Long-term results after isolated iliac wing fractures.

INTRODUCTION: Isolated iliac wing fracture is a rare pelvic fracture that is considered benign in the literature. As there is a complete lack of information on function and quality of life in patients with this injury, the primary aim of this study was to evaluate the long-term functional results, and secondly to evaluate the patients' clinical function and fracture healing. PATIENTS AND METHODS: All patients treated in Oslo University Hospital, Ullevaal (OUH-U), the Norwegian National Pelvic Service, in the time period 2006-2016 were included. Nine of 13 eligible patients (69%) were evaluated by the Patient Reported Outcome Measures (PROM); EQ-5D-3L and Majeed Score. For the secondary outcomes, the patients were clinically examined for Range of Motion (ROM) in the hips, pain, muscular function and nerve deficiencies. Finally, the patients underwent X-rays (AP-view and iliac and obturator oblique views). RESULTS: All patients were injured in high-energy trauma with severe associated injuries. Five patients were operated and four received conservative treatment. At the time of follow-up (median seven years after injury), the mean EQ-5D VAS was 84, and the mean Majeed score was 87. Two out of nine reported moderate level of pain, three reported mild pain, and the rest reported no pain. Six patients were still working, two were retired, and the last one was receiving disability benefit of other reasons than the iliac fracture. One patient had difference in range of external rotation of >10° between the hips, while the rest had no differences in ROM. The follow-up X-rays showed healed fractures in all the patients. CONCLUSION: Patients with isolated iliac wing fractures seem to have a good general state of health, scoring high on the PROMs, with minor and insignificant clinical sequela. This original finding is in accordance with the general assumption amongst pelvic surgeons that the injury is a benign one.

Efficacy of periacetabular osteotomy followed by progressive resistance training compared to progressive resistance training as non-surgical treatment in patients with hip dysplasia (PreserveHip) - a protocol for a randomised controlled trial.

INTRODUCTION: Periacetabular osteotomy (PAO) is an established treatment for adolescent and adult patients with hip dysplasia. However, the efficacy of PAO has not been tested against another surgical intervention or conservative treatment in a randomised controlled trial before. We suggest that progressive resistance training (PRT) could be an alternative to PAO. The primary aim of this trial is therefore to examine the efficacy of PAO followed by 4 months of usual care followed by 8 months of PRT compared to 12 months of solely PRT in patients with hip dysplasia eligible for PAO in terms of patient-reported pain measured by The Copenhagen Hip and Groin Outcome Score (HAGOS). METHODS AND ANALYSIS: This trial is a single-blinded multicentre randomised controlled clinical trial, where patients with hip dysplasia, who are eligible for PAO, will be randomised to either PAO followed by usual care and PRT or PRT only. Primary outcome is patient-reported pain, measured on the subscale pain on the HAGOS questionnaire 12 months after initiation of PAO or PRT. The key secondary outcomes are the other subscales of the HAGOS, adverse and serious adverse events, usage of painkillers (yes/no) and type of analgesics. Based on the sample size calculation, the trial needs to include 96 patients. ETHICS AND DISSEMINATION: The trial is approved by the Central Denmark Region Committee on Biomedical Research Ethics (Journal No 1-10-72-234-18) and by the Danish Data Protection Agency (Journal No 1-16-02-120-19). The trial is also approved by The Regional Committee for Medical and Health Research Ethics, Region South-East Norway (Ref. 2018/1603). All results from this trial will be published in international peer-reviewed scientific journals regardless of whether the results are positive, negative or inconclusive. TRIAL REGISTRATION NUMBER: NCT03941171.

Muscle Strength Is a Poor Screening Test for Predicting Lower Extremity Injuries in Professional Male Soccer Players: A 2-Year Prospective Cohort Study.

