2. Foot factors: A common phrase used in sports medicine is “Don’t just look at the site of the crash.” In the case of an ACL tear, the muscles around the knee are not the only ones to be considered. One must also look at the feet. The three most common foot factors related to ACL injury are

• Pronation
• Limited Dorsi flexion (ability to curl toes towards shin)
• Flat footed

Landing flat footed form a jump can cause ACL injury. The proper landing progression is toe, ball, heel, squat.

3. Lack of Neuromuscular Coordination: Even recreational athletes with minimal muscular imbalances may be susceptible to ACL tears due to faulty muscular firing patterns. The hamstrings may be strong, but if they don’t fire at the exact right moment, they will not protect the ACL. Sport conditioning experts often use the phrase, “Train the Chain.” This refers to the kinetic chain, which describes the sequence of muscular contractions in any movement pattern. Cutting edge sport fitness professionals seek out training patterns that mimic the kinetic chain sequences of specific sports.

4. Insufficient Balance and Stability: Prior to any foot strike, your deep core muscles must to stabilize the sacroiliac (SI) joint. If this does not happen, the SI joint is destabilized, causing a misalignment of the femurs connection to the pelvis, which in turn misaligns the knee.

5. Lack of Proprioception: Proprioception refers to the awareness of your body’s position in space. Poor proprioception will make you unaware of the terrain below your feet. This lack of awareness can cause you to misjudge your movement patterns, thereby setting you up for injury.

6. Tight Hip Flexors: Tight hip flexors are usually accompanied by a weak gluteus. If your gluteus is weak, your quadriceps need to work harder, which in turn causes a hamstring/quadriceps imbalance, which sets you up for injury.

7. Tight Illiotibial Band: The IT band runs down the side of your leg. If it’s tight, it inhibits the workings of the vatsus medialis, which is the muscle above the knee responsible for correct knee tracking. Incorrect knee tracking can cause injury.

8. Weak Eccentric Strength: Since ACL injuries happen in the eccentric or lengthening phase of muscular contraction, lack of eccentric strength can cause injury.

9. Poor Technique and Malfunctioning Equipment: Even if none of the above factors are present, poor technique and malfunctioning equipment can lead to ACL injury. The Vermont Ski Safety Association has outlined the key technical faults that set a skier up for injury:

• Attempting to get up while still moving after a fall.
• Attempting a recovery from an off-balance position.
• Attempting to sit down after losing control.
• Uphill arm back.
• Skier off-balance to the rear.
• Hips below the knees.
• Uphill ski unweighted.
• Weight on the inside edge of downhill ski tail. Upper body generally facing downhill ski.

Each sport has specific guidelines for safety. Educate yourself.