Figure 3 - uploaded by Lars Nordsletten
Content may be subject to copyright.
Events leading to slip-catch mechanism (ACL injury to the right knee): (A) (− 2.16 s), the racer is late in line and not in a balanced position. (B) (– 1.44 s), he goes too directly into the next gate and leans too much inside initiating the turn. He is late timing his movements during the turn, skiing passively. (C) (− 0.48 s), the racer goes directly into a compression in an unbalanced position backwards/inwards and loses pressure on the outer ski, unable to absorb the terrain transition. (D) (index frame), the outer ski catches the inside edge abruptly, forcing the right knee into valgus and internal rotation.  

Events leading to slip-catch mechanism (ACL injury to the right knee): (A) (− 2.16 s), the racer is late in line and not in a balanced position. (B) (– 1.44 s), he goes too directly into the next gate and leans too much inside initiating the turn. He is late timing his movements during the turn, skiing passively. (C) (− 0.48 s), the racer goes directly into a compression in an unbalanced position backwards/inwards and loses pressure on the outer ski, unable to absorb the terrain transition. (D) (index frame), the outer ski catches the inside edge abruptly, forcing the right knee into valgus and internal rotation.  

Source publication
Article
Full-text available
The authors have recently identified three main mechanisms for anterior cruciate ligament (ACL) injuries among World Cup (WC) alpine skiers, termed as "the slip-catch", "the landing back-weighted" and "the dynamic snowplow". However, for a more complete understanding of how these injuries occur, a description of the events leading to the injury sit...

Similar publications

Article
Full-text available
We have limited insight into how injuries occur in professional ski racing. The aim of this study was to describe the injury situations in World Cup alpine skiing. Injuries reported through the International Ski Federation Injury Surveillance System for three consecutive World Cup seasons (2006-2009) were obtained on video. In total, 69 injuries an...

Citations

... The mechanisms of ACL injuries in alpine skiing have been studied over the last few years, with three injury mechanisms described: "slip-catch", "landing back-weighted" and "dynamic snowplow" mechanisms (Bere et al., 2011a;Bere et al., 2013;Jordan et al., 2017;Spörri et al., 2017). These situations mainly occur during turns and jump landings and are in most cases the result of out-of-balance situations (Bere et al., 2011a;Bere et al., 2011b;Bere et al., 2014a). ...
Article
Full-text available
This study aimed 1) to assess the test-retest reliability of dynamic postural stability index (DPSI) assessments using a ski-specific jump protocol that consists of single-leg landings on a three-dimensional force plate after forward-performed double-leg drop jumps from a box over a hurdle (DJSLLs), 2) to provide reference values for female and male youth competitive alpine skiers; 3) to explore their changes in DPSI over 3 years during adolescence; and 4) to investigate potential associations of DPSI with age and biological maturation. Using three-dimensional force plates, 16 healthy subjects were tested on the same day (test-retest reliability experiment; five test-retest assessments of right leg landings), and 76 youth skiers aged 13–15 years were tested 3 times within 2 years (main experiment; average of two trials per leg each time). The test-retest reliability experiment revealed an ICC(3,1) and 95% CI of 0.86 [0.74, 0.94] for absolute DPSI assessment. The within-subject SEM of absolute DPSI was 16.30 N [13.66 N, 20.65 N], and the standardized typical error was moderate (0.39 [0.33, 0.50]). Both absolute and relative DPSI values were comparable between male and female youth competitive alpine skiers. The mean absolute DPSI in year 1 (195.7 ± 40.9 N), year 2 (196.5 ± 38.9 N) and year 3 (211.5 ± 41.3 N) continuously increased (i.e., worsened) (p < 0.001). Mean relative, i.e. body weight force normalized, DPSI values significantly decreased, i.e., improved, from year 1 to 2 (0.42 ± 0.01 vs. 0.36 ± 0.004; p < 0.001) and year 1 to 3 (0.42 ± 0.01 vs. 0.36 ± 0.01; p < 0.001). Absolute DPSI correlated with age and biological maturation, while no such correlations were found for relative DPSI values. Our findings suggest that DPSI is a reliable and sensitive measure of dynamic postural control during DJSLLs and that relative DPSI improves annually in competitive youth skiers when accounting for body weight. Future work should consider biological maturation testing during the growth spurt, and normalizing to body weight force could be a possible solution.
