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Busted knees and broken legs

Why ACL ski injuries have skyrocketed and what you can do about it

When Robert Johnson first moved to Vermont to be a sports medicine doctor, skiing was pretty much the sport of choice for the mountain town. He threw himself at it enthusiastically — and busted up his knee in his first season on the slopes. "It happened pretty quick," he laughs.

After decades of researching ski injuries, Johnson now knows a host of factors played a role in his 1972 injury, including bad equipment that wasn't set up right. Today, the technology has moved on — and new developments might be poised to make things even safer. But some people still don't take the time to set up their gear properly, and smashed up knees and legs are often the result. "It drives me nuts to see people walking through the gravel parking lot in their boots and then they stick their skis on. And then they don't release like they thought they would, and they say 'but the bindings were set right doctor!'" says Johnson, who has become one of the leading lights in studying ski knee injuries. In particular, Johnson says, Canadian skiers don't always abide by international recommendations for testing binding settings. As a result, "our studies show you guys are breaking legs way more up there than you need to."

Skiing is actually safer today than it was decades ago: the total number of injuries per year has gone down 55 per cent since the `70s. But knees have taken the brunt of the accidents that remain. From the `70s to the `90s, the most common knee injury — a sprain of the anterior crucial ligament (ACL) — skyrocketed by 250 per cent. Since then the risk has come back down a bit, but you're still twice as likely to sprain your ACL today as in the early days of the sport. About half of top-ranked skiers have injured their knee ligaments, including Whistler Olympic medallist Ashleigh McIvor and Olympian Julia Murray; a third have done it more than once. And women, thanks to their different physiology, are up to five times more susceptible to these nasty sprains.

When it comes to knees, the basic problem is all the torque from your ski during a twisting fall. Catch an edge and your ski can turn into a torture device that rips your knee apart. And once you've done it, more pain awaits thanks to surgery and a long stretch of physiotherapy. You might find your knee collapses under you when you try to hop or twist, or you lose your balance, for years after injury. Some people never fully recover.

Risky business

Skiing is fairly dangerous, as winter sports go; in Canada, there were 2,300 hospitalizations from skiing or boarding in 2010-11 (the most recent year for which a full report is available), compared to 1,100 for ice hockey and 1,100 from snowmobiling. Whistler Blackcomb doesn't share accident statistics, but the Canada West Ski Areas Association says the average for Western Canada is 2.3 accidents per 1,000 people on the slope, which is about the same as for other resorts internationally.

At Sugar Bush resort in Vermont, Johnson at the University of Vermont College of Medicine in Burlington and colleagues have been keeping close tabs on injuries since 1988. Over 18 seasons up to 2006, they tracked more than 4.5 million visitors (more than 80 per cent of which were skiers).

The boarders were slightly more accident prone, with three accidents per 1,000 boarders on the hill — a third of those bailed because of a jump with a bad landing, and by far the most common injury (at 20 per cent) was to their wrists (next common, at 11 per cent, was to the shoulder). Boarders are fairly immune to knee injuries: only five per cent of boarder injuries were to the knee, and of those more than half happened in the terrain park. The researchers tried to work out whether wrist guards protect boarders against mishaps, but so few people were wearing them that they couldn't come to any conclusions about that.

Amongst skiers, there were about 2.5 injuries per 1,000 visitors. Of those, a massive 32 per cent of injuries were to the knee. Next up for skiers was seven per cent of injuries to the thumb, thanks to putting pressure on a pole during a fall, and six per cent to shoulders. A similar study in Scotland found about the same numbers, with roughly a third of alpine skiing injuries to the knee; ditto the Canadian Health Institute statistics.

What's interesting is that the type of injury has changed over time, mostly because of equipment. In the early days of the 1960s and `70s, boots were softer and bindings often didn't release, and so the body part most vulnerable to injury was the ankle. As boots got higher and stiffer, the injuries tracked upwards too: everyone started fracturing their tibia (including Alex Evans, an osteopath working in Whistler, who snapped his tibia skiing when he was 19 in the early 1990s. More about him later). Better binding release settings helped to protect the tibia, but not the knee. By the late 1970s the knee had become the preferred injury site.

