Mechanisms of anterior cruciate ligament ruptures in skiing

In the years 1980–1989, 78 patients with an acute anterior cruciate ligament (ACL) rupture sustained during downhill or cross-country skiing were treated at the University Hospital of Tampere, Finland. In every case, the ACL rupture was verified at arthroscopy or open surgery. The injury mechanism could be clarified for 51 patients using a collection of pictures of the most typical injury mechanisms in skiing. Thirty-nine of them (76%) were women and 12 men (24%). In 32 cases (63%) the injury occurred during downhill skiing and in 19 cases (37%) during cross-country skiing. In 24 cases (47%) the injury mechanism was valgus-external rotation, in 21 cases (41%) flexion-internal rotation, in two cases hyperextension-internal rotation, while in four cases the exact mechanism remained unclear. The great majority of the patients with an injury mechanism of flexion-internal rotation were women (90%), and they were significantly older than the patients with an injury mechanism of valgus-external rotation (mean ages 44 and 34 years, respectively:P<0.05). According to the patients' subjective evaluation, the main reasons for the injury were poor ski area conditions (such als slippery slopes and trails) and deficient equipment, especially poorly functioning bindings. Many of them had had little skiing experience before the accident.     

双膝前交叉韧带损伤特点及治疗

目的探讨双膝前交叉韧带(ACL)先后断裂的原因及治疗原则。方法1995年1月~2005年8月收治双膝ACL先后损伤患者32例,对双膝致伤因素、先后损伤之间的关系、膝关节不稳的情况进行观察分析,回顾其受伤到手术的时间及治疗情况。结果32例双膝ACL损伤,运动性损伤占78.1%,后一侧ACL损伤的发生与先伤膝关节不稳、病人的年龄、运动程度有关。89.1%的膝关节在ACL损伤后出现不稳。所有患者均在我院接受ACL重建手术,26例患者双膝ACL重建为一次手术完成,6例分次重建。结果提示一侧ACL断裂引起的膝关节不稳可影响到健侧。膝关节ACL断裂后要早期手术重建以恢复膝关节的稳定性,防止继发损伤,降低另一侧膝关节受伤的风险。对于双膝ACL断裂,我们建议一次手术完成双侧重建,以尽早恢复双膝关节稳定性,保证双膝运动功能。     

Etiology and pathophysiology of tendon ruptures in sports

Of all spontaneous tendon ruptures, complete Achilles tendon tears are most closely associated with sports activities (1–3). Schönbauer (3) reported that 75% of all ruptures of the Achilles tendon are related to sports. In Plecko & Passl (2) the number was 60%. In our material of 430 cases, the number of sports-related Achilles ruptures was very similar (62%), while only 2% of ruptures of other tendons were sports-related (P<0.001) (1). Also, the majority of Achilles reruptures occurred in sports. The ruptures occurred most often in soccer (34%), track and field (16%) and basketball (14%). The distribution of Achilles ruptures according to different sports varies considerably from country to country, according to the national sport traditions. For example, in northern and middle Europe, soccer, tennis, track and field, indoor ball games, downhill skiing, and gymnastics are the most common; and in North America, football, basketball, baseball, tennis and downhill skiing dominate the statistics (1, 2, 4). In sports, some Achilles ruptures are not spontaneous or degeneration-induced but may occur as a consequence of the remarkably high forces that are involved in the performance (2). Ruptures in the high jump or triple jump are good examples. In such cases, failure in the neuromuscular protective mechanisms due to fatigue or disturbed co-ordination can frequently be found. The spontaneous complete rupture of the supraspinatus tendon of the rotator cuff does not occur very frequently in sports. Those sports that include high-energy throwing movements, such as American and Finnish baseball, American football, rugby and discus and javelin throwing, may, however, produce this injury. Partial tears and inflammations of the rotator cuff complex are much more frequent in throwing sports. The complete rupture of the proximal long head of the biceps brachii tendon is rare among competitive and recreational athletes. In our material, under 2% of these ruptures were associated with sports activities (5). The rupture (avulsion) of the distal tendon of the biceps muscle is rare. In sports, gymnastics, body building and weight lifting have been said to be able to produce this injury (6). In general, complete ruptures of the quadriceps tendon and the patellar tendon occur most often in older individuals. In our study, the mean age of these patients was 65 years (5). However, these injuries do also occur in younger age groups, especially in athletes. In athletes, the rupture most frequently occurs in high-power sports events, such as high jump, basketball and weight lifting, at the age of 15-30 years. A chronic patellar apicitis (jumper's knee) may predispose rupture of the tendon (7). As is the case with the rotator cuff complex, overuse inflammation and partial tears of the quadriceps and patellar tendons are one of the most characteristic athletic injuries. Complete spontaneous ruptures of other tendons in sports are rare, although the literature does provide case studies from almost every tendon the human body possesses (8–18).     

