More popular than ever, skiing remains a complex sport with a high risk of injury. Here we detail some of the pertinent data.
By Janice T. Radak
Skiing, a sport that has been around since Cro-Magnon man, is among the most popular winter sports in the United States. There were nearly 15 million skiers in the US in 2017 alone. During the 2017/18 ski season, there were 472 ski resorts in operation in the US, with more than 53 million visitors. And the numbers continue to grow, even during a pandemic.
In one of those wonky pandemic upside-downisms, skiing is tagged as a low-risk activity because the skier is outdoors and gliding down the mountain is typically a solitary adventure. But in reality, it remains the same high-risk sport it has always been when it comes to injuries. As the table shows, knees remain the most injury-prone body part for skiiers.1
While snowboarding is akin to skiing, the 2 sports are different when it comes to injuries; here, we will focus on skiing-related injuries of the lower extremity only.
Who’s at Risk?
In a recent clinical study, the mean age of injured skiers was 30.3 years (range, 24 to 35.4 years), and the populations at greatest risk of injury are children/adolescents and adults over age 50.2 However, another study found no difference in risk in the older age group, with the exception of tibial plateau fractures.3 An important note: As the Baby Boomers—the generation that popularized skiing in the US—retire, the general age of recreational skiers is rising, which could mean a trend toward more injuries in older adults in the future.
Numerous risk factors for skiing injuries have been identified and include: age, sex, skiing experience level, self-assessed skill level, body mass index, and trail difficulty.2
Ligamentous: Studies report 43% to 77% of all skiing-related injuries occur in the lower extremity, making it the most common body region for injury in the sport.2 The knee, with 27% to 41% of injuries, remains the most common site for skiing-related injury. And the most common injuries are ligamentous, namely those affecting the anterior cruciate ligament (ACL) and/or the medial collateral ligament (MCL). These ligaments are at highest risk due to the torsional forces placed on skiers’ knees.1,2 These 2 ligaments account for nearly one third of all skiing-related injuries. Fractures of the tibial plateau and tibial plafond do occur, though they account for less than 10% of injuries.
The incidence of grade III ACL injuries has fluctuated since the early 1990s, but most recent estimates place the incidence at 0.23 per 1,000 skier days.2 This compares to the calculated rate of 0.2 ACL tears per 1,000 athlete-exposures (AEs) in female soccer players but is higher than the rate for male soccer players, which is 0.09 tears per 1,000 AEs. Female sex, lower core strength, and non-dominant leg have been identified as risk factors for this specific injury. In a study aptly titled, “Why do we suffer more ACL injuries in the cold?,” Csapo et al4 concluded that “the reduced capacity of cold knee flexor muscles to explosively generate force may limit the hamstrings’ capability to counter strong and fast contractions of the knee extensor muscles that cause anterior shear force on the tibia and, thus, strain the anterior cruciate ligament.”
ACL Injury Prevention Video14
A recently released video from the Stockholm Sports Trauma Research Center, Karolinska Institutet, in collaboration with the Vermont Skiing Safety Research Group and the Swedish Ski Association Alpine Education, reviews critical strengthening exercises for the prevention of injury to the anterior cruciate ligament in teenage alpine skiers. The video provides step-by-step and ski-by-ski instructions for 3 indoor exercises (single leg hop, square hop, squat) and 3 outdoor on-snow exercises (The Shuffle, back and forth, turns with lifted inner ski).
Video: Prevention of serious knee injuries. Karolinska Institutet. Jan. 19, 2020. Available at https://www.youtube.com/watch?v=l-9CrG7lmAg&t=10s. Accessed Jan. 5, 2021.
