Carl F. Ettlinger

A Method to Help Reduce the Risk of Serious Knee Sprains Incurred in Alpine Skiing

The incidence of severe anterior cruciate ligament sprains was once only a third the current rate. This fact led the authors to believe a means to help reduce the risk of anterior cruciate ligament injury among skiers might be found. Using videotapes of the occurrences of anterior cruciate ligament sprains in alpine skiers and the data associated with more than 1400 anterior cru ciate ligament injuries observed in a 22-year study, the authors identified two common mechanisms of anterior cruciate ligament injury. From this information, a study was designed to determine if training could help reduce the risk of anterior cruciate ligament sprains. During the 1993 to 1994 season, the on-slope staff from 20 ski areas participated in a training program involving view ing videotaped scenes where knee injuries occurred. Data from 22 ski areas, where staff were not exposed to the training, were assembled to form a control group. Data concerning anterior cruciate ligament injuries were collected from both groups for the three seasons 1991 to 1994. A total of 179 serious knee sprains were evalu ated. Serious knee sprains declined by 62% among trained patrollers and instructors compared with the two previous seasons, but no decline occurred in the control group.

Alpine ski bindings and injuries. Current findings.

In spite of the fact that the overall incidence of alpine ski injuries has decreased during the last 25 years, the incidence of serious knee sprains usually involving the anterior cruciate ligament (ACL) has risen dramatically since the late 1970s. This trend runs counter to a dramatic reduction in lower leg injuries that began in the early 1970s and to date has lowered the risk of injury below the knee by almost 90%.One of the primary design objectives of modern ski boots and bindings has been to protect the skier from tibia and ankle fractures. So, in that sense, they have done an excellent job. However, despite advances in equipment design, modern ski bindings have not protected the knee from serious ligament trauma.At the present time, we are unaware of any binding design, settings or function that can protect both the knee and lower extremities fromserious ligament sprains. No innovative change in binding design appears to be on the horizon that has the potential to reduce the risk of these severe knee injuries. Indeed, only 1 study has demonstrated a means to help reduce this risk of serious knee sprains, and this study involved education of skiers, not ski equipment.Despite the inability of bindings to reduce the risk of severe knee injuries there can be no doubt that improvement in ski bindings has been the most important factor in the marked reduction in incidence of lower leg and ankle injuries during the last 25 years. The authors strongly endorse the application of present International Standards Organisation (ISO) and American Society for Testing and Materials (ASTM) standards concerning mounting, setting and maintainingmodern ’state of the art’ bindings.

Snowboarding Injuries Trends Over Time and Comparisons With Alpine Skiing Injuries

Background: Participation in snowboarding as a winter sport is comparable to alpine skiing concerning the demographics of the participants, risk of injury, and variation in types of injuries sustained. Purpose: To examine the types of snowboarding injuries and changes in injury patterns over time. We also sought to highlight important differences in injury patterns between snowboarders and alpine skiers as affected by age, experience, and sex. Study Design: Case control; Level of evidence, 3. Methods: Data were collected on injured snowboarders and skiers in a base-lodge clinic of a ski resort in Vermont over 18 seasons (1988-2006) and included extensive information about injury patterns, demographics, and experience. Control data were also obtained during this time period to provide information about the population at risk. Results: The injury rates were assessed as mean days between injuries (MDBI). The average MDBI for all injuries among snowboarders was 345 as compared with 400 for skiers (the lower the number, the higher the injury rate). The most common type of injury for snowboarders was a wrist injury (MDBI, 1258), while for skiers, it was an anterior cruciate ligament (ACL) sprain (MDBI, 2332). Wrist injuries accounted for 27.6% of all snowboard injuries and 2.8% of skiing injuries, and ACL injuries composed 1.7% of all snowboard injuries and 17.2% of skiing injuries. Among snowboarders, more wrist injuries, shoulder soft tissue injuries, ankle injuries, concussions, and clavicle fractures were seen, while skiers had more ACL sprains, medial collateral ligament (MCL) sprains of the knee, lateral collateral ligament (LCL) sprains of the knee, lower extremity contusions, and tibia fractures. The trend analysis revealed an increased incidence of clavicle fractures (P < .01) and a decrease in MCL injuries (P < .01) and ankle injuries (P < .025) among snowboarders over time. Skiers had a decrease in thumb metacarpophalangeal-ulnar collateral ligament (MCP-UCL) injuries (P < .001) and MCL injuries of the knee (P < .001) over time. We found the highest rate of injury among young, inexperienced, female snowboarders. When examining the location of injury, 21.8% of snowboard injuries occurred in the terrain park compared with 6.5% of ski injuries. Conclusion: Injury rates in snowboarders have fluctuated over time but currently remain higher than in skiers. Wrist, shoulder, and ankle injuries are more common among snowboarders, while knee ligament injuries are more common in skiers. Injured snowboarders were significantly younger, less experienced, and more likely to be female than injured skiers or snowboard control participants. We did not find any evidence that those who spend time in terrain parks are overrepresented in the injury population.

