Torn anterior cruciate ligament (ACL) definition and facts
Symptoms of an ACL tear include hearing a loud pop followed by intense pain.
- The anterior cruciate ligament is one of the four ligaments in the knee that provides stabilization for the knee joint.
- Torn ACLs are a common knee injury.
- An ACL tear or sprain occurs with a sudden change in direction or pivot against a locked knee.
- A pop, followed by pain and swelling of the knee are the most common symptoms of an ACL tear.
- Women are more likely to tear their ACL because of differences in anatomy and muscle function.
- Treatment goals are to return the patient to his or her preinjury level of function. Arthroscopic surgery may be required to reconstruct the torn ligament.
- It may take six to nine months to return to normal activity after an ACL injury.
Torn ACL & Surgery Recovery Time
For regular people and pseudo-athletes, the days after arthroscopic knee
surgery are spent reducing knee swelling and starting range-of-motion exercises.
This process is hampered by a couple of physiologic barriers.
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What tests and procedures diagnose a torn ACL?
Televised sporting events have allowed the general public to watch how knee injuries occur, often repeatedly in slow-motion replay.
The diagnosis of an ACL injury begins with the care provider taking a history of how the injury occurred. Often the patient can describe in detail their body and leg position and the sequence of events just before, during, and after the injury as well as the angle of any impact.
Physical examination of the knee usually follows a relatively standard pattern.
- The knee is examined for obvious swelling, bruising, and deformity.
- Areas of tenderness and subtle evidence of knee joint fluid (effusion) are noted.
- Most importantly, with knee injury ligamentous, stability is assessed. Since there are four ligaments at risk for injury, the examiner may try to test each to determine which one(s) is (are) potentially damaged. It is important to remember that a knee ligament injury might be an isolated structure damaged or there may be more than one ligament and other structures in the knee that are hurt.
- In the acute situation, with a painful, swollen joint, the initial examination may be difficult because both the pain and the fluid limit the patient's ability to cooperate and relax the leg. Spasm of the quadriceps and hamstring muscles often can make it difficult to assess ACL stability.
- A variety of maneuvers can be used to test the stability and strength of the ACL. These include the Lachman test, the pivot-shift test, and the anterior drawer test. Guidelines from the American Academy of Pediatrics suggest the Lachman test is best for assessing ACL tears.
- The Lachman test is performed as follows:
- The damaged knee is flexed to 20-30 degrees.
- The examiner grasps tibia and puts their thumb on the tibial tubercle (the bump of bone just below the knee where the patellar tendon attaches.
- The examiners other hand grasps the thigh just above the knee.
- The tibia is pulled forward and normally, there should be a firm stop if the ACL is intact. If the ligament is torn, the tibia will move forward and there will be no endpoint and it feels mushy.
- The unaffected knee may be examined to be used as comparison.
It may be difficult to examine some patients when muscle strength or spasm can hide an injured ACL because of the knee stabilization that they can provide.
Plain X-rays of the knee may be done looking for broken bones. Other injuries that may mimic a torn ACL include fractures of the tibial plateau or tibial spines, where the ACL attaches. This second situation is often seen in children with knee injuries, where the ligament fibers are stronger than the bones to which they are attached. In patients with an ACL tear, the X-rays are often normal.
Magnetic resonance imaging (MRI) has become the test of choice to image the knee looking for ligament injury. In addition to defining the injury, it can help the orthopedic surgeon help decide the best treatment options. However, MRI does not replace physical examination and many knee injuries do not require an MRI to confirm the diagnosis.
How is a torn ACL treated? When does it need surgery?
The major decision in treating a torn ACL is whether the patient would benefit from surgery to repair the injury. The surgeon and the patient need to discuss the level of activity that was present before the injury, what the patient expects to do after the injury has healed, the general health of the patient, and whether the patient is willing to undertake the significant physical therapy and rehabilitation required after an operation.
Nonsurgical treatment may be appropriate for patients who are less active, do not participate in activities that require running, jumping, or pivoting, and who would be interested in physical therapy to return range of motion and strength to match the uninjured leg.
The International Knee Documentation Committee, a collaboration of American and European orthopedic surgeons, developed a questionnaire to standardize the activity level assessment of patients before and after surgery to help guide surgeons and patients to decide whether surgery would be helpful. The activity levels were as follows:
- Level I: jumping, pivoting, and hard cutting
- Level II: heavy manual work or side-to-side sports
- Level III: light manual work and noncutting sports like running and bicycling
- Level IV: sedentary lifestyle without sports
Surgical repair is recommended for those who wish to return to Level I and II activities. This is generally not an emergency and is undertaken after a understanding all treatment options.
