The female athlete is unfortunately more at risk of damaging their ACL than males, even taking into account amount of time spent playing sport.
It goes without saying that the knee is a very complex piece of kit but it allows huge loads across it and yet functions to provide highly agile movements with fast pivoting and rapid deceleration and acceleration actions.
To do this the knee needs power and leverage. The ligaments are static restraints in the knee and the most important part of knee function is the muscular control that makes it work. Not only do the muscles make it work but they protect against abnormal forces that may overload and damage the knee structures.
The musculature control of the knee requires a highly tuned reflex nerve control system. It is this neuromuscular control of the knee that seems to be the possible underlying factor explaining why some may rupture their ACL in an injury whereas others may not.
Essentially it most boils down to methods of landing pivoting and twisting. Analysing positions adopted in those activities has shown that there is a difference between how women and men control their knees. In jumping and landing women tend to land with slightly straighter legs than men who land in a more powerful squat position with knees slightly apart.
Add to this the anatomical fact that women tend to have wider hips than men so that the sideways angle between thigh and lower leg is greater in women, then it becomes more understandable as to why the female knee may buckle and be injured. The muscular male squat knee that is held in line on landing seems more protected than the longer thinner and less muscular knee that can buckle sideways on landing.
This theory of poor neuromuscular control has been tested in large groups of female soccer players trialling specific landing and jumping techniques in some and showing that those trained had fewer problems of ACL rupture than untrained athletes.
The importance of all this is that if poor landing technique is recognised and acknowledged as a cause of the original ACL rupture then specific training can be undertaken which may hopefully prevent the re-injury to the same knee or new injury to the opposite knee.
Specific skills therefore need to be learnt in landing and jumping techniques – the principle being to land with the knee forwards and not buckling to the side – inwards or outwards. For the female, this means landing with the knees slightly apart, in a more squat and perhaps un-ladylike male posture. In addition the principle of landing on one leg at the same time as pivoting to throw the ball should be avoided as this is the possibly the most at-risk manoeuvre to rupture the ACL.