What is the ACL?
The ACL, or anterior cruciate ligament, is a ligament that connects the tibia to the femur. It is found in the middle of the knee joint, posterior to the patella. The ACL provides stability to the joint, as well as facilitating the structure of the joint by conjoining the bones of the upper and lower legs.
What is a torn ACL?
A torn ACL is where the ligamentous fibers of the anterior cruciate ligament are torn, separating the ligament into two pieces. This is typically caused by hard twisting motions, as well as through hyper-extension of the knee joint. The ligament is not designed to move laterally, and the aforementioned twisting motions cause a severe lateral movement that often results in a tear.
Degrees and symptoms of an ACL tear.
- Pain in posterior aspect of the knee
- Limited range of motion
- Lack of stability
1st Degree Tear: Hyper-flexion of ligamentous tissues that is equivalent to a sprain.
2nd Degree Tear: Many tissues are severed by the ligament as a whole is intact.
3rd Degree Tear: A complete severance of the ligament
How can an ACL tear be prevented?
The best way to prevent an ACL tear is to wear a knee brace, which prevents the knee from twisting, the most common mechanism of an ACL tear. However, ACL braces can be very restrictive and uncomfortable. The best way to prevent injury without a brace is to strengthen the muscles of the knee so that if a twist or impact is to occur, the majority of the force is absorbed by the muscles, which are much better equipped to dealing with this stress than the ligament. Another critical method involving the muscles is flexibility, which can be accomplished through stretching. If the muscles are tight, they will not be able to fully flex in order to accommodate the impact, some of which will be displaced onto the ligament, which can cause it to tear.