A robotic-assisted intervention (ROBERT®) to enhance muscle strength in the hip flexor muscles following spinal cord injury: A pilot within-person randomized controlled trial

Objective: To determine whether a robotic-assisted intervention increases hip flexor muscle strength in people with spinal cord injury (SCI) and marked neurological weakness. The robotic-device (ROBERT®) supports the weight of the leg and guides it through assisted active or resisted active hip flexion movements. Study design: Pilot within-person randomised controlled trial. Setting: Specialized SCI center in Denmark. Methods: Twelve people with incomplete SCI <12 months, aged ≥18 and grade 1-3/5 strength on a Manual Muscle Test in the right and left hip flexor muscles were recruited. One leg of each person was randomised to receive additional ROBERT® treatment. All other care remained the same for both legs. Randomization was stratified based on hip flexor muscle strength. Treatment of the experimental leg consisted of 60 assisted active or resisted active hip flexion movements with the robotic device three times a week for eight weeks. The primary outcome was maximal voluntary isometric contraction (MVIC). Secondary outcomes were root mean square of a surface electromyography signal, muscle thickness, the number of hip flexion movements per day, and self-reported perception of function and strength. Participants were assessed at baseline and post-intervention. Results: Eleven out of 12 participants completed the study. There were no statistically significant between-group differences for MVIC (mean and 95% CI was −2.7 Nm, −8.1 to 2.7) or any of the secondary outcomes (except the number of hip flexion movements per day). Conclusion: The robotic-assisted intervention did not increase hip flexor strength in people with incomplete SCI and marked neurological weakness.