The Harstad injury prevention study: the epidemiology of sports injuries. An 8 year study.

OBJECTIVE--To describe the epidemiology of sports injuries occurring in a community during 8 years and to evaluate the outcome of an intervention implemented against injuries occurring in downhill skiing. METHODS--Hospital treated sports injuries occurring in Harstad, Norway (population 22 600) were recorded prospectively during an 8 year period. A prevention programme targeting downhill skiing injuries was evaluated. RESULTS--2234 sports injuries accounted for 17.2% of recorded unintentional injuries. Two out of three injuries occurred in team sports. Soccer accounted for 44.8% of all sports injuries. Downhill skiing injuries had higher mean score on the abbreviated injury scale than all other sports analysed combined (P < 0.01). Postintervention injury rates for downhill skiing were reduced by 15% when adjusting for exposure (P = 0.24). Further observations are needed for assessing the effectiveness of the downhill skiing safety programme. CONCLUSIONS--Strategies for future sports injury prevention include community involvement, particularly sports organisations. Local data analysis seems to justify some priorities, for example, promotion of helmet use in downhill skiing for young adolescents and prevention of lower limb fractures in male soccer players 15+ years old. Prospective hospital recording of injuries provides a tool for the design and outcome evaluation of sports injury intervention research.     

A survey of injuries to the anterior cruciate ligament of the knee in female basketball players

This study surveyed 76 female basketball-related injuries that occurred during a 30-month period at the B.C. Sports Medicine Clinic. The knee was the most common site of injury (72%), and anterior cruciate ligament (ACL) rupture accounted for 25% of all basketball injuries seen. A total of 19 ACL ruptures in females were seen as compared to only 4 ACL ruptures in male basketball players during the same time period. During this time period a total of 151 males and 76 female basketball players were seen. Each patient was assessed as to age, height, weight, and alignment and questioned as to mechanism of injury, playing position, experience, and training plus previous injuries. Possible etiological factors postulated included player position, joint laxity, weak quadriceps mechanism, and a possible hormonal basis.     

Anterior cruciate ligament reconstruction and the long-term incidence of gonarthrosis

Knee ligament injuries are common in sport. A rupture of the anterior cruciate ligament (ACL) is the most serious of these injuries because it may cause long term disability. In this literature review, the frequency of post-traumatic gonarthrosis is examined. There are few long term prospective studies but a number of retrospective studies with follow-up times between 5 and 20 years have been published. These studies show that radiographic gonarthrosis is significantly increased after all knee injuries compared with the uninjured joint of the same patient. Isolated meniscus rupture and subsequent repair, or partial or total ruptures of the ACL without major concomitant injuries, seem to increase the risk 10-fold (15 to 20% incidence of gonarthrosis) compared with an age-matched, uninjured population (1 to 2%). Meniscectomy in a joint with intact ligaments further doubles the risk of gonarthrosis (30 to 40%), and 50 to 70% of patients with complete ACL rupture and associated injuries have radiographic changes after 15 to 20 years. Thus, an ACL rupture combined with meniscus rupture or other knee ligament injuries results in gonarthrosis in most patients. Ten to 20 years after ACL injury, gonarthrosis often presents as a slight joint space reduction or, occasionally, joint space obliteration (Ahlb?ck grades I to II), but is usually not associated with major clinical symptoms. According to the few longitudinal studies, the progress of gonarthrosis is slow, and in some cases the condition seems to remain stable. Time is an important determinant for the degree of gonarthrosis and problems demanding treatment may be encountered only at > 30 years after the initial accident.     

