Measurement of upper extremity joint moments in walker-assisted gait

Although walkers are commonly prescribed to improve user stability and ambulatory ability, quantitative study of the basic biomechanical and functional requirements for effective walker use is limited. To investigate the changes in upper extremity joint moments that occur with the use of a front-wheeled walker, a strain gauge-based walker instrumentation system was developed and integrated with an upper extremity biomechanical model for the load measurement. The designed system performance was testified via non-linearity validation, crosstalk test and force measurement accuracy check, which were found to be better than 2.90, 3.19 and 1.01%, respectively. Preliminary system data were collected for 12 healthy, right-handed young adults following informed consent. Bilateral upper extremity kinematic data were acquired with a six-camera motion analysis system. Internal joint moments at the upper extremity were determined in the three clinical planes using the inverse dynamics method. Results showed that during a basic walker-assisted gait there were several typical demands occurring in walker stance period, including shoulder adductor in the coronal plane, elbow extensor in the sagittal plane and external rotator in the transverse plane. The greatest moment demands are recorded in the shoulder-coronal plane as 0.431 N m/kg m for the study group. Complete description of upper extremity joint moments during basic walker-assisted gait may provide insight into walker use parameters and rehabilitative strategies.