Trends in skiing injuries. Analysis of a 6-year study (1972 to 1978).

The trends in skiing injuries showed a decrease during a study conducted over six seasons, 1972 to 1978, at a Vermont ski resort. Over 11,000 interviews were conducted and nearly 1,000 control skiers were evaluated. The injuries totaled 1,711 in 407,600 skier days. Upper body injuries (pelvis, trunk, neck, head, and upper extremities) totaled 713 (42%) and lower extremity injuries totaled 998 (58%). Eighty percent of the lower extremity injuries were classified as (potentially) equip ment related. The overall injury rate decreased 41 % (upper body, 25%; lower extremity equipment-related (LEER), 43%; and lower extremity nonequipment-related rate was down 71 %). Knee sprains did not decline as rapidly as the tibial fractures and ankle sprains. An increase in the relative frequency of properly functioning equipment is primarily responsible for the decline in LEER injuries. Although the relative frequency of properly adjusted bindings is increasing, more than one-half of the equipment in use is still set higher than recommended. Cooperation between all individuals responsible for equipment design, manufacture, installation, and use must continue, if further improvements in alpine skiing safety are to be realized.

Downhill skiing injuries in children

The objective of our study was to compare injuries sustained by a large group of children to those of injured adults and a control population of skiers selected from the Sugarbush North ski area in northern Vermont. We reviewed all 3182 injuries which occurred over nine ski seasons (1972 to 1973 through 1980 to 1981) at Su garbush North. Six hundred and ninety-six (22%) of these injuries occurred in children 16 years of age or younger. For all injuries combined, those under 11 years of age had the same rate of injury as adults. Adoles cents had a higher injury rate. Foot and ankle injuries were more common in younger children. Knee injuries made up one-fifth of all injuries in all age groups and in older skiers tended to be relatively more serious. Tibia fractures were more prevalent in younger skiers and declined in all age groups over the period of study. Head and spine injuries comprised 6.2% of the pediatric injuries, and were more prevalent in children than in adults. Upper body injuries were less common in chil dren than in adults. We found height, weight, and proximal tibial diameter to vary with age, but in any given age group there was no significant difference with injury type or the controls. Skiers with less skill or experience had a higher incidence of injuries than more experienced skiers or the control population. Injured skiers in all age groups were less likely to own their equipment. Adjustment of equipment by a professional or the skier did not vary with age or injury type.

Knee injury in skiing A multifaceted approach

During the past four ski seasons, all 1,141 ski injuries which occurred in a large northern Vermont ski area were evaluated prospectively. Of these injuries, 21.6% involved knee ligaments and 18.6% involved sprains of the medial collateral ligament. Females sustained a disproportionately high incidence of Grade I medial collateral sprains, but suffered the more severe sprains at a rate similar to that of males. Individuals who were smaller, younger, less experienced, and less skilled sustained a higher incidence of Grade I injuries. Skiers suffering complete tears of the medial collateral ligament were no smaller, younger, or less skilled or experienced than our control population. Medial collateral sprains are produced primarily by external rotation and vaigus forces. Two-mode release bindings are insensitive to several loading configurations which could produce knee sprains. Bindings which allow release in roll, shear, and twist at the heel, as well as twist at the toe and forward lean, appear to be necessary to protect the knee.

