Stroke is a leading cause of adult disability in the United States, affecting nearly 800,000 individuals annually [1]. Functional impairment of individuals post-stroke increases the risk of falls and reduces quality of life [1]. Post-stroke physical therapy focuses on recovering the ability to walk and improving walking quality [2, 3]. Physical therapy involving repetitive mass practice and task-specific training has shown positive results in motor recovery [4,5,6], with the amount of practice during training positively associated with gait relearning [7, 8].
In addition, individuals experience rapid changes in their neuromotor
pathway within three months following stroke incident, often defined as
subacute phase of stroke [9].
Unsurprisingly, inpatient rehabilitation during this period has a large
impact on the motor recovery, expected mobility, and independence in
activities of daily living, especially for severely to moderately
affected patients [10].
However,
the significant mobility deficits exhibited by individuals with
subacute stroke adds substantial physical burdens on physical therapists
(PTs) during inpatient rehabilitation. Specifically, PTs may experience
difficulty with manual lifting, static holding, and maintaining
challenging postures which are necessary therapeutic handling [11, 12].
To promote safe ambulation for individuals with low mobility during
gait retraining therapies, PTs must not only support body weight and
assist with balance control, but also advance the patients’ limbs
manually [13, 14] mainly due to their weakened hip flexors at movement initiation [15].
Coordinating these activities leads to high loads on the PT’s
musculoskeletal system and induces a high risk of work-related disorders
[11, 16].
Therefore, reliance on manual assistance provided by PTs makes it
challenging for patients to receive mass practice that is essential in
promoting motor recovery during inpatient rehabilitation [3, 17, 18].
In
the past few decades, various electromechanical devices have been
developed to assist ambulation of patients and reduce musculoskeletal
load in PTs by providing body weight support and limb advancement
assistance during gait retraining [16]. Examples of these devices include partial body weight supported treadmill training (PBWSTT) [19], end-effector-type gait devices [20], and portable exoskeletons [21, 22]. The use of electromechanical devices allows severely impaired patients to receive repetitive mass practice early [23, 24]
and reduces the physical burden experienced by PTs. Interventions
incorporating these devices have been shown to provide either improved
or similar benefits compared to conventional therapy [13, 19, 22, 24,25,26,27,28,29,30,31,32,33,34,35].
However, while there has been recent development of electromechanical
devices that enable gait retraining in diverse environments [36], the majority are limited to being used overground or on a treadmill [19,20,21,22]. Moreover, existing devices can involve substantial setup time, a high learning curve [37,38,39], or multiple PTs to operate [19, 27, 40]. Over the progression of rehabilitation, individuals post-stroke may no longer require substantial body weight support [26, 41]; however, they may continue to require limb advancement assistance across all stages of recovery [15, 42].
Devices that can assist limb advancement in a diverse range of
activities and environments have the potential to promote gait
relearning during inpatient rehabilitation more effectively.
The use of soft exosuits has been explored as a mean to deliver assistance for individuals post-stroke [43,44,45,46,47,48,49,50].
Contrary to rigid exoskeletons, exosuits do not provide body weight
support. Instead, they utilize a lightweight and non-restrictive
approach to allow assistance to supplement an individual’s walking
capacity. Previous studies have evaluated the effect of exosuit
assistance in individuals with chronic stroke. In these studies,
exosuits effectively targeted the ankle to provide both immediate (i.e.,
orthotic effect) [43] and rehabilitative (i.e., therapeutic effect) [44,45,46]
functional and biomechanical benefits in individuals post-stroke.
Recently, a few preliminary studies have demonstrated a positive
orthotic effect in biomechanical strategies of exosuits targeting the
hip in individuals with chronic stroke [47, 48, 50].
The weakened hip flexors typical in individuals in their early stages
of stroke recovery often contribute to difficulty in limb advancement
and require manual assistance from PTs. Therefore, we anticipate that
exosuit providing hip flexion assistance may be particularly useful
during inpatient rehabilitation for individuals post-stroke to reduce
the physical burden of PTs, promote mass practice, and maximize recovery
progress. Unfortunately, the use of hip exosuits to aid inpatient
rehabilitation during the early stages of stroke recovery is unexplored.
The
objective of this study was to assess the feasibility of implementing a
unilateral hip flexion exosuit as a tool to aid paretic limb
advancement during inpatient gait retraining for individuals
post-stroke. We describe the design of the exosuit, focusing on the
integration of different suit components that enabled PTs to use the
exosuit without in-person technical support. The exosuit was used
concurrently with standard inpatient rehabilitation for 14 patients,
each for one to two weeks. We quantified various clinical and
spatiotemporal measures to investigate the role of our exosuit in
reducing PT burden and improving the walking capacity of individuals
post-stroke with various levels of impairment over the course of their
recovery.
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