What is the ACL? The Anterior Cruciate Ligament (ACL) is an important stabilizing structure found deep within the knee joint. Although it can be injured with a blow to the knee, many injuries result from “non-contact” forces such as pivoting or twisting the knee when changing direction, or from twisting the knee when landing from a jump. The ACL does not heal on its own, therefore reconstructive surgery is usually needed if one wants to return to sports.
Signs and symptoms of an ACL Tear The athlete often hears or feels a pop when the ACL tears. Although the injury is usually quite painful, some athletes have been able to walk off the field after the injury, but are aware that they “did something to their knee.” Swelling usually sets in within a few hours and the knee becomes painful to move. The athletic trainer and/or physician will perform a series of knee tests to see if the ACL is torn.
What to do for an ACL tear Apply the RICE principle and see the athletic trainer or a physician immediately. Crutches are often necessary initially, depending on pain and instability. Research and consult an orthopedic surgeon who has experience in reconstructing ACLs in the athlete. The orthopedist will order an MRI to confirm the diagnosis and also to see if there are any other injuries in the knee such as a meniscal tear, bone bruises, fractures or other ligament tears.
Pre-operative rehabilitation Surgery is often delayed 2-4 weeks after the injury to allow knee swelling to resolve and for the athlete to regain normal knee range of motion and strength. Undergoing the operation when the knee is still inflamed can increase the risk of arthrofibrosis, or excessive scar tissue in the knee, which inhibits normal motion. Pre-operative rehabilitation focuses on therapeutic exercises than gently bend and straighten the knee, the stationary bike, and exercises to build up the hip, thigh and calf muscles. Athletes who enter surgery with normal range of motion, good leg strength and minimal inflammation have the best chance of having a good post-operative outcome.
Graft choices Since the ACL cannot be sewn back together, a graft is needed to replace the torn ligament. Talk to your doctor about the two basic graft choices…an allograft and an autograft. An allograft uses donor tissue (commonly an Achilles tendon from a cadaver) to replace the torn ACL. An autograft uses the patient’s own tissue (such as part the patellar tendon) to replace the torn ligament. Be sure to talk to your doctor about the pros and cons of each graft choice.
Post-operative rehabilitation Most athletes miss about a week of school after the operation. Some doctors prescribe a continuous passive motion device (CPM) for home use right after surgery. The CPM bends and straightens the knee to encourage range of motion and joint nutrition which minimizes joint stiffness. The athlete wears a post-operative brace to keep the knee straight and uses crutches as well. Rehabilitation begins very soon after surgery. This minimizes scar tissue formation and strength loss while improving knee function. Early on, the focus is to reduce pain, improve range of motion, reduce swelling and activate the thigh, hip and calf muscles. As rehabilitation progresses, more vigorous strength, balance and cardiovascular exercises begin. Resistive exercises are more progressive as the knee begins to function more normally. Straight ahead running can begin once your doctor gives the ok. Afterwards, functional activities are initiated (plyometrics, sprints, agilities, etc) once the athlete is fitted for a functional brace and given permission by the doctor to begin these activities.
Return to play Patients can generally expect to return to sports 8-10 months following surgery.
Bracing Your doctor may require you to wear a brace for about a year once you return to sports, particularly if you play a contact or collision sport.
ACL re-injury rates? Although unusual, ACL re-injuries do occur in about 10% of patients. Some athletes have had the misfortune of either re-tearing the same ACL more than once or tearing the ACL in the opposite knee.
ACL Prevention Programs Although there are many variables that can cause an ACL injury, research has indicated that plyometrics,strength training and learning proper landing techniques can reduce the chance of suffering an ACL injury. This is particularly the case with female athletes, who are 4-8x more likely to injure their ACL compared to males. Looser joints, hamstring weakness, knee alignment issues and hormonal influences have all been proposed as causative factors for female ACL injuries. Although not all of these factors are controllable, a well-conditioned athlete with strong leg muscles and good landing techniques is less likely to be injured.