on a curb.
Tearing the ACL usually involves a significant injury. Often sustained when playing sport, patients will describe feeling or hearing a pop, noticing very significant early swelling, and an inability to walk on the knee. However, not all patients will experience these symptoms.
Diagnosing an ACL tear requires the doctor to have a high degree of suspicion. Any injury to the knee that results in significant pain, swelling, or a need for crutches may be the indication of a meniscal or ligamentous injury to the knee, including an ACL injury. Early in the injury, it may be hard even for an expert to confirm or deny an ACL injury using examination.
Patients should have an xray to exclude fracture, see a physiotherapist to reduce swelling and restore range of motion, and obtain an MRI, which typically takes 6 weeks in the downtown Toronto region.
A torn ACL is usually readily diagnosed on MRI. Also, six weeks after injury evidence of a torn ACL is more apparent when examining the knee, as the swelling has resolved.
The indication to have an ACL reconstruction is if you would like to return to a pivoting sport such as soccer, hockey, volleyball, squash, ultimate frisbee, skiing, to mention only a few. The other indication is if, after significant rehabilitation, you continue to feel knee instability with day to day activities. However, many people who have strong leg muscles, and only wish to run in a straight line, go to the gym, or ride a bike can cope well without an ACL reconstruction, without any increased risk of osteoarthritis, if the knee is stable.
Many people who tear the ACL are very active, and wish to resume normal activities. Having an ACL reconstruction is a very common and safe operation. There is a 1/1000 risk of infection, a small risk of deep vein thrombosis, and a small risk of stiffness needing surgery (1/500). The chance of successful surgery is 95% – the ACL can always retear, especially with early return to sport. It is safest to return 9 months after surgery, when the muscle strength of the injured leg is 100% that of the other leg.
There are two main ways of reconstructing the ACL – using the patella tendon, and using the hamstring tendons. Dr Dwyer performs both. There is little difference between the two options, even after more than 30 years of research. Typically, younger patients (<35) playing aggressive sports such as soccer will receive a patella tendon graft, while older patients will have a hamstring graft. However, all decisions are made case by case, with the patient completely involved in the decision making.
Dr Dwyer tries to avoid the use of allograft at all costs, even in the revision setting, as the failure rate of cadaveric tissue is 10X that of using a patient’s own hamstring or patella tendon.
In order to reduce your risk of tearing the ACL again, Dr Dwyer will sometimes perform a Lateral Extra-articular Tenodesis (LET) as well. This is most commonly performed in conjunction with a hamstring ACL, or in the setting of a revision ACL. LET involves a second, small incision on the outside of your knee, and using some of your own tissue (IT band) to help tighten and stabilize the knee.
Postoperative rehabilitation
ACL reconstruction is performed as day surgery at Women’s College Hospital. Someone must come and pick you up and take you home. It is advised to have someone around to help you for the first two days. All patients will be provided with a script for medications that should be filled at the hospital prior to going home. Medications will usually be Celebrex in the morning for 2 weeks, Aspirin at night for two weeks, and Tylenol regularly for the first week. A script for oxycodone will also be provided.
Patients can walk on the knee immediately, although most patients use crutches for a week or two. A brace is used to sleep and walk for the first two weeks, and is removed after 2 days to begin bending the knee, when sitting in a chair. If possible, patients should rent a Gameready machine, which provides ice and compression to the knee, significantly reducing postoperative pain. The information for the rental company will be provided to you.
During surgery, your meniscus will be carefully examined for signs of injury. Sometimes, a meniscal repair will be required – if so you will need to wear the brace for the first 6 weeks after surgery, and limit your range of motion to 90 degrees. You will still be able to fully walk on the knee.
Physiotherapy is required twice a week, immediately after surgery. A physiotherapy referral and protocol will be provided for you on the day of surgery. Patients are seen in clinic two weeks after surgery, for wound review. Most patients walk normally by week 6.
Patients should take a week off work after the surgery, and then work from home for another 2 weeks if possible. Patients are not allowed to play sport for 9 months after surgery, as it takes this period of time for full quadriceps strength to be restored.
Risks of surgery
ACL reconstruction is a safe operation. There is a 1/1000 risk of deep infection, major stiffness, DVT/PE, major nerve or blood vessel damage, and patella fracture. Patients can get local areas of numbness around the graft harvest incisions, which typically improves over a year or two. The risk of retear of the ACL over your lifetime is 5%. The chance of returning to sport is approximately 90%.
Sometimes patients may need a second arthroscopy to remove scar tissue or assess the knee in the event of ongoing swelling and or pain.
Dr. Tim Dwyer 