The ACL is a ligament in your knee, more formally called the anterior cruciate ligament. Its primary function is to limit the lower tibia bone of the leg from dislocating from the knee joint. It also prevents inward rotation. The ACL is tightest when the knee is straight and loosest when the knee is half bent. It runs in a diagonal from the back top of the femur bone to the front bottom of the tibia bone.
How Does An ACL Injury Occur?
When the ligament is under maximum tension and a force is applied, it is most vulnerable to injury. The majority of ACL injuries are non-contact. The knee is usually trying to slow down, is bending sideways and is also rotating when an injury often occurs. According to the NCAA Injury Surveillance system, ACL injuries occur seven to eight times more in female athletes than male. Injuries occur often with jumping and landing.
Types Of ACL Surgical Techniques
ACL surgery involves replacing the ligament. The most frequent type of surgery is to peel apart a piece of a tendon from a knee muscle and anchor it into place with a bone screw. Another method, which produces less pain after surgery, is to use a tendon from a cadaver. The final method is to use synthetic materials. Each method has advantages and disadvantages for a successful surgery, rehabilitation and return to previous activities.
Important Considerations For Prevention and Rehabilitation
It is important after an ACL surgery to regain coordination and train the muscles. An important group of muscles to train are the hip muscles, which help with alignment of the knee during movement. The hip and trunk muscles need to be strengthened to enhance stability of the knee. It is also important to learn how to control the knee from hyperextension, or bending too straight. Coordination and endurance training also are included.
Activation Of Both The Quadriceps And Hamstring Muscles
A very important goal is muscle strengthening exercises that cause both the front and back knee muscles to be activated at the same time. This provides a protective mechanism, which is needed when returning to sports, stepping down and to prevent re-injury. Balance training is also needed to retrain nerves within the knee to fire and create stability when muscle fatigue occurs. An ACL rehabilitation program needs to begin immediately after surgery.
Rehabilitation Goals After ACL Surgery
The goals after ACL surgery are to reduce pain and swelling. The next phase is to restore full knee straightening. Patient safety involves a brace to prevent excessive bending or straightening until the surgeon allows. Improving the gliding of the knee cap and gradual full knee bending is the next phase. Learning to control knee movement and strengthening exercises are then added. A patient should then progress to returning to daily activities and sports.
References
- "Medical Exercise Therapy"; The Norwegian MET Institute; 1999
- "Essentials Of Musculoskeletal Care"; Robert Snider, MD; 1997
