Development of methods to evaluate the performance of snowboard wrist protectors

Abstract

n snowboarding, the wrist is the most common injury site, as snowboarders often put their arms out to cushion a fall. This can result in a compressive load through the carpals coupled with wrist hyperextension, leading to ligament sprains or carpal and forearm bone fractures. Wrist protectors are worn by snowboarders in an effort to reduce injury risk, by decreasing peak impact forces and limiting wrist extension to prevent hyperextension during falls. There is no international standard or universally accepted performance specification that snowboarding wrist protectors should conform to, resulting in an inability to judge which designs offer the best protection. The aim of this project was to develop mechanical test methods to evaluate the protective characteristics of snowboarding wrist protectors. Two new mechanical tests and accompanying surrogates were developed to characterise snowboarding wrist protectors. A quasi-static test to measure the rotational stiffness of protectors was developed. The test setup uses a surrogate attached to a bespoke rig mounted to standard material test equipment to facilitate the measure of angular wrist extensions over a range of torques. To ensure products were tested in a representative manner, three surrogate arms with increasing design complexity were developed and compared using the quasi-static test. A surrogate based on a 3D scan of a forearm was found to be the most representative and offer the best differentiation between products. An impact test replicating injurious snowboard falls was developed to measure peak vertical force, energy absorption and wrist extension angle. The impact test mimics boundary conditions known to result in a wrist fracture by applying a load to an instrumented surrogate via a pendulum. Experimental tests validated that both setups can detect differences in protector design. Twelve products were tested with each setup, differences in quasi-static rotational stiffness; peak vertical force, time to peak and energy absorption during impact were observed between products. However, none of the tested products effectively lower the force below fracture threshold. Future research should focus on improving the bimodality of the surrogate and investigating the influence of protector design on injury risk for a range of inbound conditions.