Lower extremity equipment-related injuries in alpine recreational skiers

Transcription

1 Lower extremity equipment-related injuries in alpine recreational skiers ARNE EKELAND,* MD, PhD, AGE HOLTMOEN, MSS, AND HARALD LYSTAD, MD From the *Department of Orthopaedic Surgery, Ullevaal Hospital, University of Oslo, and The Norwegian College of Physical Education and Sport, Oslo, and The Hemsedal Health Center, Hemsedal, Norway ABSTRACT Lower extremity equipment-related injuries are the most significant injury group in alpine skiing. The lower extremity equipment-related injuries occurring at four Norwegian ski resorts were studied during the winter of 1985 to A total of 132 skiers with injuries were included (40% of all injured skiers) and compared with a randomly selected control population of 316 uninjured skiers. The most common lower extremity equipmentrelated injuries were knee sprains (56%) and lower leg fractures (14%), usually caused by no or late binding release. Significantly more lower extremity equipment-related injuries (33%) than other skiing injuries (19%) needed hospital admittance. Children below 10 years had a risk of lower leg fractures nine times that of skiers beyond 20 years. Beginners were six times more at risk for a lower extremity equipment-related injury than skiers of higher skiing abilities. The following factors were also associated with a significantly increased risk for a lower extremity equipment-related injury: less than three skiing seasons, no skiing instruction, and no self-testing of the bindings. The term lower extremity equipment-related (LEER) injuries was presented by Johnson and coworkers19 in their classic study from As the name designates, LEER injuries depend on the skiing equipment. Most of the injuries occur when the ski acts as a lever to turn or twist the leg, and many of them can be prevented by appropriate binding release. Lower extremity equipment-related injuries are most commonly observed among beginners,9, 16,17,22 and beginners also have relatively tighter bindings and boots and bindings of lower quality than the average skier.12,16,27 same skiing areas throughout the season. These skiers were asked a series of questions about sociologic and skiing data, and thereafter allowed to bypass the lift line. Thus, the response to the study among the randomly selected control population of skiers was hearty. The data were collected on forms designed to assist in computer processing. The injuries to the lower extremity were studied in detail, and those probably related to the skiing equipment were defined as LEER injuries. The LEER injuries were related to the skier s age and sex, to skiing ability and skiing experience, to skiing instruction, to self-testing of the bindings, and to the type of skiing equipment. Regarding skiing ability, the skiers were classified by the type of turns they routinely performed: experts (short turns), advanced skiers (parallel turns), intermediate skiers (stem turns), and beginners (plow turns). lo The results are presented as percentages of the injuries or the population of skiers and as injury ratios-the percentage of injured skiers in each group divided by the percentage of uninjured skiers in that group. Differences were evaluated statistically by the two-sided Fisher-Irwin3 or Kologorovt Address correspondence and reprint requests to: Ame Ekeland, MD, Surgical Clinic, Ullevaal Hospital, N-0407 Oslo 4, Norway. 201 We have previously reported the percentage of LEER injuries to be 41% (of 328 subjects) and the most important injury group was among alpine recreational skiers. The purpose of this study was to explore these LEER injuries more thoroughly to identify risk factors. MATERIALS AND METHODS The skiing injuries reported at four Norwegian ski resorts (Hemsedal, Hovden, Oppdal, and Trysil) were recorded during the winter season of 1985 to The registration was done by the local physicians, and each resort had only one medical center. A skiing injury was defined as an injury that resulted in the skier being taken to a medical center involved in the study or reporting voluntarily to the center after sustaining a skiing accident. A control population of 316 uninjured skiers was selected randomly from lift lines in the

