According to AIHW data, 7 men per 100000 of the population and 5 women present to hospital with an ice and snow sports related injury. However, bear in mind that this is only data on who presents to hospital, not who presents to a physio or private GP clinic. When participation levels are factored into this data, it becomes clear that women represent a higher proportion of the injured.
Women have lower participation rates in snow sports than men (just over half the number of women compared to men), but disproportionate injury presentations. And what is the single highest injury for skiing? ACL damage – the anterior cruciate ligament – that pesky ligament in the knee that you hear about so often in sports injuries.We know that in elite skiers (on the World Cup), this is the highest injury for all competitors.
Between men and women the ACL injury rate is fairly even. But when it comes to recreational skiing, women suffer ACL tears far more frequently than men. Looking at the mechanism or movements involved in causing an ACL rupture, women’s natural structural and biomechanical predisposition put them at an unfair disadvantage for suffering one of these types of injuries.
WHAT MOVEMENTS CAUSE THE ACL TO RUPTURE?
Tone Bere and her pals at the Oslo Sports Trauma Research Center did a visual analysis on ACL injuries and identified the movements that cause an ACL rupture. They determined that the “slip-catch” mechanism was the reason for more than half of the knee injuries. They defined this movement as: the outer ski loses an edge and the skier is off balance. They try to regain balance by extending the outer leg. This outer leg then abruptly catches an inside edge, forcing the knee into internal rotation and valgus (knock knee). So in brief the outer leg is twisted in and the knee is bent inwards, rupturing the ACL. Ouch.
The other classic ski mechanism of injury is “phantom foot”. The knee is bent welllllllll beyond 90 degrees and the foot is internally rotated in.
In this position, the bindings can’t detect that they need to release and they stay on, tearing the ACL instead. Check out the picture on the right of this position. Snap goes his left knee!
WHAT INCREASES THE RISK OF ACL RUPTURE?
A lot of these are just suppositions and not necessarily based on evidence found in the literature, but here are some of the risk factors associated with ACL, based on expert opinion. Whilst the risks are not proven by research, when you look at the mechanisms or movements involved in injuring the ACL, it might be considered reasonable to assume that predisposition to already be standing in those positions would put you more at risk of injury.
Increased Q angle (knee valgus or knock knee) – more common in women
Joint laxity/hypermobility – more common in women
Proprioception (or neuromuscular control/functional joint stability – do your muscles activate subconsciously to control the joint’s stability?)
Low quadriceps and hamstring muscle strength – especially eccentric muscle contractions (when you’re decelerating or slowing down)
The straighter your leg the greater the strain on the ACL in motion. If your knee is flexed more than 60 degrees, the ACL is far far less strained.
THIS IS BUMMING ME OUT, WHAT CAN I DO TO LOWER MY RISK?
Yes it does sound a bit dreary, but of course there are things to do to try to lower these risk factors. And clearly it is possible to lower these factors, as we see women in the World Cup have even ACL rates with the men. So hope is not lot. A lot of these start with being fit and doing some skiing-specific strengthening and proprioceptive training. Several neuromuscular training exercises have been evaluated with impressive success. This sounds far trickier than it really is.
Here are some everyday tips you can do:
Squats and lunges to strengthen upper legs – so you can ski in a better ski stance with knees bent (without that burrrrrrn in the quads after one run) to reduce strain on ACL
Pilates to improve your core and balance
Balance board exercises
A proper ski boot alignment and set-up to reduce the biomechanical factors (this reduces the impact of things like: knee valgus, foot pronation, muscle imbalance from uneven ski stance). A good bootfitter can help you with this. Read a little more about our assessment service here.
All these exercises only work if you’re doing them with correct technique. So if you’re not 100% certain that you’re nailing the technique, it’s best to book in to see a physio or exercise physiologist to get some direction. Just do it people, it could save your holiday and your knee.