Biomechanical Engineer Discusses Injuries Suffered by Skier at Terrain Park


Biomechanics Expert WitnessThis case involves an injury suffered by a patron at a ski resort terrain park. On the date of the incident in question, the plaintiff – who was a talented downhill skier – had spent the majority of the day skiing various trails at the resort. Towards the end of the day, the man and his friends decided to spend some time on the terrain park. The park had recently been fitted with a large air bag, which was intended to provide soft landings following jumps from a large ramp. On the plaintiff’s first attempt to use the device, he performed a backflip and landed on the airbag. During the landing the man severely injured his lower back, causing permanent paralysis.

Question(s) For Expert Witness

  • 1. Please briefly describe your experience working with injury biomechanics as it relates to skiing and/or snowboarding.
  • 2. Do you have any level of participation in the winter sports industry setting any types of rules or standards for safety / injury prevention?
  • 3. Can you speak specifically to the kinematics and biomechanics of front flips and back flips? Is one any more dangerous than the other?

Expert Witness Response E-115138

I have a PhD Biomedical Engineering studying the injury biomechanics of catastrophic neck injuries in head-first impacts, and I am an expert-level snowboarder with prior experience riding, coaching, and competing in terrain parks and halfpipes. My PhD thesis dealt exactly with this type of head-first impact and I am very comfortable and knowledgeable with the literature surrounding catastrophic neck injuries from head-first impacts. I have been a snowboarder for about 30 years. In the 1990’s I was a sponsored rider and appeared in several magazines and movies. I suffered a (snowboard) career-ending injury in 1995 when I ruptured the extensor mechanism in my right knee. This was my foray into injury biomechanics and marked the start of my university education. While I have a deep understanding of the biomechanics of snowboarding I have not yet worked on any cases involving snowboarding injuries as a forensic biomechanical engineer up until this point. I can specifically speak to the kinematics and biomechanics of front flips and back flips. Both front flips and back flips can be dangerous however front flips tend to be less dangerous because the inverted part of the aerial occurs earlier and generally it is easier to keep rotating once started. With backflips, without proper technique, it is easier to end up performing only half the rotation and then landing head-first.

Expert Witness Response E-096771

I am a former expert skier from 1972 to 1989. Relative to this accident, I have analyzed trampoline and fall injuries resulting in quadriplegia, skull fractures, and head injuries. My PhD doctoral research was on quadriplegics and paraplegics and I have done testing with crash-test dummies in head first and rotating falls. I can specifically to the kinematics and biomechanics of front flips and back flips. The major difference is visibility; in back flips the skier/snowboarder can view the ground before landing and modify his rotational speed to land correctly. In front flips, the ground is usually not visible just prior to impact. In terms of landing on one’s head, it only takes a fall of about 1.5 feet or so for the momentum of the torso and body to crush the neck if the head stops. This is called a diving injury, and it has been studied since the 1970s. In a back flip, the rotational speed is often less than during a front flip, but this is not necessarily so. An expert can use the body’s center of mass position and the ground reaction force to cause the body to rotate quickly in either a front or back flip.

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