Skiing and Snowboarding Injuries in the Year 2000Edward Heneved, MD, FACEP
This material was presented at the Wilderness Medical Societyís Summer Conference and Annual Meeting, August 2000, Park City, Utah. It has been updated with data from the most recent winter season. Karl Neumann, Editor, Wilderness Medicine Letter
Alpine skiing and snowboarding are very popular winter sports. In the United States alone, there were over 52 million visitors to the ski slopes during the 1999-2000 season. This report will focus on the injuries commonly seen in this population of skiers and snowboarders. While both activities involve strapping some kind of board to the feet and sliding down a snow covered hill, each sport has its unique spectrum of injuries.
Demographics
According to the National Ski Areas Association (NSAA), the 1999-00 winter season saw 7.4 million skiers and 3.6 million snowboarders with a combined total of 52.2 million total ski area visits. (A skier/snowboarder visit represents one person visiting a ski area for all or any part of a day or night.) Eighteen percent of the snowboarders also skied. This calculates to 10.4 million total on-slope participants. The National Sporting Goods Association estimates that since 1988 the number of snowboarders has increased 77%, while the number of skiers has declined 25%. Skiers tend to be older, average age 31, and 60% are male. The average snowboarder is younger, average age 20, and 75% are male. During the 1999-2000 season, there were 503 total ski areas that operated in the U.S. (down from 735 in 1983). Of these, only five ski areas did not allow snowboarding (Aspen Mountain, Colorado; Perfect North Slopes, Indiana; Taos Ski Valley, New Mexico; Alta and Deer Valley, Utah).
Injury Rates
"Medically significant" injuries are those which require medical treatment or keep a person from skiing for at least one day. For every 1000 ski area visits, about three will result in an injury serious enough to require immediate medical attention. (By comparison, the injury rate for football is 810/1,000 participants, while tennis has an incidence of 30/1,000 players.) In a typical year there are about 135,000 medically significant snow sport injuries in the U.S. Many studies estimate that up to 40% of all injuries go unreported. One study calculated there may be as many as 500,000 skier/snowboarder injuries each year. At this rate of injury for the average skier who skis 14 days a year, the individual chance of injury each year is approximately 14%.
Over the past 27 years, skiing injury rates have declined by half. However, this rate of injury has not decreased in the past 12 years. With snowboardingís growing popularity, the incidence of snowboarding injuries has certainly increased. The injury rate for the newer sport of snowboarding is more difficult to determine. This is primarily because skier and snowboarder days are represented by lift ticket sales that do not distinguish one from the other. This forces one to estimate the percentage of each on the mountain. Most early studies report snowboarders to be injured about as often as skiers. However, recent studies suggest the rate for snowboarders may be increasing. A report from Mammoth and June Mountain (California) ski resorts estimated twice the injury rate for snowboarders, as did studies from Italy and Switzerland. A Japanese report showed three-fold increase; and one from Aspen suggests snowboarders are injured five times more often. During the 1999-2000 season, first aid data from one large North Tahoe ski resort recorded its ski injury rate as 3.2/1000 and the snowboarder injury rate as 12.7/1000. Tahoe Forest Hospital, in Truckee, California, the closest emergency department to this area documented five snowboarders injured for every one skier.
In both skiing and snowboarding, beginners suffer almost three times more injuries than the more experienced participants. One study documented 49% of injured snowboarders were beginners versus 18% of beginner skiers. First-time snowboarders sustain a significantly higher incidence of emergent injuries (such as fracture, concussion, dislocation, lost teeth) necessitating immediate intervention. Teenagers suffer the highest overall rate of injury in any one age group. Among skiers, the injury rate for anterior cruciate ligament (ACL) sprains has more that tripled since the late 1970s, while the incidence of every other injury has declined.
Factors Affecting Injury Rates
Regarding alpine skiers, the injury rate reduction seen since the 1970s is primarily due to a decrease in ankle sprains and lower extremity fractures. This is attributed to the improved grooming of slopes, ski instruction, safety innovations in ski areas, and improved ski equipment. Other factors that affect injury rates include snow conditions, visibility, number of skiers on the slopes, skier fatigue, and the use of alcohol and other drugs. Most injuries occur between 12 noon and 4 PM. The most critical determinants of injury, however, are still skier ability, relation of speed to athletic proficiency, and improper adjustment or poor functioning of equipment. It has been estimated that 44% of all downhill ski injuries are due to improper maintenance and adjustment of equipment. Failure of binding release occurs in 70% of lower leg fractures and serious knee injuries.
