Did you know approximately 150,000 to 200,000 ACL tears occur in the United States every year? These injuries commonly happen in sports during contact injuries (when your knee is either struck by another player) or non-contact injuries (when a twist occurs to the knee while your foot is planted on the ground). If you’re playing a sport, shift your knee, and feel a shift or pop you could have torn your ACL. Most athletes will develop swelling afterward and the knee can feel unstable. If an ACL tear is left untreated, more damage may occur to the knee when a person returns to playing sports due to improper healing. After an injury has occurred you should rest, ice and elevate and get in for an evaluation by an experienced sports medicine physician.
What is an ACL?
ACL stands for the anterior cruciate ligament. It is a strong piece of tissue called collagen that runs from the femur (thigh bone) to the tibia (shin bone). Other important ligaments of the knee include the PCL (posterior cruciate ligament), the MCL (medial collateral ligament), and the LCL (lateral collateral ligament). The ACL provides very important stability for cutting and pivoting activities. It runs diagonally in front of the posterior cruciate ligament and forms somewhat of a cross hence the name “cruciate”. This strong piece of collagen connects from the femur to the tibia in the central part of the knee and is composed of two bundles. The anteromedial bundle is tight in flexion while the posterolateral bundle tightens in extension. The average length is about 38 mm with an average width of 10 mm. The ACL prevents the tibia from translating forward during cutting twisting activities. Most people will still be able to run and walk without an ACL but will usually have trouble trying to participate in sporting activities that require a sudden change in direction such as basketball, football, and soccer.
To learn more about ACL injuries, see our extensive ACL injury page here.
What athletes are most at risk for ACL tears?
Did you know that women are more likely to tear their ACL than men? Women are 3.5 times more likely to tear their ACL in basketball and 2.8 times more likely to tear it in soccer. The reason for this is probably multifactorial and may include anatomic differences, hormonal influences, and most importantly neuromuscular factors. The most common sports where ACL tears take place include football, basketball, and rugby.
What are Pediatric ACL tears?
Pediatric ACL tears occur among children and are treated differently from adult ACL tears. An interesting article comparing the two can be found here. Children can definitely tear their ACL but it is not as common as in adults. Most injuries to the ACL in the pediatric population results in a fracture to a small piece of bone called the tibial eminence. If the fracture is displaced it can be repaired arthroscopically. If it is non-displaced it can be treated without surgery using either a brace or cast. The overall healing time is much quicker than with a typical ACL reconstruction.
How can ACL tears be fixed?
ACL tears can rarely be fully “repaired” but most require reconstruction using a graft. A graft is a piece of collagen tissue that is used to replace the damaged ACL. There are different types of grafts that can be used for ACL reconstruction. Two major categories are allograft and autograft. Allografts involve the use of a cadaver while autografts are when the tissues used in the reconstruction come from your own body. Autograft tissue options include patellar tendon, hamstring, and/or quadriceps. At ISMI the type of graft to be used is personalized to each patient depending on their age and activity level.
How can ACL tears be prevented?
Working on improving muscular strength and control prior to sports participation can markedly reduce the risk of an ACL tear.
To learn more about ACL tears and reconstructive surgery please click the following link: ACL (Anterior Cruciate Ligament) Injury