Injury risk in female floorball: a prospective one-season follow-up

The purpose of this prospective study was to examine the incidence, nature, causes, and severity of injuries in female floorball. Three hundred and seventy-four licensed female floorball players from Finnish top leagues were observed prospectively for one season (6 months). The practice and game hours of floorball were recorded on an exercise diary. All injuries were registered with a structured questionnaire and verified by a physician. During the study period, 133 out of the 374 (35%) players sustained 172 injuries. The injury incidence was 1.8 per 1000 practice hours and 40.3 per 1000 game hours. Of all injuries, 70% were traumatic and 30% were from overuse. The most common injury type was joint sprain (27%). The most commonly injured sites were the knee (27%) and ankle (22%). Twenty-one of the knee injuries (46%) were serious including 10 anterior cruciate ligament (ACL) ruptures. Eight of ACL ruptures occurred during floorball games, giving an ACL rupture incidence of 3.6 per 1000 game hours. Eleven injuries (6%) needed hospital admission. The study attested that injury rate in floorball game is very high. Injury prevention strategies in female floorball should be targeted at injuries occurring at the knee and ankle.     

Compression or distraction of the anterior cruciate injured knee

100 consecutive patients with a recent anterior cruciate ligament injury were examined with respect to type of sports activity that caused the injury, mechanism of injury and the occurrence of collateral ligament and meniscal lesions. There were 53 medial collateral ligament injuries, 12 medial, 35 lateral and 11 bicompartmental meniscal lesions. 59 patients were injured during contact sports, 30 in downhill skiing and 11 in other recreational activities, traffic accidents or at work. An associated medial collateral, ligament tear was more common in skiing (22/30) than during contact sports (23/59), whereas a bicompartmental meniscal lesion was found more frequently in contact sports (9/59) than in skiing (0/30). Weightbearing was reported by 56/59 of the patients with contact sports injuries and by 8/30 of those with skiing injuries. Non-weightbearing in the injury situation led to the same rate of MCL tears (18/28) as those reporting weightbearing (35/72) but significantly more intact menisci (19/28 vs 23/72). Thus, contact sports injuries were more often sustained during weightbearing, with a resultant joint compression of both femuro-tibial compartments as shown by the higher incidence of bicompartmental meniscal lesions. This might be an important prognostic factor for future joint disease and arthrosis. The classic unhappy triad was a rare finding (8/100) and we suggest that this entity should be replaced by the unhappy compression injury.     

Cross-country skiing injuries and biomechanics

Cross-country skiing exercises most of the joints, muscles and tendons in the body giving the skier an all around workout. This, in combination with a low incidence of injury, makes cross-country skiing an ideal recreational and competitive sport. The new skating techniques developed during the last decade have resulted in greater velocity. The maximum speed during the diagonal stride technique is 6 m/sec compared to 8 to 9 m/sec when skating and double poling. Top-level skiers today use strong and ultra light skis of fiberglass and graphite. The ski weight is less than 500g. Today's skating technique does not require any waxing and only the cambered portion of the ski is waxed when performing the diagonal stride. The preparation of the ski course has improved with the development of special track machines. This allows top-level skiers to reach 60 to 80 km/h on downhill slopes, which has resulted in an increased risk of injury. Because cross-country skiing takes place wherever snow is available, it is difficult to establish accurate injury rates in comparison to alpine skiing which is performed on very specialised terrain at ski areas. Studies estimate the cross-country ski injury rate in Sweden to be around 0.2 to 0.5 per thousand skier days. A prospective study of cross-country ski injuries conducted in Vermont revealed an injury rate of 0.72 per thousand skier days. 75% of the injuries sustained by members of the Swedish national cross-country ski team during 1983 and 1984 were overuse injuries while 25% resulted from trauma. The most common overuse injuries included medial-tibial stress syndrome, Achilles tendon problems and lower back pain. Most common among traumatic injuries were ankle ligament sprains and fractures, muscle ruptures, and knee ligament sprains. Shoulder dislocation, acromioclavicular separation and rotator cuff tears are not infrequent in cross-country skiing. Injuries to the ulnar collateral ligament of the metacarpal phalangeal joint of the thumb (Stener's lesion) is the most common ski injury involving the upper extremity. Cross-country skiers 16 to 21 years of age complained more frequently of mild lower back pain than similarly aged non-skiers. This may result from repetitive hyperextension motions during the kick phase and the recurring spinal flexion and extension during the double poling phase. Repeated slipping on hard and icy tracks infrequently produce partial tears or microtrauma in the muscle tendinous units of the groin.(ABSTRACT TRUNCATED AT 400 WORDS)     

