ACLs And Why They Tear


The anterior cruciate ligament (ACL) … we all have heard the term and recognize it the most when we see an athlete go down holding the knee.

200,00 athletes tear their ACL every year. That number was recorded some 5+ years ago and it still hasn’t changed to date. And still amongst those numbers a 9:1 ratio of ACL tears belong to females than males.

The age range varies amongst this excruciating tear but the most common sufferers range between 15-45 y/o with (Griffin, 2000 & Chapman, 2001) stating the focus was on youth athletics being the culprit.

Most oftentimes, a greater number of ACL injuries reside in non-contact situations. This is most likely due to factors such as pattern overload and compensation and also insufficient strength and stability. Poor movement in the participation of sport requirements also come into play.

The lesser degree tears are contact injuries where an external force causes the ACL to snap. Football, soccer, rugby come to mind.

These sports represent the higher risk to ACL injuries with contact or not: basketball, soccer, football and skiing.


We Must Ask Why Do ACL Tears Occur?

The Female Target

The first assessment area to focus on is the Q angle.

The Q angle is quite evident in wide hips or the outside width of the pelvis. From there look and measure if need be to identify the line straight down to the floor from the outside hip or outer pelvis and then remeasure from the starting point to the knee. The distance between the 2 lines is the Q angle measurement.

Women either naturally and/or from giving childbirth have an average Q angle of 11-15 degrees which is 4-5 degrees greater than males. This position adducts the femur and makes the pathway for a vagus knee (see below) to occur and lead to an all tear.

The second factor to mention is this… we tend to just think of quadricep dominance to be all about females. All athletes at some point in time over compensate through the quads because they have learned to fire the posterior chain. There are other factors to discuss here but that goes beyond this blog today. But getting the glutes to activate and be dominant force is key. Get this we have less stress on the knee.

Lastly, the menstrual cycle monthly visit reads havoc on the ligamentous system and therefore causes laxity in various regions in the body that increase risk to ACL tears.


Knee Valgus Angle

A knee valgus angle is defined by the angle formed at the knee joint and you get “knocked knees”.

When athletes are not trained correctly and/or do not have the proper body awareness during functional and sports specific movements, increased knee valgus angles at the knee are common causing significant amounts of stress on the ACL. (Hewett et al, 2006)


Early Specialization In Youth Athletics

One of my favorite sayings is, “We can thank the club sports in the world for destroying young athletes.” Why is this so? Back in the day it was an absolute accomplishment to be a 2-3 sport athlete in high school. And as youth athletes we were well rounded by playing a number of sports throughout the year. This indeed developed the whole athlete. A good athlete.

Nowadays,  early specialization equals lack of overall skill development with basic human movements…which in the end we have undeveloped, under-prepared bodies who are over-exposed to one sport they play.

If coaches and parents won’t allow full exposure to developmental movements then inevitably those little athletes will endure more physiological stressors that use to only happen soon the collegiate and professional level. That is why you have so many injuries with kids these days with extreme sprains and tears to tommy john surgeries and UCL complications from throwing sports. Let them participate in multi sports over the year instead of demanding they play one sport as if they are a professional already. What you put them through today will most certainly be borrowed from their tomorrow.


Poor Technique and Lack of Muscular Activation/Strength 

One cannot stress the value and need for proper technique with all sports specific movements and the developmental process of building a strength in all musculature groups important for their given sport.

It is common to see several athletes on a field or court performing sports specific movements with poor form…a lot.

Take the time to work on balance, coordination, mobility, strength and stability to with your athletes to decrease risk of injury and elevate their level of performance. That is high performance training. You do this you have less punishing suicides and gassers because they are not performing to ‘your standard’  and less injuries to boot. Killing 2 with one stone lol.


Balance and Proprioception Deficits

Balance is defined by the ability for an athlete to maintain stability and control during sports specific and functional movements. Proprioception is the ability for an athlete to understand where the body is in space during a given time both on and off the field.

If you have these one will be better able to demonstrate control in practice and competition.



The best action is prevention and develop your these young kids to be well rounded from the start and as time goes by let them pave their legacy.