Powered Orthotic Exoskeleton Training in Stroke

Ninety percent of stroke survivors have clinically significant gait impairments that lead to secondary medical complications, including cardiovascular deconditioning and reduced quality of life (QOL). Several rehabilitative interventions that increase the level of activity and mobility have been shown to be beneficial. Challenges posed by most of these locomotor gait training interventions require recurring visits to a rehabilitation center. The recent development of novel powered exoskeletons offers a potential mechanism for stroke survivors to improve mobility in the home and community. Although the predominant research using these devices have been in persons with spinal cord injury, there are currently two devices are commercially available for use in patients with stroke and additional devices are being developed. The Keeogo powered orthotic exoskeleton is a novel device intended for persons with stroke who can ambulate but have gait impairment. This device consists of a ridged orthotic structure placed over clothing on the legs and batteries to the power motors that assist both knees in gait movement. The system monitors hip movement driven by the user and interprets this movement to apply the appropriate assistance at the knee joint. This unique approach makes learning intuitive, enabling the user only to acclimate to the system rather than learning how to control the device to initiate the desired movement.

This proposal is a randomized controlled pilot study. Fifteen veterans with chronic stroke (>6months) and who retain some ability to take steps but have impaired gait will be recruited. Ten participants will be randomized into the exoskeleton group and 5 into the control group. Both groups will be asked to complete 36 one-hour sessions of ambulation training. The exoskeleton group will train using the Keeogo powered orthotic exoskeleton and the control group will train without using their own conventional aide.

The primary aim is to determine the efficacy of training with this exoskeleton and its ability to improve transfers to standing and sitting as assessed by the five times sit-to-stand test. A secondary aim will be to assess effects of the device during overground ambulation. Outcome measurements to investigate changes of knee range of motion and loading of the paretic limb. An exploratory outcome of changes in energy expenditure during ambulation with and without the powered exoskeleton. Additional exploratory outcome measures of QOL will be determined.

Inclusion criteria

• Males and female between 18 and 89 years old;
• Hemiplegia or hemiparesis due to stroke (>6 months);
• [Able to walk between 0.15-0.75m/s]
• Self-reported limitations to mobility and walking activities due to paretic side knee stiffness and loss of range of motion;
• Weight under 250lbs
• Desire to increase daily activity levels; and
• Able and willing to commit to participation and follow directions and communicate basic needs.

Exclusion criteria

• Neurological paralysis causing an inability to stand, weight bear or take stepping movements;
• Fixed contractures resulting in limited range of motion in the hip, knees, or ankles that prevent sitting, standing, walking, and/or squatting activities;
• Modified Ashworth Scale for spasticity greater than 3 in the lower limbs
• Able to walk at a normal walking speed (1.4 m/s, 3.2 mph) or better during the Six Minute Walk Test (6MWT)
• Anthropometric incompatibility with the device

• Femur length less than 36 cm or greater than 45 cm;
• Upper thigh circumference less than 55 cm or greater than 75 cm;
• Lower thigh circumference less than 27 cm or greater than 40 cm;
• Calf circumference less than 33 cm or greater than 49 cm;
• Ankle circumference less than 27 cm or greater than 40 cm;
• Shin length less than 26 cm;
• Waist circumference less than 71 cm or greater than 107 cm;
• Any medical complication or co-morbidity as judged by the study physician to be contraindicated for wearing the device or walking (e.g., cardiovascular disorders, pressure ulcers, open wounds, lower limb vascular disorders, or other medical conditions); and
• Pregnant or planning to become pregnant (Females only).