Long-term outcome of knee and ankle injuries in elite football

To estimate the risk and evaluate the long-term outcome of knee and ankle injuries in former national team elite football, 69 players were randomly selected, followed by clinical and stress radiographic examinations. Thirty-nine players (49 knees) had had knee injuries and 29 ankle injuries (35 ankles). The median time from injury until study examination was 25 years. The knee injuries were tears of the medial collateral ligament (MCL) in 24 cases combined with rupture of the anterior cruciate ligament (ACL) and meniscus lesions in three. Meniscus lesions had occurred in 17 cases including three combined with ACL and MCL and another two with ACL ruptures. Isolated rupture of the ACL had occurred in four cases. The ankle lesions were in 26 of 35 cases ruptures of the lateral ligaments. In all, 12 players had completely stopped football and three had changed occupation. Signs of arthritis were present in 63% of the injured knees and in 33% of the injured ankles. The incidence of arthritis in the group of 17 uninjured players was 26% in the knee and 18% the ankle. In elite football players knee and ankle injuries seem to have a serious long-term outcome, but also uninjured players have a higher risk of developing arthritis than the normal population.     

A prospective study of health problems at the 2018 17/U and 19/U Australian National Netball Championships with comparison of surveillance methodology

ObjectiveTo investigate the incidence, site, nature and cause of injuries sustained during and four weeks following the 2018 Australian National Netball Championships (ANNC’s) using medical attention and self-report surveillance tools.DesignProspective cohort study.MethodInjuries were recorded prospectively using medical attention and self-report data collection methods. One hundred and ninety-two athletes competed at the 2018 ANNC’s with 96 athletes in each age group (17/U & 19/U).ResultsThere were 103 medical attention injuries sustained by 80 athletes resulting in an incidence rate of 89.4 per 1000 player hours. The most frequently recorded medical attention injury diagnoses across both age groups were lateral ankle ligament sprain (n = 14, 13.6%), foot blisters (n = 11, 10.7%), and lumbar pain (n = 10, 9.7%). Ankle sprains (n = 4), anterior cruciate ligament (ACL) ruptures (n = 3) and concussion (n = 3) recorded as the highest sports incapacity injuries. The self-report data collection revealed that 46 (27.2%) athletes arrived at the tournament with an existing self-reported injury/illness and 57 (39.3%) athletes had a self-reported injury/illness at the conclusion of the ANNC (RR 1.44 95%CI 1.05–1.99, p = 0.030).ConclusionThere are no recent studies reporting injury rates specifically in pre-elite netball players. This study found an incidence rate of 89.4 per 1000 player hours. Ankle sprains are the highest medical attention and sports-incapacity injury in pre-elite netball athletes. Foot blisters and low back pain also feature in the highest medical attention injuries and ACL rupture and concussion were high sports incapacity injuries at the ANNC’s. Finally, combining both the medical attention and self-report injury/illness data collection methods identified more injuries/illnesses than the use of one method alone.     

Occurrence and trends in ski injuries in Norway

OBJECTIVES: To provide an overview of ski injuries in Norway and to describe the changes between 1990 and 1996. METHODS: All ski injuries (7966) treated at four hospitals providing health care to a defined population of about 11% of the Norwegian population were registered prospectively from 1990 to 1996. For this study, 6462 injuries sustained in cross country skiing, downhill skiing, telemark skiing, and snowboarding were selected for further analysis. RESULTS: The relative distribution of ski injuries by type of skiing changed significantly from 1990 to 1996 (p<0.001). Injuries from snowboarding showed the highest relative increase, and those sustained during downhill skiing showed a decline. The proportion of fractures in all types of skiing increased during the study period (p=0.001). The proportion of injuries to knee/lower leg decreased and the proportion to the forearm/wrist/hand increased during the study period (p=0.03). The mean age of the injured skiers differed significantly among the different types of skiing activity (p<0.001): cross country skiers were the oldest followed by telemark skiers, downhill skiers, and snowboarders. CONCLUSIONS: Ski injury surveillance results in early detection of changes in temporal injury trends, allowing timely adjustment of injury prevention strategies. Injuries from snowboarding are on the increase in Norway, warranting more effective injury prevention measures.