Young athletes may require surgical repair of the ACL because of the potential for knee instability and inability to return to their level of competition.
A nonsurgical approach might be considered for patients who have level III and level IV lifestyles.
Those who are candidates for nonoperative treatment benefit from physical therapy and exercise rehabilitation to return strength to the leg and range of motion to the injured knee. Even then, some patients might benefit from arthroscopic surgery to address associated cartilage damage and to debride or trim arthritic bony changes within the knee. Recovery from this type of arthroscopic surgery is measured in weeks, not months.
If surgery is planned, there is usually a waiting period of a few weeks after the injury so that pre-habilitation can occur to strengthen the muscles that surround the knee. The waiting period also decreases the risk of developing excess scar formation around the knee (arthrofibrosis) that might restrict knee motion after the operation.
Surgery is usually planned to occur within five months of injury.
The anterior cruciate ligament can be reconstructed by an orthopedic surgeon using arthroscopic surgery. There are a variety of techniques, depending on the type of tear and what other injuries may be associated. The decision as to what surgical option is appropriate is individualized and tailored to a patient's specific situation. Because of its blood supply and other technical factors, the torn ACL ends are not usually sewn together and instead, a graft is used to replace the ACL. Often an autograft, tissue taken from the patient's own body, is a piece of hamstring or patellar tendon that is used to reconstruct the ACL.
Research is ongoing about the potential role for biologic enhancements to the surgical repair, using stem cells, platelet-rich plasma, and growth factors to help promote healing and ligament regeneration.
Rehabilitation physical therapy and exercise program is often suggested to strengthen the quadriceps and hamstrings before surgery. It may take six to nine months to return to full activity after surgery to reconstruct an ACL injury.
The first three weeks concentrate on gradually increasing knee range of motion in a controlled way. The new ligament needs time to heal and care is taken not to rip the graft. The goal is to have the knee capable of being fully extended and flexing to 90 degrees.
By week six, the knee should have full range of motion and a stationary bicycle or stair-climber can be used to maintain range of motion and begin strengthening exercises of the surrounding muscles.
The next four to six months is used to restore knee function to what it was before the injury. Strength, agility, and the ability to recognize the position of the knee are increased under the guidance of the physical therapist and surgeon. There is a balance between exercising too hard and not doing enough to rehabilitate the knee and the team approach of patient and therapist is useful.
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What is the recover time after torn ACL surgery?
Rehabilitation and return to normal function after surgical repair of an ACL tear can take six to nine months. There needs to be a balance between trying to do too much work in physical therapy returning strength and range of motion and doing too little. Being too aggressive can damage the surgical repair and cause the ligament to fail again. Too little work lengthens the time to return to normal activities.
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What is the prognosis of a torn ACL?
Most people who have surgery to repair their ACL have good return of function and lifestyle. Long-term success rates are reported between 82%-95%.
Fewer patients develop permanent knee instability. Up to 8% develop graft failure or instability.
For patients who do not have surgery to repair a torn ACL, only half have a fair outcome with no knee instability. This is an option for sedentary people or for those whose activities require no pivoting or cutting.
Can ACL tears be prevented?
ACL injuries usually occur in active people engaged in activities that are enjoyable. The risk of injury can potentially be decreased by maintaining muscle strength and flexibility. Warming up, stretching, and cooling down are ways of protecting joints and muscles.
Wearing braces to prevent injury may or may not be useful.
Strengthening exercises and agility drills can help prevent injury.
Plyometric exercises to help build power, strength, speed, and balance can teach the body how to jump and land properly to minimize the risk of injury, especially in women. It is important to avoid landing on a fully extended and locked leg.
Which types of doctor treats torn ACL injuries?
The diagnosis of an ACL tear may be made by emergency physicians, primary care providers, sports-medicine providers, and/or orthopedic surgeons.
Once the diagnosis is made, referral is often made to an orthopedic surgeon who would discuss the potential risks and benefits of surgery and other options. The orthopedic specialist would be the one to perform the surgery.
After the operation, a physical therapist under the direction of the orthopedic surgeon, would work with the patient to return them to normal activity.
If no surgery is planned, the primary care provider or the orthopedic surgeon could direct care in association with a physical therapist.
Anti-inflammatory medications, such as ibuprofen (Motrin, Advil), naproxen (Aleve), or ketorolac (Toradol), may be suggested to decrease swelling and pain. Narcotic medications for pain, such as codeine or hydrocodone (Vicodin, Lortab), may be prescribed for a short period of time after the acute injury and again after surgery.