In-area and backcountry snowboarding: medical and safety aspects

In-area and backcountry snowboarding: medical and safety aspects

Wilderness and Environmental Medicine, 11, 102-108 (2000) CLINICAL UPDATES IN WILDERNESS MEDICINE In-area and backcountry snowboarding: medical and ...

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Wilderness and Environmental Medicine, 11, 102-108 (2000)

CLINICAL UPDATES IN WILDERNESS MEDICINE

In-area and backcountry snowboarding: medical and safety aspects CHRISTOPHER VAN TILBURG, MD From the Emergency Medicine Associates, Vancouver, WA, and Mountain Medical Clinic, Mt Hood, OR.

Snowboarding is now a well-established winter sport and a popular mode of mountaineering. In-area and backcountry snowboarding are defined, as well as a new tenn, glisse, that refers to all types of skis and snowboards. New developments in equipment focus on boot and binding systems. Backcountry travel is highlighted, including ascent with snowshoes, skis, a splitboard, and crampons. Injuries are about 4-6 per 1000 snowboarding days. Upper extremity injuries are most often wrist sprains or fractures. Lower extremity injuries are primarily ankle sprains and are generally less severe than knee injuries in skiers. Fracture to the lateral process of the talus has been called snowboarder's fracture. Backcountry injuries include avalanche suffocation and trauma, deep snow immersion asphyxiation, hypothermia, frostbite, dehydration, fatigue, acute mountain sickness, and sunburn. Specific recommendations for prevention and safety are discussed. Key words: avalanche, backcountry, deep snow immersion asphyxiation, fim gliders, glisse, snowboard, snowboarder's ankle, snowshoes, splitboard

Snowboarding is not just for unruly teens anymore. It is now a well-established winter sport and form of mountaineering. Rumors report that experiments with a standup sled began in the 1920s. The first commercial breakthrough was in 1963, when engineer Sherman Poppen of Michigan watched his daughter try to ride a ski standing up, He screwed 2 skis together and later created the Snurfer, a metamorphosis of skiing and a precursor to the modem snowboard. In the late 1960s, snowboard pioneer Dimitrije Milovich of Salt Lake City, UT, invented Winterstick-the first modem snowboard. Milovich had a patent by 1973 and was selling it in Europe and the United States. Jake Burton Carpenter of Vermont and Tom Sims of California began modifying Snurfers and then building their own boards. Jeff Grell developed the high-back binding. Many others helped advance the sport using technology of skiing and motions of surfing and skateboarding. I Snowboarding is now one of the most popular and fastest growing of winter sports. In 1998, in-area snowboarders numbered about 3.6 million in the United States, in comparison with 9.1 million alpine skiers and Direct correspondence to Christopher Van Tilburg, MD, Emergency Medical Associates, PO Box 1600, Vancouver, WA 98668 (e-mail: [email protected]).

2.6 million cross-country skiers. A significantly higher proportion of snowboarders were men (76.4%), in comparison to alpine skiers (59.2%). They also tended to be younger: 37.8% of snowboarders were aged 12-17 years, whereas the largest 2 groups of skiers were ages 25-34 (23.2%) and ages 35-44 (24%). In fact, snowboarders have begun to outnumber skiers in some regions and winter resorts in the United States. 2 In addition, snowboarders are now full members of winter resort safety crews, ski patrols, and doctor-nurse patrols. Similarly, backcountry snowboarding is rapidly growing (as is backcountry skiing). Popular magazines, equipment manufacturers, adventure travel outfitters, and even many winter resorts cater to backcountry snowboarders. Snowboarders have climbed and ridden the world's largest mountains, including Alaska's Denali, Argentina's Aconcagua, Europe's Mount Elbrus, and Nepal's Pumori. 3 Mountain rescue personnel are utilizing snowboards as well. Although it may seem simple, defining in-area and backcountry snowboarding (and skiing) is somewhat problematic. In-area snowboarding traditionally refers to utilizing the lifts and runs of a winter resort. Backcountry snowboarding usually means snowboarding outside the boundaries of a winter resort or riding inside the boundaries before the resort opens for the season or after