... 10 In the first 2 mechanisms, the ski racer initially loses balance inward and/or backward, with the outside ski reducing its contact with the snow and drifting away. 11 In the further sequence, the inner edge of either the outer or inner ski abruptly catches on the snow surface, resulting in excessive compression of the knee joint, knee valgus, and internal rotation. 12 While the arthrokinematics during these injury mechanisms are similar to those known for ACL injuries in Peer review under responsibility of Shanghai University of Sport. ...
... As part of the "landing back-weighted" mechanism, the third competitive alpine ski racing specific ACL injury mechanism, the ski racer typically loses balance during flight due to backward angular momentum received at the jump take-off. 11 This results in the ski racer landing on the tails of the skis first, with the entire skis "clapping" down on the snow surface secondarily. 10 Thus, upon first contact with the ground, an angular momentum rotates the skis forward as the ski racer falls backward, thereby inducing tibiofemoral compression and causing the tibia to be pushed forward by the stiff rear part of the ski boot. ...
Article
Full-text available
Background During an experiment, a ski racer equipped with various measurement devices suffered an anterior cruciate ligament (ACL) rupture in his right knee. The aim of this study was to describe the underlying injury mechanism from a functional perspective. Methods Eight giant slalom turns (i.e., 4 left turns), followed by 1 left turn at which the ACL injury occurred, were recorded by 2 video cameras, electromyography (EMG) of 4 relevant muscle groups, inertial measurement units (IMUs) to measure knee and hip angles, and pressure insoles to determine ground reaction forces. Results Due to a loss of balance, the ski racer began to slide sideways at the apex of a left turn. During sliding, his right (outside) leg was actively abducted upward without touching the ground. The ski racer then attempted to stand up again by dropping his leg back towards the snow surface. The end of this dropping was accompanied by a decrease in EMG activity in the knee stabilizing muscles. Once the inside edge of the outer ski caught the snow surface, a rapidly increasing peak force, knee flexion, and an aggressive sudden activation of the vastus medialis muscle were observed, while biceps femoris and rectus femoris further decreased their activation levels. This likely resulted in excessive anterior translation of the tibia relative to the femur, causing damage to the ACL. Conclusion Our example emphasizes that ski racers should not get up until they stop sliding. Remember: “When you're down, stay down”.
... Poor visibility is a known relevant key component of events leading to ACL injuries in alpine ski racing. 34 The proposed measures certainly seem plausible, although difficult to optimise given the high level of professionalism in the sport at the WC level. ...
Article
Full-text available
Objectives: (1) To update experts’ priorities of perceived key injury risk factors in alpine ski racing based on a framework and list derived 10 years ago, (2) to identify additionally emerging risk factors since then and (3) to compile a list with countermeasure suggestions. Methods: A sample of 532 expert stakeholders (athletes, coaches, team medical staff, Ski Racing Suppliers (SRS) and International Ski Federation (FIS) representatives) from the World Cup (WC), European Cup (EC) and FIS-race level participated in a cross-sectional online survey. Experts were asked to name those risk factors with the highest believed impact on injury risk and rank them according to their current priority from a predefined list. In addition, experts were encouraged to name additional (not listed) risk factors and to suggest countermeasures. Results: Regardless of stakeholder role and competition level, snow-related factors appeared to have the highest perceived priority. However, WC athletes’ and coaches’ perceptions were also related to equipment, while at the EC and FIS-race level fatigue and physical fitness-related factors were considered important. Athletes’ perceptions were largely in agreement with SRS (ie, snow-related and equipment-related factors). At the same time, while coaches, team medical staff and FIS representatives additionally emphasised fatigue and physical fitness-related factors. Conclusion: Experts’ perceptions on key injury risk factors in alpine ski racing depend on the stakeholder role and differ between the competition levels. Thus, to develop effective prevention measures and to successfully implement them, all relevant stakeholders should be given a voice, and prevention efforts should be targeted to the specific level.
... Also, previous studies [7,8] show that using skis with greater sidecut radius reduce the self-steering of the ski and also has the potential to reduce the kinetic energy in GS. The selfsteering behavior of the ski and the kinetic energy are two important factors in the mechanism of anterior cruciate ligament rupture in alpine ski racing [7,9,10]. In an attempt to reduce the risk of injury in the alpine World Cup (WC), the International Ski Federation (FIS) changed the regulations for WC racing skis, prior to the 2012/2013 season [11,12]. ...
