Introduction: Shoulder-to-head contact is the most common cause of concussions in ice hockey, accounting for 42% of cases in the National Hockey League. The goal of this project was to determine how shoulder pad stiffness, modified by adding foam padding over the shoulder cap of existing shoulder pads, affected head impact severity when participants delivered checks to an instrumented dummy.
Methods: Fifteen participants administered "the hardest shoulder checks they were comfortable delivering" to the head of a dummy equipped with triaxial accelerometers and gyros mounted in its helmet. Trials were conducted with participants wearing two common types of shoulder pads, with and without a 2-cm-thick layer of polyurethane foam over the shoulder pad cap.
Results: When participants delivered checks with foam-modified pads versus unmodified pads, there was a decrease of 25.0% in the average peak linear head acceleration (28.73g vs 38.31g, mean difference = 9.58g, 95% confidence interval = 6.35-12.81, P < 0.0001) and a decrease of 12.4% in the average value of peak rotational head velocity (838.0°·s vs 956.7°·s, mean difference = 118.65°·s, 95% confidence interval = 55.37-181.94, P = 0.001). The protective benefit of the foam layer did not depend on the type of shoulder pad or the checking scenario.
Conclusion: The integration of foam padding on top of the plastic caps of shoulder pads reduced impact severity to the head and warrants further examination as a method for contributing to the prevention of brain injuries in ice hockey.