2 . 202 Smirnov2l tests and were considered significant when P < RESULTS Injury-related factors A total of 341 injuries in 328 skiers were recorded. The LEER injuries accounted for 140 injuries (41% ) in 132 skiers (40%). Type and location of injury. The LEER injuries accounted for 90% of the injuries to the lower extremity. Fifty-six percent of the LEER injuries were sprains and 27% were fractures (Table 1). Most of the injuries were located in the knee (Fig. 1) The LEER injuries were more serious than other skiing injuries since 33% and 19%, respectively, needed hospital admittance (P < 0.05). The most common LEER injuries were knee ligament sprains (56%) and lower leg fractures (14% ). Causes and mechanisms of injury. Ninety-two percent of the LEER injuries occurred during a fall with no collision, whereas collision-induced falls resulted in a LEER injury in 8% of the accidents. Injuries to the lower extremities directly attributable to the collision itself were excluded as LEER injuries., Skier-related factors Age and sex. Most of the skiers were young; 56% were less than 25 years. Skiers below 10 years of age had an injury ratio of 2.1 and were significantly overrepresented among the injured skiers (P < 0.05) (Fig. 2). This was most dramatically observed for lower leg fractures, where the injury ratio was nine times as high for skiers below 10 years (4.5) as for skiers more than 20 years old (0.5) (P < ). Thirty-six percent of the skiers were female. No significant difference was observed between the injury ratios for female (1.1) and male (1.0) skiers, but more female skiers than male skiers suffered knee sprains. Skiing ability and experience. The skiing injury risk was related to skiing ability, and beginners had an injury ratio more than six times higher than skiers of higher abilities (P < ) (Fig. 3) Also, the skiing experience influenced the injury risk, displaying significantly increased injury ratios for skiers with three skiing seasons or less, and a reduced ratio for those with five seasons and more (Fig. 4). However, TABLE 1 Types of lower extremity equipment-related injuries (N = 140) Figure 2. Injury ratios of lower extremity equipment-related injuries as a function of age. Values significantly different from 1.0 are indicated (N = number of injured/uninjured skiers). Figure 1. Site of lower extremity equipment-related injuries in alpine recreational skiers (number of injuries = 140). Figure 3. Injury ratios of lower extremity equipment-related injuries as a function of skiing ability. Values significantly different from 1.0 are indicated (N = number of injured/ uninjured skiers).

3 Figure 4. Injury ratios of lower extremity equipment-related injuries as a function of skiing experience. Values significantly different from 1.0 are indicated (N = number of injured/ uninjured skiers). TABLE 2 Skiing experience for injured and uninjured beginners (N, number of skiers) TABLE 3 Skiing instruction for injured and uninjured skiers. Significant differences are indicated (N = number of skiers) were especially poor for children below 10 years of age. Corresponding observations were made for skiers with grade III knee sprains or lower leg fractures, whereas about half the skiers with less serious knee sprains had bindings that released during the accident. The injury ratio was significantly lower (P 0.02) for = skiers who had self-tested bindings compared to skiers with untested bindings (Table 4). In addition, injured skiers had performed binding test less recently than the control population (P < 0.001) (Fig. 5). An especially low injury ratio was observed for skiers who both self-tested their bindings and had attended current or previous ski school classes (0.5) as opposed to skiers who did neither (1.5) (P < 0.001). Skis and boots. Standard equipment consists of common alpine skis with release bindings; Telemark equipment consists of more narrow skis with bindings only where the toe of the boot is fixed to the ski. (At the time of our study, however, Telemark equipment had no release bindings.) Ninety-six percent of the skiers used standard alpine equipment. About 3% used Telemark equipment, and they had a higher injury ratio (3.0) than skiers with standard equipment (1.0) (P < 0.05). DISCUSSION Lower extremity equipment-related injuries are the largest injury group in alpine skiing, and they also proved to be TABLE 4 Previous self-release testing of the bindings in skiers with lower extremity equipment related (LEER) injuries and in uninjured alpine recreational skiers. Significant differences are indicated (No. = number of skiers) Injury ratio injured skiers ( % )/uninjured skiers (%). = a Injury ratio = injured skiers (%)/uninjured skiers (%). the skiing experience of injured and uninjured beginners was similar (Table 2). Skiing instruction. Skiers with present or previous skiing instruction had an injury ratio significantly below that of uninstructed skiers (Table 3). Half the skiing populationmore male than female skiers-never received any formal skiing instruction. Equipment-related factors Bindings: The binding released in 48% of the accidents, more often for experts (86%) than for beginners (35%) (P < 0.001). More experts (69%) than beginners (41%) had self-tested their bindings before the accident, and 59% of the self-tested bindings released during the accident, compared to 40% of those not tested (P < 0.05). The binding release percentage (30%) and the binding testing behavior Figure 5. Binding testing frequency of skiers with lower extremity equipment-related injuries and uninjured skiers. A significant difference is indicated (N = number of skiers).