Clinical updates in wilderness medicine

it closes for the year. However, it is much more complicated. Some people hike and ride inbounds in winter resorts during hours of operation but without a ticket. Many winter resorts now allow one to buy a lift ticket, ride a lift, then hike out-of-bounds, usually through a control gate after checking in with ski patrol. Other resorts supplement lift access terrain with backcountry tours that often utilize lifts, professional mountain guides, and snowcats. To confuse matters more, some winter resorts have sections within their boundaries that they call "backcountry" or "out back," even though it is within the area boundaries and regularly patrolled. 4 Another point of confusion is terminology referring to snowboarding and skiing. Skiing, in popular vernacular, usually refers to one of the many forms of skiing but often refers to skiing and snowboarding. A more general term, glisse or glisse alpinism, is now being used to define all snow sports utilizing an edged tool for gliding down the mountain, including snowboarding and the numerous types of skiing: alpine, alpine touring, telemark, and backcountry touring (cross-country or light nordic is generally excluded from this group since it uses skis without metal edges and generally refers to travel across flat or low-angle terrain). The word glisse stems from the French glisser, to glide, and was made popular by Colorado writer Louis Dawson. 5 The terms snowriding or snowgliding may also used to refer to skiing and snowboarding, but the former is sometimes confused with "snowboard riding." A need to collect snowboarding and skiing under one term is frequently necessary because their similarities begin to outnumber the differences; this is punctuated by the invention and now widespread use of the splitboard described below. Since publication of the collective review, "Backcountry snowboarding: medical and safety aspects," many issues involving snowboarding have been clarified or underscored, and a few new concepts have been highlighted. 6 This clinical update is neither exhaustive nor extensive. It is a brief overview of equipment, mechanics, injuries, backcountry issues, and injury prevention tips; it especially focuses on recent developments in the sport and newly available data. Equipment

New developments in snowboarding equipment have primarily revolved around boots and bindings. In resorts, many riders use the standard high-back bindings that have 2 or 3 straps for the dorsum of the foot and fit soft boots. Soft boots are a variation of a pack boot, with a rubber sole and lace-up leather or synthetic upper. Step-in boots and bindings are becoming increasingly

103 popular. Step-in binding hardware is built into the sole of the boot and mates to a plate in the board. This allows for quick attachment and detachment that is usually accomplished by moving a lever or pulling a cord. Importantly, these do not spontaneously release, as alpine ski bindings do. Step-in boots are widely variable and have no universal standard. Some step-ins are similar to soft boots, with minimal mounting hardware on the sole. Others have incorporated the high-back binding into the boot by using internal plastic supports and external buckles. Convenience is cited as the preference of stepins over high-backs. Hard boots have a plastic shell with a separate laceup or molded foam liner similar to alpine or alpine-touring ski boots. These are used with a plate binding that connects with a heel bail and toe clip similar to a stepin crampon. Hard boots come in several varieties. Race boots used in resorts are similar to alpine ski boots with stiff plastic uppers and, usually, 4 buckles. Backcountry boots are similar or identical to alpine touring ski boots with 2 or 3 buckles and a softer plastic cuff that converts from walk to snowboard mode. Some lace-up plastic mountaineering boots are also available for snowboarding; these are not as stiff as other plastic boots and fit plate or high-back bindings. Most backcountry riders use the standard high-back bindings or the newer step-in binding, especially since short skis, snowshoes, split boards, and crampons are available with step-in bindings. Increasingly, backcountry riders are using plastic boots. The advantage of a plastic boot includes warmth, durability, waterproofness, and performance. This is especially important with foul weather, mixed climbing (rocks, ice, and snow), and technical ascents. Importantly, stiffness varies widely between styles and brands; some step-in boots are stiffer than some plastic boots. In general, soft and step-in boots are getting stiffer to improve performance. In the future, a standard may be instituted for step-in bindings. Furthermore, plastic boots used with plate bindings will likely evolve to be the standard, as did alpine, alpine touring, and telemark ski boots. Fully releasable bindings that spontaneously release with a fall, such as alpine ski bindings, have been developed and marketed. 7 However, the main difficulty has been to get both feet to simultaneously release. If only I leg were to release, the huge torsional impact on the contralateral leg would almost certainly produce a disastrous injury. As discussed below, having both feet fixed to a single board probably protects one from serious injury.8-12 To address the issue of being fixed to a snowboard, some backcountry riders are setting up their plate or