Article
Full-text available
The International Ski Federation (FIS) implemented new ski regulation prior to the 2012/2013 season for men and women and for the men again prior to the 2017/2018 season in an effort to increase skiers’ safety in the Giant Slalom (GS) event in the Alpine World Cup (WC). At present, no study has investigated how these changes impacted total race times, gate-to-gate times or number of gates per race. Hence, the purpose of this study was to investigate how the regulation changes have affected these parameters. Data were collected from the official result lists, by the FIS, for the GS event during 15 WC seasons (2005/2006-2019/2020), for men and women, respectively and grouped into Rule 1 (2005/2006-2011/2012), Rule 2 (2012/2013-2016/2017) and Rule 3 (2017/2018-2019/2020). Differences (for total race time, gateto-gate times and number of gates) between rules were analyzed using Mann-Whitney tests and Kruskal Wallis rank sum tests for women and men, respectively. For male skiers, the race time during Rule 2 was 152.51 (138.72-157.55) s, which was significantly slower (p < 0.01) than Rule 1, 147.42 (143.13-154.26) s and to Rule 3, 149.37 (135.63-158.32) s (p<0.05). For women, race times during Rule 1 was significant slower (p<0.001, r=0.23, df =455, U=939852.5, z = 12.079) than Rule 2, 141.3 (132.71-148.78) s vs. 137.12 (125.05-146.78) s. The men’s gate-to-gate times increased for Rule 2 compared to Rule 3, 1.49 (1.45-1.55) s vs. 1.48 (1.45-1.52) s, p<0.05), whereas the women’s gate-to-gate times decreased for Rule 2 compared to Rule 1, 1.53 (1.48-1.57) s, vs 1.57 (1.52-1.62) s, p<0.001. Changing the ski equipment regulations affected men and women differently as well the course setting and should not be considered as the sole effort to reduce skiing speed and risk of injury in GS in the alpine WC.
... Estos dos últimos mecanismos representan el 65% de todas las lesiones de LCA en esquiadores a nivel competitivo. 9 Como se aprecia en las descripciones anteriores, el valgo y/o rotación interna son los mecanismos principales para la lesión del LCA. Estudios biomecánicos de torque demuestran que el LCA es más vulnerable a lesionarse estando la rodilla en flexión profunda o extensión, tal como ocurre en este grupo de deportistas. ...
Article
Full-text available
Resumen El esquí es un deporte individual con una tasa de lesiones de 1,84 por 1.000 días esquiador en la población general. Las roturas del ligamento cruzado anterior (LCA) son algunas de las más comunes, llegando a una tasa de 5 por cada 100 esquiadores por temporada a nivel competitivo, debido a la gran exigencia a la que se encuentran sometidas las rodillas. Lo anterior presenta un desafío para el traumatólogo a la hora de plantear un manejo. Se realizó una revisión de la literatura respecto de los mecanismos de lesión, tratamiento, prevención, rehabilitación y uso de órtesis en el retorno deportivo. Se describen los mecanismos clásicos de lesión en esquiadores amateurs y competitivos. La mayoría de las lesiones de LCA son de resolución quirúrgica, en que la recomendación de reconstrucción debe ser con injerto autólogo de hueso-tendón patelar-hueso, salvo en los pacientes mayores o en pacientes con fisis abierta, en los que se recomienda el uso de injerto autólogo de semitendinoso-gracilis. La prevención y rehabilitación se basan en mejorar la fuerza y el control neuromuscular de los estabilizadores dinámicos de la rodilla implementándose programas específicos, evaluación del gesto deportivo, y pruebas de control neuromuscular. Se recomienda el uso de órtesis funcionales adecuadas en los pacientes sometidos a reconstrucción del LCA. Las lesiones de LCA en esquiadores de nivel competitivo son habituales, de manejo específico y multidisciplinario. La elección del injerto y del tipo de rehabilitación son fundamentales en el retorno deportivo del esquiador. Nivel de evidencia: V.
... In order to develop efficient strategies in preventing these injuries, a comprehensive model of the causes of injuries should be used. Internal and external factors should be considered, such as course setting, weather and snow conditions, skier's technical errors and equipment that contributes most to injuries [4,5]. ...
