Published: June 22, 2011
Updated: June 22, 2011
An anterior cruciate ligament (ACL) injury is a common injury treated by sports medicine specialists. Learn more about this injury, how it will be fixed, and how long it takes to recover from injury.
The anterior cruciate ligament (ACL) is one of the primary stabilizing knee ligaments. It helps to prevent the knee from slipping out of joint while performing sports and other activities that require pivoting, sudden stops and starts, and changes in direction.
An ACL tear can usually be diagnosed by a detailed history of injury and a thorough physical exam.
Typically the injury occurs with a twisting or hyperextension stress and is accompanied by a painful "pop" and/or sensation of the knee giving way. Knee instability can be detected by a trained examiner by applying specific stresses to the joint.
An x-ray will rule out fractures or dislocations. An MRI may be obtained if the diagnosis is uncertain or if there is suspected cartilage or other ligament damage.
A torn ACL will not heal and results in chronic knee instability with pivoting and strenuous activity. However, it does not always require surgery.
Most people with an ACL-deficient knee will not experience instability with work and other normal daily activities. By strengthening the muscles around the knee and perhaps wearing a knee brace for certain activities, most people can jog, swim, bike, and do many other aerobic exercises without difficulty.
Individuals who must perform strenuous physical labor or who want to continue playing team sports are more likely to have episodes of the knee giving way. Bracing and physical therapy are helpful but will not completely eliminate the instability.
The amount of instability is variable and depends on many individual factors including age, strength, joint laxity, and level of sports activity.
Most orthopaedic surgeons will advise surgery for younger, athletically-active people or for those who develop instability with activities of daily living.
Frequently when the ACL is torn, there is also damage to the meniscus cartilage of the knee. If left untreated, a torn meniscus can result in persistent pain, locking, or swelling. If a meniscus tear is identified, this may be treated with a relatively minor outpatient procedure.
It is possible to have only the meniscus repaired and avoid ACL reconstruction surgery if the physician recommends or the patient opts to avoid or delay ACL reconstruction.
ACL reconstruction is an elective (not emergency) surgery and does not have to be performed immediately. In fact, it is generally advisable to wait for several days or weeks until swelling has resolved and range-of-motion has returned to normal. This will make recovery from surgery much easier and reduce the risk of complications.
Physical therapy may be recommended prior to surgery. If the knee is "locked" due to cartilage tears or if there is other ligament damage, the surgeon may advise earlier surgery.
Attempts to repair the torn ACL by simply sewing it back together have proved unsuccessful. The current approach is to "reconstruct" the ligament using a graft of tissue taken from somewhere else.
The two most commonly used grafts are either the central third of the patella tendon or one of the hamstring tendons. An allograft -- donated cadaver tissue obtained from a tissue bank -- may also be used.
Each of these grafts has some advantages and disadvantages, but generally they all provide adequate strength and are unlikely to fail if placed correctly. Your surgeon will discuss which graft may be most appropriate for your situation.
Surgery is done using an arthroscope for guidance, although some small incisions must be made to obtain the graft and position it inside the knee joint.
Using specialized instruments, tunnels are drilled in the femur and tibia where the old ACL attached. The graft is then pulled through the tunnels and attached to the bone at each end.
Depending on the type of graft, it may be attached using screws, staples or other metal fixation devices. This hardware normally does not cause any long-term problem and does not need to be removed later. Any other damage, such as cartilage or meniscus tears, will also be repaired arthroscopically.
Surgery usually lasts two to three hours and is generally done using a regional nerve block to numb the leg. You will also receive intravenous sedation during the procedure so you will not be awake unless you elect to do so.
The nerve block avoids the need for general anaesthesia, has fewer risks of side effects, and provides post-operative pain relief for up to 24 hours. You will be able to go home the day of surgery.
Supervised rehabilitation is recommended for several months after surgery. Some of the therapy can be done independently if you have access to a gym or other exercise facility with weights, bike, pool, etc. and follow the prescribed rehab protocol.
Gait training, range-of-motion, strengthening, and balance exercises will begin the week after surgery. After three months, you will progress to jogging, agility, and sports-specific exercises.
With normal progress, you can expect to return to sports activity by six to eight months following surgery. However, your knee may not feel completely recovered for up to a year.
The goal of ACL reconstruction is to restore knee stability and allow patients to return to sports.
Most patients will report some persistent minor symptoms (pain, stiffness, swelling, clicking, weakness, etc.) during the first year after surgery. About two out of three patients will experience some minor long-term symptoms, although generally these symptoms do not significantly limit knee function or activity.
Patients who have had meniscus or other cartilage or ligament injury to the knee are more likely to have some long-term symptoms or develop arthritis over time.
At Duke Orthopaedics, our doctors often treat anterior cruciate ligament (ACL) injury with ACL reconstruction surgery. The following video demonstrates this procedure.
Watch the following video to learn more about ACL injuries in women.