Knee Injury Epidemic - Part 1

This post was super easy to write for a couple of different reasons. Primarily because I was writing something very similar for a class presentation and have been gathering a bunch of resources on the topic already. The second reason is because I had a request that I cover it. This really is awesome because sometimes as I write this blog I wonder if there is any interest. The topic is the knee injury epidemic that is running rampant through the world of athletics. Part 1 will address the anatomy of the knee and some of the reasons behind knee injuries. I did not discuss female athletes and the plethora of additional factors that predispose them to knee injuries. There is enough content for a completely separate post and it has also been addressed already by quite a few coaches. I tried to keep this as basic and non-technical as possible but if you have any questions fire me an email.

Torn Ligament can really ruin your day

Joe Susi, one of my professors and good friends, sent me a few power point presentations (from different athletic trainers that had presented in his class) last week and one of them had some great statistics. First though a little background on the different types of injuries. In viewing knee injuries they can be classified into two categories. Contact- meaning the injury occurred as a direct result of external contact. This makes the cause of injury very easy to diagnose. The second category is: Non-contact - meaning just that. The injury occurred without any external force.This makes it much more difficult to pin point the exact cause of the injury.

As I learned this week 70% of serious knee injuries are non-contact, meaning no opponent was touching them as the injury occurred. The average number of ACL surgeries each year is est. at 100 000.  So, 70 000 of these occurred without the athlete being touched. The two most important questions are: Why? and How can I prevent this?

Knee Anatomy 

 When studying then knee it is important to understand that the joint is designed for stability and not mobility. The knee is supported by a variety of muscles, ligaments, and passive tissue. They all act on the knee in different directions, creating tension but also protecting it from shearing forces.  Your knee is very similar to a ball with strings extending off in all different directions. If one string gets pulled tighter than the others the ball is rotated and taken out of optimal alignment. Once pulled out of this alignment the ball will no longer act as it should and one of the strings may snap during movement. It is the snapping of these "strings" that can sideline someone for months. (2 years for 100 percent performance recovery) As stated earlier it is very difficult to pinpoint the exact source behind non-contact injuries, there are multiple factors at play that influence the injury. Even if the injury is a contact injury and a specific cause can be identified it is likely that these factors still played a role. 

1.) Poor Mobility in the Ankle and Hip
     The knee is designed for stability, not mobility. The ankle and hip are designed to provide mobility and if these joints are excessively tight or lack full ROM the body may compensate by creating mobility at the knee. It is similar to trying to twist a long stick. You may get some rotation but it does not take much to cause the stick to splinter and break. The knee behaves in the same fashion, it has some mobility but if pushed something will break.

2.)Weak / underdeveloped Muscles
     The strength of your glutes can go a long way in avoiding knee injuries, the glutes acts directly on the femur which is obviously a major part of the knee joint. Most of us sit to much which leads to tight hip flexors and weak glutes and inhibits its actions on the femur. A weak glute will cause valgus forces (forces collapsing inward) and internal rotation of the femur which puts the knee in the "danger zone".

3.) Tight Adductors

Valgus Force

     The muscles that draw the femur inwards toward the mid-line of your body are the adductors. These muscles are typically VERY tight due to overuse through body compensations. This further compounds the issue with our glutes by further adducting and internally rotating our femur.

4.) Poor Proprioceptive Abilities
    Often people will not even realize that they are allowing their knees to collapse inward during their activities. The rate is even higher in untrained individuals. They may have not received the type of coaching that would educate them on knee heath.


These are by no means the only factors that influence knee injuries but they are 4 of the more important ones IMO. In Part 2 I will discuss ways to prevent these injuries and different movements that should be incorporated into a training program.