104 step-in bindings to allow for quick release. This usually works by attaching a cord to the release levers or toe bails of the bindings (some step-in bindings are switched from right to left so the release mechanisms of both bindings are on the medial aspect of both feet). When a rider needs to exit, a single pull on the cord located between the riders legs releases both bindings. This is perhaps most useful in such situations as avalanche, deep snow, or other dangerous situations when one needs to get out of bindings immediately. Again, the problem is trying to release both feet simultaneously-releasing with 1 foot, when the rider is in motion, is potentially disastrous. Another rather recent trend is the presence of helmets at winter resorts. Now widely used by instructors, patrollers, and the general public, a number of companies make helmets for skiers and snowboarders. Not all goggles or hats are compatible with all helmets. Some helmets can dampen peripheral vision and hearing, especially from face guards or ear flaps, respectively. One of the most significant improvements has been in ascent systems for backcountry snowboarding: snowshoes, short skis, splitboards, and crampons. A plethora of snowshoes are available in a wide variety of styles. One recent innovation is the collapsible snowshoe that can be disassembled and stored easily in a pack for descent. Another new trend is fixed-heel, or climbing, snowshoes. These are usually molded plastic and are fixed to one's toe and heel, unlike the free-heel binding of standard snowshoes. A fixed heel allows mobility and the ability to front point to some extent on hard snow. Snowshoes are a popular mode of ascent for snowboarders because they are relatively inexpensive, easy to use, and allow one to use standard snowboard boots. Some snowshoes come with step-in and plate snowboard bindings as well. Many ski companies make short skis traditionally designed for summer ski mountaineering. Called firn gliders (after hard consolidated snow found on permanent snowfields and glaciers in the summer), or figeles for short, some snowboarders use these for ascent. Budgetminded riders mount universal bindings (similar to snowboard high-back bindings) on children's skis. At least 1 snowboard company markets firn gliders with step-in snowboard bindings. Riders using plastic boots can use alpine touring bindings. Firn skis are short enough to fit on a backpack for descent, but because of their decreased surface area, they have limitations in deep snow. Splitboards are becoming more and more popular in the backcountry. These boards have a seam down the middle lengthwise. The bindings are removed and the 2 halves of the board split into 2 skis. The bindings reat-

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tach in ski mode and have a free-heel mechanism to be used with climbing skins for ascent. Once atop the slope, they are converted back to a snowboard for descent. These are advantageous because there is only 1 tool for both climbing and riding; therefore, the backcountry snowboarder is not hindered by a board on his or her back for ascent or snowshoes or skis in a pack for descent. Also, the large surface area gives excellent traction and flotation in a variety of conditions, especially soft snow. The seam in the middle does compromise performance somewhat on hard snow or ice. One brand of splitboard has the capability of locking down the heel when in ski mode, thus fully integrating skiing and snowboarding. Crampons are likewise being used for technical climbs. Most step-in crampons fit hard boots. One company makes crampons for step-in snowboard boots. Lace-up crampons fit standard soft boots. Instep crampons can be used with all boots. Many other innovations or adaptations of old ideas are being used by backcountry snowboarders. Some riders tow their board when hiking to reduce pack weight and wind problems. A grommet or hole in the nose or tail of the board attached to a cord makes this possible on smooth inclines. Snowmobiles are being used to shuttle riders up slopes. Poles are used by snowboarders for ascent, for obvious reasons, but also on descent to help overcome deep snow and terrain limitations such as flat spots or traverses. Ice axes and poles equipped with selfarrest grips are frequently used by snowboarders when descending steep slopes where the ability to stop after a fall is essential. Packs designed for backcountry snowboarding that provide a means for attaching the board are now in widespread use. Interestingly, a huge number of snowboard companies carry their own backcountry products beyond boots, snowboards, and bindings. These products include backpacks, poles, shovels, clothing, and accessories. Numerous recent advances in backcountry equipment are not specific to snowboarding, so they are not fully discussed here. Some examples include avalanche air bags, avalanche breathing vests, weatherproof clothing, snow shovels with integrated saws or avalanche probes, and electronic devices such as digital avalanche transceivers, global positioning systems, and cell phones. Mechanics

