Leg Stretching Using a Controllable Wearable Exoskeleton on Demand for People with Spasticity

Spasticity is a debilitating condition in people with upper motor neuron disorders that interferes
with an individual’s activities of daily living and sleep. Spasticity can lead to loss of body control
and balance resulting in falls, pressure injury of the skin, contractures, and pain. Spasticity hinders
the ability to functionally use voluntary muscle contraction; thus, limiting body transfers,
ambulation, and exercise. Despite the negative impact of spasticity in people with spinal cord
injury (SCI), the available tools to manage spasticity and overcome functional deficits are limited.
Oral medications are typically prescribed at the start of treatment due to its ease of administration;
however, they may induce significant side effects including drowsiness and muscle weakness,
and their effectiveness is sensitive to dosing fluctuations. Neurosurgery can treat severe
spasticity, but it carries surgical risks, and the long-term benefits vary across individuals.
Manual therapy and leg stretching are primary treatments for a large subset of people with
spasticity, which is usually performed by caregivers and nurses with relatively low adverse effects.
Manual stretching can provide relief from muscle spasms, decrease joint stiffness, normalize
muscle tone, reduce pain, and improve range of motion. However, providing on-demand, reliable
manual limb stretching is caregiver intensive and imposes a heavy burden on nurses in hospitals
and caregivers at veterans’ homes. COVID-19 has exacerbated difficulties in receiving manual
stretching to manage spasticity by limiting physical assistance in veterans with SCI due to family
visit restrictions and staffing shortages. Moreover, existing devices used to mitigate spasticity
such as passive stretchers, casts and night splinters do not fully conform to the user's body and
are typically bulky and lack versatility to customize the forces applied to the user. People wearing
them may feel discomfort, weakness, or pain, and even experience pressure sores.
Our long-term research goal is to develop novel, non-invasive rehabilitation strategies
addressing the debilitating effects of spasticity, which can play an integral role in improving quality
of life and independence in persons with upper motor neuron injury. This feasibility study will
establish preliminary evidence for the development of a novel wearable, portable leg exoskeleton
capable of providing leg stretching - similar to the manual stretching provided by caregivers. The
objectives in this project are to 1) integrate a wearable exoskeleton and its closed-loop control
algorithm to provide strategic joint forces to assist dynamic leg stretching; and 2) evaluate the
stretching approach in 10 veterans with spasticity to establish safety, acceptability, ease of use,
and user satisfaction. Our central hypothesis is that the intelligent velocity control of the wearable
device can apply safe forces about the hip and knee joints to yield safe, automated stretching as
needed in veterans with spasticity. The control algorithm enables leg stretching while veterans lie
on a bed (supine position with their knee extended) and sit down (with their knee flexed) with
customized stretching rates to account for differences in range of motion across participants.
Questionnaires are used to collect veteran’s and clinician’s feedback on the device performance.
This study contributes to advancing non-invasive, non-pharmacological tools to manage
spasticity by establishing the feasibility of the wearable stretching device in veterans with SCI.
The project can lead to a customized, on-demand tool for the clinic and home, which can alleviate
the burden on caregivers, aid quantifying the long-term effects of stretching using clinical and
functional measures, and facilitate the integration of the device with other treatment modalities.

Grant Number: 5I21RX004652-02
NIH Institute/Center: VA
Principal Investigator: Steven Brose