Alpine Ski Racing Injuries

Abstract

Context:

This article reviews the epidemiology of alpine ski racing–related injuries, risk factors, mechanisms of injury, and injury prevention strategies.

Evidence Acquisition:

Pertinent literature from peer-reviewed publications from 1976 through 2018.

Study Design:

Clinical review.

Level of Evidence:

Level 5.

Results:

The rate of injury in alpine ski racing is high. In general, knee injuries are the most common, with anterior cruciate ligament (ACL) disruptions being the most significant in terms of time loss from sport. Three specific mechanisms of ACL injury in alpine ski racers have recently been described (slip-catch, dynamic snowplow, and landing back-weighted). In contrast to other sports, female ski racers are not clearly at greater risk for ACL injury, especially at the highest level of competition. A high percentage of ski racers are able to return to their previous level of competition after ACL injury. Risk factors for injury and methods of injury prevention have been proposed; however, the rate of injury, particularly ACL injuries, has not decreased significantly.

Conclusion:

Alpine ski racing has a high injury rate. ACL injuries in particular remain problematic. Further study is needed to identify modifiable risk factors and implementation of injury prevention strategies.

Historically, skiing as a form of locomotion was instrumental in activities such as hunting, medical transportation, and military conflict. It was not until the early 1800’s that skiing became popular as a means of exercise, and it would take nearly 100 years to be adapted as a sport.³⁴ Alpine ski racing became an Olympic sport in 1936, and the first International Ski Federation (FIS) World Cup race was held in 1967.¹⁶ Alpine skiing is now well organized, with competitions ranging from junior through masters levels. Although recreational skiing injuries have been well described, there is less published work on injuries sustained during alpine ski racing. The forces, speeds, and slope conditions that ski racers encounter differ greatly from the average recreational skier.^14,53

The purpose of this article is to comprehensively review the existing literature with regard to alpine ski racing injuries and to identify further areas of study and potential strategies for injury prevention.

Methods

A review of the published literature from 1976 to 2018 pertaining to alpine ski racing injuries was performed. Pertinent articles were identified from PubMed, Ovid, and Google Scholar using the search terms “ski racing,” “alpine ski racing,” “injury,” and “epidemiology.” Additional studies, including studies regarding specific ski racing injuries, were identified from the references of relevant articles. Studies focused on snowboarding injuries or on recreational alpine skiing injuries were excluded.

Epidemiology

Reported injury rates in alpine skiing are high.^{2,9,11,15,28,36,51,56} At the World Cup level, which is the highest level of competition, the incidence of injury ranges from 23.5 to 36.7 injuries per 100 athletes per season.^15,19,28 Nearly half (45.0%) of injuries in World Cup athletes occur during competition^15,19 as opposed to training, despite the majority of runs being taken during training.

The most commonly injured body part in adult ski racers is the knee.^{3,9,11,15,19,31,36,51,56} The second most commonly injured body parts are the lower leg or back,^15,19 the head and upper extremity,³ or the upper extremity alone.⁵¹ In the youth population (<18 years of age), the second most commonly injured body parts are reported as the spine and hand⁵⁶ and lower leg/foot/ankle.³¹ Anterior cruciate ligament (ACL) injury is the most frequent specific diagnosis in both the adult and youth populations,^{3,15,19,30,31,36,51,56} followed by concussion^15,19 and lower leg fracture.^30,31,51

During the 2006-2007 and 2007-2008 World Cup seasons, most injuries were considered time-loss injuries, with the majority classified as moderate (8-28 days) or severe (>28 days) in terms of absence from training or competition.¹⁹ The number of time-loss injuries decreased after the introduction of new FIS regulations in the 2012-2013 season, but remains high at 23.5 injuries per 100 athletes per season.¹⁹

Discipline

There are 4 different disciplines in alpine ski racing: downhill, super giant slalom (SG), giant slalom (GS), and slalom. Downhill is considered a speed event, with skiers reaching speeds well over 100 km/h.² Downhill courses cover the longest distance and the greatest drop in elevation. Slalom is considered a technical event, with the shortest distance between gates, the smallest turning radius, the slowest speeds, and the least drops in elevation. GS is also considered a technical event with gate distances greater than slalom but much shorter than downhill. SG is a speed event with gate distances and elevation drops greater than GS, but less than downhill.