Prior to discussing injury patterns and backcountry issues, it is worth reviewing snowboard mechanics, especially how they differ from alpine, alpine-touring, and backcountry touring ski mechanics. The different me-

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Clinical updates in wilderness medicine chanics play an important role in injury patterns and safety.6 • Feet are fixed to a single board. • Snowboards have a large surface area. • A separate tool is needed for ascent or travel over flat terrain (except when using a splitboard). • Snowboards have a single, short edge. • Snowboarders have a sideways stance that has different characteristics when turning or traversing right or left (heel-side edge or tow-side edge). • Snowboard boots, in general, have more flex both side to side and front to back. Injuries

In recent years, several studies have been completed on snowboarding injuries. Many studies use ski injuries in comparison. In general, research supports earlier studies that demonstrated specific injury patterns for snowboarders. Snowboarding has about 4 to 6 injuries (though some studies claim as high as 16) per 1000 snowboarding days, a rate similar to that of alpine skiing. 9,1O,12,13 As previously documented, many injuries occur to beginners. 14 Studies show that most snowboard injuries are either split between upper and lower extremities or slightly favor upper extremity. This is in contrast to alpine skiing, where injuries are predominately to the legs. 10, 13-1 S Upper extremity injury in snowboarders is most often a wrist sprain or fracture, This primarily occurs when a snowboarder falls on an outstretched hand and most often occurs to beginners. Few injuries occur to the ulnar collateral ligament, the primary injury to the upper extremity of a skier, because snowboarders in resorts usually do not ride with a pole in hand. 8,9,16 Shoulder injuries include fractures, dislocations, and sprains. IS Elbow injuries often occur when snowboarders fall on an outstretched arm. I? Lower extremity injury in snowboarders is primarily to the ankle, in contrast to the knee injury of skiers. Most injuries occur to the front leg. Importantly, most ankle injuries in snowboarders are less severe than knee injuries in skiers. 8- 1O The trend toward less severe ankle injury is most likely because the aforementioned mechanics: the relatively flexible boots worn by snowboarders, fixed footing on a single board, and nonreleasable bindings. This minimizes much of the torsional stretch to the individual knees common with skiing. As snowboard boots become stiffer to improve performance, a trend toward more knee injuries and fewer ankle injuries may develop. A similar trend was seen

in alpine skiing in the 1970s and telemark skiing in the 1990s, when higher, stiffer plastic boots replaced lower, softer leather boots. Releasable bindings are universally not recommended by researchers because of the potential for a severe knee injury with the release of only 1 foot. 8-12,16,18-20 One injury particular to the lower extremity of a snowboarder is the fracture of the lateral process of the talus, called snowboarder's fracture. Several authors cite dorsiflexion and inversion of the rear foot as the mechanism leading to injury.8,13,18,20,21 However, since most ankle injuries occur to the lead foot, dorsiflexion and eversion of the forward foot is another likely mechanism. This injury can mimic a sprain and is often not seen on plain radiographs; computed tomography is usually necessary for diagnosis. It requires prompt referral because it can result in avascular necrosis or nonunion. 11,13,20,21 Head injuries are also a point of concern. They occur most often when snowboarders jump, execute aerial maneuvers, or collide with trees, hard snow, or other snowriders. 22,23 Backconntry issues