The raw injury rate in women exceeds that in men. Women are more likely to sustain upper extremity injuries and are twice as likely to suffer an ACL sprain. When ability, experience, and size (weight and height) are taken into consideration, the overall risk of injury for women in skiing is similar to men.
Fatalities
During the past 15 years, there has been an average of 34 deaths per year among skiers and snowboarders. During 1999-2000 season, 30 fatalities occurred out of the 52.2 million skier/snowboarder days reported. Twenty-three of the fatalities were skiers (19 male, 4 female) and seven were snowboarders (6 male, 1 female). This equates to a fatality rate of 0.57 per million skier/snowboarder visits or 2.88 deaths per million on-slope participants. Sixty percent of all fatal injuries in skiing involve head injuries. The most common cause of fatal injury is classified as "skier lost control, hit tree." Most fatalities in skiers occur in the same population that exhibits "high-risk behavior." Victims are predominantly male (85%), in their late teens to early 20s (70%), possess better than average experience, go at a high rate of speed at the margin of an intermediate trail. This is the same group who sustain 74% of the fatal car crashes and 85% of all fatal industrial accidents.
By comparison, in 1999, there were 41,300 deaths in automobile accidents, 17,100 deaths from falls, and 11,000 deaths by poisoning. During 1998, lightning killed 90 people and there were 130 deaths from tornadoes. The rate 2.88 deaths per million participants for skiing/snowboarding compares to 31.9 for scuba diving, 25.9 for swimming, 64.7 for boating, and 21.2 for bicycling.
Catastrophic Injury
Catastrophic injury is a nebulous term that has yet to be clearly defined and is therefore not a real statistic over time. Serious injuries (coma, paraplegia, and serious head or spinal injury) occur at a rate of 38 per year. In the 1999-2000 season, there were 44 serious injuries, 30 were skiers (21 male and 9 female) and 14 were snowboarders (13 male, 1 female). The rate of serious injury in 1999-2000 was 0.84 per million skier/snowboarder visits. There is no credible evidence that catastrophic injuries are increasing at a statistically significant rate.
Equipment
Boots. In the 1960s, the most common injury in skiing (25%) was a fracture of the lateral malleolus, termed "skierís ankle." It was seen with low, soft leather boots. Over the past 25 years, the incidence of tibia and fibula fractures and of lower extremity equipment-related (LEER) injuries has been reduced by 72% and 43%, respectively. Todayís ski boot consists of a hard plastic outer shell and a soft inner liner which extends to the mid-tibia and allows better control of the ski. Modern ski boots transmit forces to the knee and contribute to making sprained knees the most common injury (25 ,38%) in alpine skiing. The incidence of ACL sprain (about 25,000 per year in the U.S.) represents 33% of all knee injuries. Curiously, the left knee is more likely to be injured than the right. ACL tears account for a quarter of all medically significant injuries and half the treatment dollars spent each year.
This same phenomenon has been reproduced in the evolution of snowboarderís boots. Soft boots give the snowboarder twice the risk of ankle injury compared to hard boots. "Snowboarderís ankle," a fracture of the lateral process of the talus, is caused by forced dorsiflexion and inversion at the ankle permitted by softer boots. Hard boots place the snowboarder at risk for "boot-top" fractures of the tibia and fibula as well as double the risk for knee injury.
Bindings. Snowboard bindings are of three general types: (1) soft-boot bindings employ two or three straps across the boot; (2) hard-boot (or plate) bindings use wire bales to secure the heel and toe of the boot; (3) a newer step-in type binding utilizes hardware affixed to the bottom of either soft (stiff-shank) or hard-shelled boots and lets the rider "click-in." Current snowboarding technology utilizes non-releasable bindings. Two companies, Meyer of Switzerland and Miller of Utah, have marketed releasable bindings since 1991. However, the industry has not endorsed this concept. Whether releasable bindings will reduce or simply change the snowboarderís likelihood of injury remains a heated controversy. If a rider were "upside down in a tree well" or trying to "swim out of an avalanche," releasable bindings may be beneficial. Obviously, in a release situation, both bindings would need to release or twisting injuries similar to those of skiers would result. Eight percent of snowboarder injuries occur while loading onto or unloading from a ski lift (while only the lead foot is in the binding).
After a fall, the current non-releasable system acts as a "sea anchor" and lessens the distance a snowboarder slides down the hill. Along with generally slower speed, this shortened "fall zone" (the area which snowboarders will probably slide if they fall) partly explains why snowboarders suffer fewer fatal and catastrophic injuries than skiers. Snowboard bindings lock both feet in the same plane and create an entirely different spectrum of injury than seen in skiing with its independent movement of each leg.