The definition of injury across studies is inconsistent, with definitions including the following: an event that affected the health of the skier greater than 20 days after the event,²⁸ an event requiring medical attention during training both on and off snow,^15,19 and any event requiring medical attention⁶ (Table 1). Multiple studies failed to define injury at all.^9,36 Additionally, the method of reporting incidence varies among studies.^{6,9,15,19,28,36}

Table 1.

The incidence of injuries in each discipline of alpine ski racing

	N			Incidence
First Author	Athletes	Runs	Injuries	Downhill	SG	GS	Slalom
Margreiter28	114		96	57 injuries	n/a	16 injuries	14 injuries
Raas36	148			66% of injuries	n/a	11% of injuries	23% of injuries
Ekeland9	25,445			10.3/1000 skiers	n/a	0.7/1000 skiers	0.8/1000 skiers
Flørenes15	521			17.2/1000 runs	11.0/1000 runs	9.2/1000 runs	4.9/1000 runs
Bere6		27,489	1593	18.1/1000 runs	11.1/1000 runs	8.0/1000 runs	4.0/1000 runs
Haaland19a		13,384	217	13.3/1000 runs	10.4/1000 runs	6.5/1000 runs	2.1/1000 runs

GS, giant slalom; n/a, not applicable; SG, super giant slalom.

^aOnly data from 2012-2015 are presented in this row, data from 2006-2012 were included in the study by Bere et al.⁶

Among the studies that included all events, the greatest incidence of injuries was seen in downhill followed by SG then GS and slalom (Table 1). However, Gilgien et al¹⁷ found that the injury rate per unit time was nearly equal between disciplines. Additionally, the cause of injury varied across disciplines. Injuries occurring in downhill and SG were most frequently related to high speeds and jumping, with fatigue due to longer run times also playing a role in downhill.^{2,9,11,17,28,36} Injuries occurring in GS and slalom were related to high loads during turning.¹⁷

Age

As with adults, injury rates in youth alpine ski racers are also high.^{9,23,31,51,56} A retrospective study⁵¹ of injuries among ski racers of all ages in Finland over a 2-year period (age range, 9-36 years) noted that the mean age of both male and female injured athletes was 14 years, with injury defined as a pause in training longer than 1 week. In this study, the most frequent injury was a ligamentous knee injury, and 47% were ACL sprains.⁵¹

In a study of 431 elite alpine ski racers within Swedish ski high schools (mean age, 16.7 ± 1.1 years) from 2006 to 2011, nearly 50% of skiers sustained at least 1 injury during their enrollment, with a total incidence of 1.7 injuries per 1000 ski hours or 3.11 injuries per 100 months.⁵⁶ Eighty-five percent of these injuries occurred during skiing versus dryland training, and 97% of injuries were classified as moderate or severe.⁵⁶ In a similar study of 82 elite alpine ski racers within an Austrian high school (age range, 9-14 years) from 2014 to 2016, 58.5% of athletes sustained at least 1 traumatic or overuse injury, with 57.7% occurring during training, 9.6% occurring during competition, and the remainder occurring during “leisure time activities” or unclassified activity. Fifty-five percent of all injuries were classified as moderate (8-28 days lost from training) or severe (>28 days lost from training).³¹ In another study of young elite alpine skiers, nearly 50% of the injuries were classified as severe.⁵⁶

Overuse injuries, commonly involving the trunk and back, accounted for a relatively high proportion of time-loss injury during summer training.²³

Among youth skiers, the highest prevalence of injuries occurred in GS (56%) followed by slalom (31%) and SG (13%).⁵¹ Downhill injury prevalence was not recorded because the frequency of participation in downhill events was low in youth and adolescent ski racers.⁵¹

With regard to physical development, there was a trend toward higher injury rates in late-maturing athletes compared with early-maturing athletes, with biological maturity status based on calculating the age at peak height velocity with sex-specific prediction equations.³¹