BACKGROUND: Lower extremity muscle strength tests are commonly used to screen for injury risk in professional soccer. However, there is limited evidence on the ability of such tests in predicting future injuries. PURPOSE: To examine the association between hip and thigh muscle strength and the risk of lower extremity injuries in professional male soccer players. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Professional male soccer players from 14 teams in Qatar underwent a comprehensive strength assessment at the beginning of the 2013/2014 and 2014/2015 seasons. Testing consisted of concentric and eccentric quadriceps and hamstring isokinetic peak torques, eccentric hip adduction and abduction forces, and bilateral isometric adductor force (squeeze test at 45°). Time-loss injuries and exposure in training and matches were registered prospectively by club medical staff throughout each season. Univariate and multivariate Cox regression analyses were used to calculate hazard ratios (HRs) with 95% CIs. RESULTS: In total, 369 players completed all strength tests and had registered injury and exposure data. Of these, 206 players (55.8%) suffered 538 lower extremity injuries during the 2 seasons; acute muscle injuries were the most frequent. Of the 20 strength measures examined, greater quadriceps concentric peak torque at 300 deg/s (HR, 1.005 [95% CI, 1.00-1.01]; P = .037) was the only strength measure identified as significantly associated with a risk of lower extremity injuries in multivariate analysis. Greater quadriceps concentric peak torque at 60 deg/s (HR, 1.004 [95% CI, 1.00-1.01]; P = .026) was associated with the risk of overuse injuries, and greater bilateral adductor strength adjusted for body weight (HR, 0.75 [95% CI, 0.57-0.97; P = .032) was associated with a lower risk for any knee injury. Receiver operating characteristic curve analyses indicated poor predictive ability of the significant strength variables (area under the curve, 0.45-0.56). CONCLUSION: There was a weak association with the risk of lower extremity injuries for 2 strength variables: greater quadriceps concentric muscle strength at (1) high and (2) low speeds. These associations were too small to identify an "at-risk" player. Therefore, strength testing, as performed in the present study, cannot be recommended as a screening test to predict injuries in professional male soccer.

Landing-related ankle injuries do not occur in plantarflexion as once thought: a systematic video analysis of ankle injuries in world-class volleyball.

BACKGROUND: Ankle injuries are prevalent in elite volleyball and suggested to result from player contact at the net. Traditionally, ankle sprains are thought to happen in a plantarflexed position, but case studies suggest plantarflexion may not be involved. AIM: Describe the injury situations and mechanisms of ankle injuries in world-class volleyball based on systematic video analysis of injuries reported through the Fédération Internationale de Volleyball (FIVB) Injury Surveillance System. METHODS: Videos of 24 injuries from major FIVB tournaments were included for analysis (14 men, 10 women). Five analysts reviewed the videos to determine specific situations and mechanisms leading to injuries. RESULTS: The majority of injuries occurred during two volleyball situations, blocking (n=15) and attacking (n=6). Injuries to blockers were the result of landing on an opponent (n=11) or teammate (n=4). Attacking injuries most frequently occurred when a back-row player landed on a front-row teammate (n=4 of 6). When landing on an opponent under the net, the attacker landed into the opponent's court in 11 of 12 situations but without violating the centre line rule. Injuries mostly resulted from rapid inversion without any substantial plantarflexion. CONCLUSIONS: The majority of injuries occur while blocking, often landing on an opponent. The attacker is overwhelmingly to blame for injuries at the net secondary to crossing the centre line. Injuries while attacking often result from a back-row player landing on a front-row teammate. Landing-related injuries mostly result from rapid inversion with the absence of plantarflexion.

The functional movement test 9+ is a poor screening test for lower extremity injuries in professional male football players: a 2-year prospective cohort study.

BACKGROUND: The 9+ screening battery test consists of 11 tests to assess limitations in functional movement. AIM: To examine the association of the 9+ with lower extremity injuries and to identify a cut-off point to predict injury risk. METHODS: Professional male football players in Qatar from 14 teams completed the 9+ at the beginning of the 2013/2014 and 2014/2015 seasons. Time-loss injuries and exposure in training and matches were registered prospectively by club medical staff during these seasons. Univariate and multivariate Cox regression analyses were used to calculate HR and 95% CI. Receiver operating characteristic (ROC) curves were calculated to determine sensitivity and specificity and identify the optimal cut-off point for risk assessment. RESULTS: 362 players completed the 9+ and had injury and exposure registration. There were 526 injuries among 203 players (56.1%) during the two seasons; injuries to the thigh were the most frequent. There was no association between 9+ total score and the risk of lower extremity injuries (HR 1.02, 95% CI 0.99 to 1.05, p=0.13), even after adjusting for other risk factors in a multivariate analysis (HR 1.01, 95% CI 0.98 to 1.04, p=0.37). ROC curve analysis revealed an area under the curve of 0.48, and there was no cut-off point that distinguished injured from non-injured players. CONCLUSION: The 9+ was not associated with lower extremity injury, and it was no better than chance for distinguishing between injured and uninjured players. Therefore, the 9+ test cannot be recommended as an injury prediction tool in this population.

Head injury mechanisms in FIS World Cup alpine and freestyle skiers and snowboarders.

INTRODUCTION: Head injuries represent a concern in skiing and snowboarding, with traumatic brain injuries being the most common cause of death. AIM: To describe the mechanisms of head and face injuries among World Cup alpine and freestyle skiers and snowboarders. METHODS: We performed a qualitative analysis of videos obtained of head and face injuries reported through the International Ski Federation Injury Surveillance System during 10 World Cup seasons (2006-2016). We analysed 57 head impact injury videos (alpine n=29, snowboard n=13, freestyle n=15), first independently and subsequently in a consensus meeting. RESULTS: 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. 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% of cases), and 41% of alpine skiing injuries occurred due to inappropriate gate contact prior to falling. Athletes had one (47%) or two (28%) head impacts, and the first impact was the most severe (71%). Head impacts were mainly on snow (83%) on a downward slope (63%). CONCLUSION: This study has identified several characteristics of the mechanisms of head injuries, which may be addressed to reduce risk.

Reduced survival for uncemented compared to cemented total hip arthroplasty after operatively treated acetabular fractures.

BACKGROUND: Post traumatic arthritis and avascular necrosis of the femoral head are common complications after operatively treated acetabular fractures. This may cause severe disabilities for the patient, necessitating a total hip arthroplasty. Even though an arthroplasty may provide good symptomatic relief, the long-term results are more uncertain and no consensus exists according to preferred prosthetic designs. With this cohort study, we aimed to investigate the medium to long term arthroplasty survival and clinical results of total hip arthroplasty after operatively treated acetabular fractures. METHODS: We included 52 patients treated with a secondary total hip arthroplasty at a median of 2.4 (0.1-14.1) years after an operatively treated acetabular fracture. The median age was 54 (11-82) years. Cemented arthroplasty was used for 33 patients, 10 patients had an uncemented arthroplasty and 9 patients received a hybrid arthroplasty. Average follow up was 8.0 (SD 5.0) years. RESULTS: Ten-year revision free arthroplasty survival was 79%. Uncemented arthroplasties had a significantly worse 10-year survival of 57%. Arthroplasties performed at a centre without a pelvic fracture service also had a significantly worse 10-years survival of 51%. Cox regression showed similar results with an 8-fold increase in risk of revision for both uncemented arthroplasties and operations performed at a non-pelvic trauma centre. CONCLUSION: Total hip arthroplasty secondary to an operatively treated acetabular fracture provides good symptomatic relief. These patients are, however, complex cases and are probably best treated at specialist centres with both pelvic trauma surgeons and arthroplasty surgeons proficient in complex revisions present.

Health conditions detected in a comprehensive periodic health evaluation of 558 professional football players.

BACKGROUND: Despite the widespread use of periodic health evaluation (PHE) to detect and prevent injury and illness in athletes, its effectiveness in detecting health conditions and relevant risk factors is still debated. AIM: To assess health conditions detected by a comprehensive PHE in professional male football players and evaluate their consequences for participation clearance. METHODS: A total of 558 professional football players in Qatar completed a PHE prior to the 2013 or 2014 seasons: history, general medical (including blood test), cardiovascular (12-lead ECG and echocardiography) and a musculoskeletal examination, including a specific test battery targeting lower extremity strength and flexibility. On the basis of the PHE, players were either cleared or not cleared for participation. RESULTS: In 533 players (95.5%), at least one health condition was detected requiring treatment or follow-up. Vitamin D deficiency or insufficiency (≤30 ng/mL) was the most common medical condition (n=499, 89.4%), followed by hepatitis B non-immunity or infection (n=164, 29.4%). Cardiac screening identified 48 players (8.6%) with one or more abnormal findings (ECG (n=19, 3.4%) and echocardiography (n=14, 2.5%)). Musculoskeletal conditions were observed in 180 players (32.3%); injuries to or strength deficits of the hip/groin and thigh accounted for the largest proportion. Medical clearance was temporarily not given in 69 players (12.4%), while further examinations were being conducted. One player was disqualified from competitive football. CONCLUSIONS: PHE revealed a high prevalence of health conditions requiring treatment or follow-up in professional footballers; however, only 12.4% of conditions impacted on final clearance for participation.

Injury rate and injury patterns in FIS World Cup Alpine skiing (2006-2015): have the new ski regulations made an impact?

BACKGROUND: New regulations for ski equipment were implemented prior to the 2012/2013 season in the International Ski Federation (FIS) Alpine World Cup (WC). OBJECTIVE: To investigate the effect of the new ski regulations on the rate and pattern of injuries by comparing data before (2006-2012) and after the implementation (2012-2015). METHODS: Injuries were recorded on the basis of the FIS Injury Surveillance System (FIS ISS) through retrospective interviews at the end of each of the nine WC seasons. All acute injuries that required medical attention were registered. Exposure was calculated on the basis of the official result lists. RESULTS: The absolute injury rate (injuries/100 athletes/season) was lower in the three seasons after the new ski regulations compared with the six seasons before (risk ratio (RR) 0.74, 95% CI 0.63 to 0.87). This was also the case for the relative injury rate (injuries/1000 runs) (RR 0.76, 95% CI 0.59 to 0.98). These changes were evident for male skiers, not for female skiers. There was a lower absolute injury rate for upper body injuries (RR 0.56, 95% CI 0.43 to 0.77), while no difference was found for lower extremity injuries (RR 0.84, 95% CI 0.70 to 1.01). CONCLUSIONS: We found a lower rate of injuries in the three seasons after the new ski regulation compared with the six seasons before. However, the ability to draw conclusions on the effects of the equipment change in subgroups of sex, discipline or body part is restricted by the limited statistical power.

Injury and illness surveillance during the 24th Men's Handball World Championship 2015 in Qatar.

BACKGROUND: The IOC encourages international federations to establish systematic athlete injury and illness surveillance programmes. OBJECTIVE: To describe pattern of injuries and illnesses during the 24th Men's Handball World Championship 2015 by implementing the IOC injury and illness surveillance protocol. METHODS: The medical staff of participating teams (n=24) were requested to report all new injuries and illnesses during matches and/or training on a daily basis throughout the event (15 January to 1 February, 2015). Exposure (number of player-hours) during all matches was calculated for all players (n=384) and for each of the 4 player positions (wing, back, line and goalkeeper). RESULTS: Medical staff of all teams submitted 96.7% (n=325) of the daily report forms. In total, 27.1% of the players were injured, and of the 132 injuries reported, 40% were time-loss injuries. The total incidence of injuries was 104.5 per 1000 player-hours. The highest risk of injury was found among line players, and more injuries occurred during the first half of the matches. The most frequent injury location was the ankle, followed by the thigh, knee and head/face. The majority of injuries were contusion, sprain or strain. In total, 10.9% of the players were affected by an illness during the event. Of the 42 cases recorded, 31 (73.8%) were reported as respiratory tract infection. CONCLUSIONS: The risk of injury in handball is high among Olympic sports. Preventive measures should focus on contusions, ankle sprains, and thigh muscle strains, as well as measures aimed to reduce upper respiratory tract infections.

Injury risk is low among world-class volleyball players: 4-year data from the FIVB Injury Surveillance System.

