Safety assessment and feasibility of the TWIICE powered exoskeleton for assisted ambulation in individuals with spinal cord injury.

Background: Following spinal cord injury (SCI), powered exoskeletons have been shown to enable assisted walking and may also positively impact secondary health conditions. The TWIICE exoskeleton is intended to enable individuals with SCI to train at home or in community during their activities of daily living under the supervision of a therapist. The aim of this pilot clinical trial was to assess the safety and feasibility of the TWIICE powered exoskeleton for assisted ambulation in a clinical setting.

Methods: This single-arm, open label feasibility study included 5 non-ambulatory individuals at least 6 months after onset of traumatic or non-traumatic SCI. Participants used the TWIICE exoskeleton during 6 sessions in the therapy premises of a Swiss SCI-specialized clinic undergoing a progressive mobility training. The incidence of adverse device effects (ADEs) was the primary outcome. In addition, standard walking tests such as 10 m Walk Test (10MWT), 6-minute Walk Test (6MWT), and Timed Up and Go (TUG) were performed using the device during the final session to evaluate usability after short-term training. Data are presented as median (range).

Results: We recruited 5 non-ambulatory individuals with SCI (2 females / 3 males, 32 (21-45) years of age). Four participants were motor complete (T6-T11) and 1 was motor incomplete (C7). Of the 10 adverse events occurring over the course of the 30 cumulative sessions, 4 were categorized as ADEs: reddening of the skin at contact points with the device (2x), transient intensification of neuropathic pain, and transient increase of spasticity. All ADEs subsided after a short time and without any sequelae. After 6 sessions, participants walked the 10MWT in 33 (24-144) seconds and were able to achieve 98 (37-137) meters during a 6MWT while using the device. Finally, the TUG was performed with the device and moderate assistance in 103 (61-135) seconds.

Conclusions: No serious safety concerns were identified during this feasibility study in a clinical setting. After 6 sessions, our relatively young and fit study population showed a variable but generally good performance in clinical measures when compared to reports on commercialized powered exoskeletons.

Trial registration: ClinicalTrials.gov ID: NCT05926310.