ACL IQ: Did you know?
- There are an estimated 100,000 ACL tears a year
- 80% of these are non-contact injuries
- The majority of those who tear their ACL’s are female
- Almost all tears occur while playing sports
You have probably all heard of or known someone who has recently torn his or her ACL. This injury has become more prevalent in the last few years and has taken many athletes, young and old, out of sport for at least six months. In my college career I was able to count the number of ACL tears on two hands from the men’s and women’s soccer teams alone. These injuries required intensive surgery and rehabilitation that took the athlete out for an entire season.
What is the ACL?
The ACL (Anterior Cruciate Ligament) is a ligament connecting the femur to the tibia that works together with the PCL, MCL, and LCL to stabilize the knee. More specifically, the ACL controls pivoting and sliding movements of the knee, aiding the quadriceps and hamstrings in stabilization of the joint. When the ACL is torn, the rest of the knee is compromised, causing more falls and further injury due to internal collapsing.
How is it torn?
The major factors for ACL tears combine the instantaneous loss of motor control while landing with the knees and hips straight. For example, while an athlete cuts inside, the knee collapses due to a valgus force (forcing the knee inward) while the foot and tibia point straight, causing the ACL to stretch beyond its limit and tear(Picture 1A). The loss of control is usually contributed to internal rotation of the hips, muscle imbalances in the quad and hamstrings, and/or failure to activate knee flexors, leading to excessive stress on the knee ligaments.
The ACL is often torn when an athlete plants and tries to turn at a 180 degree angle. The foot often gets caught in the turf, but the knee and hip still turn at that angle. This stretches the ACL to a point past its limit and results in the athlete hearing a “pop” in which they simultaneously lost stability.
Good News
In the last few years there have been a few groups who have taken on research in order to find a preventative program to avoid this injury. One research group from the Vanderbilt Orthopaedic Institute found that girls age 14-17 involved in a preventative program were 74% less likely to tear their ACL. Although many of these prevention programs differ slightly, they all include neuromuscular training consisting of plyometrics, balance, and technique training. The main focus of these programs is to alter neuromuscular risk factors so that the knee joint is more stable and the musculature surrounding the knee can preactivate and activate correctly in order to protect the ACL.
- Velocity is looking to implement a program like this in the future
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