BACKGROUND: Little is known about the rate and pattern of injuries in international volleyball competition. OBJECTIVE: To describe the risk and pattern of injuries among world-class players based on data from the The International Volleyball Federation (FIVB) Injury Surveillance System (ISS) (junior and senior, male and female). METHODS: The FIVB ISS is based on prospective registration of injuries by team medical staff during all major FIVB tournaments (World Championships, World Cup, World Grand Prix, World League, Olympic Games). This paper is based on 4-year data (September 2010 to November 2014) obtained through the FIVB ISS during 32 major FIVB events (23 senior and 9 junior). RESULTS: The incidence of time-loss injuries during match play was 3.8/1000 player hours (95% CI 3.0 to 4.5); this was greater for senior players than for junior players (relative risk: 2.04, 1.29 to 3.21), while there was no difference between males and females (1.04, 0.70 to 1.55). Across all age and sex groups, the ankle was the most commonly injured body part (25.9%), followed by the knee (15.2%), fingers/thumb (10.7%) and lower back (8.9%). Injury incidence was greater for centre players and lower for liberos than for other player functions; injury patterns also differed between player functions. CONCLUSIONS: Volleyball is a very safe sport, even at the highest levels of play. Preventive measures should focus on acute ankle and finger sprains, and overuse injuries in the knee, lower back and shoulder.

Injuries in World Cup telemark skiing: a 5-year cohort study.

BACKGROUND: There are limited data on injuries in World Cup (WC) telemark skiing. OBJECTIVE: To describe the injury incidence and injury pattern seen among WC telemark skiers during the competitive season. METHODS: We interviewed all WC athletes (or their coach, if the athlete was not present) at the end of five winter seasons from 2008 until 2013. All acute injuries occurring in the competitive season that required the attention of medical personnel were registered. Exposure was calculated based on the official International Ski Federation (FIS) results database. RESULTS: 149 acute injuries were registered during 565 WC skier seasons. The absolute injury incidence was 26.4 injuries per 100 athletes per season (95% CI 22.1 to 30.6), higher for females than males (risk ratio (RR) 1.49, 95% CI 1.07 to 2.08). During the FIS WC competitions, 69 injuries were registered, corresponding to a relative incidence of 8.2 injuries per 1000 runs (95% CI 6.3 to 10.1). The most frequently injured body part was the knee (21%) followed by the hand-finger-thumb (20%), ankle (13%) and shoulder/clavicle (13%). The absolute risk of knee and shoulder/clavicle injuries was higher for females versus males (RR for knee injuries 2.72, 95% CI 1.35 to 5.51; RR for shoulder/clavicle injuries 2.55, 95% CI 1.06 to 6.14). No differences were detected in the injury incidence between disciplines. CONCLUSIONS: Female telemark skiers are at 1.5 times greater risk of injury than male skiers. The most commonly injured body part was the knee. The risk of knee and shoulder/clavicle injuries was higher for female athletes than for male athletes.

Analysis of a severe head injury in World Cup alpine skiing.

UNLABELLED: Traumatic brain injury (TBI) is the leading cause of death in alpine skiing. It has been found that helmet use can reduce the incidence of head injuries between 15% and 60%. However, knowledge on optimal helmet performance criteria in World Cup alpine skiing is currently limited owing to the lack of biomechanical data from real crash situations. PURPOSE: This study aimed to estimate impact velocities in a severe TBI case in World Cup alpine skiing. METHODS: Video sequences from a TBI case in World Cup alpine skiing were analyzed using a model-based image matching technique. Video sequences from four camera views were obtained in full high-definition (1080p) format. A three-dimensional model of the course was built based on accurate measurements of piste landmarks and matched to the background video footage using the animation software Poser 4. A trunk-neck-head model was used for tracking the skier's trajectory. RESULTS: Immediately before head impact, the downward velocity component was estimated to be 8 m·s⁻¹. After impact, the upward velocity was 3 m·s⁻¹, whereas the velocity parallel to the slope surface was reduced from 33 m·s⁻¹ to 22 m·s⁻¹. The frontal plane angular velocity of the head changed from 80 rad·s⁻¹ left tilt immediately before impact to 20 rad·s⁻¹ right tilt immediately after impact. CONCLUSIONS: A unique combination of high-definition video footage and accurate measurements of landmarks in the slope made possible a high-quality analysis of head impact velocity in a severe TBI case. The estimates can provide crucial information on how to prevent TBI through helmet performance criteria and design.

Head injuries among FIS World Cup alpine and freestyle skiers and snowboarders: a 7-year cohort study.