Sex

Studies reporting injury rates for both males and females are presented in Table 2.^6,9,15,19,56 An exact comparison cannot be performed due to the varying definitions of injury and the varying methods of reporting incidence. Three studies reported no significant difference in injury rates between males and females.^9,19,56 In a study of Swedish skiing high schools, there was a significantly greater number of lower extremity injuries involving the left side compared with the right among females, which was not the case in males.⁵⁶ However, leg dominance was not clearly specified in this study. Two studies of World Cup–level athletes reported a higher injury rate in males than in females.^6,15 There was a relative injury risk of 1.58 (range, 1.22-2.04) in males relative to females, but no significant difference in the incidence of time-loss injuries or of ACL injuries.¹⁵ In a review of the same data with the addition of the 2009 to 2012 seasons, there was a significantly increased risk of injury and of time-loss injuries in males, but no difference in the rate of ACL injuries.⁶ This is contrary to the findings by Stenroos and Handolin,⁵¹ who showed a greater incidence of lower leg injury and of ligamentous knee injury in females than in males. There was no difference between male and female injury rate in the youth population in an Austrian study.³¹

Table 2.

The incidence of injuries in male and female athletes

First Author	Male Injury Rate	Female Injury Rate	Relative Risk (Male vs Female)	95% CI
Ekeland9	1.3 per 1000 skiers per season	2.0 per 1000 skiers per season	0.65	0.15-2.88
Flørenes15	42.1 per 100 athletes per season	29.7 per 100 athletes per season	1.42	1.06-1.91
Bere6	39.7 per 100 athletes per season	31.9 per 100 athletes per season	1.24	1.05-1.47
Westin56	1.62 per 1000 ski hours	1.77 per 1000 ski hours	0.92	0.74-1.13
Haaland19	28.1 per 100 athletes per season	25.1 per 100 athletes per season	1.09	0.94-1.27

Mechanism Of Injury And Risk Factors

Nearly half of all injuries to alpine ski racers occur during competition^15,19 as the result of falling and out-of-balance situations.⁵¹ These situations can result from misjudgment, fatigue, inattention, challenging course settings, and poor visibility,^28,36 which can cause the skier to reach an uncontrollable speed, lose balance, and/or “hook” a gate.⁹ Spörri et al⁴² examined subjective perceived risk factors by interviewing 61 elite alpine athletes. The most common risk factors described were the ski system (ski, plate, binding, and boot) function, changing snow conditions, skier speed, course design, the physical aspects of the racer, and the general speed of the course.⁴²

In a video analysis of 69 injuries in World Cup alpine skiers during the 2006 through 2009 seasons, turning (n = 55) and landing from a jump (n = 15) were the 2 most common activities when an injury occurred. Furthermore, 45% of injuries were associated with gate contact.³ Additionally, studies have repeatedly shown that the majority of injuries occur during the last segment of races,^{2,9,11,17,28,36} suggesting a fatigue factor and the subsequent negative effect on skier balance and concentration.^17,30 Among youth ski racers (<15 years old), 1 study determined that decreased core strength and below average drop-jump ability were associated with increased risk of sustaining a severe injury, and suggested there might be a benefit to neuromuscular training as a potential means of injury prevention.³⁰

Specific Injuries

Anterior Cruciate Ligament

Epidemiology and Sex Differences

ACL injury is by far the most common specific injury in alpine ski racing.^{3,15,19,29-31,36,51,52,56} In an early attempt to characterize ACL injury, Ellman et al¹² surveyed 600 alpine ski racers in Vermont and found that 33 of 135 (24.4%) male racer respondents had a history of knee injuries, with 4 of those indicating an ACL injury (2.9%). Of the 61 female ski racer respondents, 23 indicated a previous knee injury (37.7%) and 11 of those were an ACL injury (18%).¹² Stevenson et al⁵² reported a similar prevalence of ACL injuries between recreational alpine skiers and alpine ski racers. They also reported a 2.3 times increased likelihood for knee injury in female racers compared with male racers, and a 3.1 times increased likelihood for ACL injury in females compared with males.⁵²

