Researchers work to make skiing safer on knees

BOISE, Idaho -- Downhill skiers often lug more than skis, boots and poles to the slopes. They also bring a nagging fear of a knee injury, a trauma that has prompted some to switch to snowboarding and others to give up the sport entirely.

A handful of researchers across the country is trying to change that.

They hope to make skiing safer by analyzing ski-related knee injuries and using the information to design bindings that will sense ligament-ripping forces and release milliseconds before an injury occurs.

"There are four major ligaments of the knee and you can injure all of them in a bad ski crash," said Dr. Kevin Shea, an orthopedic surgeon with Intermountain Orthopaedics in Boise. "Right now, ski bindings protect the tibia (shin bone) at the expense of the knee. So we want to create a smarter binding that doesn't forget about the tibia but stops ignoring the knee."

Both Shea and Carl Ettlinger, a ski injury expert and president of Vermont Safety Research, are running separate research projects on the subject.

If the work being done by Shea or Ettlinger is successful, it could have a big impact.

Overall, skiing injuries have declined by about 55 percent since 1972, and injuries to the lower limbs have dropped by about 58 percent, according to numbers gathered by Ettlinger and his co-researchers. But in the two decades since 1972 serious knee sprains increased by about 268 percent, Ettlinger said. Since the mid-90s, serious knee sprain rates have dropped somewhat, but not nearly as much as injuries to other parts of the leg.

"If you look 30 or 50 years ago, most of the injuries we saw were called boot-top fractures," Shea said. "Because of the way the boots and bindings were designed, most of the force in a crash was transferred right to the top of the boot, breaking the tibia."

Shin fractures were greatly reduced thanks to research on the problem in the 1970s and 1980s, much of it by Ettlinger,

Improvements in bindings allowed a skier's boot to pull free of the ski in a crash, lessening the chance of injury. The research also led to new standards for bindings' release settings based on a skier's weight, height, age and skill.

However, there was a trade-off.

Some skiers' whose bindings unexpectedly released during aggressive turns tightened them to the point where they didn't release when needed to prevent an injury. That's when many found themselves visiting the likes of Shea for knee surgery.

Shea, an avid skier, would rather not get his patients that way. Current ski bindings are based on simple spring mechanisms, he said, and the design is overdue for refining.

"Technology has allowed the creation of sensors that are relatively small -- about the size of a couple of postage stamps -- that you could integrate into a ski boot-and-binding design. These sensors can recognize acceleration and angular velocity using small gyroscopes embedded into chips," Shea said. "They're getting small enough and most importantly cheap enough that they could be used as a ski binding-and-boot interface."

First, however, researchers have to figure out a way to differentiate between the forces generated during aggressive skiing and the forces that will injure a knee.

Shea and Dr. Ron Pfeiffer, co-director of the Center for Orthopedic and Biomechanics Research at Boise State University, are sending out detailed surveys to ski resorts, ski patrollers and hospitals that treat injured skiers.

Money for the work is coming from Shea and Intermountain Orthopaedics' research foundation.

"If we find one mechanism that contributes to 75 or 80 percent of the knee injuries, then we want to go back to the lab and redesign those bindings so it doesn't occur," Shea said.

But it could be a race to the lab. In the coming winter, Ettlinger and partner David Dodge plan to begin skiing on a small prototype interface that fits between the bindings. The interface will measure not only the twisting loads on a skier's leg, but where that load is coming from -- be it the inside edge, outside edge, front or back of the ski.

Ettlinger's background research is funded by Fletcher Allen Health Care, a hospital affiliated with the University of Vermont Medical School. His company, Vermont Safety Research, is paying for development work on the knee-friendly binding invention.