ACL Injuries

by Brandon Byquist, PT, DPT

He goes down in a hard tackle, rolls and grabs his knee.  Is he faking, trying to get a penalty call or is this the real deal? Approximately 200,000 anterior cruciate ligament (ACL) injuries occur each year. The ACL is one of four critical ligaments that attaches the upper leg bone (femur) to the lower leg bone (tibia).  This structure can be injured during excessive loading from pivoting, sudden deceleration, cutting movements or being struck in the knee while in a compromised position.  Surprisingly, nearly 80% of ACL tears are non-contact injuries.  Female athletes are at an especially high risk.  Studies indicate that females involved in cutting sports (soccer, basketball, volleyball) are 2 to 8 times more likely to sustain a non-contact ACL injury compared to male counterparts.  Strength or balance deficits, previous knee injuries, alignment of the lower extremities, certain movement patterns and hormonal fluctuations are all risk factors for ACL injuries.  

Symptoms of an ACL Injury Include:

  • An audible "pop" in the knee during the injury
  • Pain on the outside and back of the knee
  • Swelling of the knee within a few hours of the injury
  • Limited range of motion in the knee due to swelling or pain
  • Sudden instability or buckling of the knee after jumping, rapid change in direction or being struck in the side of the knee

If you believe that you or someone you know may have an ACL injury, it is wise to begin a regimen of rest, ice, compression and elevation (RICE).  A qualified medical professional (athletic trainer, physical therapist or physician) may be able to check for ligamentous injury using specific physical tests immediately, but ultimately an MRI will be required to definitively diagnose an ACL tear.  

There is good news!  Studies find that injury rates are reduced by up to 75 percent in adolescents by performing a specific injury prevention program.  Although numerous prevention programs exist, any reputable system should be based on the same basic principles.  A good prevention program will address avoidance of vulnerable positions, increasing strength, flexibility and proprioception, and will incorporate some plyometric training.  Typically, these programs take 15 to 25 minutes per day and need to be performed at least 2-3 times per week.  

Here is a video demonstrating a typical injury prevention program: