Irving S. Scher

2010/2011 NSAA 10-Year Interval Injury Study

Skiing and snowboarding are common activities at ski resorts that may result in injury. In 1980, The National Ski Areas Association (NSAA) commissioned the first 10-Year Interval national injury study. This is the fourth such study. The objective of the study was to obtain estimates of the prevalence, incidence, and nature of snow sports injuries across the US. These studies are used to evaluate injury trends. The method for the study was to obtain Ski Patrol Incident data from selected ski resorts in the US on the basis of size and geographical location. The data were weighted by the % of resort visits based on size and location. National skier and snowboarder control demographic data came from the NSAA 2010 National Demographic Study. Resort visit totals came from the NSAA 2010 Kottke National End-of-Season Survey. A retrospective stratified study design was used. Statistical package for the social sciences (SPSS) was used to evaluate incidence trends using linear regression. Incidence rate differences were evaluated using t-test. Prevalence was evaluated using Chi-Square tests. The 0.05 level of significance was used. The sample areas generated 13 145 incident reports and 4 618 194 visitation days. The weighted skiing incident rate was 3.1 per 1000 visits in 1980, 2.7 in 1990, 2.6 in 2000, and 2.5 for 2010. The weighted 2010 snowboard rate was 6.1 per 1000 visits; it was 3.3 in 1990, and 7.0 for 2000. Ultimately, skiing injury rate continues to decrease. Snowboarding injury rate has decreased since the last study: injury patterns for snowboarding versus skiing is unchanged, injury patterns for males versus females is unchanged, incidence of jumping related incident reports has declined since last report, the prevalence of collision incidents with fixed objects on the slope decreased, and Terrain Parks are not associated with increase in injury rates or prevalence of jumping injuries. KEYWORDS: ski, snowboard, injury trend analyses Language: en

Reaction Times of Skiers and Snowboarders

Collisions with obstacles, such as trees, rocks, and other people, are a common occurrence in the sports of skiing and snowboarding. Once an obstacle becomes visible, whether or not the skier has time to avoid it is largely determined by that skier’s reaction time (RT)—the time it takes to detect and identify the obstacle, make a decision about how to respond, and initiate that response. Stopping and turning RTs were measured in ten expert skiers and four expert snowboarders at Mammoth Mountain, California. Participants were told to search for a sign along a closed intermediate course and to execute the instruction on the sign as quickly as possible. The sign was positioned such that it was not visible until participants crested a berm. Two high-speed video cameras captured the movements of each participant. RT was defined as the time between when the sign first came into view and when the skier or snowboarder initiated a response (the time of initial ski, snowboard, or body movement away from the original path or arc of the participant). The average RT for skiers and snowboarders was 856 and 1056 ms, respectively. No difference in RT was observed between stopping and turning responses. These data can be used to estimate the limits of performance for an attentive, experienced skier or snowboarder under good environmental conditions.

Multiplane Loading of the Extensor Mechanism Alters the Patellar Ligament Force/Quadriceps Force Ratio

Since the direction of the quadriceps force and location of the patellofemoral contact point likely differ between axial and multiplane loadings, the force and moment balance solutions for a multiplane loading condition may not yield the same patella ligament force/quadriceps force ratio (F(PL)/F(Q) ratio) when compared with an axial loading condition. The purpose of this study was to compare the effects of an axial loading condition and an anatomical, multiplane loading condition on the F(PL)/F(Q) ratio at various knee flexion angles. Ten cadaver knees were used in this investigation. Each was mounted on a custom jig that was fixed to an Instron frame. Quadriceps muscle loads were applied with same resultant force magnitudes under two force directions, as follows: (1) axial loading (central quadriceps tendon loading parallel to the femoral axis), and (2) an anatomically based, multiplane loading condition (individual vasti loaded, taking into consideration physiologic muscle fiber orientation). Patellar ligament tension was measured using a buckle transducer. The patellar ligament force/quadriceps force ratio (F(PL)/F(Q) ratio) was calculated for both loading conditions at 0 deg, 20 deg, 40 deg, and 60 deg of knee flexion. Across the range of knee motion evaluated, the F(PL)/F(Q) ratio for the axial loading condition was significantly greater than the F(PL)/F(Q) ratio for the multiplane loading condition. Our results suggest that loading orientation affects the transfer of forces from the quadriceps tendon to the patellar ligament.