4 204 more serious than other skiing injuries. Longitudinal studies have, however, shown a decreased in LEER injuries during the last 15 years.13,17 This is mainly because of improvement in the quality and release function of ski boots and bindings, but the skiers may also have been more aware of having their bindings correctly set and tested for release.lo,12,17,24 Also, the work for skiing safety offered by skiing-related organizations-voluntary standards writing organizations and the Product Control Authorities-have probably been important in this respect.,,, 11,25 More than 70% of the skiers who suffered lower leg fractures and serious knee sprains had bindings that did not release during the accident. Most of these bindings had never been self-tested; about half the skiers who suffered less serious knee sprains had bindings that did release during the accident. This means that many of the presently used bindings release too late. The knee was the site most susceptible to LEER injuries, and new binding designs, preceded by biomechanical knee loading studies, may reduce these injuries in the future.2o,23 Skiers below 10 years old were overrepresented among the injured skiers, and many of them had lower leg fractures. This is probably related to poor quality and release function of the boot-binding complex, as also reported by others. 15,16, 27 Most of the injured children below 10 years old were beginners (75%), and children as a group were not especially injury-prone when adjustment was made for skiing ability.8, ls Beginners had an injury ratio more than six times higher than that of the other skiers.16,26 Injured beginners did not seem to be slow learners since they had about the same skiing experience as uninjured beginners (Table 2). Skiing instruction seemed to reduce the injury ratio (Table 3), and the injury risk of beginners drops significantly if they improve their ability up to the level of an intermediate skier (Fig. 3).4 The view on skiing instruction for reducing the injury risk in skiing is, however, controversial. Some authors have found no effect of skiing instruction on the injury risk,14,18 whereas Shealy2s reported a reduced risk during instruction. Appropriate skiing experience (Fig. 4) and previous binding testing (Table 4) reduced the risk for a skiing injury,2,,12 but being a beginner proved to be the most significant of all risk factors studied (Fig. 3). The skiers using Telemark equipment were significantly more prone to injury than skiers using standard alpine equipment. This may be related to the lack of release bindings for the Telemark skiers. However, the skiing population using Telemark equipment was small in this study; therefore, the figures should be interpreted with care. CONCLUSIONS In this study, 40% of the injured skiers suffered LEER injuries, and these injuries were more serious than other skiing injuries. Children had an injury ratio of lower leg fractures nine times higher than that of adult skiers, but the most important risk factor for skiing injuries proved to be a low level of skier ability. Also, skiing instruction and previous binding testing reduced the injury risk, and skiers who both self-tested their bindings and had attended ski school classes had one-third of the injury ratio for skiers who did neither. About half the injuries occurred in skiers with bindings that released during the accident. This calls for bindings of better design.2o ACKNOWLEDGMENTS The authors thank Sivert R. Asphaug, MD, Oppdal; Dag S. Skagestad, MD, Bykle; and Jon A. Sparby, MD, Trysil, who treated many of the injured skiers and collected some of the data for this study. District leader Hjalmar Hansen and other members of the Red Cross Rescue Service provided some of the data for the control population of uninjured skiers. Marit Eriksen, graduate student at the Norwegian College of Physical Education and Sport, provided technical help. This study was financially supported by grants from the Norwegian Confederation of Sport and the Norwegian Research Council for Science and the Humanities. REFERENCES 1. Asang E, Hauser W, Nagel A, et al: Skifahren-aber mit sicherer Ausrüstung, Munich, Bayerisches Staatsministerium fur Arbeit und Sozialordnung, 1983, pp Ascherl R, Schlemmer H, Lechner F, et al: A ten year survey of skiing injuries, in Hauser W, Karlsson J, Magi M (eds): Ski Trauma and Skiing Safety IV. Munich, Publication Series of TUV-Edition, 1982 pp Bhattacharyya GK, Johnson RA: Statistical Concepts and Methods. New York, John Wiley & Sons, 1977, pp Bouter LM, Knipschild