Feasibility, Usability, and Preliminary Kinematic Outcomes of a Hand-Tracking Virtual Reality Rehabilitation System...

Upper extremity motor impairments following stroke substantially limit independence in daily living. Hand-tracking virtual reality (VR) rehabilitation systems may support intensive task-oriented practice while enhancing motivation; however, evidence integrating objective kinematic indicators with usability and patient-reported outcomes for controller-free consumer-grade VR remains limited. The primary aim of this single-arm pilot study was to evaluate the feasibility, safety (tolerability), and usability of a hand-tracking VR rehabilitation system delivered as an adjunct to conventional physiotherapy in individuals with stroke; describing its preliminary in-game kinematic profile and exploring participants' experiences through open-ended feedback were secondary aims. The study was explicitly not designed or powered to test clinical efficacy.

Ten individuals with stroke completed a 20-session (8-week) single-arm pilot intervention; all participants concurrently received standard hospital-based physiotherapy (median 3 sessions/week, ∼45 min/session). Early-phase (sessions 1-5) and late-phase (sessions 16-20) within-subject performance were compared using the Wilcoxon signed-rank test with Holm-Bonferroni correction across four pre-specified primary outcomes. Movement smoothness was assessed using the Spectral Arc Length (SPARC), usability was evaluated using the System Usability Scale (SUS), and cybersickness was monitored with the Simulator Sickness Questionnaire (SSQ).

Sixteen patients were screened, of whom fourteen started the intervention and ten completed the 8-week per-protocol program (intervention completion rate, 10/14 = 71.4%; per-protocol session adherence among the ten completers, 200/200 = 100%; no SSQ-defined adverse events). Within-subject comparisons showed a +10.6-point increase in success rate (adjusted p=0.020), a +0.10 m/s increase in mean movement speed (adjusted p=0.020), a -341 ms reduction in pause duration (adjusted p=0.022), and a +27.0-point Hodges-Lehmann median-difference increase in SS-QOL (95% CI 14.0-41.0; participant-level median Δ+18.5; adjusted p=0.020). The mean SUS score was 78.5±5.4, indicating "good" usability. Thematic analysis of post-intervention open-ended feedback identified three themes-motivation and engagement, the value of feedback, and design and comfort suggestions-that converged with the high adherence and good usability ratings. Correlations between VR-derived kinematic change and clinical change were non-significant trends (p≥0.12).

A controller-free hand-tracking VR system was found to be feasible, well tolerated, and rated as having good usability when delivered as an adjunct to conventional therapy. Because the study used a single-arm design, included only ten participants, and did not control for the confounding effect of concurrent conventional physiotherapy or natural recovery, the observed within-subject changes cannot be causally attributed to the VR intervention and should be interpreted as exploratory feasibility signals. Adequately powered randomized controlled trials with stroke-specific clinical scales (e.g., FMA-UE, ARAT) are required before clinical efficacy can be claimed.