     

A 7-year study on risks and costs of knee injuries in male and female youth participants in 12 sports

Knee injuries are common and account in various sports for 15-50% of all sports injuries. The cost of knee injuries is therefore a large part of the cost for medical care of sports injuries. Furthermore, the risk of acquiring a knee injury during sports is considered higher for females than for males. The nationwide organization "Youth and Sports" represents the major source of organized sports and recreation for Swiss youth and engages annually around 370000 participants in the age group of 14 to 20 years. The purpose of this study was to combine data on knee injuries from two sources, the first being data on the exposure to risk found in the activity registration in "Youth and Sports" and the second injuries with their associated costs resulting from the activities and filed at the Swiss Military Insurance. This allowed calculation of knee injury incidences, to compare risks between males and females and to estimate the costs of medical treatment. The study comprises 3864 knee injuries from 12 sports during 7 years. Females were significantly more at risk in six sports: alpinism, downhill skiing, gymnastics, volleyball, basketball and team handball. The incidences of knee injuries and of cruciate ligament injuries in particular, together with the costs per hour of participation, all displayed the same sports as the top five for both females and males: ice hockey, team handball, soccer, downhill skiing and basketball. Female alpinism and gymnastics had also high rankings. Knee injuries comprised 10% of all injuries in males and 13% in females, but their proportional contribution to the costs per hour of participation was 27% and 33%, respectively. From this study it can be concluded that females were significantly more at risk for knee injuries than males in six sports and that knee injuries accounted for a high proportion of the costs of medical treatment.     

Are oral contraceptive use and menstrual cycle phase related to anterior cruciate ligament injury risk in female recreational skiers?

Oral contraceptive use and menstrual cycle phase are suggested to influence the risk of anterior cruciate ligament (ACL) injuries in female athletes. However, only few data are available for recreational sports. Therefore, female recreational skiers with a non-contact ACL injury and age-matched controls completed a self-reported questionnaire relating to menstrual history, oral contraceptive use and previous knee injuries. Menstrual history data were used to group subjects into either preovulatory or postovulatory phases of menstrual cycle. Our findings suggest that oral contraceptive use did not show any protective effect against ACL injuries nor did self-reported previous knee injuries show any association with ACL injury rate in recreational alpine skiing. Analysis of menstrual history data revealed that recreational skiers in the preovulatory phase were significantly more likely to sustain an ACL injury than were skiers in the postovulatory phase.     

前交叉韧带损伤的临床流行病学研究

为总结分析前交叉韧带(Antenor cruciate ligament,ACL)损伤的临床流行病学特点,进而指导临床,做好有关预防、诊断、治疗、康复工作,我们回顾性研究了1992年1月～2000年12月在我科住院手术治疗的ACL断裂息者共437例,其中运动员175例(男72例,女103例),非运动员262例(男175例,女87例).对损伤发生率、好发项目、男女性别特点、运动员与非运动员间特点、损伤原因及机制、膝关节不稳发生时间与临床的关系等进行统计分析.结果表明女运动员ACL损伤发生率(58.9%)高于男性(41.1%),尤其在柔道、摔跤项目中更为明显(P＜0.01);在跳箱、跨栏项目中,在校女生ACL损伤发生率较高(P＜0.01);运动员与非运动员的非接触性ACL损伤中女性多于男性(P＜0.05).致伤因素运动员以技术失误为主,非运动员以误伤为主.伤后出现膝关节不稳临床症状的时间为2～3个月.为减轻及防止继发损害,恢复膝关节稳定性,ACL重建术应在伤后3个月内进行.     

Role of sports in etiology and prognosis of surgically treated acute knee ligament injuries

During the period 1975-1981, 48 persons were operated on at Tampere University Central Hospital for an acute knee ligament sports injury. Their mean age was 31.6 years. A total of 40 patients had a postoperative follow-up ranging from 2 to 7 years (average 41 months). The number of operations increased greatly during the observation period: in 1980-1981, 29 operations (60%) were performed. Of all the injuries, 29 (60%) occurred in the winter season (January-March). Cross-country skiing was the cause in nearly half of the cases (23), and 21 of these were spare time sports injuries involving mainly middle-aged women (15). According to the questionnaire and clinical and radiological reexamination, the patients injured in spare time sports did not differ significantly from the patients with no sports injury in respect to the amount, quality, or position of the pathological changes in the knee. However, the whole group of top-level or competitive sportsmen had significantly better healing results than the other patients. Slippery cross-country skis made from glass fibers seem to be dangerous, especially for older female spare time skiers. Competitive sportsmen's better healing results are obviously based on their younger age, better muscular performance, and higher motivation, and better possibilities for rehabilitation.     

Relationship between jump landing kinematics and peak ACL force during a jump in downhill skiing: A simulation study

Recent data highlight that competitive skiers face a high risk of injuries especially during off‐balance jump landing maneuvers in downhill skiing. The purpose of the present study was to develop a musculo‐skeletal modeling and simulation approach to investigate the cause‐and‐effect relationship between a perturbed landing position, i.e., joint angles and trunk orientation, and the peak force in the anterior cruciate ligament (ACL) during jump landing. A two‐dimensional musculo‐skeletal model was developed and a baseline simulation was obtained reproducing measurement data of a reference landing movement. Based on the baseline simulation, a series of perturbed landing simulations (n = 1000) was generated. Multiple linear regression was performed to determine a relationship between peak ACL force and the perturbed landing posture. Increased backward lean, hip flexion, knee extension, and ankle dorsiflexion as well as an asymmetric position were related to higher peak ACL forces during jump landing. The orientation of the trunk of the skier was identified as the most important predictor accounting for 60% of the variance of the peak ACL force in the simulations. Teaching of tactical decisions and the inclusion of exercise regimens in ACL injury prevention programs to improve trunk control during landing motions in downhill skiing was concluded.     

Deficits in neuromuscular control of the trunk predict knee injury risk: a prospective biomechanical-epidemiologic study

BACKGROUND: Female athletes are at significantly greater risk of anterior cruciate ligament (ACL) injury than male athletes in the same high-risk sports. Decreased trunk (core) neuromuscular control may compromise dynamic knee stability. HYPOTHESES: (1) Increased trunk displacement after sudden force release would be associated with increased knee injury risk; (2) coronal (lateral), not sagittal, plane displacement would be the strongest predictor of knee ligament injury; (3) logistic regression of factors related to core stability would accurately predict knee, ligament, and ACL injury risk; and (4) the predictive value of these models would differ between genders. STUDY DESIGN: Cohort study (prognosis); Level of evidence, 2. METHODS: In this study, 277 collegiate athletes (140 female and 137 male) were prospectively tested for trunk displacement after a sudden force release. Analysis of variance and multivariate logistic regression identified predictors of risk in athletes who sustained knee injury. RESULTS: Twenty-five athletes (11 female and 14 male) sustained knee injuries over a 3-year period. Trunk displacement was greater in athletes with knee, ligament, and ACL injuries than in uninjured athletes (P < .05). Lateral displacement was the strongest predictor of ligament injury (P = .009). A logistic regression model, consisting of trunk displacements, proprioception, and history of low back pain, predicted knee ligament injury with 91% sensitivity and 68% specificity (P = .001). This model predicted knee, ligament, and ACL injury risk in female athletes with 84%, 89%, and 91% accuracy, but only history of low back pain was a significant predictor of knee ligament injury risk in male athletes. CONCLUSIONS: Factors related to core stability predicted risk of athletic knee, ligament, and ACL injuries with high sensitivity and moderate specificity in female, but not male, athletes.     

Biomechanical analysis of anterior cruciate ligament injury mechanisms: three-dimensional motion reconstruction from video sequences

BACKGROUND: Methods for analyzing the mechanisms of injuries in sports from video sequences of injury situations are so far limited to a simple visual inspection, which has shown poor accuracy. PURPOSE: To investigate whether a new model-based image-matching technique could successfully be applied to estimate kinematic characteristics of three typical anterior cruciate ligament (ACL) injury situations. METHODS: A four-camera basketballvideo, a three-camera European team handball video and a single-camera downhill skiing video were imported into the program Poser 4, where a skeleton model and a model of the surroundings were matched to the background image frame by frame. When the match was considered satisfactory, joint angles as well as velocity and acceleration of the center of mass were calculated using Matlab. RESULTS: In the basketball and handball matchings, the skeleton and surrounding models were successfully matched to the background through all frames in all camera angles. Detailed time courses for joint kinematics and ground reaction force were obtained, while less information could be acquired from the single-view skiing accident. CONCLUSION: The model-based image matching technique can be used to extract kinematic characteristics from videotapes of actual ACL injuries, and may provide valuable information on the mechanisms for ACL injuries in sports.     

Downhill skiing injuries and their cost at a Finnish skiing area

During the 1987–1990 ski seasons. 325 consecutive patients sustained downhill skiing injuries at a skiing area in central Finland. The calculated injury rate was 0.94 per 1000 skier-days (0.9%) and 0.56 per 1000 skiers (0.06%). Forty-one percent of the injuries were located in the lower limbs and 37% in the upper limbs. Sprain was the most common type of injury (34%), followed by fractures (22%) and contusions (17%). Only 7% of the patients needed surgery. The estimated mean cost of medical treatment and sick leave was FIM 5500 (USD 1400) per patient.