Your knee is basically a hinge connecting the tibia of your lower leg with your femur, or thigh bone, which is protected by a knee cap. A handful of ligaments hold these three pieces together, including the critical anterior crucial ligament (ACL), which ties the femur and tibia tightly together in the middle of your knee, and the medial collateral ligament (MCL), on the inside of your knee. These are the ones most likely to over-stretch, or tear, when skiing.

Even the snowplow — the tamest of skiing techniques, taught to all beginners — can be dangerous. Skiing with your legs that wide and toes pointing inwards puts a lot of pressure on the MCL; crossing your skis, or catching an edge, can twist your knee enough to cause a sprain.

But the most serious knee injuries — the ones that most often need surgery to fix — are ACL tears. And the majority of those happen from one specific type of fall: when a skier sits too far back on their skis, basically trying to sit down to the rear, and catches the inside edge of the lower weighted ski. This kind of fall was nicknamed the "phantom foot" by Johnson's team, because your ski tail creates a strange extension that acts like a backwards-facing foot, and which can trip you up. Studies with traditional, long skis showed that this type of fall accounted for about three quarters of torn ACLs from skiing.

Backwards-leaning falls are what injured Daryl Treadway, a freestyle competition-winning skier living in Pemberton who is sponsored by Rossignol and others. He has blown both his knees. The first time was from a fall on a hard and mogully qualifier run at a competition in Rossland. "It hurt a little bit when it happened. I skied the rest of the run, but it felt a bit loose," he says. "In hindsight I would have known what it was, but I thought 'huh, I'll be fine.'" But being forewarned didn't save him from it happening again — the next time right at the start of a week-long ski tour on the Freshfield Glacier after a helicopter drop. "I hit some ice on a ridge and when I landed my big heavy pack just hauled me back," he says. "I had to ski out another five days. It was a huge mission. Again it wasn't really painful, just really loose."

After studying video footage of ski accidents, Johnson and his colleagues instigated a massive education campaign to try and limit ACL tears. Their tips include not "back-seat driving" — skiing off-balance to the rear with your knees bent and your butt hanging too far back. If you start to fall, throw your weight and arms forwards. Don't put your hand out behind you to stop a fall, as this increases the chance of straightening your leg in a way that puts more strain on your knee. And, importantly, don't try to get up again while you're still sliding down the hill, even if that does look cool. Mantras like: "when you are down, stay down" and "don't land on your hand" have helped to stop skiers from accidentally twisting badly on falling and recovery. When Johnson and others put ski patrollers through a training program to drill all that in, knee sprains in that group went down by 75 per cent.

But things might be changing, as practically everyone now uses shorter, carving skis instead of the old-school long ones. With shorter skis, there is less of a "phantom foot" to get tangled up with. With these skis, falling forward with a twist might be a more common way to bust your ACL, though Johnson hasn't seen any evidence of this yet. "The back end is still sticking out," he notes. Forward falls are less well understood, but Rick Greenwald, at the Thayer School of Engineering at Dartmouth in New Hampshire, is investigating. Greenwald said Johnson's campaign to prevent backwards twisting falls is great, but "for other falls, like forward twisting falls, we still need to learn about them so we can prevent injury through training or equipment."



The Classic Fall

Here are the key components of a fall that commonly busts knees

1) Uphill arm back

2) Skier off balance to the rear

3) Hips below the knees

4) Uphill ski un-weighted

5) Weight on the inside edge of downhill ski tail

6) Upper body facing downhill ski


Better bindings

What should help in both cases — a forward or backwards fall — is bindings that can better release your foot during a twist. Most bindings only release the heel upwards, while the toe can twist out sideways. If you catch the front tip of your ski, this usually causes the ski to rotate around your heel, creating enough torque to release your toe. In fact, in many forward twisting falls, the bindings do release — although often not in time to prevent an injury. But if you catch an edge near your heel, there's no torque to cause your boot to release; instead, your whole lower leg twists. "We instrumented all kinds of bindings and skied on them to look at times when the load isn't normal. What you'd like is to have a release mode for those settings," says Greenwald, who is working with Solomon on a not-yet-released binding that should help to do this.

