Overground Walking Program With Robotic Exoskeleton in Long-term Manual Wheelchair Users With Spinal Cord Injury

Many individuals with a spinal cord injury (SCI) use a wheelchair as their primary mode of locomotion. The prolonged non-active sitting time associated to this mode of locomotion contributes to development or worsening of numerous adverse health effects affecting musculoskeletal, endocrino-metabolic and cardiorespiratory health. To counter this vicious circle, engaging in a walking program with a wearable robotic exoskeleton (WRE) is a promising physical activity intervention. This study aims to measure the effects of a WRE-assisted walking program on musculoskeletal, endocrino-metabolic and cardiorespiratory health.

Many individuals with a spinal cord injury (SCI) rely on manually propelled wheelchairs as their primary source of locomotion, leading to increased non-active sitting time, reduced physical activity and reduced lower extremity (L/E) weight bearing. This contributes to the development or worsening of complex and chronic secondary health problems, such as those affecting musculoskeletal (e.g., osteoporosis), endocrine-metabolic (e.g., hypertension, dyslipidemia, type 2 diabetes) and cardiorespiratory (e.g., poor aerobic fitness) health. Ultimately, these health problems may negatively affect functional capabilities and reduce quality of life.

Preliminary evidence has shown that engaging in a walking program with a wearable robotic exoskeleton (WRE) is a promising intervention. In fact, WRE-assisted walking programs promote L/E mobility and weight bearing (a crucial stimulus for maintaining bone strength in individuals with SCI), while also soliciting the trunk and upper extremity muscles and cardiorespiratory system.

This study aims to measure the effects of a WRE-assisted walking program on 1) bone strength, bone architecture and body composition, 2) endocrino-metabolic health profile and 3) aerobic capacity.

Twenty (20) individuals with a chronic (\> 18 months) SCI will complete 34 WRE-assisted training sessions (1 h/session) over a 16-week period (1-3 sessions/week). Training intensity will be progressed (i.e., total standing time, total number of steps taken) periodically to maintain a moderate-to-vigorous intensity (≥ 12/20 on the Borg Scale). All training sessions will be supervised by a certified physical therapist.

Main outcomes will be measured one month prior to initiating the WRE-assisted walking program (T0), just before initiating the WRE-assisted walking program (T1), at the end of the WRE-assisted walking program (T2) and two months after the end of the WRE-assisted walking program (T3).

Descriptive statistics will be used to report continuous and categorical variables. The alternative hypothesis, stipulating that a pre-versus-post difference exists, will be verified using Repeated Mesures ANOVAs or Freidman Tests.

Eligibility Criteria:
Inclusion Criteria:

* Traumatic or non-traumatic spinal cord injury between C6 and T10 neurological level at least 18 months pre-enrollment
* Long-term wheelchair use as primary means of mobility (non-ambulatory)
* Normal cognition (Montreal Cognitive Assessment Score ≥26/30)
* Understand and communicate in English of French
* Reside in the community within 75 km of the research site

Exoskeleton-specific inclusion criteria:

* Body mass ≤100 kg
* Height=1.52-1.93 m
* Pelvis width=30-46 cm
* Thigh length=51-61.4 cm
* Lower leg length=48-63.4 cm
* Standing tolerance ≥30 minutes with full lower extremity weight-bearing

Exclusion Criteria:

* Other neurological impairments aside from those linked to the spinal cord injury (e.g., severe traumatic brain injury)
* Concomitant or secondary musculoskeletal impairments (e.g., hip heterotopic ossification)
* History of lower extremity fracture within the past year
* Unstable cardiovascular or autonomic system
* Pregnancy
* Any other other conditions that may preclude lower extremity weight-bearing, walking, or exercise tolerance in the wearable robotic exoskeleton

Exoskeleton-specific exclusion criteria:

* Inability to sit with hips and knees ≥90° flexion
* Lower extremity passive range of motion limitations (hip flexion contracture ≥5°, knee flexion contracture ≥10°, and dorsiflexion ≤-5° with knee extended)
* Moderate-to-sever lower extremity spasticity (\>3 modified Ashworth score)
* Length discrepancy (≥1.3 or 1.9 cm at the thigh or lower leg segment)
* Skin integrity issues preventing wearing the robotic exoskeleton