While walkers are commonly prescribed to improve patient stability and ambulatory ability, quantitative study of the biomechanical and functional requirements for effective walker use is limited. To date no one has addressed the changes in upper extremity kinetics that occur with the use of a standard walker, which was the objective of this study. A strain gauge-based walker instrumentation system was developed for the six degree-of-freedom measurement of resultant subject hand loads. The walker dynamometer was integrated with an upper extremity biomechanical model. Preliminary system data were collected for seven healthy, right-handed young adults following informed consent. Bilateral upper extremity kinematic data were acquired with a six camera Vicon motion analysis system using a Micro-VAX workstation. Internal joint moments at the wrist, elbow, and shoulder were determined in the three clinical planes using the NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page.

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A noninvasive method for determining the instantaneous axis of rotation (IAOR) of the foot and ankle during human ambulation has been developed. The algorithm uses three-dimensional (3-D) external marker trajectories to describe the IAOR of the calcaneus with respect to the tibia. Multiple optimization techniques were used to fit a plane and a sphere to the marker trajectories, with the constraint that the center of the sphere lie on the plane. The IAOR was defined perpendicular to the plane and passed through the center of the sphere. The results from validation procedures have demonstrated the applicability of the method. Experimental IAOR data acquired from normal adult subjects indicated the ability to track the IAOR during gait. This self-determining system for locating a patient's foot and ankle IAOR during gait may benefit rehabilitation applications in pedorthic and prosthetic design, surgical and nonsurgical treatment, and rehabilitative approaches to suprasegmental functional accommodation.

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