Role of Helmets in Mitigation of Head Injuries: Epidemiologic Study of Head Injuries to Skiers

Helmets have been proposed as a means of injury mitigation. Head injuries are of particular interest due to the potential for death or permanent cognitive impairment. The objective of this paper was to determine the degree that a recreational ski sports helmet can mitigate head injuries. The authors conducted a prospective epidemiological study of all medically significant skiing injuries at the Sugarbush Resort. All injuries were diagnosed and initially treated at a clinic at the base of the resort by orthopedic physicians. Various control group strategies were used to assess the characteristics of the population at risk. The numbers of resort visits by various sub-groups of the population were carefully audited. Controls consist of random assessments of the population at risk as well as equipment examinations and evaluations. During the time period of this study (17 seasons from the 1995/1996 season through the 2011/2012 season), within the population at risk, helmet usage increased from 8 to 84 %. Our analysis began at the time that helmet usage became popular. We specifically focused on all injuries to the region of the head. For the 17 seasons of interest, the prevalence of all injuries to the head decreased from 8.4 to 6.8 %; the prevalence of potentially serious head injuries (PSHI) declined from 4.2 to 3.0 %. The incidence of PSHI declined from 1 in 4200 days of activity to 1 in 11 000 days of activity; the incidence of any head injury declined from 1 in 8600 days of activity to 1 in 26 000 days of activity. RESULTS of the study also stated that over this same time, the incidence of helmet usage increased from 8 to 84 %. The average helmet use for the period of interest was 45 %. Of the 10 observed skull fractures, only 1 was to a person wearing a helmet. Of 47 scalp lacerations, only 1 was to a person wearing a helmet. Helmets are mechanical devices that attenuate a finite amount of energy during a head impact. We observed that helmets offer very effective mitigation for head injuries such as skull fractures and scalp lacerations. Increased use of helmets was also associated with a significant reduction in potentially serious head injuries, as well as all head injuries. KEYWORDS: helmets, head injury mitigation, alpine skiing Language: en

Helmet Use in Sledding: Do Users Comply with Manufacturer Warnings?

Sledding, like other recreational sports, is associated with inherent risks of injury in which behavioral factors may influence the accident and injury modes. In the present work, we examined the rate of personal protective equipment (PPE) usage and its relationship to various environmental and user characteristics at three popular sledding sites in California. Experimenters measured speeds and collected observations of equipment type, helmet use, sledder age and gender, along with on-product warnings and safety information for some of the products observed during data collection. The recorded sledder speeds were within the range of impact speeds for which helmets have been shown to reduce the likelihood of head injury. Despite this, and despite the prevalence of on-product warnings recommending helmet use, the observed usage rate of protective equipment while sledding was less than 5 percent for all sledders. Given the importance of helmets in reducing the risk of head injury in snowsports, these findings have important implications for the snowsport and broader safety community.

