ACL injury mechanisms and related factors in male and female carving skiers: a retrospective study

In recreational alpine skiing, ACL injury risk is 3 times greater in females. However, since the introduction of carving skis ACL injury risk seems to have decreased. No study has yet investigated the distribution of ACL injury mechanisms in male and female carving skiers. Therefore, the aim of the study was to investigate potential gender specific differences of ACL injury mechanisms and related factors among carving skiers. In total, 220 recreational carving skiers (59 males and 161 females) suffering from an ACL injury volunteered for this study. Demographic data, skiing ability, equipment related and environmental factors, circumstances and causes for the fall, and type of fall (injury mechanisms) were collected by questionnaire. The forward twisting fall is the most reported ACL injury mechanism in both gender (p=0.672) accounting for 54% of all injuries, although male and female skiers differed significantly with regard to circumstances of fall (p=0.001) and actions when ACL injury occurred (p=0.04). Bindings not releasing at the time point of accident occurred 2.6 times more with females than with males (p=0.005). The forward twisting fall seems to have become the dominant ACL injury mechanism both in male and female recreational skiers since the introduction of carving skis.     

Impact of environmental factors on knee injuries in male and female recreational skiers

In alpine skiing, the knee represents the dominant injury location with marked gender differences. Snow, slope and weather conditions as well as altitude and low temperatures are thought to influence the prevalence of knee injuries. Therefore, ski patrol injury reports were used to compare gender-specific prevalence of knee injuries with regard to several environmental factors including the actual air temperatures. A total of 1039 non-contact knee injuries were reported with a corresponding prevalence of knee injuries of 44.4% (males: 30.1%; females: 57.4%). Temperature quartiles of all recorded injuries were calculated to compare gender-specific prevalence of knee injury with regard to temperatures. Comparing the first quartile (mean temperature -11°C) with the fourth quartile (mean temperature +3°C), the prevalence of knee injury in female skiers was higher at low ambient temperatures (61% vs 50%, odds ratio: 1.60, 95% confidence interval: 1.16-2.22; P=0.005) while no such association was found for male skiers. Additionally, knee-injured females showed a twofold prevalence when skiing during snowfall compared with females with other injuries (15.4% vs 8.6%; P=0.001). No other environmental factor showed a significant association with the gender-specific prevalence of knee injury. In conclusion, low ambient temperature and snowfall are important environmental risk factors for knee injuries in female skiers.     

Anterior cruciate ligament injury incidence among male and female professional alpine skiers

A retrospective review of anterior cruciate ligament injuries among professional alpine skiers was performed to compare sex-related differences in injury incidence. We screened 7155 ski patrollers or instructors (4537 men and 2618 women) for knee injuries before each ski season between 1991 and 1997. Screening involved a ski history questionnaire, a knee injury history questionnaire, and a knee physical examination. Any patient with an equivocal Lachman or pivot shift test was evaluated by KT-1000 arthrometry and excluded from the study if the manual maximum side-to-side difference was 3 mm or more. Thus, the study population was limited to subjects with intact anterior cruciate ligaments. Skiers injured during the study were identified through mandatory workers' compensation claims. Each injured skier was reevaluated using an injury questionnaire and physical examination. The men skied an average of 110 days per year (499,070 skier-days) and the women skied an average of 87 days per year (227,766 skier-days). Thirty-one skiing-related anterior cruciate ligament injuries were diagnosed, 21 in men and 10 in women. The incidence of ACL disruption was 4.2 injuries per 100,000 skier-days in men and 4.4 injuries per 100,000 skier-days in women. These data suggest that the incidences of anterior cruciate ligament injuries among male and female professional alpine skiers are similar.     

Interaction of potential intrinsic and extrinsic risk factors in ACL injured recreational female skiers

The aim of this study was to investigate the interaction of potential intrinsic and extrinsic risk factors in ACL injured recreational female skiers. 93 female recreational skiers who had suffered a non-contact ACL injury and 93 age-matched controls completed a self-reported questionnaire relating to intrinsic risk factors (menstrual history, BMI, previous knee injuries, self reported weekly sports participation) and extrinsic risk factors (type of ski used, time of last binding adjustment, snow condition, weather and slope difficulty). A logistic regression model revealed the following independent ACL injury risk factors for female recreational skiers: icy snow conditions (odds ratio, 24.33; 95% confidence interval, 6.8-86.5, P<0.001), skiing during snowfall (odds ratio, 16.63; 95% confidence interval, 1.8-152.1, P=0.013), use of traditional skis (odds ratio, 10.49; 95% confidence interval, 2.0-54.5, P=0.005), and preovulatory phase of menstrual cycle (odds ratio, 2.59; 95% confidence interval, 1.2-5.5, P=0.013). In conclusion, ACL injuries in female recreational skiers are the result of a complex interaction of intrinsic and extrinsic risk factors.     

An unusual ankle injury in top skiers

Although skiers' feet are immobilized in extremely rigid boots, ligamentous lesions of the ankle may occur, especially in world class slalom skiers. The lesion arises when a sudden external rotation of the ankle causes the talus to press against the fibula and thus open the distal tibiofibular articulation. This study reports on a group of 10 skiers recruited between 1975 and 1986. These are professional skiers participating in World Cup races. Three patients underwent an operation for lesion of the tibiofibular syndesmosis, while the other seven were treated conservatively. All were able to resume their previous level of competition and only one skier later complained of painful instability in distal tibiofibular joint.     

Self-reported skill level and injury severity in skiers and snowboarders

There is evidence to suggest that the rate of injury is lower for expert skiers and snowboarders than for beginners. A better understanding of the relation between injury severity and skill level is also needed for planning injury prevention strategies. Our objective was to examine the severity and location of injuries sustained by self-reported expert and beginner skiers and snowboarders. A case-control study design was used. Injured skiers and snowboarders had to report their skill level on a 5 point scale (1: “beginner”; 5: “expert”). Two sets of severely injured cases were defined based on the type of injury and ambulance evacuation. Controls were those who did not sustain severe injuries. Logistic regression analyses were performed to relate injury severity to skill level. Subjects were 22 078 injured skiers and snowboarders who reported to the ski patrol with an injury sustained on the slopes of an alpine ski centre of the Canadian province of Québec during the seasons 2001–2002 to 2004–2005. Compared with beginners, experts had an increased risk of suffering from a severe injury (adjusted odds ratio [AOR]: 1.88; 95% CI: 1.58–2.23). Expert snowboarders were also more likely to suffer from a severe injury or be evacuated by ambulance (AOR: 1.18; 95% CI: 1.02–1.38). Results suggest that the type of activities or manoeuvres performed by expert skiers and snowboarders may increase the risk of sustaining a severe injury compared with beginner participants.     

Are injury rates in female volleyball players age related?

The purposes of this study were to record the injury incidence in all age categories of female volleyball players and to clarify the role of age in injury occurrence. The injury incidence rate, severity, diagnosis and the anatomical location of the injuries, which occurred during practice and competition during the championship period, were recorded prospectively during the 2005–2006 period. A total of 689 Greek female volleyball players participating in all volleyball championships in Greece were observed on a weekly basis. The injury incidence rate was recorded as number of injured players and also number of injuries per player-year (total exposure time). No significant differences in injury occurrence rate were observed between the different age categories (youth, junior, senior). Acute injuries were significantly more commonly than overuse syndromes, and the ankle was the most common injured anatomical location. The injury rate in the competitive season was significantly greater than that in the preseason and post-season periods for all the participants. We suggest that any findings in injury occurrence rate must be interpreted in relation to the total exposure time in order to have more realistic conclusions.     

Patterns of meniscal injury associated with acute anterior cruciate ligament injury in skiers.

To determine if the incidence and patterns of meniscal injury associated with acute anterior cruciate ligament injury in skiers are different from those seen in individuals injured in nonskiing athletic activities, we reviewed the records of 150 patients with acute anterior cruciate ligament injuries. All patients had undergone arthroscopic evaluation within 21 days from the time of injury. There were 75 individuals who were injured while skiing and 75 individuals who sustained an injury in some other high-load athletic activity. Associated meniscal injury was documented at the time of arthroscopy and characterized by location, region, zone, depth, shape, size, and stability. Thirty-one of 75 skiers had an associated meniscal injury as compared to 47 of 75 of the nonskiers. This suggested a strong trend of decreased incidence of meniscal injury in the skier group, but the nonskiers had a higher incidence of major meniscal tears that required repair or partial meniscectomy. The location of the meniscal tear was also significantly different. The incidence of isolated lateral meniscal injury in skiers was higher than in nonskiers. There was a strong trend of increased incidence of medial meniscal involvement in the nonskiers than in the skiers. While there was no difference in the zone or region of tear between the two groups, the skier group was more likely to have a longitudinal tear of the posterior horn of the lateral meniscus. In both groups, lateral meniscal tears were more likely to require conservative treatment or partial meniscectomy while medial meniscal tears were more likely to be repaired than excised.     

Risk factors for acute knee injury in female youth football

Purpose

To prospectively evaluate risk factors for acute time-loss knee injury, in particular ACL injury, in female youth football players.

Methods

Risk factors were studied in 4556 players aged 12–17 years from a randomised controlled trial during the 2009 season. Covariates were both intrinsic (body mass index, age, relative age effect, onset of menarche, previous acute knee injury or ACL injury, current knee complaints, and familial disposition of ACL injury) and extrinsic (no. of training sessions/week, no. of matches/week, match exposure ratio, match play with other teams, and artificial turf exposure). Hazard ratios (HRs) and 95 % confidence intervals (CIs) were calculated from individual variable and multiple Cox regression analyses.

Results

Ninety-six acute knee injuries were recorded, 21 of them ACL injuries. Multiple Cox regression showed a fourfold higher ACL injury rate for players with familial disposition of ACL injury (HR 3.57; 95 % CI 1.48–8.62). Significant predictor variables for acute knee injury were age >14 years (HR 1.97; 95 % CI 1.30–2.97), knee complaints at the start of the season (HR 1.98; 95 % CI 1.30–3.02), and familial disposition of ACL injury (HR 1.96; 95 % CI 1.22–3.16). No differences in injury rates were seen when playing on artificial turf compared with natural grass.

Conclusion

Female youth football players with a familial disposition of ACL injury had an increased risk of ACL injury and acute knee injury. Older players and those with knee complaints at pre-season were more at risk of acute knee injury. Although the predictive values were low, these factors could be used in athlete screening to target preventive interventions.

Level of evidence

II.

     

Maximal strength training improves work economy in trained female cross-country skiers.

PURPOSE: The present study examines the hypothesis that maximal strength training improves work economy and anaerobic threshold in trained female cross-country skiers while working on a ski ergometer. METHODS: Fifteen female cross-country skiers (17.9 +/- 0.3 yr, 166.7 +/- 1.3 cm, 60.1 +/- 1.9 kg, and 55.3 +/- 1.3 mL x kg(-1) x min(-1)) participated in the study. Eight skiers made up the high-intensity strength-trained group, and seven served as the control group. Endurance performance was tested on a specially instrumented ski ergometer. Strength training and testing simulated double poling in cross-country skiing. RESULTS: A significant (P < 0.001) improvement in double-poling economy on the ski ergometer was observed among the strength-trained group. Anaerobic threshold did not change during the experimental period for either group. After a 9-wk training period, time to exhaustion increased from 5.2 (+/-0.9) to 12.3 (+/-1.6) min (P < 0.001) and from 4.0 (+/-0.9) to 6.3 (+/-0.9) min (P < 0.01) for the strength and control group, respectively. Time to exhaustion was significantly higher (P < 0.001) for the strength group compared with the control group after training. One repetition maximum increased 14.5% (1.8) (P < 0.001) in the strength group but was unchanged in the control group. Expressed in relation to peak force at one repetition maximum, strength training resulted in a significant reduction in the relative available force employed working on the ski ergometer (P < 0.01). Time to peak force at maximal aerobic velocity on the ski ergometer was significantly reduced in the strength-training group (P < 0.01). CONCLUSIONS: It is concluded that maximal strength training in the upper-body improved the double-poling performance by improved work economy. Work economy was improved by a reduction in relative workload and time to peak force while double poling.     

Nonoperative treatment for anterior cruciate ligament injury in recreational alpine skiers

Purpose

The purpose of this study was to test whether low-grade Lachman test (i.e. Grade 0–1+) and a negative pivot shift at 6–12 weeks post-ACL rupture in recreational alpine skiers can be used to predict good function and normal knee laxity in nonoperated patients at minimum 2 years after the injury.

Methods

Office registry was used to identify 63 recreational alpine skiers treated by the senior author within 6 weeks of a first-time ACL injury between 2003 and 2008. Of these, 34 had early ACL reconstruction but 29 patients were observed and re-evaluated. Office charts and MRI were reviewed. Inclusion criteria for this study were as follows: ACL rupture documented on MRI after the injury, and minimum 2-year follow-up. Exclusion criterion was contralateral knee ligament injury. Of the 29 patients treated nonoperatively, 17 had low-grade Lachman and negative pivot shift tests within 6–12 weeks after the injury and were recommended to continue follow-up without surgery. Of these 17 patients, 6 were lost to follow up, but 11 patients were recalled and evaluated at more than 2 years after the injury. They completed Marx and Tegner activity level and IKDC subjective scores, physical examination of the knee and KT-1000 anterior laxity assessment.

Results

Median age at injury was 43 years (range 29–58). Median follow-up was 42 months (range 30–68). Mean IKDC subjective score at latest follow-up was 91.6 ± 6.7. Median Tegner score was 6 (range 6–9) before the injury and 6 (range 4–6) at latest follow-up (p = n.s). Median Marx score was 6 (range 0–16) before the injury and 4 (range 0–12) at latest follow-up (p = 0.03). Ten patients had Lachman Grade 0–1+, and one had Lachman Grade 2+ at latest follow-up. KT-1000 showed mean side-to-side difference of 0.8 ± 1.6 mm, and less than 3 mm difference in the 10 patients with Lachman Grade 0–1+.

Conclusion

Recreational alpine skiers who sustain ACL injury should be re-evaluated at 6–12 weeks after the injury rather than being operated acutely. If they have negative Lachman and pivot shift tests at that point, they can be treated without surgery since good outcome and normal knee anterior laxity at more than 2 years after the injury is expected.

Level of evidence

Case series, Level IV.     

Increased injury risk among first-day skiers, snowboarders, and skiboarders

BACKGROUND: Inexperience predisposes skiers, snowboarders, and skiboarders to a higher risk of injury. HYPOTHESIS: Individuals on their very 1st day's experience of skiing, snowboarding, or skiboarding are at greater risk of injury. STUDY DESIGN: Case control study. METHODS: All individuals injured at the three largest ski areas in Scotland during the three winter seasons 1999-2000 through 2001-2002 were included. First-day participants were identified. Individual demographic details and snow sports-related parameters were recorded. Control data were collected from uninjured individuals. Factors associated with injury were explored in univariate and multivariate analyses. RESULTS: First-day participants were overrepresented in the injured population by a factor of 2.2. Participant age younger than 17 years or older than 26 years, snowboarding, taking professional instruction, and the use of rented or borrowed gear were all independently associated with increased injury risk among 1st-day participants. CONCLUSIONS: First-day participants are at increased risk of injury. Several independent risk factors for injury have been identified. CLINICAL RELEVANCE: First-day participants should be targeted in any future educational programs with emphasis on gear selection, use of protective gear, and the risks of exceeding the limits of their ability.     

Echocardiographic examination of cardiac structure and function in elite cross trained male and female Alpine skiers

OBJECTIVE: To assess cardiac structure and function in elite cross- trained male and female athletes (Alpine skiers). METHODS: Sixteen athletes (10 male, six female) and 19 healthy sedentary control subjects (12 male, seven female) volunteered to take part in the study. Basic anthropometry determined height, body mass, body surface area, and fat free mass. Cardiac dimensions and function were determined by two dimensional, M mode, and Doppler echocardiography. Absolute data and data corrected for body size (allometrically determined) were compared by two way analysis of variance and post hoc Scheffe tests. RESULTS: Absolute left ventricular internal dimension in diastole (LVIDd), septal and posterior wall thickness and left ventricular mass were larger in athletes than controls (p < 0.05) and also increased in the men (p < 0.05) compared with women (except for septal thickness in controls). An increased LVIDd, septal thickness, posterior wall thickness, and left ventricular mass in athletes persisted after correction for body size except when LVIDd was scaled by fat free mass. Cardiac dimensions did not differ between the sexes after correction for body size. All functional indices were similar between groups. CONCLUSION: There is evidence of both left ventricular chamber dilatation and wall enlargement in cross trained athletes compared with controls. Differences in absolute cardiac dimensions between the sexes were primarily due to greater body dimensions in the men.


     

放射治疗相关肝损伤的CT影像及其影响因素

放射治疗致肝损伤的病理表现为典型的肝静脉闭塞性疾病。正常肝脏、肝硬化肝脏放射性肝损伤CT平扫显示为照射区低密度改变,而脂肪肝放射性肝损伤显示为照射区高密度改变。正常肝脏、肝硬化肝脏动态CT增强扫描表现不同。放射性肝损伤的不同表现与肝脏基础相关。放射性肝损伤的发生与照射剂量、肝脏基础、放射性肝炎的关系需进一步研究。     

Immuno-endocrine and metabolic responses to long distance ski racing in world-class male and female cross-country skiers

The purpose of this study was to characterize the extent of immune, endocrine, substrate and metabolic changes during a long-distance cross-country ski race in extremely well-trained athletes and evaluate if the blood perturbations would indicate signs of health risk. Ten male (M) and six female (F) national team skiers were investigated as they followed their usual routines of race preparations. Blood samples were drawn before and immediately after a World Cup 50-km M and 30-km F ski race with a mean finish time of 142 and 104 min, respectively. Hemoglobin, electrolytes, and C-reactive protein remained unchanged for both M and F. Serum testosterone remained unchanged in M, but doubled in F. Significant increases were observed in concentrations of granulocytes (F: 5 x, M: 5 x), natural killer cells (F: 2 x, M: 1.5 x), adrenaline (F: 12 x, M:10 x), noradrenaline (F: 7 x, M:5 x), growth hormone (F: 30 x, M: 2 x), cortisol (F: 1.5 x, M:2 x), glucose (F: 2 x, M:1.5 x), creatine kinase (F: 2 x, M:2 x), uric acid (F: 1.5 x, M: 1.5 x) and non-organic phosphate (F:2 x, M:2 x), while insulin concentration decreased (F: 0.5x, M: 0.8 x). Free fatty acid (FFA) concentration increased (F:2 x, M: 3 x). In conclusion, we observed substantial changes in several immuno-endocrine, substrate and metabolic measurements after long distance cross-country ski racing and suggest that some of these marked changes may reflect the large amount of muscle mass involved during skiing.     

Kinetic risk factors of running‐related injuries in female recreational runners

Our objective was to prospectively investigate the association of kinetic variables with running‐related injury (RRI ) risk. Seventy‐four healthy female recreational runners ran on an instrumented treadmill while 3D kinetic and kinematic data were collected. Kinetic outcomes were vertical impact transient, average vertical loading rate, instantaneous vertical loading rate, active peak, vertical impulse, and peak braking force (PBF ). Participants followed a 15‐week half‐marathon training program. Exposure time (hours of running) was calculated from start of program until onset of injury, loss to follow‐up, or end of program. After converting kinetic variables from continuous to ordinal variables based on tertiles, Cox proportional hazard models with competing risks were fit for each variable independently, before analysis in a forward stepwise multivariable model. Sixty‐five participants were included in the final analysis, with a 33.8% injury rate. PBF was the only kinetic variable that was a significant predictor of RRI . Runners in the highest tertile (PBF  < −0.27 BW ) were injured at 5.08 times the rate of those in the middle tertile and 7.98 times the rate of those in the lowest tertile. When analyzed in the multivariable model, no kinetic variables made a significant contribution to predicting injury beyond what had already been accounted for by PBF alone. Findings from this study suggest PBF is associated with a significantly higher injury hazard ratio in female recreational runners and should be considered as a target for gait retraining interventions.