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dc.contributor.authorSteenstrup, Sophie E.
dc.date.accessioned2019-03-08T11:38:56Z
dc.date.available2019-03-08T11:38:56Z
dc.date.issued2019
dc.identifier.isbn978-82-502-0550-5
dc.identifier.urihttp://hdl.handle.net/11250/2589344
dc.descriptionAvhandling (doktorgrad) - Norges idrettshøgskole, 2018nb_NO
dc.description.abstractBackground: Head injuries represent a concern in skiing and snowboarding, where traumatic brain injury is the most common cause of death. We therefore wanted to describe the risk of head injuries across disciplines and sex among World Cup (WC) skiers and snowboarders. No systematic video analysis of head/face injury mechanisms at the WC level has been conducted. Prior to the 2013/14 season the International Ski Federation (FIS) increased the helmet testing speed from 5.4 m/s to 6.8 m/s for alpine downhill, super-G and giant slalom, and for freestyle ski cross, but not for other disciplines. Whether this increased testing speed reflects impact velocities in real head injury situations on snow is unclear. Therefore, our aims were to describe: 1) the epidemiology of head/face injuries, 2) the gross mechanisms of head/face injuries, and 3) the gross head impact biomechanics, to compare the head impact characteristics with relevant helmet standards. Methods: We conducted retrospective interviews with FIS WC athletes at the end of 10 consecutive seasons (2006-2016), to register injuries sustained during the competitive season. We collected injury videos at the end of each season. Head injuries were classified as “head/face” injuries and did not include neck or cervical spine injuries. To calculate the exposure, we extracted data from the official FIS results database for all WC competitions for each of the athletes interviewed (Paper I). We performed a qualitative visual analysis of videos of head and face injuries reported through the FIS ISS during 10 WC seasons (2006-2016), to describe gross head injury mechanisms. We analysed 57 head impact injury videos (alpine n= 29, snowboard n=13, freestyle n=15) (Paper II). We reconstructed 13 head impacts in total from 11 broadcast head injury videos (snowboard n=2, freestyle n=2, alpine n= 7) in detail. We used video-based motion analysis software to estimate head impact kinematics in two dimensions, including directly preimpact and postimpact, from the broadcast videos. The sagittal plane angular movement of the head in 9 impacts was also measured using angle measurement software (Papers III and IV). Results: During 7 WC seasons (2006-2013), 2080 injuries were reported. Of these, 245 (11.8%) were head/face injuries; nervous system injuries/concussions were the most common (81.6%) and 58 of these were severe (23.7%). The injury incidence per 1000 competition runs was higher in freestyle (1.8, 95% CI 1.2 to 2.4) than in alpine skiing (0.9, 95% CI 0.6 to 1.2; RR 2.05, 95% CI 1.25 to 3.46) and snowboard (1.0, 95% CI 0.6 to 1.3; RR 1.85, 95% CI 1.15 to 2.99). Females had a higher injury incidence (5.8, 95%CI 4.8 to 6.9) vs. males (3.9, 95% CI 3.2 to 4.6; RR 1.48, 95% CI 1.15 to 1.90) throughout the season (per 100 athletes) (Paper I). During the crash sequence, most athletes (84%) impacted the snow with the skis or board first, followed by the upper or lower extremities, buttocks/pelvis, back and, finally, the head (Paper II). Alpine skiers had sideways (45%) and backwards pitching falls (35%), with impacts to the rear (38%) and side (35%) of the helmet. Freestyle skiers and snowboarders had backwards pitching falls (snowboard 77%, freestyle 53%), mainly with impacts to the rear of the helmet (snowboard 69%, freestyle 40%). There were three helmet ejections among alpine skiers (10%), and 41% of alpine injuries occurred due to inappropriate gate contact prior to falling. Athletes had one (47%) or two (28%) head impacts, mainly on snow (83%) (Paper II). In 11 of 13 head impacts, the estimated normal-to-slope preimpact velocity was higher than the current FIS helmet rule of 6.8 m/s (mean 8.3 ± 2.6 m/s, range 1.9 ± 0.8 m/s to 12.1 ± 0.4 m/s). The 13 head impacts had a mean normal-toslope velocity change of 9.6 ± 2.3 m/s (range 5.2 ± 1.1 m/s to 13.5 ± 1.3 m/s). There was a large change in sagittal plane angular velocity (mean 40.2 ±15.1 rad/s, range 21.2 ± 1.5 rad/s to 64.2 ± 3.0 rad/s) during impact (Papers III and IV). Perspectives: In addition to the incidence of head/face injury, we have provided important information about real gross head injury mechanisms and gross head impact biomechanics in alpine, snowboarding and freestyle skiing, which are important considerations if helmet testing is to be developed and evaluated under realistic impact conditions. Future laboratory or field based studies should examine snow properties and perform helmet impact tests on real-life snow, to increase our understanding of the equivalence between real head impacts on snow and impacts in a laboratory. Continued research into head injuries and helmet standards in all disciplines is needed. Future prevention strategies should address severe injuries across all disciplines, promote adequate recognition and medical attention for all head injuries, and target freestyle and snowboarding athletes, with at least equal attention to female athletes. Safety for the athletes may improve by improvements in course design, focusing on safe jump constructions, and reducing alpine skier speeds, especially during turns and terrain transitions. Further research into the optimal design of release gate panels and poles should continue, and helmet fit and wearing correctness must be adressed to prevent future helmet ejections.nb_NO
dc.description.abstractPaper I: Steenstrup SE, Bere T, Bahr R. Head injuries among FIS World Cup alpine and freestyle skiers and snowboarders: a 7-year cohort study. Br J Sports Med. 2014 Jan;48(1):41-5. doi: 10.1136/bjsports-2013-093145.nb_NO
dc.description.abstractPaper II: Steenstrup SE, Bakken A, Bere T, Patton DA, Bahr R. Head injury mechanisms in FIS World Cup alpine and freestyle skiers and snowboarders. Br J Sports Med. 2017 Nov 13. pii: bjsports-2017-098240. doi: 10.1136/bjsports-2017-098240. [Epub ahead of print]nb_NO
dc.description.abstractPaper III: Steenstrup SE, Mok KM, McIntosh AS, Bahr R, Krosshaug T. Head impact velocities in FIS World Cup snowboarders and freestyle skiers: Do real-life impacts exceed helmet testing standards? Br J Sports Med. 2017 Jul 8. pii: bjsports-2016-097086. doi: 10.1136/bjsports-2016-097086. [Epub ahead of print]nb_NO
dc.description.abstractPaper IV: Steenstrup SE, Mok KM, McIntosh AS, Bahr R, Krosshaug T. Reconstruction of head impacts in FIS World Cup alpine skiing. Br J Sports Med. Published Online First: 25 November 2017. doi:10.1136/bjsports-2017-098050nb_NO
dc.language.isoengnb_NO
dc.subjectnihnb_NO
dc.subjectdoktoravhandlingernb_NO
dc.subjectskiidrettnb_NO
dc.subjectalpine grenernb_NO
dc.subjectfreestylenb_NO
dc.subjectsnowboardnb_NO
dc.subjectskadernb_NO
dc.subjecthodenb_NO
dc.subjectrisikonb_NO
dc.subjectanalysernb_NO
dc.titleHead injuries in FIS World Cup alpine skiers, snowboarders and freestyle skiers: Epidemiology and video analyses of head impact injury mechanismsnb_NO
dc.typeDoctoral thesisnb_NO
dc.description.localcodeSeksjon for idrettsmedisinske fag / Department of Sports Medicinenb_NO


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