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Canadian Orthopaedic Foundation - Fondation Canadienne d'Orhopedie
Canadian Orthopaedic Foundation - Fondation Canadienne d'Orhopedie
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Anterior Cruciate Ligament Repair

Anterior Cruciate Ligament (ACL) Surgery

Anterior cruciate ligament (ACL) injuries occur most often to athletes, typically as a result from collisions in contact sports or twisting and pivoting motions under full body weight or coming to a hard, fast stop and then cutting, twisting or jumping. Football, basketball, downhill skiing, snowboarding, squash and tennis all take their toll on amateur and pro athletes' ACLs.

Ligaments are the tough fibrous bundles that lash bones together. In the knee, four separate ligament groups attach the end of the femur (the thigh bone) to the relatively flat head of the tibia (shin) and provide joint stability. On the outside face of the joint is the lateral collateral ligament (LCL) on the inside is the medial collateral ligament (MCL). Together, the LCL and the MCL provide side-to-side stability to the joint.

Beneath the knee cap (patella) are the criss-crossed anterior and posterior (front and back) cruciate ligaments (ACL and PCL), which also stabilize the knee. All four ligaments are susceptible to injury, and the ACL in particular. The ACL provides joint stability, reinforces the MCL and prevents the tibia from rotating and sliding too far forward (hyperextension) during physical activity. The ACL also contributes to rotation motions of the knee. To learn more about how knees are put together, go to Anatomy.

Signs and Symptoms
ACL injuries range from a simple sprain to partial or complete ligament tears (those who suffer a tear often report hearing a "popping" sound). Usually, pain and swelling immediately follow the injury. Even a minor ACL injury can cause short-term disability because the instability in the joint can make normal activities involving weight-bearing and a twisting motion painful and difficult.

An unstable knee often causes people to complain of a feeling that the knee will "give way" from under them. What they're feeling is the knee joint sliding forward too much. Such symptoms should be treated as soon as possible, since extended repetition of the "giving way" sensation increases the risk of permanent damage to joint cartilage, as well as a risk of tears to the ACL and the meniscus (about half of those who suffer ACL injuries also suffer a meniscal tear). If untreated, an unstable knee will almost certainly lead to osteoarthritis.

An ACL tear usually involves bleeding into the joint and fairly rapid swelling. It's a disabling injury that often bounces athletes right out of their sport, though it usually has less of an impact on non-athletes. In fact, approximately one in seven people adjusts relatively easily to living with a ruptured ACL, so a patient profile is important in assessing the indications for surgery.

Children, adolescents, young adults, the middle-aged and the elderly represent different surgical problems. Functional disability may vary from an undiagnosed asymptomatic rupture to the patient whose knee gives way on a daily basis. Functional needs vary from sedentary patients with low activity requirements through those patients with active sporting lives or physically demanding jobs to elite athletes whose way of life depends on a highly functional knee.

The vast majority of patients - the most vigorously active segment of the population - fall into the young- adult and middle-aged groups, males more frequently than females, though the pattern is reversed on the slopes, where a disproportionate number of female skiers are injured, and in college basketball, where women may be as much as eight times more likely to sustain an ACL injury than their male counterparts.

The smallest patient group consists of children and the elderly, who represent less than five per cent of all ruptured ACLs and are usually treated conservatively - the starting point of most treatment regimens: rest, ice, compression and elevation (RICE), plus a brace to immobilize the knee, as well as crutches and pain relievers.

The first step, though, is to see a doctor to get a proper evaluation based on a physical examination, perhaps including x-rays to assess the extent of damage to the knee and help determine whether surgery will be needed.

That decision will be based on the patient's age, the degree of functional disability he/she is facing due to the injury and the patient's functional requirements: If surgery is being considered, that decision will also involve assessment by an orthopedist, who may employ another range of tests to determine the function of the ligament and the degree of injury.

If surgery is deemed appropriate, it will take three to four weeks before it can take place - an interval to allow the inflamed and irritated knee to "cool down:" Swelling decreases, inflammation subsides and range of motion improves. This results in fewer complications and better post-operative joint function.

Depending on the doctor's evaluation treatment may be as simple as rest, ice, compression and elevation (RICE), plus a brace to immobilize the knee, crutches and pain relievers.

If surgery is required, it is usually same-day. The choice of spinal or general anesthesia will be made after discussion with an anesthesiologist. Depending on the injury, the surgeon may elect to do repair surgery, in which the ends of the torn ligament are sewn back together, or, far more commonly, ACL reconstruction surgery, in which graft tissue replaces the damaged ligament. Most often, an autograft from the patient's own tissue - generally from either the kneecap tendon or the hamstring tendon - is used, although donor tissue (allograft) may be used instead.

The procedure, which lasts approximately two hours, is usually done through two small incisions with an arthroscope or a single tiny incision with an endoscope. The surgeon drills two holes on an angle - one in the femur and one in the tibia where the two ends of the ACL once attached - and then anchors the graft to the bones with graft-stabilization hardware, such as staples or bioabsorbable screws.

Unlike hip-replacement surgery, after which patients are encouraged to get up and walk as soon as possible, ACL reconstruction surgery entails a long and demanding rehabilitation. In the wake of surgery, patients will be dependent on crutches for one to three weeks, with an emphasis placed on controlling swelling, joint flexibility and, as range of motion improves, joint strength. Patients are often encouraged to swim or cycle as a means of strengthening muscles around the knee, which is vitally important in recovering muscle mass lost as a result of surgery. It also helps to increase joint stability, since increased muscle strength reduces stress on the joint ligaments.

Every individual is different, of course, but normal (as opposed to high-demand) activity may generally be resumed after two to four months following ACL surgery, but a full physical rehab program may take several months to a year.



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