One obvious, theoretical solution to this problem is to create a binding that releases sideways from the heel too. That way, "you get a second pivot point," says John Springer Miller, CEO and chairman of KneeBinding, a company that does just this. "No matter where the force is on the ski, it's always far away enough from one of them that you get a release," he says.

"It's incredibly simple. There's nothing complicated about it."

KneeBinding has been around for about seven years, and their bindings are sold by at least five companies including REI in the United States. Miller won't release statistics on their sales, but says that for all the bindings now out there, they should have seen 200-300 rear-weighted ACL injuries by now. "So far we haven't had one reported," he says.

There are other, less common ways to bust your knee, in particular the gruesomely named "boot induced anterior drawer (BIAD)." This happens when a skier takes a jump and lands hard, with legs straight, on the tails of their skis. In this case the foot gets thrown forwards inside the boot, and when your lower leg stops at the front of the boot, the upper leg tries to keep going, forcing your knee to blow open. Miller said they have seen about 10 of these on their equipment, which just goes to show that the people using it aren't totally immune from accidents.

Johnson and Greenwald are reserving judgement for now. "People come to me and ask me to endorse their equipment, and I say 'no you haven't proven it,'" says Johnson. "I don't blame them; it's too expensive to prove. It would take years of controlled studies." Things are complicated, adds Greenwald. "Is it the same for adults and kids? The same for men and women? We don't know the answers." Even the phase of a woman's menstrual cycle can change how their knees react, he says. The perfect binding somehow needs to account for all that. And, just as important as releasing during a twist is not releasing at an inconvenient time. "You have to add value, and don't make it any worse than it currently is," says Greenwald.

New bindings like these haven't hit the mainstream yet; Treadway has heard of their development, but didn't know they were available. Would he use them? "Oh yeah, for sure," he says, "if Rossignol (his sponsor) would let me."

Even without changing bindings, notes Johnson, you can improve your chances against some injuries just by making sure your bindings release when they're supposed to. About 15 per cent of all ski injuries — knees or otherwise — are due to malfunction of the bindings. The International Standards Organization, and the non-profit standards group ASTM International, both recommend that binding release settings be tested with something like a release calibrator — a device that checks the torque needed for a binding to pop. That's important, says Johnson, because anything from an improperly aligned screw, to wear and tear, or a broken or missing friction plate, can mean a binding no longer releases when it's supposed to for any given setting. "You have to test it to see if it's releasing when it says it is," he says.

MAny rental and tuning shops in Whistler offer this service though few customers take advantage of it. "We do our own fleet of rentals once a year," says rental tech Jordan Hodder at Summit Sports. "To be honest very few customers ask for it." The result of poorly-calibrated bindings, says Johnson, is more broken tibias in Canada.

In 2000, the French recommended that binding settings be reduced by about 15 per cent for certain at-risk groups (so they pop open more easily); since then they have seen fewer ACL injuries, perhaps because of better releases during forward twisting falls, though they can't say for certain. Of course, it can cause other kinds of accidents if your ski releases too easily — it's hard to keep going downhill in a controlled fashion if your ski pops off.

Another obvious way to help prevent falls is to make sure that skiers are actually fit before they hit the slopes. Mike Conway, a physiotherapist who co-owns Back in Action Physiotherapy in Whistler, says he always sees people in the gym in the run-up to ski season working on their quads. "Their quads are usually fine, because people use them for biking in summer," he says. "What you actually need to work on is hamstrings and hips; they're what supports your knee." Conway has developed an app, called SKIRAD, that helps skiers identify weak muscles before heading out on the slopes. And he recommends a short test you can do in your living room to see if your bindings will release if you twist — a low-tech version of a release calibrator. "You have to be careful not to hurt yourself while doing it," Conway cautions.

