Pilot usability and participant experience evaluation with an investigational self-balancing overground exoskeleton in adult users with chronic motor-complete paraplegia

Given the increasing interest in self-balancing robotic gait rehabilitation, it is critical to assess usability, operational reliability, and safety considerations prior to clinical deployment. This pilot study evaluated the safety and usability of the XoMotion Beta 2 investigational prototype (hereafter, the Beta 2 prototype), a self-balancing overground exoskeleton intended for supervised walking in adults with motor-complete spinal cord injury (SCI), the primary goal was to collect structured participant and operator feedback during beta-stage testing to inform subsequent device development. This usability evaluation included (i) operator training and familiarization sessions and (ii) intervention sessions with three participants with chronic motor-complete SCI (T3–T10, AIS A–B) conducted over a 4-week period (12 sessions) across three phases. Phase 1 involved an initial screening and intake where participants underwent anthropometric evaluations and device familiarization with a simulator. Phase 2 included device fitting, donning/doffing practice, and baseline performance measurements. Phase 3 consisted of intervention exposure and exoskeleton-assisted training, including sit-to-stand movements, overground walking, and Functional Gait Assessment (FGA)-based tasks. Participants completed a self-administered user experience questionnaire assessing ease of use, user confidence, and system design. Additionally, six operators (research team members) completed an operator experience questionnaire. Adverse events (AEs) and serious adverse events (SAEs) experienced during and after the study were reported. Participants reported high usability including ease of system setup and user confidence, while identifying areas for improvement such as the process of transferring onto the device prior to device donning, clarity of device messaging, and movement transitions. Operator ratings indicated moderate usability, with challenges noted in device setup, joystick responsiveness, and perceived system stability during early familiarization activities. AEs included skin irritation and bruising. One participant experienced a SAE, including a fracture of the tibia during a sit-to-stand-to-sit transfer; contributing factors were considered multifactorial, and post-event review did not identify a confirmed device malfunction. A brief manufacturer commentary providing context on device evolution and development context is included at the end of this manuscript. The Beta 2 investigational prototype demonstrated positive usability from users and potential to support rehabilitation-related activities from operators. Future work should focus on improving system responsiveness and operator workflow, as well as on multifactorial risk-mitigation strategies encompassing participant-specific factors, training and setup conditions, and device operation prior to broad clinical dissemination.