A biomechanical study of upper extremity kinetics during walker-assisted gait

Rebecca Ann Bachschmidt, Marquette University

Abstract

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 quantitated the changes in upper extremity kinetics that occur with the use of a standard walker, which was the objective of this study. The following specific aims were accomplished. A strain gage-based walker instrumentation system was developed for the six degree-of-freedom measurement of resultant subject hand loads. An upper extremity kinetic model was developed for determination of internal forces and moments at the wrist, elbow and shoulder in the three clinical planes using the inverse dynamics method. Preliminary system data were collected for ten 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. Subjects were taught a 3 count, delayed 5-point walker-assisted gait pattern. Weight bearing on the right lower limb was prescribed (0%, 10%, and 50% $\pm$ 5% body weight). A battery-powered, audio feedback system was employed to ensure adherence to specified weight bearing levels. Subjects were then asked to walk using the instrumented walker on a 10 m walkway at a randomly assigned weight bearing level. Three trials were conducted for all subjects for each of the testing conditions. Results of the study showed that the ranges of upper extremity joint motion were significantly (p $\le$ 0.05) greater in the sagittal plane, similar to the lower extremities. Adduction moments at the shoulder $({-}0.36\pm 0.15$ Nm/kgm) were significantly greater than at either the elbow $({-}0.19\pm 0.10)$ or wrist $(0.06\pm 0.03).$ However, elbow extensor and rotator moments $({-}0.47\pm 0.15,\ {-}0.18\pm 0.09)$ were significantly greater than shoulder $(0.29\pm 0.15,\ {-}0.08\pm 0.04)$ or wrist $(0.09\pm 0.05,\ {-}0.06\pm 0.02)$ extensor and rotator moments for all loading levels. Internal joint moments at the wrist, elbow, and shoulder significantly increased as lower limb loading was decreased from 50%, to 10%, and to 0% body weight. This preliminary work suggests that with a pick-up walker the arms partially take on the role of legs, supporting the body against ground reaction loads and experiencing intersegmental demands similar in magnitude to level walking.

Recommended Citation

Bachschmidt, Rebecca Ann, "A biomechanical study of upper extremity kinetics during walker-assisted gait" (1997). Dissertations (1962 - 2010) Access via Proquest Digital Dissertations. AAI9823976.
http://epublications.marquette.edu/dissertations/AAI9823976

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