PG, Volovicx A: Ability and physical condition in relation to injury risk in downhill skiing, in Bouter LM: Injury Risk in Downhill Skiing (Thesis), Haarlem, Uitgeverij De Vrieseborch, 1988, pp Danielsson K, Eriksson E, Jonsson E, et al: Attempts to reduce the incidence of skiing injuries in Sweden, in Johnson RJ, Mote CD Jr (eds): Skiing Trauma and Safety: Fifth International Symposium, ASTM STP 860. Philadelphia, American Society for Testing and Materials, 1985, pp Ekeland A: Forebyggelse av skiskader (Prevention of skiing injuries) (Editorial) Nord Med 103: 3, Ekeland A: Injuries to advanced and expert skiers during summer skiing, in Johnson RJ, Hauser W, Karlsson J, et al (eds): Ski Trauma and Skiing Safety III. Munich, Publication Series of TÜV-Edition, 1982, pp Ekeland A, Holm A: Injury and race completion rates in alpine competitions, in Johnson RJ, Mote CD Jr (eds): Skiing Trauma and Safety: Fifth International Symposium, ASTM STP 860. Philadelphia, American Society for Testing and Materials, 1985, pp Ekeland A, Holtmoen Å, Lystad H: Skiing injuries in alpine recreational skiers, in Johnson RJ, Mote CD Jr, Binet MH (eds): Skiing Trauma and American Society for Testing and Materials, 1989, pp Ekeland A, Holtmoen Å, Lystad H: Skiing behavior of alpine recreational skiers, in Johnsson RJ, Mote CD Jr, Binet MH (eds): Skiing Trauma and American Society for Testing and Materials, 1989, pp Ekeland A, Larsen SR, Tuxen AG, et al: Organization of skiing safety in Norway, in Johnson RJ, Mote CD Jr, Binet MH (eds): Skiing Trauma and American Society for Testing and Materials, 1989, pp Ekeland A, Lund O: Functional control of release bindings in uninjured Scandinavian skiers, in Hauser W, Karlsson J, Magi M (eds): Ski Trauma and Skiing Safety IV. Munich, Publication Series of TUV-Edition, 1982, pp Johnson RJ, Ettlinger CF, Shealy JE: Skier injury trends, in Johnson RJ, Mote CD Jr, Binet MJ (eds): Skiing Trauma and Safety: Seventh Interna-

5 205 tional Symposium ASTM STP Philadelphia, American Society of Testing and Materials, 1989, pp Garrick JG, Requa R: The role of instruction in preventing ski injuries. Physician Sportsmed 5: 57-59, Gundersen TM: Comparative laboratory tests of release bindings for children and young skiers with special reference to the influence of boot material and boot sole length, in Mote CD Jr, Johnsson RJ (eds): Skiing Trauma and Safety: Sixth International Symposium, ASTM STP 938. Philadelphia, American Society for Testing and Materials, 1987, pp Hauser W, Asang E, Muller B: Injury risk in alpine skiing, in Johnson RJ, Mote CD Jr (eds): Skiing Trauma and Safety: Fifth International Symposium, ASTM STP 860. Philadelphia, American Society for Testing and Materials, 1985, pp Johnson RJ, Ettlinger CF: Alpine ski injuries: Changes through the years. Clin Sports Med 1: , Johnson RJ, Pope MH: Safety in skiing, in Scott WN, Nisonson B, Nicholas JA (eds): Principles of Sports Medicine. Baltimore, Williams & Wilkins, 1984, pp Johnson RJ, Pope MH, Ettlinger C: Ski injuries and equipment function. J Sports Med 6: , Johnson RJ, Pope MH, Weisman G, et al: Knee injury in skiing: A multifaceted approach. Am J Sports Med 7: , Lindgren BW (ed): Statistical Theory. New York, MacMillan, 1968, pp Lystad H: A one-year study of alpine ski injuries in Hemsedal, Norway, in Johnson RJ, Mote CD Jr (eds): Skiing Trauma and Safety: Fifth International Symposium, ASTM STP 860. Philadelphia, American Society for Testing and Materials, 1985, pp Mills OS, Hull ML: Flexibility of the human knee as result of varus/valgus and axial moments in vivo, in Mote CD Jr, Johnson RJ (eds): Skiing Trauma and Safety: Eight International Symposium, ASTM STP Philadelphia, American Society for Testing and Materials, 1991, pp Moraeus L: Report on a binding test in a lift queue at Sundsvall, Sweden. Orthop Clin North Am 7: 149, Nagel A, Mosch S: Test devices for ski bindings sold in sports shops: State of the art and future development, in Mote CD Jr, Johnson RJ (eds): Skiing Trauma and Safety: Sixth International Symposium, ASTM STP 938. Philadelphia, American Society for Testing and Materials, 1987, pp Shealy JE: Overall analysis of NSAA/ASTM data on skiing injuries for 1978 through 1981, in Johnson RJ, Mote CD Jr (eds): Skiing Trauma and Safety: Fifth International Symposium, ASTM STP 860. Philadelphia, American Society for Testing and Materials, 1985, pp Ungerholm S, Gustavsson J: Skiing safety in children: A prospective study of downhill skiing injuries and their relation to the skier and his equipment. Int J Sports Med 6: , 1985