CORR Insights®: A 40-year Study of the Factors Associated with Diaphyseal Forearm Fractures in Skiers and Snowboarders

Where Are We Now?

Every sport has patterns of injury that are determined by the unique stresses experienced by those athletes. Evaluating these patterns of injuries and the mechanisms that are associated with them can lead to injury-prevention strategies and the development of effective protective equipment. The use of knee braces in football linemen [1, 10] and protective gloves in baseball players [3] as a way to avoid hand injuries while sliding into a base are examples of researchers mining injury data to decrease injury in a particular sport.

But in some instances, protective equipment may not function as desired and may lead to new problems. For example, previous research [8] has suggested that wrist guards may result in a transfer of stress to the forearm and increase the chances of forearm fractures. Additionally, studies on skiing and snowboarding injuries [2, 6] indicate that although they are similar, each sport is associated with different rates of injury. In this context, corroboration of previous findings is especially important to assure that unique factors in previous datasets (such as the differences between snow conditions in the Rockies and the Appalachians) did not influence the results. There currently are no good data on the incidence of forearm injuries or their surrounding circumstances associated with skiing.

The retrospective study by Twining et al. [11] attempts to fill that gap in knowledge. The authors evaluated a database of 40 years’ worth of injuries at one ski slope in the Northeast United States to determine the frequency and types of diaphyseal forearm fractures and the factors associated with those injuries. They found that wrist guards did not increase the incidence of forearm fractures, although their research did not comment on whether they were of any benefit.

One of the important findings of this study is that often skiiers are injured by collisions with other skiers when they are standing still. Physicians may help their patients most by pointing out the importance of being aware of other skiers when on the slopes.

Where Do We Need To Go?

Epidemiologic studies such as this one attempt to find patterns of injuries and factors associated with them under the theory that better understanding of the actual mechanics associated with the injury will allow the development of mitigation strategies to decrease their incidence. But the challenge for Twining et al. [11] was the fact that they selected a rare injury, such that even with 40 years of data, the numbers remain small. The incidence of forearm fractures among skiers was 0.004 per 1000 person-days, and among snowboarders it was 0.03 per 1000 person-days. Based on the study data, this is a very small percentage of the injuries seen on the ski slopes during this period (< 1% to 2%), and once they began looking at subgroups, problems of statistical power and what the authors called “statistical fragility” came up. Underpowering results in a limited ability to find differences that are present when making comparisons, and fragility means that the detection of a few more (or fewer) events could result in a change in a key finding. The obvious solution to both problems would be an experimental design that yielded a larger number of events for analysis; this could be obtained by pooling data from multiple ski slopes.

Additionally, Twining and colleagues [11] are sitting on a huge database of other injuries, which can be mined for the evaluation of more common injuries such as ACL tears and tibial fractures [7]. Future studies should evaluate those injuries, which are more common in skiing and which may be adequately supported by data from just one ski slope.

Another challenge the authors faced relates to the evolution of equipment that has occurred over 40 years. The evolution of ski equipment affects how people ski and likely has changed the incidence of injuries. Given the longitudinal nature of this database, future studies could consider the effect changes in boot and binding technology had, if any, on lower extremity injuries on their ski slopes.

Finally, these authors clearly show that wrist guards do not increase the incidence of forearm fractures in skiers, but we still need to identify a piece of protective equipment that could possibly protect against forearm fractures.

How Do We Get There?

These authors have successfully answered the question regarding whether wrist guards increase the risk of forearm fractures, but some of the unusual findings in their dataset—including injuries occurring more often when standing still than when going fast or that they were more common on the easy slopes rather than the more challenging ones—may have been a function of the statistical fragility encountered because of the low incidence of forearm injuries. The solution to this problem, as I alluded to earlier, is more data, which could be obtained by pooling data from multiple ski slopes. A larger governing body to oversee such data consolidation and evaluation may be necessary, perhaps through the US Ski Association or a national orthopaedic association such as those for hand or sports medicine injuries. Currently, data are typically reported from hospitals or National Trauma Registry [9, 12] but not from individual slopes.

Data pooling from multiple ski slopes will enhance the power of these data. It is possible that other ski slopes have similar databases and are unaware of the fact that similar data collection philosophies have been followed at ski slopes elsewhere. Collaboration between these ski slopes could immediately result in improvement in data analysis and management of injuries. These authors obviously had an interest in forearm fractures and may focus their practice in the upper extremity. Sharing this with their colleagues who manage lower extremity injuries or closed head injuries would allow extraction of even more information from the available data set.

Depending on the length of time the data have been collected, both longitudinal studies and studies utilizing current data could produce meaningful results. Multiple studies on ski boots, bindings, and helmets have been produced over the past several decades [4, 5], but subtle changes in equipment can be evaluated through databases such as these.

For studies seeking to evaluate the development of protective equipment, such research may require partnering with industry. Industry partnership for safety equipment and sports is complex and has ramifications in terms of both liability and profitability for companies. Despite this, extensive research has been performed in other areas including knee braces, football helmets, and helmets used for bicycle riding and skiing. Biomechanical data taken from the laboratory must be tested in the field, and databases such as this would be ideal to quantify the improvements in participant safety with modifications in equipment. Again, the longitudinal nature of databases such as this would be beneficial in creating a comparison group for changes in safety equipment design.