By Joshua Bruner, Physical Therapist
With high school and college sports starting once again, it’s important to understand what the ACL (anterior cruciate ligament) is, what causes tears, and most importantly, how tears and injury can be prevented.
The ACL is one of the most frequently injured ligaments in the knee. Each year 100,000 to 200,000 ACL injuries are reported in the United States. So what exactly does the ACL do? It prevents forward movement of the tibia (shinbone) on the femur (thighbone) and assists with stabilizing the knee during fast movements. When the ACL is torn, individuals often feel unstable, as if the knee is “giving out”.
The most common way to injure the ACL is through non-contact movements such as pivoting and jumping. Risk factors for experiencing an ACL injury can be separated into two groups: non-modifiable and modifiable. Non-modifiable risk factors, which can’t be changed with exercise, including gender, family history, bony structure and laxity (looseness) of the ligament. Modifiable risk factors, which can be improved with exercise and guidance, include landing and jumping mechanics, poor body awareness, and hamstring, core and gluteal muscle weakness.
The most common cause of an ACL tear is through a combination of movements that incorporate inward motion of the knee and inward rotation at the hip.
How to prevent an ACL tear:
Although an ACL tear cannot be completely prevented, participating in an ACL prevention program may decrease the risk of injuring this ligament. An ACL prevention program can be separated into four phases: mobility, strengthening, landing mechanics, and body awareness.
The first phase should focus on assessing range of motion of the ankles, knees, hips, and trunk. If you don’t have adequate motion in these joints, you may be at risk for placing increased stress on the knee. Therefore, gaining motion in these joints should be the main priority before progressing through the ACL prevention program.
The second phase involves strengthening the posterior chain (a group of muscles on the back of the body), which includes the hamstrings, gluteus medius, and gluteus maximum. These muscles control the movements that prevent inward motion and rotation of the knee during landing, pivoting, and jumping activities. Exercises that target these muscles include squats, deadlifts, bridging, poor man’s glute-ham raises and hamstring curls on a Swiss ball.
The third phase of the program focuses on correct landing mechanics and should be addressed only when you have enough lower body strength. When jumping, you should land with knees bent in order to absorb the impact. The knees should also be aligned with the toes, preventing inward motion of the knees.
The final phase emphasizes proper body awareness when performing high-level activities. You should be taught to land equally on each leg in order to avoid placing greater stress on one knee. Training should involve side-to-side drills that incorporate single leg balancing and strengthening exercises. This phase should also contain strengthening exercises that target the abdominals, back extensors and oblique muscles because these muscles stabilize the trunk and allow for a more equal landing position. The EDGE at Southwest Health offers programs that do an excellent job of incorporating these phases into their sports performance training and ACL Bridge program.
ACL tears cannot be completely prevented, but incorporating an ACL prevention program into your regular training can reduce the risks. If an injury does occur, a physician, physical therapist, or orthopedic specialist should be contacted to address any concerns. For further questions or additional information, contact the The EDGE (608.342.4790) or The Orthopedic Institute and Physical Therapy Rehab Department (608.342.4748).