Ski injuries and equipment function

that many accidents may be caused by improperly designed, mounted and adjusted bindirrgs.l 1 2 5 9 10 12 14 15 19 However, no studies have yet been designed which evaluate the equipment of the injured skier immediately upon sustaining injury. Much of the equipment in use today has theoretical efficacy as shown by vanous mechanical testing devices, yet the rates of ski injuries have changed little since the use of release bindings became popular about twenty years ago.1~ 1, 7, 1 It has never been conclusively demonstrated in a skiing population that bindings mounted, adjusted and set properly do improve the skiers chances of avoiding injury. In fact, several investigators state that no differences exist between the equipment used by injured and uninjured skiers 2, 6 7 is 19 In contrast, two papers recently read suggest the existence of such variations. Apparently injuries were reduced by twothirds when antifriction devices (AFD’s)

Do Helmets Reduce Fatalities or Merely Alter the Patterns of Death

The use of helmets has been proposed as a means of reducing the incidence of fatality in skiing and snowboarding. This paper presents results that suggest that while helmets may be effective at preventing minor injuries, they have not been shown to reduce the overall incidence of fatality in skiing and snowboarding even though as many as 40% of the population at risk are currently using helmets. The results indicate that the use of a helmet will indeed influence the primary cause of death, but perhaps not the ultimate outcome.

Epidemiology and Risk Factors of Humerus Fractures Among Skiers and Snowboarders

Background The incidence of humerus fractures while participating in snowboarding and skiing is undefined. Very little is known about the risk factors associated with these fractures. Hypothesis Snowboarders are at increased risk for sustaining humerus fractures when compared with skiers. In addition, the types of fractures, laterality, and risk factors differ between the 2 groups. Study Design Case-control study; Level of evidence, 3. Methods At a major ski area clinic, 318 humerus fractures were evaluated over 34 seasons. Radiographs were classified according to the AO and Neer systems. Patient data were analyzed and compared with that of a control population of uninjured skiers and snowboarders to determine incidence and risk factors. Results The incidence of humerus fractures among snowboarders (0.062 per 1000 snowboarder days) was significantly higher than that of skiers (0.041 per 1000, P < .05). Skiers were more likely to sustain proximal fractures, and snowboarders were relatively more likely to sustain diaphyseal and distal fractures (P < .05). Of glenohumeral dislocations, 6.56% were associated with proximal humerus fractures among skiers (1.7% among snowboarders). Snowboarders who lead with their left foot were more likely to fracture their left humerus (P = .023). Helmet use and gender were not risk factors for humerus fractures among either skiers or snowboarders. Jumping was involved in 28.3% of humerus fractures among snowboarders and in 5.4% among skiers. Skiers with humerus fractures were more skilled, older, and fell less frequently than controls. Snowboarders were less skilled, younger, and fell at a similar rate compared with controls. Conclusion Snowboarders are at significantly higher risk of sustaining humerus fractures than skiers. In skiers, humerus fractures show no laterality and most often involve the proximal humerus. In contrast, snowboarders more often fracture the left humerus at the diaphysis.

Functional and Release Characteristics of Alpine Ski Equipment

Releasable bindings were developed to reduce the risk of lower leg injuries. However, the relationship between the incidence of specific alpine injury groups and the function and calibration of the release system has not been well understood. Over the 32 years between December 1972 and April 2004, the authors conducted a case control study at a northern Vermont ski area involving 17 967 injuries and 3617 uninjured controls. During that time, approximately 6.4 million skier visits were recorded at the area. Injured skiers were treated at clinic in the base lodge and their injuries diagnosed by the clinic staff. Data relating to the accident, the injury, and the equipment used were recorded. The release moments of equipment associated with lower extremity injuries and uninjured controls were measured using a commercially available test device. Case studies of 43 anterior cruciate ligament (ACL) sprains, 79 lower leg injuries, and 99 uninjured controls were conducted using data collected over seven years between December 1997 and April 2004. In terms of quantitative critical defects, 17 % of the control group, 14 % of the ACL group, and 39 % of the lower leg group exhibited release levels more than 30 % above recommended. When qualitative critical defects were considered, 27 % of the control group, 25 % of the ACL group, and 54 % of the lower leg group were found to exhibit one or more defects capable of having a significant effect on equipment function. The authors concluded that sprains, fractures, strains, and contusions of the lower leg among alpine skiers were associated with measurable or observable qualities of the release system. Serious sprains of the knee were not. A substantial reduction of injuries below the knee can be expected if potentially defective equipment can be identified and repaired, or replaced.