Development and Application of a Virtual Reality Stumble Method to Test an Angular Velocity Control Orthosis

Stance control orthoses stabilize and support users during weight bearing while permitting free knee motion during swing. An angular-velocity control knee joint (Ottawalk-Speed, OWS), prevents knee collapse during a stumble while offering a lightweight and compact design. The purpose of this study was to develop a virtual perturbation to measure OWS response to a stumble, when worn by knee-ankle foot orthosis (KAFO) users.;A split speed perturbation, developed for the CAREN-Extended system, was tested on five able-bodied participants during treadmill level walking. Three KAFO users, with the OWS, were subjected to the perturbation during five level walking trials. Kinematic data were collected at 120 Hz during testing and OWS user feedback was collected via a questionnaire. Lower body joint kinematics and questionnaire responses were evaluated.;Two recovery strategies were observed for able-bodied participants: hopping and stopping. Knee flexion increased at recovery weight acceptance for all trials. OWS participants used a straight-legged strategy to recover from the split speed perturbation, with an extended knee throughout weight acceptance. OWS questionnaire evaluation revealed positive responses to walking ability, with ease of use receiving some negative comments.;The split speed perturbation was not able to produce sufficient knee flexion upon landing for the KAFO users, for OWS stumble evaluation. The OWS was successful in allowing free knee motion when walking on level, incline, and uneven surfaces. Further study is required to measure OWS response in stumble situations typically experienced by the target population.