Training Persons with Spinal Cord Injury to Ambulate Using a Powered Exoskeleton

The overall goal of this training program is to provide some guidelines and standardize a training program to teach individuals with spinal cord injury how to ambulate using a powered exoskeleton. This method can help answer key questions in the powered exoskeleton field, such as progression of training, and types of activities to develop necessary skills to use these devices independently. The main advantage of this technique is that it provides specific guidelines and structured activities to train individuals with little to no volitional movement in their lower extremities to ambulate using the powered exoskeleton, which is an emerging technology.

The implications of this technique may extend towards stroke therapy, since neural plasticity potentially allows new regions of the brain to make new neural connections in order to perform functional tasks. Generally, individuals new to this method will struggle because they're not accustomed to properly shifting their own body weight to allow for the device to walk, let alone standing upright. Begin by placing the participant in the supine position.

Use a flexible tape measure to determine the pelvic width, upper leg length, as well as lower leg length, and record in centimeters. Measure the upper leg length from the most prominent point of the greater trochanter of the hip to knee joint line. Measure the other limp in the same manner and record any discrepancies in limb length.

Adjust the powered exoskeleton from the center of the hip axis to the center of the knee axis, according to the distance measured on each of the participant's upper leg lengths. Next, measure the lower leg length from the knee joint line to the bottom of the foot. Repeat this measure for the other lower leg length.

Adjust the length from the bottom of the foot plate to the center of the knee access of the powered exoskeleton for each lower limb, according to the distance measured from the participant in a similar manner done with the upper leg. Place the pelvic band closest in size to the participant's pelvic width behind the person and slowly move it forward to test for a fit. Next, place the exoskeleton in a seated position on a chair with an open back.

Next, have the participant sit down in the device, and instruct them to place their feet in the shoes. Continue securing the straps, starting at the most distal point and moving proximally up the body, finishing with the chest straps. Then, guide the foot completely into the shoe, taking special care to ensure that the toes are not curled.

After securing the feet in the shoes, secure the straps directly below the knees. Then, secure the straps above the knees, and those on the upper thighs, taking care to avoid crumpling any clothing beneath the straps, which may lead to unwanted friction or pressure points of contact. Finally, secure the chest strap.

Begin by equipping the participant with a set of forearm crutches to assist with balance and maneuverability of the device. While seated in the exoskeleton, instruct the participant to place the tips of the crutches posteriorly in a manner that gives them the ability to push their weight over their feet. Next, explain the sit to stand procedure to the participant.

Have one trainer assist from behind, and another guard from the front. Then, instruct the participant to stand on their own, and only use trainer assistance as needed. Instruct the participant to press the stand command, and then place the crutches posteriorly and lean forward while pushing off the crutches to assist the device in standing them upright.

During the first occasions of standing, assess if the pelvic band needs adjustment in the front and back. Position appropriately so that the trochanter is in line with the rotation of the hip joint. Ensure the participant is capable of balancing while standing by asking them to demonstrate the ability to stand in the home position by using both crutches to maintain balance.

Then, ask the participant to practice slight shifting of their weight laterally and posteriorly to understand the location and feel of the home position. Next, instruct the participant to maintain balance with only one crutch, by lifting one crutch off the ground, and holding that stance up to one minute. Add some complexity to this one handed balance exercise by having one arm balancing while the contralateral arm reaches over to touch the balancing arm's wrist.

Finally, teach he participant to weight-shift laterally, allowing one foot to offload, with the goal of lifting the foot completely off the ground for five seconds. Instruct the user to repeat this exercise with the other leg. Begin by instructing the participant in the mechanism of walking with the powered exoskeleton.

Use the controller to select the walk mode, and ask the participant to shift slightly forward toward a predetermined target in order to initiate forward swing of the right leg. Next, instruct the user to move their crutches forward while simultaneously shifting their weight forward into the right in order to maintain balance while stepping onto the right foot and unweighting the left foot. Explain to the participant that the device will sense the participant's movement and will initiate forward swinging of the left leg.

If needed, spot the user by grasping the powered exoskeleton, or provide assistance in an area of the body in which the user has intact sensation, such as the shoulder area. Correct the participant as they perform the proper weight shifting while walking. Next, describe the list of mobility skills to the participant that will be practiced as part of the training.

Incorporate different walking surfaces during the training session, such as carpet, concrete, asphalt, and grass so that the participant is able to practice walking on a variety of surfaces with the exoskeleton. Additionally, ask the participant to walk on surfaces with varying slopes, such as up a ramp, down a ramp, across a curb cutout, and on uneven surfaces. Then, have the participant walk in a noisy environment, such as a hallway with other pedestrians.

Practice navigation of doorway thresholds, opening and closing doors, and walking through automatic doors. Incorporate additional activities such as reaching overhead into a cabinet, or sitting on and standing up from a bench. Finally, have the participant practice stopping on command or at will.

Begin by placing a chair behind the user when they are ready to sit. Use the controller of the exoskeleton to activate the sit mode for which there is a five second delay. During this delay, ask the participant to place their crutches posteriorly to maintain their center of balance over the chair.

Finally, during the sitting process, instruct the user to bend forward at the hip to maintain balance over the feet, and have the trainers assist the participant as needed. In this protocol, measurements were obtained from spinal cord injury patients with intact upper extremity function during training sessions that were indoors and outdoors, as well as during mobility skills such as navigating revolving doors. For the ten meter walk test, participants have varying initial ability across sessions to use the powered exoskeleton, as well as varying rates of improvement.

On average, participants walked 0.0048 meters per second faster each session, with an average initial speed of 0.16 meters per second. Once mastered, a typical training session will last between one to one and a half hours, but will vary according to the tolerance of the participant with spinal cord injury. While attempting this procedure, it's important to remember to be patient with the person learning, and if needed, switch to a different exercise, and come back to the troublesome task on a different day.

Following this procedure, other methods like walking on complex surfaces, like carpeted ramps, can be performed to answer additional questions such as if a person may have limitations to use the powered exoskeleton.