BACKGROUND: Traumatic brain injury is the leading cause of death for skiers and snowboarders. Fatal head injuries have also occurred at the International Ski Federation (FIS) World Cup (WC) level. We therefore wanted to describe the risk of head injuries across disciplines and sex among WC skiers and snowboarders. METHOD: We conducted retrospective interviews with FIS WC athletes at the end of seven consecutive seasons (2006-2013) to register injuries sustained during the competitive 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 website for all WC competitions for each of the athletes interviewed. RESULTS: A total of 2080 injuries were reported during seven WC seasons. Of these, 245 (11.8%) were head/face injuries. Of the 245 head/face injuries reported, 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; risk ratio (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). Women had a higher injury incidence (5.8, 95% CI 4.8 to 6.9) versus men (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). CONCLUSIONS: The majority of head/face injuries were nervous system injuries/concussions and one in four injuries was severe. Freestyle skiers had the highest overall head injury incidence. Across all disciplines, the injury incidence was higher in women than in men.

Injury situations in Freestyle Ski Cross (SX): a video analysis of 33 cases.

BACKGROUND: Although injury risk in Freestyle Ski Cross (SX) is high, little is known about the situations leading up to time-loss injuries. OBJECTIVE: To describe the situations leading up to time-loss injuries in elite Freestyle SX. STUDY DESIGN: Descriptive video analysis. METHODS: Thirty-three video recordings of SX injuries reported through the International Ski Federation Injury Surveillance System for four World Cup seasons (2006/2007 through 2010) were obtained. Five experts in the fields of sport medicine and SX analysed each case to describe in detail the situation leading up to the injury (skiing situation and skier behaviour). RESULTS: Injuries occurred in four different skiing situations: jumping (n=16), turning (n=8), jumping and turning (n=7) and rollers (n=2). All injured skiers lost control before time of injury (n=33), due to skier-opponent contact (n=13), technical errors (n=8) or inappropriate strategy (n=8), which led to a fall (n=29). Contact occurred in 21 of 33 cases, usually unintentional at landing or take-off, caused by the opponent (n=11) or injured skier (n=8). The technical error cases (n=8) were dominated by bad jumping technique (n=6) and too much inside lean in turning situations (n=2), while inappropriate course line and bad timing at take off (n=7) dominated the inappropriate strategy cases (n=8). CONCLUSIONS: We identified four main injury situations in elite SX, dominated by jumping situations. The primary cause of injury was unintentional skier-opponent contact in jumping, bank turning and roller situations. Another common cause of injury was personal errors (inappropriate technique and strategy) at take-off and in turning situations.

Sex differences in the risk of injury in World Cup alpine skiers: a 6-year cohort study.

BACKGROUND: In competitive alpine skiing, there is a controversy regarding the sex-related risk of injury. OBJECTIVE: To compare the risk of injury in female versus male World Cup (WC) alpine skiers. METHODS: Injuries were recorded through the International Ski Federation Injury Surveillance System for six consecutive winter seasons (2006-2012), based on retrospective interviews with athletes from 10 teams at the end of each season. All acute training and competition injuries which required medical attention were recorded. Race exposure was calculated based on the exact number of runs started in the WC for each of the interviewed athletes each season. RESULTS: Men had a higher overall rate of injury (relative risk (RR) 1.24, 95% CI 1.05 to 1.47), as well as a higher rate of time-loss injury (RR 1.23, 95% CI 1.03 to 1.48) than women in training and competitions, expressed as injuries/100 athletes/season. These sex differences were even more pronounced during WC races (RR 1.58, 95% CI 1.22 to 2.04 and RR 1.72, 95% CI 1.29 to 2.31, for overall and time-loss injuries, respectively). There was no sex difference in the risk of knee/anterior cruciate ligament (ACL) injuries. CONCLUSIONS: No previous studies from competitive skiing have reported a significantly higher risk of injuries in men than women. In contrast to recreational skiing and team sports, there was no sex difference in the risk of knee/ACL injuries and prevention efforts should be directed as much towards male as female competitive skiers.

Kinematics of anterior cruciate ligament ruptures in World Cup alpine skiing: 2 case reports of the slip-catch mechanism.

