Protecting the (ACL) anterior cruciate ligament

By: Melanie Brewer, PT, DPT, OCS

"I came down funny on my leg, felt a pop in my knee, and it buckled on me…" As a physical therapist, I cringe when I hear one my athletes tell me that…and when I have to say "I think you may have torn your ACL…", the athlete and parent are devastated instantly. Why the feeling of devastation? Well that little bundle of tissue called the anterior cruciate ligament (ACL) is pretty important. When torn, it's not like most other injuries. In an athlete, it usually requires surgery, affects mental toughness, the rehab is extensive, and it takes a massive amount of commitment from the athlete in order to bounce back and return to sport with confidence.

An ACL injury is one of the most commonly known sports-related injuries. It is becoming more prevalent in our young athletes, particularly in girls. Over 120,000 ACL injuries occur annually, and nearly 80% are in girls ages 15-19. In fact, girls are 4-8x more likely to tear an ACL as compared to boys. The most concerning statistic is that 2/3 of all ACL injuries are from noncontact resulting from one-step/stop deceleration, cutting movements, sudden changes in direction, landing from a jump with inadequate knee and hip flexion or at full extension, or lapse of concentration. Straight-ahead sports like jogging, swimming, and biking place minimal stress on the ACL. Sports such as football, soccer, basketball, and volleyball that involve cutting, planting, and changing direction, in which the ACL plays its most important role, put all athletes but particularly girls, at highest risk for injury. But there is some good news. Because most of these are non-contact injuries, a majority of them can be prevented.

The female athlete may be more at risk for noncontact ACL injuries due to anatomical and hormonal differences that occur in girls versus boys, but these factors are probably minimal. There are modifiable risk factors that we as therapists and trainers can impact: PROPER COACHING AND TRAINING, strength, movement patterns during dynamic movements, landing techniques, conditioning, and skill. There are differences in strength and muscle recruitment patterns in females. Girls tend to have an imbalance between quadriceps and hamstring strength where they are more quadricep dominant and rely less on the hamstrings and posterior chain to balance out the power of the quadriceps. Proper leg muscle strength training and core training should include a focus on the posterior chain: the glutes, the hamstrings, and the calves. Specific exercises to address the posterior chain include: hip thrusts/bridging (including both legs and single leg and progressing from body weight to weighted), deadlifts, cable leg extension, GHRs, side lying clam shells, banded walks in all directions, and reverse lunges. When performing squats it is imperative to properly cue the athlete, as females tend to be more quad dominant with this activity. Emphasize bracing with the core, maintaining appropriate stance for that individual, not allowing knees to cave in, and pushing through the heels.

The jumping and landing technique of the athlete needs to be closely observed. What needs to be prevented is the "position of no return". This is the position where upon landing from a jump, the athlete caves in the leg(s) and the hip and ankle rotate in, trunk control is poor, and the knee is at near or full extension. This position is most taxing on the ACL and is the typical position that occurs when an ACL is injured. The athlete who demonstrates this poor position typically has deficits with neuromuscular control (muscle and brain connection).

Strength and neuromuscular deficits are the principal culprits in injuries. Strengthening alone doesn't work. Proprioceptive training (balance and awareness) alone doesn't work. What works and has been proven by research to reduce injury risk is the combination of strength, stability, and movement…what we call dynamic neuromuscular training. That is technical jargon for retraining the brain and muscles to communicate better during functional movements (squatting, landing, jumping, accelerating, decelerating). Research suggests that by implementing a simple 15 minute dynamic warm-up into sports programs, there is a significant reduction in ACL tears. The evidence is there, the knowledge is there, the problem is in the implementation into athletic programs.

A basic dynamic warm-up is 10-15 minutes and combines warm-up, stretching, plyometrics, and sport specific agility drills while emphasizing correct posture, straight up and down jumps to minimize side to side movement, and soft landings. It requires monitoring of your athletes to ensure proper form and observe for lower extremity asymmetries. There are a wide variety of programs out there, but some movements that could be included are toy soldiers, inchworms, grunges (walking lunge with trunk rotation), walking knee hugs, over the gait/under the fence (side to side stepping with exaggerated hip rotation into squatting), and skipping forward and backward.

There are many variables involved in ACL injuries, but there are definitely methods to reduce risks for injury and put everyone on a level playing field. Proper communication between athletes, coaches, therapists, trainers, and parents will keep our kids in the game.

Melanie Brewer is a Doctor of Physical Therapy at KORT - Kentucky Orthopedic Rehab Team.