There are some important limitations to recent studies, especially when data are extrapolated to backcountry snowboarding. Nearly all studies and reviews published in the medical literature evaluated patients injured in mountain resorts and used subjects that sought medical treatment. Many activities dramatically change in the terrain and snow conditions in winter resorts, in comparison to backcountry areas. These include logging and bulldozing runs, skiing and snowboarding the runs over the season, and making and grooming the snow. Quick access to help via ski or snowboard patrol, mountain clinics, warming huts, and other amenities make environmental injuries less common in winter resorts. In general, backcountry snowboarder musculoskeletal injuries are probably similar to those acquired in area. It is likely that they are less frequent, however, since backcountry riders are generally more conservative. Environmental injuries such as frostbite, hypothermia, dehydration, fatigue, acute mountain sickness, and sunburn are probably similar for all travelers in the mountain wilderness. A few issues particular to snowboarding are worth discussing, especially regarding how snow and terrain are handled differently by snowboarders and skiers. In some terrain, snowboarders are less mobile than skiers, especially in traverses, flat areas, or rolling hills. Hence, in addition to a snowboard, all backcountry snowboarders need a method for travel such as short skis, snow-

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shoes, crampons, or a splitboard. In contrast, on steep, icy slopes, it may be easier to stay up on a snowboard, because the rider can put all of his or her weight on a single edge. The tight turning radius of a snowboard makes it easier to negotiate narrow chutes6 (R. Collins, written communication, April 11, 1999). With regards to snow conditions, in deep snow, wet snow, slush, or crud, snowboards excel because of the large surface area. Hardpack and ice can be much worse with the single, shorter edge of the snowboard. Snowboarders are also less likely to recover from a skid the way skiers can with two independent edges6 (R. Collins, written communication, April 11, 1999). All in all, performance differences in terrain and snow conditions between skiers and snowboarders are most likely less important than qualities such as skill, knowledge, and judgment when it comes to safety. It seems that deep snow immersion asphyxiation tends to have a worse outcome for snowboarders than for skiers. Deep snow immersion asphyxiation occurs when riders fall upside down in deep snow or a tree well. When unable to right themselves, they suffocate. The greater risk is probably because of mechanics: snowboarders have both feet fixed to a single board with nonreleasable bindings. When falling upside down in deep snow or in a tree well, snowboarders fare worse than skiers who have independent skis and the ability to kick them off. 24 The primary safety method to avoid deep snow immersion is to ride with a partner, stay within voice and visual contact of your partner, ride slopes one at a time using a spotter, ride within one's skill level, and use caution to avoid tree wells. Avalanches are one of the more romantic and much discussed hazards in the mountains, especially among snowboarders and skiers. Avalanche deaths of snowboarders are increasing, probably because of the general increase in snowboarders and the greater percentage of them heading into the backcountry (Table). Fortunately, both avalanche safety and mountain safety education and awareness target snowboarders specifically. A frequently asked question is whether snowboarders do better or worse than skiers when caught in an avalanche. The question may be more academic than practical. Differences in equipment, mechanics, and performance in different terrain and snow conditions certainly playa part in avalanche safety. Some experts point out that because of the large surface area, crouched stance, and single edge, a snowboarder may be better able to avoid an avalanche by escaping to one side early in a slide. Since snowboarders perform well in deep powder and have a large surface area, they may be less apt to trigger an avalanche (R. Collins, written communication, April 11, 1999). However, if caught in an avalanche, a

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Deaths of snowboarders by avalanche in the United States over the past 14 seasons* Year

Deaths

1985-1986 1986-1987 1987-1988 1988-1989 1989-1990 1990-1991 1991-1992 1992-1993 1993-1994 1994-1995 1995-1996 1996-1997 1997-1998 1998-1999