Current dual-mode alpine ski bindings release in two different directions, toe rotation and heel lift. Some manufacturers have introduced toe-up release binding that may affect the "boot-induced" injury. Unfortunately, criteria for ski bindings have been based solely on protecting the tibia from injury, using calculations based on the width of the tibial plateau and studies of the tibiaís breaking point, not the failure point of the knee ligaments.
Shape of Skis and Snowboards. Shaped (formerly called "parabolic") skis have taken over the alpine ski market. It is not clear if they will lead to a new type of injury. One 3-year study suggests there may be an increase in the isolated ACL knee sprain and possibly an increase in ankle fractures (although the author speculates the latter is more likely to be an equipment system failure.) The recent rise in tibial plateau fractures among skiers is probably more age related than due to equipment. Entry level skiers show no increase injury incidence with the new shaped skis while advanced skiers are injured slightly more often. "Older skiers" who have learned to constantly face "square down the fall line" must now learn not to "over turn" but to "follow their skis." Alpine skiers suffer rotational injuries as their separate, individual skis catch inside or outside edges. The length of the ski acts as a lever arm to the foot and leg, often twisting the knee (which is meant to be a hinge, not a rotational joint).
Snowboards also have generous side cuts and are of three general types: free-style, free riding, and carving. Side-standing snowboarders get slammed forward when they catch a toe-edge and fall on the outstretched hand (FOOSH). If riders do not get their hands out, they impact their shoulders (clavicle fracture, acromioclavicular separation, or humeral head contusion or fracture) or their faces (concussions, cervical sprains). More commonly, snowboarders fall backward as they lose their heel-edge and suffer wrist impacts, buttock contusions, axial loading spinal compressions, and occipital head injuries.
Poles."Skierís thumb," a sprain of the ulnar collateral ligament of the first metacarpophalangeal joint is the most common injury of the upper extremity. Since so many go unreported, it may be the most common injury in alpine skiing. Because 10% of skiers and only 1% of snowboarders report this injury, it is easy to conclude that the skierís pole grip and strap contribute to this injury. The ski pole is implicated in 24% of shoulder dislocations by causing the arm to be externally rotated and forcibly abducted in a fall.
Helmets. In 1999, the U.S. Consumer Product Safety Commission (CPSC) formally recommended that skiers and snowboarders wear helmets. They calculated that doing so would help prevent or reduce the severity of head injuries from falls and collisions by 50%. Between 1993 and 1997, CPSC reported the number of skiing related injuries treated in the emergency room declined, while the number of skier head injuries remained constant. During the same period, snowboarding injuries nearly tripled and their head injuries increased five-fold. In 1997, there were 17,500 head injuries (3,400 "potentially serious") associated with skiing and snowboarding. The CPSC concludes helmet use would prevent 11 deaths per year. A study from Vermont notes that during the 1998-1999 ski season, 15.5% of all injured skiers used helmets while 32% of those diagnosed with any degree of concussion used helmets. Also, 35% of fatally injured skiers and snowboarders wore helmets. The National Ski Areas Association suggests that helmets afford little protection beyond 12 mph (skiers typically travel at 25 to 40 mph). They further express concern that there is no U.S. standard for recreational helmets and that "consumers not gain a false sense of security by wearing a helmet."
Wrist guards. For snowboarders, the wrist is the most common site of injury, accounting for one quarter of all injuries and one half of all fractures. Wrist guards have been shown to be very effective in preventing wrist injuries in in-line skaters. However, they may transfer the forces more proximal, leading to mid-shaft forearm fractures, posterior elbow dislocations, or shoulder injuries. One survey of 21 snowboarders who had been injured while wearing wrist guards revealed no wrist injury, but six had shoulder injury and four had radial shaft fractures. Snowboard instructors advise the "closed-fist" position for falling. Falling backward is the mechanism of injury in about 75% of wrist injuries.
Mechanisms of Injury
Falling.Falling is the leading cause of skiing (87%) and snowboarding (75%) injuries. Skiers most commonly fall forward while snowboarders more often fall backwards.
Jumping. Unsuccessfully landing jumps is the second most common cause of snowboarding injury. Snowboarders are injured three times more frequently jumping than are skiers. Jumping includes dropping from great heights and getting "big air" (a.k.a. "hospital air") off moguls or terrain park mounds. The impacts are associated with head, facial, spinal, and abdominal injuries.
Collisions . Collisions account for 10% of all injuries but 67% of hospital admissions and most of the fatalities. Most commonly collisions involve a stationary object, but often it is another person. Contrary to popular myth, skiers are more likely to hit a snowboard rider than are riders to hit a skier. Only 1% of injuries to skiers are caused by collisions with snowboarders while 7.7% of all ski injuries are the result of skiers running into skiers and only 2.6% of snowboard accidents are caused by snowboarders running into other snowboarders.