Other studies have shown a similar rate of ACL injury in females and males, including at the World Cup level.^11,15,51 In a longitudinal study of the French national alpine ski racing team from 1980 to 2005, ACL injuries occurred in 27.2% of men and 28.2% of women (P = 0.21).³⁵ They reported an ACL injury rate of 5.4 per 100 skiers per season for men and 6.5 per 100 skiers per season for women (P = 0.21).³⁵ Though Pujol et al³⁵ found no significant difference between female and male ACL injury rates, Raschner et al³⁸ identified a 2.3 times increased risk of ACL injury in females aged 14 to 19 years compared with their male counterparts (P < 0.05; 95% CI, 1.3-4.2).

Risk Factors

In an evaluation of an injury database of 70 elite alpine skiers from 2004 through 2013, Schmitt et al⁴⁰ found that a higher skier seasonal ranking (FIS score at time of injury) was significantly associated with a history of knee injury. According to 2 studies, both males and females were more likely to sustain knee ligament injuries to the left rather than the right leg, although leg dominance was not discussed.^56,57 Additional risk factors for ACL injury include a parent with a history of ACL injury⁵⁸ and lower strength in the upper body and legs.³⁸ In contrast, improved performance on a standardized fitness test (Swiss ski power test) was not associated with a decreased risk of injury.⁴⁰ In a recent study, fatigue was not clearly identified as a risk factor for ACL injury in adolescent skiers.⁵⁷

Mechanisms of Injury

Johnson²⁴ originally described ACL injury mechanisms in elite ski racers as being distinct from those in recreational skiers due to the higher loads on the knee in ski racers. Skier error and tactical choices were described as the dominant factors putting the athlete at high risk of injury. Other factors include bumpy conditions, “aggressive” or grippy snow, reduced visibility, and course difficulty.⁵ Three mechanisms of ACL injury have been identified in video analysis: slip-catch (10 of 20 injuries), landing back-weighted (4 of 20 injuries), and dynamic snowplow (3 of 20 injuries). The slip-catch mechanism occurrs while turning, when the skier becomes out of balance backward and inward, which causes the weight to shift completely to the inner ski, allowing the outer ski to drift away from the center of mass. When the skier attempts to extend the leg and reestablish grip with the outer ski, it abruptly catches the snow surface and forces the knee into flexion, internal rotation, and valgus.^4,7 The dynamic snowplow mechanism occurs when the skier is out of balance backward with the weight unequally distributed between the skis. Similar to the slip-catch mechanism, the unweighted ski drifts away from the center of mass. The loaded ski then moves from the outside edge to the inside edge, forcing the knee into internal rotation and valgus.⁴ The landing back-weighted mechanism occurs when the skier is balanced with a center of gravity posterior to neutral after a jump, landing on the ski tails with nearly extended knees, resulting in tibiofemoral compression with a boot-induced and quadriceps induced anterior drawer.⁴ This is similar to the mechanism described by McConkey²⁹ and Ettlinger et al¹³ and has been studied in a computer model of a skier landing from a jump.²¹

In ski racers who sustain an ACL tear, associated knee injuries are common.^25,54 In a study of operative reports for 28 elite alpine ski racers with ACL injuries, only 5 skiers (18%) suffered isolated ACL injuries; 32% had concomitant ligamentous injury, 54% had concomitant chondral lesions, and 61% had concomitant meniscal injuries.²⁵

