INJURY CRITERIA FOR ATHLETES SUBJECTED TO HEAD IMPACT
AbstractINTRODUCTION - Among the athletic actions leading to human body contact the ones involving head impact and spine loading are particularly problematic as they may lead to serious injuries, even disabilities. This fact has been recognized in different sports, such as American football or cycling where head protective equipment is mandatory. Due to tight safety requirements, the aerospace and automotive industries have their activities bounded by regulations that use measures of the human tolerance to body impact and large accelerations. The criteria used to predict injury, the Head lnjury Criteria (HIC) or the Severity Index (SI), are based on the integral of the head acceleration for a period of time. The potential for injury that they provide have been established as a result of extensive testing. The objective of this paper is to show that these measures can still be used in sports activities. METHODOLOGY - In order for the injury criteria to be used in different situations it is necessary to use a human body model and a proper description of the impact situations A model made of 12 rigid segments is used for this purpose. Here the biomechanical segments are prevented from achieving unacceptable relative positions by a set of penalty forces In the biomechanical joints. The contact of the body segments of different athletes and the surrounding obstacles is modelled using an Hertzian contact theory which accounts for energy dissipation. The model used is general and can be improved to include body protection equipment. RESULTS - The biomechanical model is applied in two cases involving of impact: a car driver and a player experiencing a tackle. For each case the injury criteria are used to predict the potential for injury. Based on the results the application of the automotive industry measures of head injury in sports activities are discussed. CONCLUSIONS - The injury criteria for head impact used in the aerospace and automotive industries is still suitable for application to sports activities. However more detailed models of the head-neck complex and of the spine should be considered. The limits that define the injury potential must also be redefined for sports activities. REFERENCES Jalon, J.G. (1994). Ktnematic and dynamic simulation of multrbody systems, Heidelberg: Springer-Verlag. Wismans, J (1994). Course Notes on Injury Biomechanics, Faculty of Mechanical Engineering, Eindhoven University of Technology, The Netherlands Laananen, D (1 983). Computer Simulation of an aircraft seat and occupant in a crash environment - Vol. 1: Technical report, US Dep. of Transportation, F A A,, Technical Report DOTIFANCT-82133-1 Ruan, J.S., Khalil, T., King, A I. ('1994). Dynamic response of human head to impact by three-dimensional finite element analysis. ASME J. of Biomechanical Engineering, 116. 44-50 Lankarani. H . Malapati. S R., Menon, R. (1993). Evaluation of Head lnjury Criter~a NlAR Report 93-2, National Institute for Av~ation Research. Wichita State University.
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