Snow Sports Trauma and Safety

Introduction: The Norwegian Ski Lift Association has since 1996 conducted a central registration of the injuries occurring in the major Norwegian ski resorts to survey the injury types. The aim of this study was to report injury trends in the period 1996–2012. Material and methods: The injuries occurring in 7–16 Norwegian ski resorts were recorded by ski patrols during the 16 winter seasons 1996/1997–2011/2012 and related to a series of demographic factors. The number of skiing/boarder days was calculated from sold lift tickets (day cards), but these were only centrally recorded from the 2000/2001 season. Results: A total of 55127 injured skiers and boarders were recorded. The injury rate dropped from 1.47 to 1.27 injuries per 1000 skier/boarder days (P < 0.001), and the skiing/boarding ability increased (P < 0.001) in the period 2000–2012. Most of the injuries occurred on groomed slopes, but an increasing number of injuries occurred in terrain parks, from only 4% in the 2000/2002 seasons to 24% in the last two seasons. More serious injuries (fractures and back injuries) were recorded in terrain parks than those occurring at other locations. Many of the injuries were similarly distributed among skiers and boarders, but alpine skiers suffered more lower extremity injuries, especially knee injuries (24%) compared to snowboarders (7%), whereas the reverse was observed for wrist injuries with 22% for snowboarders and 5% for alpine skiers in the last 2-year period (P < 0.001). The prevalence of knee injuries among alpine skiers has been about 25% in the period 1996–2012, but wrist injuries among snowboarders dropped from 29 to 22% (P < 0.001). The prevalence of knee injuries was twice as high for females (31%) as for males (15%), whereas the reverse was observed for shoulder injuries with 19% for males and 7% for females in the last 2-year period (P < 0.001). These differences have been observed during the whole period. Lower leg fracture for alpine skiers <13 years dropped from 20 to 13% in the period (P < 0.001), but has remained unchanged with about A. Ekeland, M.D., Ph.D. (*) • S. Heir Orthopaedic Department, Martina Hansens Hospital, Box 823, N-1306 Sandvika, Norway e-mail: arekelan@online.no A. Rødven Norwegian Ski Lift Association, Fridtjofs Nansens vei 19, N-0369 Oslo, Norway

Jumping Features at Ski Resorts: Good Risk Management?

Injuries associated with jumping can result in catastrophic and fatal consequences. The concentration of designed jumping features within a segregated part of the resort called a Terrain Park (TP), likely results in an increase in jumping. Hypothesis: Is the increase in TPs associated with an increase of injuries, to include catastrophic and fatal injury? National Ski Areas Association (NSAA) US national data from 1990 to 2010 was used to compute the rates per million resort visits from 1990 to 2010 for trauma related catastrophic and fatal injuries to resort users while skiing and snowboarding. Data from selected resorts was used to estimate the overall incident rate of ski patrol reports per 1000 days of exposure at ten-year intervals for 2000 and 2010. From 1990 to 2010, the number of resorts having one or more TPs with designed jumping features went from none to 94 %. During this time, the rate of fatal and catastrophic injury and the overall incidence of any injury has not changed. The hypothesis that jumping features resulted in increased risk of injury has not been substantiated. TPs may offer benefits. These include a reduction of incidence and severity of injuries to jumpers by providing specifically designed jumping features that are tested before being opened. Segregating jumping may reduce the incidence of individuals being struck by jumpers. The increase in TPs has not been associated with an increase in the catastrophic, fatal, or overall injury rate. KEYWORDS: terrain parks, injury rates, risk management policy Language: en

HEAD MOTION IN THE CORONAL PLANE DURING LOW-SPEED LATERAL IMPACT COLLISIONS

INTRODUCTION Although numerous studies have been done on frontal and rear impact collisions and the resulting occupant kinematics, relatively few have considered the effects of lateral impacts on occupant kinematics. Understanding the kinematics of the head during lateral impacts can assist in determining how the passive response of the human body relate to one another when presented with such a stimulus. This information is invaluable in the design of motor vehicle safety systems, amusement park rides, and other situations where an unexpected lateral impact may occur.

The Influence of Age on the Forces Produced During Normal Seat Belt Buckling

Historically, the observed seat belt usage rate for occupants has varied across a number of factors (e.g., primary or secondary use law, seat location, etc.). Of these factors, the age of the driver or occupant has been consistently noted as an important characteristic that is linked to the use of the seat belt. For example, the seat belt use rate for drivers and front seat passengers in the U.S. in 2002 was estimated to be over 70% for adults [1] but over 10% less for pre-teens [2] and teenagers [3], which are generally less than 60%. This discrepancy between younger age groups and adults has been reported in several states across the country [2–5]. Eby et al. [4] reported that individuals 4–15 years old, seated in the second and third rows, wore seat belts about 50% of the time in the left and right positions. In a separate four-state observational study of teenage and older occupants by Womack et al. [6], teen seat belt use in the back seats was only 10.9%. Together, these studies indicate pre-teen and teenagers wear seat belts less frequently than comparable adult cohorts, and that they will be even less likely to wear a seat belt when they are located in the back seat positions.Copyright