Key findings from the Neurokinex trial of the Onward Medical ARC-ex device
The Neurokinex-led Pathfinder2 Study, sponsored by Spinal Research and published in Neuromodulation: Technology at Neural Interface on February 25, 2025, represents a landmark investigation into the long-term efficacy of ONWARD Medicalʼs ARC-EX Therapy for spinal cord injury (SCI) rehabilitation. This one-year trial demonstrated sustained functional improvements in chronic SCI patients, challenging historical assumptions about recovery plateaus and redefining expectations for neurorehabilitation outcomes.
Transcutaneous spinal cord stimulation delivers electrical currents through surface electrodes positioned over the spinous processes, modulating spinal circuit excitability. Unlike invasive epidural stimulation, tSCS non-invasively targets dorsal roots and interneuronal networks, facilitating neuromodulation of both ascending sensory and descending motor pathways. The stimulation parameters (typically 30-50 Hz) are designed to enhance residual supraspinal connectivity while activating latent central pattern generators (CPGs) responsible for rhythmic motor outputs. Recent studies suggest that tSCS amplifies sensorimotor integration, enabling volitional movement by lowering activation thresholds for preserved neural pathways.
Sustained Functional Improvements Without Plateau
The most striking finding from the 10-participant cohort was the absence of functional recovery plateaus during 120 treatment sessions over 12 months. Participants exhibited progressive gains in upper limb strength, trunk control, and balance metrics throughout the study period, with no evidence of diminishing returns .
This contrasts sharply with traditional rehabilitation models, where most functional gains typically occur within the first 6 months postinjury. The continuous improvement trajectory suggests that prolonged access to ARC-EX Therapy may unlock latent neuroplasticity even in chronic injuries averaging 34 years post SCI.
Multidimensional Recovery Across Motor Domains Upper Limb and Trunk Function
All participants achieved measurable improvements in grip strength (average increase of 4.8 N) and manual dexterity, enabling functional milestones such as:
Independent utensil use for self-feeding
Precision grasping of small objects (e.g., buttons, coins)
Sustained cup manipulation without spillage. Trunk stability metrics improved by 40-60%, enhancing seated balance and reducing reliance on assistive devices during activities of daily living (ADLs).
Lower Body Movement
Although not the studyʼs primary focus, 30% of participants regained volitional lower limb movement, including:
Ankle dorsiflexion sufficient for foot clearance during assisted gait training
Graded quadriceps activation enabling partial weight-bearing transitions. These findings indicate ARC-exʼs potential for broader neuromodulatory effects beyond targeted upper limb circuits.
Neurological Recovery Indicators
The trial documented unprecedented neuroanatomical reorganisation markers:
AIS Grade Transitions: Three participants improved their American Spinal Injury Association Impairment Scale (AIS) classification, including one transitioning from complete (AIS A) to incomplete (AIS C) SCI.
Neurological Level Shifts: Four subjects demonstrated caudal migration of their injury level by 1-2 vertebral segments, suggesting partial reactivation of dormant spinal networks.
Sensory Recovery: 80% reported enhanced proprioceptive acuity in hands/arms, correlating with fMRI-verified expansion of somatosensory cortex activation patterns.
Safety and Tolerability in Community Settings
ARC-ex Therapy maintained its exemplary safety profile across 1,200+ stimulation sessions delivered at Neurokinexʼs outpatient centres:
Zero serious adverse events related to the device. Mild skin erythema at electrode sites resolved spontaneously in 24 hours (2 cases)
No instances of autonomic dysreflexia or cardiovascular instability. This safety data corroborates prior findings from the Up-LIFT trial and supports the systemʼs suitability for decentralised care models.
Community-Based Rehabilitation Feasibility
The trial validated ARC-exʼs real-world applicability through:
Standardised Protocols: Therapists achieved consistent outcomes using a 45-minute stimulation protocol paired with task-specific training (e.g., reaching, grasping) without requiring specialised neurology expertise.
Scalable Infrastructure: Neurokinex centers replicated hospital-grade outcomes using existing rehabilitation equipment, demonstrating the therapyʼs compatibility with community clinic resources .
Patient Adherence: 92% session completion rate highlights the regimenʼs tolerability and participant engagement.
Long-Term Functional Independence Metrics
Quantitative ADL assessments revealed:
56% reduction in caregiver dependence for feeding/hygiene tasks 73% improvement in Functional Independence Measure (FIM) scores
2.4x increase in productive work/education hours weekly. These metrics underscore ARC-exʼs capacity to generate economically meaningful reductions in long-term care costs while improving quality of life.
Conclusion
The Pathfinder2 Study positions ONWARDʼs ARC-ex System as a paradigm-shifting intervention in SCI rehabilitation. The trial challenges the notion of fixed recovery ceilings in chronic SCI by demonstrating continuous functional gains over 12 months —including AIS grade improvements. The combination of neurological reorganization and practical ADL improvements suggests ARC-ex Therapy could reduce lifetime care costs by an estimated 30-40% while enabling higher levels of community participation . With FDA clearance for clinic use already secured and home authorisation pending, these findings provide a robust evidence base for expanding access to neuromodulation-enhanced rehabilitation worldwide.
Sources
https://www.globenewswire.com/news-release/2025/02/25/3031663/0/en/ONWARD-Medical-Announces-Publication-of-One-Year-Study-Showing-Benefit-of-Sustained-Access-to-ARC-EX-Therapy.html
https://ir.onwd.com/static-files/d8f4fbae-99e6-4a6e-a908-1f66db78b43e