1 0 0 0 1 0 0 3 0 3 4

1 4

8

* This includes backcountry snowboarders and resort snowboarders riding out of bounds. Data are from Colorado Avalanche Information Center25 and Westwide Avalanche Network. 26

snowboard with nonreleasable bindings cannot be easily removed. This is widely recognized to be a hazardous aspect of backcountry snowboarding. 4 ,6,7.27,28 Similarly, without a quick method of ascent, snowboarders are less mobile and may prolong their exposure to dangerous situations. As mentioned above, some bindings with modifications are easier to manually release. In an avalanche, this still may be difficult, and the risk of only 1 binding releasing is a problem. Because it is easy to learn to snowboard, a greater number of inexperienced snowboarders find there way to the backcountry, often without any mountaineering or backcountry skills, knowledge, and experience. All in all, it is interesting and noteworthy to discuss the differences among skiers and snowboarders with respect to avalanches and other mountain hazards, but differences between individual glisse alpinists is probably more significant, no matter what tool they use. Employing good judgment, knowledge, skill, and experience to avoid avalanche terrain, snow, and weather is the mainstay of safety, This should be practiced by all backcountry travelers. Prevention

Probably the single most important function of wilderness medicine professionals, other than treating snowboard injuries, is education on prevention of injury and

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Clinical updates in wilderness medicine illness. Recommendations which apply to most mountain travelers are listed briefly below: • Seek formal instruction, routine practice, and experience. • Ride with a partner. • Ride within one's skill level, especially since beginners sustain a fair number of injuries. • Head into the backcountry only when one has the skill to safely ride the most difficult slope in one's mountain resort in the worst weather and snow conditions. • Guard against foul weather, poor snow conditions, and terrain hazards. • Utilize a mode of ascent when snowboarding in the backcountry. • Employ good judgment. • Learn and exercise mountain safety, especially avalanche safety. • Check with ski or snowboard patrol, avalanche professionals, weather sources, and public safety officials concerning access and snow, terrain, and weather conditions. Safety gear recommendations can be somewhat more difficult. It is universally recommended that all mountain travelers should have the basic mountain safety gear such as map, compass, altimeter, headlamp, matches, food, water, extra clothing, first aid kit, repair kit, glacier glasses, sunscreen, water purification tablets, tarp, avalanche rescue equipment, proper winter clothing, and other gear and skill for foul weather, sun, and cold protection. Some sources offer detailed lists for snowboarders. 4 ,6 Particular gear for snowboarders include gauntlet gloves or mittens, repair materials and tools specific to a snowboard, a backpack designed to carry a snowboard, and a mode of ascent. It is probably a good idea to carry a minimum of emergency gear when riding in-area, although this is not widely practiced. An important and often overlooked point is that the proper use of safety equipment requires formal instruction and routine practice. This is especially important with route finding with a map and compass and avalanche rescue with a beacon. Helmets are commonly recognized as a useful safety item for in-area riders. 8,} 1,16,22,23 They have long been a part of the backcountry traveler's equipment list. It is important to note that not all goggles and hats are compatible with every helmet. Face masks and goggles can hamper peripheral vision, and ear flaps can dampen hearing. Some snowboard and ski helmets may not be adequate for backcountry travel; mountaineering helmets are constructed to protect one from rock and ice fall and use different standards for certification than do helmets designed for snowboarding. Wrist guards are controversial. Some experts recom-