Article
Full-text available
Introduction. Alpine skiing is one of the most dangerous winter sports that entails a high number of injuries, most commonly affecting the knee. Kinesiophobia is a condition in which an individual experiences fear of physical movement and activity as a result of feeling susceptible to injuries or recurrent injuries. The objective was to examine the level of kinesiophobia in skiers who have sustained knee injuries. Material and methods. The sample consisted of 22 female and 11 male professional skiers, with the average age of 24 ± 7.391 years. For the purpose of the assessment, the Tampa scale for kinesiophobia (TSK) was employed. Results. The number of knee injuries in skiers totals at least 1 and 11 at most, on average 2.45, most commonly involving the anterior cruciate ligament and meniscus. There were no significant differences between the left and the right knee or bilateral injuries. The average score in the TSK totals 36 points, which is close to the critical threshold of 37 points. 36% of the participants possess a high level of kinesiophobia. With respect to the general level of kinesiophobia, no significant differences were found in relation to gender, with regard to the number of surgeries or whether one or both knees were affected by injuries. Older skiers have also been found to have significantly lower fear of recurrent injuries. Conclusions. The number of knee injuries in skiing is high and aggravating, in such a way that almost one third of skiers that have sustained knee injuries experience a critical level of kinesiophobia, and that requires intervention. During rehabilitation, psychological support should also be provided to athletes in order to prevent or reduce kinesiophobia and thus prevent recurrent or new injuries.
... The "slip and catch" mechanism means that the skier loose the pressure on the outer ski, while the inside edge of the outer ski is catching the snow and forces the knee into valgus and internal rotation. Moreover, Bere et al. (2011b) found that the majority of knee injuries occurred while skiing, and a technical as well as an inappropriate tactical mistake could lead to an ACL injury. ...
... Like Ettlinger et al. (1995) the authors of the present study have tried to teach both the ski coaches and the alpine skiers to be aware of possible ACL injury risk situations. Awareness of certain risk situations may help to reduce the skier's technical mistake and thereby preventing an ACL injury (Bere et al., 2011b). ...
Article
Full-text available
Anterior cruciate ligament (ACL) injury is one of the most serious injuries among Swedish alpine ski high school students. An ACL injury forces the skier to stop skiing for several months, and some skiers even have to give up their skiing career. Therefore, an ACL injury prevention program might play an important role for alpine skiers. In the present study ski high school students have been followed in terms of ACL injuries during 1–2 ski seasons between 2006/2007 and 2012/2013. Alpine skiers studying at the Swedish ski high schools during the ski seasons 2011/2012 and 2012/2013 received a specific ACL injury prevention program (n = 305), while alpine skiers who attended a Swedish ski high school between the ski seasons 2006/2007 and 2010/2011 served as controls (n = 431). The prevention program was based on earlier studies and included indoor and outdoor exercises on snow focusing on core stability and neuromuscular control. Alpine skiing is an equilateral sport. Therefore, the goal of the prevention was to encourage the skiers to practice these exercises in order to perform equally good on both legs. The outcome measure consisted of the number and incidence of ACL injuries. The 2 years of prevention resulted in 12 ACL injuries (3.9%) compared with 35 ACL injuries during the control period (8.1%). The absolute risk rate showed a decreased incidence rate of −0.216 [CI −0.001–(−0.432)]/100 months attending a ski high school in favor of the intervention group. A prevention program focusing on the skier's ability to perform neuromuscular exercises equally good on both legs led to a reduction of ACL injuries.
... À notre connaissance, ces facteurs n'ont pas été spécifiquement décrits pour les skieurs alpins adolescents. Les facteurs intrinsèques et modifiables ont étés décrits chez le skieur alpin adulte tels que neuromusculaires, hormonaux, liés aux qualités physiques, physiologiques, psychologiques ou encore annexés à la technique de ski [12,13]. Chez le jeune skieur, peu de résultats étaient disponibles : deux études uniquement s'y étaient intéressées. ...
Article
Objectives: To provide a comprehensive overview of what is known about injury prevention in the 14–19-year-old competitive alpine skier following the 4-step injury prevention sequence from van Mechelen et al. (1992). Method: A systematic review was conducted in November 2018 using two database (“Pub Med” and “Science Direct”) and the following keywords: “Injury”, “Sports injuries”, “Young”, “Teenager”, “Epidemiology”, “Risk factor”, “Prevention”, “Alpine skiing” and “Alpine skiing” to include articles dealing with epidemiology, identification of risk factors, implementation and/or injury prevention programs for alpine competitive skiers from 14 to 19 years old. Results: Five studies reported on the epidemiology of 14–19 years old competitive alpine skier injuries: these injuries were mainly localized at the knee, involved ligaments, and the most common injury was Anterior Cruciate Ligament (ACL) injury. Two studies identified the asymmetry of strength between the flexors and extensors muscles of the trunk as well as the asymmetry of performance on the one leg hop test as risk factors for ACL injury. One study showed that a prevention program based on the improvement of neuromuscular control of the lower limbs and strengthening of the spine muscles could limit the number of ACL lesions. Discussion and conclusion: ACL lesions are the most common lesion in 14- to 19-year-old competitive alpine skiers. Poor neuromuscular control and muscular asymmetry of the trunk were predictive of this lesion and it would appear that prevention program could reduce the incidence of this injury. However, other longitudinal studies seeking to identify potential risk factors, their evolution over time and their modification through prevention programs are still necessary. Level of evidence: 4.