Print Source: Westin M, Harringe ML, Engstrom B, Alricsson M, Werner S. Prevention of anterior cruciate ligament injuries in competitive adolescent alpine skiers. Front. Sports Act. Living. 2020: doi.org/10.3389/fspor.2020.00011
Three major mechanisms have been identified as the cause of most skiing-related ACL injuries:1,2,5
- Valgus-external rotation associated with a forward fall where the inner edge of the front ski catches in the snow: this causes tibial abduction with external rotation, causing a valgus force about the knee with the ski acting as a lever to maximize torque; this may also produce an MCL sprain as well (Figure 1, page 29).6
- “Phantom foot” effect of a backward fall (so called because the downhill ski produces a force as if an imaginary foot were pushing on its tail), causing internal rotation of the downhill knee (Figure 1, page 29).6
- Boot-induced mechanism where an anterior force is applied to the tibia by the boot top while landing on the tail of a ski from a jump with a fully extended knee, resulting in anterior translation of the tibia relative to the femur, rupturing the ACL.
In a patient survey seeking to understand mechanism of knee injury, Shea et al7 found that 33% identified valgus-external rotation as the cause of their injury, followed by phantom foot at 22%, hyperextension at 19%, boot-induced at 8%, collision at 2%, and all other causes at 16%. Interestingly, while valgus-external rotation was most common in their study, the authors noted that individuals age 30 to 40 years had an increased risk for the phantom foot mechanism. They also reported that bindings released during injury in nearly 20% of adults and 54% of youth.
Fractures: Since the adoption of International Organization for Standardization (ISO) and ASTM International standard shop practices, the incidence of tibial fracture has fallen, though it remains a common cause of skiing-related injuries. Beginners, children, and adolescents are at increased risk, with children under age 10 at 9 times greater risk than skiers over age 20.
In a 6-year study from Finland, Stenroos et al8 reported that fracture of the tibial shaft was the most common fracture in adult skiers (63%), followed by fracture of the proximal tibia (27%), and fracture of the distal tibia (10%). In their review of the data, a fall on the snow surface was the most common cause of injury.
The evolution of shaped skis as well as better boots and bindings, including standards for equipment and boots and for ski-boot-binding compatibility, has led to a significant decrease in tibial shaft fractures. However, these remain a common injury for skiers, with boot bindings failing to release properly as the major cause.
Contrary to the decline in tibial shaft fractures, fractures of the tibial plateau are on the rise. Age is the culprit here, as several studies point to the increasing age of the skiing population as the risk factor. Indeed, one prospective study looked at 18,692 injuries sustained by 17,197 skiers in a moderate-size Vermont ski area and found that skiers over age 55 were at greater risk for tibial plateau fractures—5.7 times greater risk than the general skiing population.3
While many attribute the overall decrease in fractures to improved ski boot-binding systems, it is important to note that the revised designs were in response to fractures and as such these systems are NOT designed to protect the knee from serious sprains.5 Most researchers and ski pros advised making sure equipment is checked daily by the local pro shop before hitting the slopes.
A Word About Ski Patrol
The National Ski Patrol (nspserves.org) is the leading authority of on-mountain safety. It boasts a membership of 31,000 trained emergency medical technicians (EMTs), advanced EMTs, and paramedics, as well as affiliated physicians. There are 650 patrols across the United States, Canada, Europe, and Asia. Members work on behalf of local ski/snowboard areas and bike parks to improve the overall experience for outdoor recreationalists.
Members must pass the Outdoor Emergency Care (OEC) course for emergency medical responders, which is tailored to the non-urban rescuer.
The course focuses on 3 skills:
- performing safe and effective stabilization and extrication of injured persons in the outdoor environment
- scene safety (identifying hazards to both responders and visitors)
- safe and efficient use of outdoor emergency care skills to prevent further injury to visitors.
There is an additional course specifically for Outdoor Emergency Transportation, which teaches how to safely transport injured skiers in a toboggan.
How Injuries Happen
Most injuries are fall-related, and while most occurred on groomed intermediate (blue) runs, the quick-change line between groomed and ungroomed snow has claimed plenty of skiers.