Surgical solutions

If you do tear your ACL, then you have to decide how to treat it. Around the world, most young people who want to get back to skiing aggressively, like Treadway, are advised to have surgery — there are more than 200,000 ACL reconstructions done a year in the United States alone. But some doctors have questioned whether that's necessarily the best course of action. A recent review, published in the Journal of Orthopaedic & Sports Physical Therapy, questioned whether surgery has just become the usual done thing, regardless of the evidence. Author Yonatan Kaplan, director of the Jerusalem Sports Medicine Institute at the Hebrew University of Jerusalem in Israel, notes that some people can "cope" without surgery "even at a high level of function and sports participation." Other doctors agree.

Duncan Jacks, an orthopaedic surgeon in Victoria who sees a lot of busted knees, still thinks surgery is the best option for young people who want to keep bashing the slopes. Some can get back to skiing without reconstruction, he says, but they "tend to stick to easy runs, ski at slower speeds, and avoid jumps and moguls." That's basically what Treadway was advised. "The surgeon said (going without an ACL) is like a vehicle without shocks; your tires take more wear and tear without it. You take the short-term loss of the surgery for the long-term gain of stability."

There are different types of reconstructive surgery for ACL injuries: you can replace the busted ligament with tendons from your hamstring (that's what Treadway had done), quadriceps, or patella (kneecap), or from a cadaver (that sounds gruesome, but remember that all organ transplants are technically from cadavers). "I've always thought the patella tendon graft is one of the better ones, but it can leave you with chronic anterior knee pain, from where it was removed," says Evans in Whistler, who, as an osteopath, helps to manipulate muscle tissues after injury to help with recovery. Every case is different, he said. "Some people are happy; some wish they had something different done." Less than 10 per cent of surgical reconstructions fail, says Jacks, though "the reconstructed knee may never quite feel like a 'normal' knee."

In all cases, the body has to re-learn its sense of balance. Ligaments are responsible for "proprioception" — our sense of where our body parts are in space. So tearing your ACL and/or having it replaced can muck with your sense of self and leave you off-kilter. Some people are off-balance for years. And patients also need to build up the surrounding muscles to support the weakened ligament — in particular the inside of the knee. Treadway took about four months of physio before getting back to skiing, he says. For the most part he's now back to normal, he says, though "for one of my legs, if I close my eyes and do one-legged squats, I don't have quite the same balance."

Once back on the slope, studies have shown that knee braces can help to protect a busted knee from further injury (Treadway used one between his accident and surgery). Other products are out there too — the Ski Mojo and Constant–force Articulated Dynamic Struts (CADS) try to take some of the pressure off your legs to ease up the forces on your knees. CADS are basically sticks that go from the boot up to your butt; the Ski Mojo is less visually obvious by connecting the back of the boot to a knee brace. "My wife used them," says Johnson, because of sore, uninjured knees. "It made her ski more comfortably."

Evans says such devices might be most useful for people who opted not to have surgery and only want to ski occasionally. But in the long term, he says, strengthening muscles and body function is a better option: "The body tends to get lazy when it's braced," he says.

Evans is familiar with the long-term problems that can be caused by knee injuries. "I see people further down the line when they realize, hang on I've got a problem with my hip or my lower back, because it shifted their weight-bearing pattern," he says. "Once you've injured it you have to work continuously on it. Most people do physio for six months and then they regress a bit, and wonder why they have aches." Studies have also shown that people who bust their knee are more likely to get osteoarthritis, regardless of whether they had surgery or not.

In the end, laughs Jacks, the best prevention is simply "not falling, or sticking to après ski." In the meantime, Johnson will keep banging his drum about how best to avoid injury, in hopes that fewer people wind up in his clinic with busted knees.

Nicola Jones is an award-winning freelance writer living in Pemberton, B.C. (She also writes for the science journal Nature, Yale e360, and more.) Her knees are intact (so far).



The Stats

Ski injuries have gone down 55 per cent since the 1970s

From the `70s to the `90s, ACL sprains skyrocketed by 250 per cent

There are about two injuries for every 1,000 ski days — About a third of those are to the knee

In the U.S., 200,000 ACL reconstructions are done per year