... It is possible that, owing to the less developed and less stable skiing technique in youth athletes compared with adolescent and elite athletes, youth athletes may be at a higher risk for injuries that occur because of technical mistakes, as, for example, ACL ruptures based on slip catch or dynamic snow plow mechanisms. 52 In such situations, and perhaps also owing to less well-prepared slopes in youth races, it is possible that limb differences in strength capacities may lead to traumatic injuries. 12 Thus, in addition to training that focuses on the development of a stable skiing technique, training for youth athletes should concentrate on the individual neuronal and physical development of young ski racers to detect and prevent asymmetries. ...
Article
Purpose The aims of this study were to assess differences of limb symmetry index (LSI) in strength- and coordination-related tasks between high-level, competitive, noninjured ski racers of different age-related performance levels and to prospectively assess limb differences as a possible risk factor for traumatic and overuse injury in youth ski racers. Methods The study (Study 1) included 285 high-level competitive ski racers (125 females, 160 males) of 3 age-related performance levels and based on the school system: 95 youth (10–14 years, secondary modern school), 107 adolescent (15–19 years, grammar school), and 83 elite athletes (20–34 years). To investigate the second aim (Study 2), 67 of the 95 youth athletes were included and any traumatic or overuse injuries were prospectively recorded over 2 seasons. All athletes performed 4 unilateral tests (strength related: one-leg counter movement jump (OL-CMJ) and one-leg isometric/isokinetic press strength test (OL-ILS); coordination related: one-leg stability test (OL-ST) and one-leg speedy jump test (OL-SJ)). The LSI was calculated by dividing the dominant leg by the nondominant leg and multiplying by 100. Kruskal-Wallis H tests and binary logistic regression analyses were conducted. Results There were significant differences between the LSI of the 3 age-related performance-level groups only in the strength-related tests: the OL-CMJ (χ²(2, 285) = 9.09; p = 0.01) and the OL-ILS (χ²(2, 285) = 14.79; p < 0.01). The LSI for OL-ILS was found to be a significant risk factor for traumatic injury in youth ski racers (Wald = 7.08; p < 0.01). No significant risk factors were found for overuse injuries. Conclusion Younger athletes display slightly greater LSI values only in the strength-related tests. The cut-off value of limb differences of <10% for return to sport decisions seems to be appropriate for elite athletes, but for youth and adolescent athletes it has to be critically discussed. It seems to be necessary to define thresholds based on specific performance tasks (strength vs. coordination related) rather than on generalizations, and age-related performance levels must be considered. Limb differences in unilateral leg extension strength represent a significant injury risk factor in youth ski racers.
... 25 29 30 Focusing on injury cases in competitive alpine skiing, landing out of balance backwards was identified as one out of the three main mechanisms of ACL injury. 31 However, the importance of landing height (eLH) should not be underestimated especially in case of approaching the maximum values which a skier can absorb actively by muscle forces. Exceeding values of the eLH might result in excessive impact loads and consequently a collapse and fall of the skier. ...
Article
Background Competitive skiers face a high risk of sustaining an ACL injury during jump landing in downhill skiing. There is a lack of knowledge on how landing height affects this risk. Objectives To evaluate the effect of varied landing height on peak ACL force during jump landing and to compare the effect of the landing height with the effect of the landing position varied by the trunk lean of the skier. Methods A 25-degree-of-freedom sagittal plane musculoskeletal model of an alpine skier, accompanied by a dynamic optimisation framework, was used to simulate jump landing manoeuvres in downhill skiing. First, a reference simulation was computed tracking experimental data of competitive downhill skier performing a jump landing manoeuvre. Second, sensitivity studies were performed computing 441 landing manoeuvres with perturbed landing height and trunk lean of the skier, and the corresponding effects on peak ACL force were determined. Results The sensitivity studies revealed that peak ACL force increased with jump height and backward lean of the skier as expected. However, peak ACL was about eight times more sensitive to the trunk lean of the skier compared with landing height. The decreased sensitivity of the landing height was based on the lower effects on the knee muscle forces and the shear component of the knee joint reaction force. Conclusion Preventive measures are suggested to focus primarily on avoiding trunk backward lean of the skier, and consequently on proper jump preparation and technique, and secondarily on strategies to reduce landing height during jumps.