Other causes include:9
- Poor physical preparation: Knee movement is key to skiing and quadricep support is essential to long-lasting knee flexion/extension for shock absorption. Squats are essential to building fitness for this particular sport—they draw on trunk and leg muscles in the same manner as the sport maneuver itself.
- Mental errors: This covers a host of issues—eg, poor judgement due to age (too young or too old) or lack of skill or expertise (choosing a trail too far above ability), losing focus, fatigue.
- Obesity, as it hampers flexibility and increases forces.
- Poorly fitting equipment
– Boots too snug.
– Bindings release set too tight.
- Skis not tuned: Generally, skis should be tuned every 5 to 7 days of skiing, not just once a season. Imperfections in ski surfaces result from everyday use on changing ground conditions and prevent skis from performing as they should. Tuning regularly fixes these and keeps skis in proper working condition.
- Incorrect equipment (wrong type of skis): Modern skis come in different lengths, widths, weights, flex patterns, and sidecuts. Skis should be fitted based on the skier’s ability and what type of skiing will be done.
A key challenge in treating injured skiers is their location. Most ski resorts are in the mountains, far from advanced medical centers with all the needed technology to assess and evaluate injuries. The ski patrol typically is first to assess and manage injured skiers on the slope at the accident site. Ski patrollers are specially trained in outdoor emergency care (and typically basic and advanced life support) and how to transport injured skiers in a toboggan. (See “A Word About Ski Patrol,” below.) Getting skiers off the mountain and to appropriate treatment before hypothermia sets in is key. While some larger resorts have their own clinics with basic imaging technology, many of the smaller venues do not, meaning more transport time to reach the appropriate level of medical care. The advent of hand-held ultrasound technology is helping, but cost remains a factor for smaller locales.10 Thankfully, most injuries seen in this active population are nonemergent (eg, ACL rupture, nondisplaced clavicle fracture, acromioclavicular joint sprain) and require initial immobilization, pain management with oral medications, and follow up within 2 to 5 days.11
When Do Injuries Occur
In a 2016 video interview with University of Utah Health Sciences Radio, Travis Maack, MD, a sports medicine expert and Head Orthopedic Team Physician for the Utah Jazz, noted that in his experience, injuries occurred more often during 2 different times—the first, a timeframe, the second a frame of mind.12
The high-risk time tends to occur between 3:30 and 5:00 pm, toward the end of the day. Maack identified this timeframe for 2 reasons: First, the sun is beginning to set, and the temperature is cooling down, so the snow is getting a bit harder. “During the afternoon, it starts to cool down, so [the snow] gets a little bit rockier, a little bit skied out. So, the terrain itself is more difficult.” Second, is muscle fatigue—the decline in a muscle’s ability to generate force, which happens after repeated use.12
The high-risk frame of mind occurs during that last run—no matter what time of day it is. “Let your body be your guide,” Maack said. “At the end of the day there’s always one last run. That’s unavoidable. So the message that we try to get out is to make that one last run a fun one… Don’t go hit the double-black as the last run, maybe take a groomer. Take a nice, little, smooth one down. Enjoy yourself. You don’t have to be a hero at the end of the day. At the end of the day, if you do it that way, you’ll be able to come back the day after.”
Maack’s observations are backed up by the American Orthopaedic Society for Sports Medicine,13 which notes that skiing-related injuries are most likely to occur on:
- the first day of ski week
- in the early morning when the skier is not warmed up
- in the late morning and late in the day when fatigue sets in
- at the end of the week when the cumulative effects of the vacation make the skier tired.
Injury Prevention Works
Skiing is an equilateral sport, where athletes need good neuromuscular balance between the quadriceps and hamstring muscles and between the dominant and non-dominant leg, as well as good postural control.14 ACL injuries are known to impair neuromuscular function, making primary prevention ideal, and secondary prevention mandatory for when such injuries do occur.15
Beginners are at the highest risk of injury, and so proper education, sport-specific instruction, and education on risk awareness is important for novices. Education should include use of protective equipment and proper chairlift technique. Helmet use has been shown to decrease risk and severity of head injuries without increasing risk of cervical spine injury or risk-taking. Other prevention techniques that show possible benefit include neuromuscular training and improving core strength.1,14 (See “ACL Injury Prevention Video,” page 25).