BACKGROUND: Based on visual video analyses of 20 injury situations, the main mechanism of anterior cruciate ligament (ACL) injury in World Cup alpine skiing, termed the "slip-catch" mechanism, was identified. This situation is characterized by a common pattern in which the inside edge of the outer ski catches the snow surface while turning, forcing the knee into valgus and tibial internal rotation. To describe the exact joint kinematics at the time of injury, a more sophisticated approach is needed. PURPOSE: To describe the knee and hip kinematics in 2 slip-catch situations utilizing a model-based image-matching (MBIM) technique. STUDY DESIGN: Descriptive laboratory study. METHODS: Two typical slip-catch situations in World Cup alpine skiing reported through the International Ski Federation (FIS) Injury Surveillance System were captured on video with several camera views and high video quality. The injury situations were analyzed using the MBIM technique to produce continuous measurements of knee and hip joint kinematics. RESULTS: Within 60 milliseconds, the knee flexion angle increased rapidly from 26° to 63° in case 1 and from 39° to 69° in case 2. In the same period, we observed a rapid increase in internal rotation of the tibia with a peak of 12° and 9°, respectively. The knee valgus angle changed less markedly in both cases. We also observed a rapid increase of hip flexion as well as substantial hip internal rotation. CONCLUSION: Knee compression and knee internal rotation and abduction torque are important components of the injury mechanism in a slip-catch situation. CLINICAL RELEVANCE: Prevention efforts should focus on avoiding a forceful tibial internal rotation in combination with knee valgus.

Events leading to anterior cruciate ligament injury in World Cup Alpine Skiing: a systematic video analysis of 20 cases.

BACKGROUND: 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 situations is also needed. OBJECTIVE: To describe the skiing situation leading to ACL injuries in WC alpine skiing. METHODS: Twenty cases of ACL injuries reported through the International Ski Federation Injury Surveillance System (FIS ISS)for three consecutive WC seasons (2006-2009) were obtained on video. Ten experts (9 WC coaches, 1 former WC athlete) performed visual analyses of each case to describe in their own words, factors they thought may have contributed to the injury situation related to different predefined categories: (1) skier technique, (2) skier strategy, (3) equipment, (4) speed and course setting, (5) visibility, snow and piste conditions and (6) any other factors. RESULTS: Factors related to the three categories, namely skier technique, skier strategy, and visibility, snow and piste conditions, were assumed to be the main contributors to the injury situations. Skier errors, technical mistakes and inappropriate tactical choices, were the dominant factors. In addition, bumpy conditions, aggressive snow, reduced visibility and course difficulties were assumed to contribute. CONCLUSION: Based on this systematic video analysis of 20 injury situations, factors related to skier technique, skier strategy and specific race conditions were identified as the main contributors leading to injury situations.

Mechanisms of injuries in World Cup Snowboard Cross: a systematic video analysis of 19 cases.

BACKGROUND: Snowboard cross (SBX) became an official Olympic sport in 2006. This discipline includes manoeuvring several obstacles while competing in heats. It is common for the riders to collide, making this sport both exciting and at risk of injuries. Although a recent study from the 2010 Olympic Games has shown that the injury risk was high, little is known about the injury mechanisms. OBJECTIVE: To qualitatively describe the injury situation and mechanism of injuries in World Cup Snowboard Cross. STUDY DESIGN: Descriptive video analysis. METHODS: Nineteen video recordings of SBX injuries reported through the International Ski Federation Injury Surveillance System for four World Cup seasons (2006 to 2010) were obtained. Five experts in the field of sports medicine, snowboard and biomechanics performed analyses of each case to describe the injury mechanism in detail (riding situation and rider behaviour). RESULTS: Injuries occurred at jumping (n=13), bank turning (n=5) or rollers (n=1). The primary cause of the injuries was a technical error at take-off resulting in a too high jump and subsequent flat-landing. The rider was then unable to recover leading to fall at the time of injury. Injuries at bank turn was characterised by a pattern where the rider in a balanced position lost control due to unintentional contact with another rider. CONCLUSION: Jumping appeared to be the most challenging obstacle in SBX, where a technical error at take-off was the primary cause of the injuries. The second most common inciting event was unintentional board contact between riders at bank turning.