I hadn’t intended to discuss ski injuries at this point. But in preparing the visuals for my last post, NEUTRAL? ANYTHING BUT, my mind kept running through the horrific, gut wrenching crash of Lindsey Vonn in the women’s downhill in February 2013. This post segues to an issue that is central to my efforts, skier safety.

When I did a research project in 1991 with a company called MACPOD (Steve Podborski and I) on the mechanics, biomechanics and physics of skiing,  I was fortunate to have worked with some exceptionally talented scientists. One such scientist was Alex Sochaniwskyj, P. Eng. Alex is a biomedical engineer. At the time that we started our project I specifically requested that we ask Alex if he would work with me. He was working as a consultant at the Hugh MacMillan Rehabilitation Centre in Toronto. When Alex was approached he left his position to work on our research project. Alex’s impression of me, as expressed in his letter in support of my nomination for a science award in 1995, is as follows:

“The design and development strategies used by David MacPhail are very holistic in nature, placing the human as the central and most critical component in a biomechanical system. His intent is to maximize human performance and efficiency, while foremost preserving the well-being and safety of users (emphasis added) and minimizing biomechanical compromises.” – Alex Sochaniwskyj, P. Eng.

In an ideal world, there would be no injuries in sports. Although some injuries are unavoidable, I believe that every effort should be made to keep the number as close to zero as possible.

The official explanation of the events of Lindsey Vonn’s crash was that she came off the jump off line, tried to correct, could not hold her line, crashed and injured her knee. Other than Vonn appearing to come off the jump off line, I disagree with the events. What I saw after much frame by frame study is that Vonn landed with her right extended and angulated in anticipation of beginning a correction when her skis made contact with snow. She appears to have landed with her right ski on edge. Landing jumps on anything other than in a straight line on a pitch incurs risk because the feet and legs have limited ability to dissipate the energy of impact. Landing on one foot multiplies the risk. If this post helps even one skier avoid injury it will be worth my effort.

Here is a short clip of Vonn’s crash in slow motion with a number of stop action frames at critical events.


Here are a series of still images.

In the first image below Vonn appears to be caught back and trying to get over her skis. Her left arm is up. Her right arm appears to be directed across to the left as if she is trying to make a left turn. The angle of her right leg appears to be angulated in the direction of a left turn.

Vonn 1

In this image it appears as if Vonn’s right knee has moved towards her left knee. Her right ski has acquired more edge. I think it probable that her knee was injured in this frame.

Vonn 2

In this image it appears that Vonn has lost support of her right leg

Vonn 3

In this image Vonn’s right leg is giving way.

Vonn 4

This image is hard for me look at. The angle of her right leg is brutal. It was after this frame that she tumbled forward. I believe she fell because her knee was injured and did not injure her knee in the forward fall as some claim.

Vonn 5

I hope that I never see anything like this again.


    1. Hi Doug, it is hard to make definitive conclusions as to the exact injury mechanism from one perspective, or especially to predict whether Vonn could have done something to avoid the injury. But years ago I understood enough about how rigid ski boots limit the ability to absorb the energy of impact when landing a jump on a slope that is substantially flat to know that such a format involves high risk for the racer. In any event, the worst thing one can do is to land a jump with the outside leg of the next turn extended and on its inside edge. From what I can see from the video, Vonn’s right ski touched down on its inside edge. The force would have rotated her ski to the outside of the turn. This would have rotated her leg towards the outside of the turn against her thigh which was rotating into the turn. At the same time, the inner aspect of her boot cuff was pushing her leg to the outside of the turn; in effect applying a bending moment on her lower limb which would manifest itself at the knee. In summary – instantaneous opposing rotational forces or torques at the knee acting in combination with bending movement towards the outside of the turn. When I saw the slow motion replay on television I felt sick. Vonn’s knee didn’t break. It exploded. Horrific!

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