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	Search  SITE MENU Homepage Becoming a Member Member Directory Members Only Board of Directors PFOLA Research Grant PFOLA Technical Standards BAPFOL Accredited Facilities BAPFOL Quality Standards Professional Partners Supporting PFOLA Technical Topics Calendar of Events PFOLA   Prescription Foot Orthotic Laboratory Association   info@pfola.org   Sitemap		PFOLA Message Board Welcome to PFOLA's message board. Please feel free to discuss issues related to orthotics, pedorthics, and biomechanics with your professional colleagues. Subject Effects of orthotic shell rigidity Date Fri Jul 27 2001 14:05 Author Chris MacLean (cmaclean@parisorthotics.com) Dear PFOLA friends: I have a question for you and it is more of a technical question pertaining to how anatomy and design issues can affect the functional performance of an orthotic shell. We have believed for quite some time and have had confirmation from an engineer friend that several factors can affect the functional rigidity or stiffness of an orthotic shell. These factors include: heel cup depth, foot architecture and the addition of an extrinsic rearfoot, or forefoot, post. For instance, if the shell material and thickness were held constant: 1) a fabricated shell for a cavus foot would be more rigid than for a planus foot; 2) an orthotic shell with no added components, i.e. extrinsic RF or FF post would be more flexible than one with added components; and 3) an orthotic shell with an 18mm heel cup would function more rigid than one with an 8mm heel cup. Do you have any insight into the physics that dictates this performance? Do you agree with our observations? Are you aware on any research that has looked at the stiffness of orthoses on axial load, i.e. different shell materials, with and without post components, etc? Any information would be greatly appreciated. Cheers, Mac Christopher L. MacLEAN, M.Sc. (Human Kinetics) Biomechanics Laboratory Department of Exercise Science University of Massachusetts-Amherst Amherst, MA USA 413-545-2906 Paris Orthotics Lab Division National Lab Service Marketing 48 East 69th Avenue Vancouver, BC Canada 604-301-2158 800-848-0838 (X15) Click here for this discussion's index
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