mend them, but others point out that wrist guards may be ineffective at preventing wrist injuries and may even translate the force of a fall to the elbow or shoulder. 9 ,1416,18 Learning proper riding methods and correct falling technique is probably more beneficial than the use of wrist guards. Elbow, hip, gluteal, and knee pads help protect soft tissue contusion, but they are bulky, They are probably most useful for beginners. Snowboard leashes are mandatory in most winter resorts. Although coming out of both bindings is a rare event, boards can escape downhill when one is getting in or out of the bindings. This happens most frequently when riding a gondola, tram, snowcat, or helicopter. Acknowledgment The author extends thanks to Madelyn Hall, head medical librarian at Southwest Washington Medical Center, for her assistance with research. References 1. Howe S. Early history. In: Sick: A Cultural History of Snowboarding. New York, NY: St Martins; 1998:6-23. 2. Ski Industry Association. 1999 Snowsports Industries America Snow Sport Fact Sheet. McLean, VA: Ski Industry Association. Available at http://www.snowlink.com. Accessed October 10, 1999. 3. McKoy W. The highest ride. Men's J. December-January 1996;5:72-78,171. 4. Van Tilburg C. Backcountry Snowboarding. Seattle, WA: The Mountaineers Books; 1998. 5. Dawson L. Wild Snow: A Historical Guide to North American Ski Mountaineering. Golden, CO: American Alpine Club; 1997. 6. Van Ti1burg C. Backcountry snowboarding: medical and safety aspects. Wilderness Environ Med. 1996;8:225-231. 7. O'Brian J. Safe shredding. Salt Lake Tribune, December I, 1996:Jl-J4. 8. Chissell HR, Feagin JA, Warme WJ, et al. Trends in ski and snowboard injuries. Sports Med. 1996;22:141-145. 9. Davidson TM, Laliotis AT. Snowboarding injuries: a fouryear study with comparison with alpine ski injuries. West J Med. 1996;164:231-237. 10. Pigozzi F, Santori N, Di Salvo V, et a1. Snowboard traumatology: an epidemiological study. Orthopedics. 1997; 20:505-509. 11. Sacco DE, Sartorelli DH, Vane DW. Evaluation of alpine skiing and snowboarding injury in a Northeastern state. J Trauma. 1998;44:654-659. 12. Sutherland AG, Holmes JD, Myers S. Differing injury patterns in snowboarding and alpine skiing. Injury. 1996;27: 423-425. 13. Boon AJ, Smith J, Laskowski ER. Snowboarding injuries:

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Van Tilburg general patterns, with a focus on talus fractures. Phys Sportsmed. 1999;27:94-104. O'Neill DF, McGlone MR. Injury risk in first-time snowboarders versus first-time skiers. Am J Sports Med. 1999; 27:94-97. Kocher MS, Dupre MM, Feagin JA. Shoulder injuries from alpine skiing and snowboarding: etiology, treatment, and prevention. Sports Med. 1998;25:201-211. Young CC, Niedfeldt MW. Snowboarding injuries. Am Fam Physician. 1999;59:131-136. Takagi M, Sasaki K, Kiyoshige Y, et al. Fracture and dislocation of snowboarder's elbow. J Trauma. 1999;47:7781. Binder SR, Geiger KM. The downside of snowboarding: common injuries in novices and those seeking "hospital air." Postgrad Med. 1999;105:83-88. Estes M, Wang E, Hull ML. Analysis of ankle deflection during a forward fall in snowboarding. J Biomech Eng. 1999;121:243-248. Kirkpatrick Dp, Hunter RE, Janes PC, et al. The snowboarder's foot and ankle. Am J Sports Med. 1998;26:271277.

21. McCrory P, Bladen C. Fractures of the lateral process of the talus: a clinical review, "snowboarder's ankle." elin J Sport Med. 1996;6:124-128. 22. Hackam DJ, Kreller M, Pearl RH. Snow-related recreational injuries in children: assessment of morbidity and management strategies. J Pediatr Surg. 1999;34:65-69. 23. Nakaguchi H, Fujimaki T, Ueki K, et al. Snowboard head injury: prospective study in Chino, Nagano, for two seasons from 1995 to 1997. J Trauma. 1999;46:1066-1069. 24. Cadman R. Eight nonavalanche snow-immersion deaths. Phys Sportsmed. 1999;27:31-43. 25. Colorado Avalanche Information Center. US avalanche fatalities by activity. Available at: http://www.caic.state.co.us. Accessed October 10, 1999. 26. Westwide Avalanche Network. Available at: http:// www.avalanche.org. Accessed October 10, 1999. 27. Adamski DE Backcountry Snowboarder Safety: Know Before You Go. Portland, OR: Portland Mountain Rescue; 1998. 28. Jamieson B, McDonald J. Smart riding habits. In: Free Riding in Avalanche Terrain: A Snowboarder's Handbook. Revelstoke, BC, Canada: Canadian Avalanche Association; 1999:44-48.