Overuse syndromes. Muscle strains and tendinitis are probably the most common types of injury sustained by skiers. Since symptoms usually do not declare themselves until the following day, estimates on the incidence of such problems are inaccurate.
Deep snow immersion. Avalanches kill by causing massive trauma or asphyxiation. With deep powder, tree-well immersion deaths have been recorded in the last 10 years. Three snowboarders died in separate but nearly identical incidents at Lake Tahoe ski resorts in a 3-week period in December 1992 , January 1993. Each was vertically buried, head down in deep snow at the base of a tree. Postmortem examinations were strikingly similar: small facial contusions, marked upper lobe pulmonary congestion, and frontal lobe brain contusions. Although cause of death was listed as suffocation, it is impossible to conclude the contribution of other factors such as hypothermia, brain injury, head-down position, duration of immersion, and/or non-releasable bindings, for example. More skiers die each year from snow immersion injuries than do snowboarders.
Injury Patterns
Snowboarders have an increased rate of head injuries at 10% compared with skiers at 5%, but skiers are five times more likely to suffer a fatal head injury. Spinal injury rates are four times more common among snowboarders (0.04/1000 snowboarding-days vs. 0.01/1000 skier-days). Similarly snowboarders are twice as likely to suffer a chest injury (6.1% versus 2.7%) or a splenic injury (13% vs. 2%) as are skiers.
Almost one quarter of snowboarding injuries occur during the personís first experience, and almost one half occur during the first season. Skill level influences snowboarding injuries. One study showed wrist injuries predominated (41%) in the beginner group, shoulder injuries were most common (38%) in the intermediate group, and head injuries predominated (36%) in the expert group. Another study reported: beginning snowboarders were most likely to injure the wrists (30%); low intermediates, their knees (28%), intermediates, their ankles (17%), and advanced and experts, their shoulder or clavicle (14%).
Prevention
Preventing the injury is obviously favorable to treating after the fact. Several suggestions are intuitive; some are controversial.
Personal fitness. Get in shape. Regular general fitness and training will help protect from injury. Avoid drugs and alcohol. Do not ski/snowboard if you are sick or fatigued. Take time to acclimatize to altitude (especially over 8,000 feet).
Equipment. Be sure your equipment is properly maintained, repaired, or replaced. The majority of lower leg injuries in skiing are related to the quality and condition of the release system. Use certified and reputable ski/snowboard shops. Children need special attention to match equipment to their size, weight, and ability. Release settings for ski bindings need to be checked before each season and periodically throughout the season. Releasable snowboard bindings could reduce the incidence of ankle injuries but have not been sufficiently studied or accepted to endorse. A proper technologic study needs to answer this question. Ski poles grips and straps should allow the hand to fall free and avoid hyperabducting the thumb. Avoid strapless saber pole grips, and grasp any tether with the thumb over the strap. Wrist guards probably benefit the beginning snowboarder, especially on icy, firm-packed snow. Helmets can be recommended for novice snowboarders and all skiers and riders who venture among the trees. The U.S. Ski Association requires helmets for most competitions and official training under their sanction. Head protection gear for all skiers and snowboarders can be considered protective as long as it is recognized that wearing a helmet does not confer invincibility or invulnerability to the user.
Instruction. Professional and certified instructors can significantly lessen injury rates and severity. Novice snowboarders might consider the use of poles to lessen wrist and head injuries while learning. All participants should be taught how to recover from a loss of control, when recovery is inappropriate, and how to make a controlled landing. The Vermont ACL Awareness program has reduced ACL sprains by 75% among participating ski-patrollers, and by 55% among ski area employees. Snowboarders should fall with closed fists and try to roll into a fall like a paratrooper, spreading the force of the fall out over the body instead of in one place. Those choosing to jump must know their landing site.
Snow Conditions. Avoid icy slopes. Do not ski alone in deep powder. Avoid crowded slopes, particularly at the end of the day. Be informed about the snow conditions. Dress properly, in layers. Outer wear should be of a fabric to reduce sliding. Wear protective eyewear. Be prepared for changeable weather.
Responsibility Code. Ski and ride within your ability. Watch for skiers downhill. Look uphill before entering a trail. Move to the side of the trail when stopping. Use devices to help prevent runaway equipment. Observe all posted signs and warnings. Have the ability to load and unload lifts. Practice courteous ski habits. "Look before you leap" , use caution when jumping and leaping on the slopes, especially in snowboard and terrain parks.
Wilderness Medicine Letter, Volume 19, Number 2, Spring 2002
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