Extending reach: hybrid robotic-functional electrical stimulation training for post-stroke upper extremity rehabilitation.

The study was non-blinded, and the clinical outcome measures (Fugl-Meyer, ARAT, RPSS, MAS) were assessed by an evaluator who knew the group allocation, introducing potential observer expectancy bias. The sample size was very small (20 participants), and the study was a pilot designed for preliminary efficacy, limiting the generalizability of the findings. The intervention duration was relatively short (18 sessions over 6 weeks), which may be insufficient to detect changes in movement velocity or long-term retention of gains. The FES was triggered manually by the therapist rather than automatically, which may affect the consistency and timing of stimulation relative to patient effort. There was no follow-up assessment after the intervention ended, so it is unknown whether the improvements persisted. The study did not compare the hybrid intervention to standard care or other active treatments, only to robotic training alone.

The study was funded by Maryland Industrial Partnerships. The authors declared no other conflicts of interest.

Do not assume that the observed improvements were due solely to the electrical stimulation. The hybrid group received both robotic training and FES, while the control group received robotic training alone, so the specific contribution of FES versus the robot cannot be fully separated. Additionally, the clinical outcomes were rated by a non-blinded evaluator, which may have inflated the apparent benefits of the hybrid intervention.