Janice T. Radak, not an avid skier, is Editor of Lower Extremity Review.
- Weinstein S, Khodaee M, VanBaak K. Common Skiing and Snowboarding Injuries. Curr Sports Med Rep. 2019;18(1):394-400.
- Davey A, Endres NK, Johnson RJ, and Shealy JE. Alpine skiing injuries. Sports Health. 2018;11(1):18-26.
- Shealy J, Ettlinger J, Johnson R. Aging Trends in Alpine Skiing, J ASTM Int. 2010;7(4):1-6.
- Csapo R, Folie R, Hosp S, Hasler M, Nachbauer W. Why do we suffer more ACL injuries in the cold? A pilot study into potential risk factors. Phys Ther Sport. 2017;23:14-21.
- Ettlinger C, Johnson R, Shealy J. Functional and Release Characteristics of Alpine Ski Equipment. In Johnson R, Shealy J, Yamagishi T, eds. Skiing Trauma and Safety. Vol. 16.West Conshohocken, PA: ASTM International; 2006:65–74.
- Apps M. Causes of ACL Injuries. Ski-Knee.com. Available at http://www.ski-knee.com/causes Accessed Jan. 5, 2021.
- Shea KG, Archibald-Seiffer N, Murdock E, Grimm NL, Jacobs JC Jr, Willick S, Van Houten H. Knee Injuries in Downhill Skiers: A 6-Year Survey Study. Orthop J Sports Med. 2014 Jan 22;2(1):2325967113519741.
- Stenroos A, Handolin L. Incidence of recreational alpine skiing and snowboarding injuries: Six years experience in the largest ski resort in Finland. Scand J Surg. 2014;104:127-131.
- Stone KR. How to avoid ski injuries. The Stone Clinic. Available at https://www.stoneclinic.com/how-to-avoid-ski-injuries. Accessed Jan. 5, 2021.
- Gammons M, BoyntonM, Russell J, Wilkens K. On-mountain coverage of competitive skiing and snowboarding events. Curr. Sports Med. Rep. 2011;10:140–6.
- Ellerton J, Tomazin I, Brugger H, Paal P, International Commission for Mountain Emergency Medicine. Immobilization and splinting in mountain rescue. Official Recommendations of the International Commission for Mountain Emergency Medicine, ICAR MEDCOM, intended for mountain rescue first responders, physicians, and rescue organizations. High Alt. Med. Biol. 2009;10:337–42.
- TheScopeRadio.com. Why Most Ski Injuries Happen After 3:30 PM. University of Utah Health. Feb. 17, 2016. Available at https://healthcare.utah.edu/the-scope/shows.php?shows=0_7m18zo0t. Accessed Jan. 5, 2021.
- AOSSM Sport Tips. Alpine Skiing and Snowboarding Injuries. American Orthopaedic Society for Sports Medicine. 2008. Available at file:///C:/Users/jrada/OneDrive/Desktop/LOWER%20EXTREMITY%20Feb%2017%202020%208am/01%20Jan%202021/Skiing_Snowboarding/Skiing%20Injuries%20ASSOM.pdf. Accessed Jan. 5, 2021.
- Westin M, Harringe ML, Engstrom B, Alricsson M, Werner S. Prevention of anterior cruciate ligament injuries in competitive adolescent alpine skiers. Front. Sports Act. Living. 2020: doi.org/10.3389/fspor.2020.00011.
- Jordan MJ, Morris N, Lane M. Monitoring the return to sport transition after ACL injury: an alpine ski racing case study. Front. Sports Act Living. 2020;2:12. doi: 10.3389/fspor.2020.00012.