Outcomes

A total of 27 competitive ski racers with 30 ACL tears reconstructed primarily were followed for 57.6 months postoperatively, with all but 3 patients resuming ski racing at an average of 9.1 months from surgery.²² One small study looking at 5 youth alpine ski racers had a much lower return to sport, with only 2 athletes returning to their preinjury level.³² In a study of 477 professional French alpine skiers from 1980 to 2013, skiers with an ACL injury went on to have longer and more successful professional careers than those without.²⁰ There may be a beneficial effect to going through the recovery period associated with ACL reconstruction, and more talented skiers may be at higher risk of ACL tear. The lengthened careers could also be explained in part by the additional time required by the recovery after ACL surgery for injured ski racers. Athletes who ruptured their ACL at a younger age were more likely to have improved performance after injury than older athletes.²⁰ A recent study of elite alpine skiers who sustained an ACL injury and underwent reconstruction noted that the athletes’ FIS points increased immediately after return to competition, but decreased to below preinjury levels within the first year, although these changes were not statistically significant.⁸ The ACL reconstruction revision rate among alpine ski racers may be as high as 19% to 28%.²⁵

Back and Hip Pain

More than one-third of World Cup–level skiers have a history of recurrent or chronic low back pain.^23,41 Lumbar spine radiographs in 120 adolescent alpine ski racers with no history of back pain on admission to an elite-level training alpine ski racing high school demonstrated anterior vertebral endplate lesions with greater than 18% vertebral body height involvement.³³ Likewise, Rachbauer et al³⁷ compared a similar cohort of elite alpine ski racers with control participants and found anterior endplate lesions occurred significantly more often in competitive ski racers compared with controls. These studies suggest that the anterior thoracolumbar abnormalities are a result of excessive loading of the spine, which increases when the athlete is flexed forward. Because elite skiers begin training at an early age, it is likely that the anterior endplate lesions are a result of an imbalance between the applied load and the loading capacity of the immature spine.³⁷ A recent study by Todd et al⁵⁵ demonstrated no difference in the prevalence of spine and hip pain in young elite skiers compared with the general population. However, this study did note a significantly greater back pain level, as determined by visual analog scale, for skiers compared with controls.⁵⁵

Spörri et al⁴⁶ examined mechanisms leading to overuse injuries of the back in alpine ski racing in a study of trunk kinematics and loading on 8 European Cup–level racers during 32 runs on a GS course. Forward and lateral bending coupled with high ground reaction forces during turning generates large repetitive forces at the intervertebral disc, likely contributing to accelerated wear.⁴⁶

Abrahamson et al¹ examined the effect of cam morphology on hip and lumbar range of motion in adolescent elite skiers. After 2 years of continued skiing, the athletes with cam morphology had significantly decreased internal rotation of the hip in a sitting position compared with athletes without cam morphology.¹

Articular Cartilage

Steadman et al⁴⁹ reported the outcomes of knee microfracture on 20 elite alpine ski racers (16 females, 4 males) with full-thickness chondral lesions; 19 of the 20 patients returned to competitive skiing in an average of 13.4 months, with 6 of the 9 skiers improving their average overall World Cup ranking after surgery. There are no data on long-term outcomes in this cohort.

Injury Prevention

ACL ruptures, in particular, can occur when the ski acts as a lever to generate high forces and torque at the knee.¹⁵ Many racers ranked the ability of a binding to prevent inadvertent release higher in importance than its ability to prevent injury.¹¹ In one study, seventy-three percent of the racers who had ACL ruptures had bindings that failed to release.¹¹ Ski racers may intentionally adjust their bindings too tightly in an effort to prevent inadvertent binding release.¹⁰ There are select instances in which maximum bending and torsional loads are exerted on the leg after binding release, resulting in post-release injuries⁹; however, inadvertent binding release is felt to account for less than 5% of all skiing injuries, while over-tightened bindings may contribute to as much as 30% to 40% of injuries.¹⁰

Standing height (the distance between the sole of the ski boot and the bottom surface of the ski) may be a modifiable factor to decrease overuse injuries of the back. In a study measuring ground-reaction forces and trunk kinematics with varied standing height, decreased standing height was associated with significantly decreased ground-reaction forces, with no significant difference in trunk kinematics.⁴⁴ Spinal protective devices may decrease the risk of traumatic back injuries due to external forces.⁴⁸

Ski geometry has been examined in relation to injury. With more aggressive side-cuts it may be more difficult to get the ski off its edge while cornering (carving).²⁷ This allows for more aggressive turning at the cost of decreased control, potentially increasing the likelihood of an out-of-control scenario and a higher risk of injury.²⁷ After evaluating training runs with ski racers using 4 different ski set ups with different side-cuts, greater side-cut radius decreased injury risk at the cost of a loss of spectator visual aesthetics.²⁶ Additional studies found that increased side-cut radius was associated with a statistically significant decrease in ground-reaction force and kinetic energy during specific phases of turning.^27,45 Similarly, the combination of increased standing height and increased ski length with decreased ski width decreases kinetic energy during downhill runs.¹⁸ Prior to the 2012-2013 season, the FIS regulations for side-cut radius and ski length were increased. These regulations were successful in decreasing the absolute injury rate by 26% in males during World Cup events as well as the time-loss injury rate; however, there was no significant change in the injury rate for females or in the rate of lower body injuries, including ACL tears.¹⁹

Updated FIS regulations have also attempted to decrease the number of head injuries by increasing the helmet testing speed. In a recent study using video-based motion analysis to estimate head impact kinematics, 7 of the 9 impacts analyzed had an estimated preimpact velocity greater than the current standard for helmets required by the FIS regulations.⁵⁰

In addition to equipment variables, course design has been studied as a modifiable risk factor. Increased horizontal gate spacing can reduce speed, ground-reaction forces, and trunk kinematics that place less load on the back.⁴³ Increased gate offset in slalom events was effective in decreasing ground-reaction forces, but the same effect was not seen in GS.⁴³ Moreover, this strategy was proven to be ineffective for speed reduction; skiers were able to compensate for the shifted spacing by adjusting timing strategy on turns.⁴⁷ Additionally, increased gate spacing may increase overall skier fatigue due to longer sustained loading forces associated with the longer turn-cycles.⁴⁷ It may also increase the risk of out-of-balance situations because the increased and sustained loads of the smaller radius turns leave the skier with less of a compensatory buffer if additional factors precipitate an out-of-balance situation.^17,47 There is a method of predicting the injury hazard of jumps in downhill ski races to aid course layout and minimize injury risk, but the efficacy of this method is unproven.³⁹

Conclusion

The injury rate in alpine ski racing remains high at the junior level as well as the World Cup level.^{2,9,11,15,28,36,51,56} There are no studies reporting injury rates at the masters level. Of concern is that many of the injuries sustained in alpine ski racing are classified as severe and lead to a substantial time away from sport.^15,31,56 The effect of injury on the long-term health of ski racers (ie, knee osteoarthritis) is not known.

At the World Cup level, the highest rate of injury is seen in downhill, where speeds are the greatest and jumps are integrated into the course.^{6,9,15,19,28,36} At the junior level, the majority of injuries are seen in GS, as participation in downhill events is infrequent.⁵¹

ACL injuries remain very problematic in alpine ski racing. Unlike other sports, there is not a clear difference in the rate of injury between sexes.^11,15,51,52 At the junior level, some studies demonstrate a higher injury rate in females,⁵⁷ but at the highest level of competition, there is no difference in ACL injury rate between males and females.^15,19

Despite the high rate of ACL injury, the rate of return to sport is also high.²⁰ Ski racing is not technically a cutting and pivoting sport; ACL tears in ski racing are most likely to occur in out-of-balance situations, awkward landings, or crashes.⁵¹ The most common mechanism, the “slip-catch,” is very similar to the “phantom-foot” phenomenon described in recreational skiers.^4,7,13

Overuse injuries in ski racing, particularly involving the low back, are also problematic and are likely because of the high loads generated during turning.^23,41

The most common scenario leading to injury seems to be an off-balance situation.⁵¹ It would seem logical, therefore, to try and reduce these situations. Courses and speeds should be appropriate to the level of competition, and athletes should learn proper landing techniques from jumps. The role of fitness and strength with relation to injury is unclear, with conflicting results in the literature. However, the increased incidence of injury in the final segment of races may implicate fatigue as a significant risk factor.^{2,9,11,17,28,36} As of this point, equipment changes introduced to reduce injuries, specifically ACL injuries, have not demonstrated a significant reduction in injury rate.¹⁹