Development of a DIY rehabilitation device for lower limb weakness in acute to subacute ischemic stroke

Many patients have significantly lower limb weakness after getting a stroke. Continuous regular physical therapy is essential to promote the improvement of the weakness and overall outcomes. Home rehabilitation provides motivation and enhances regular rehabilitation in stroke patients. The Do-It-Yourself (DIY) medical device is developed to fill the gap of unmet medical management needs and becomes increasingly applied in rehabilitation. The DIY device should support the concept of home rehabilitation in stroke patients. We designed and developed a low-cost, easy-to-use, DIY rehabilitation device to promote regular physical therapy in stroke patients with lower limb weakness. The methods and rationale of device development were described. The feasibility and safety of the device were also evaluated.• The DIY rehabilitation device for the lower limb is convenient and easy to assembly.• Regular home rehabilitation is enhanced with the DIY rehabilitation device.• The device is feasible and safe for physical therapy in stroke patients with lower limb weakness.


Specifications table
Subject area: Medicine and dentistry More specific subject area: Rehabilitation Method name: Semi-assisted robotic rehabilitation device for lower limb weakness Name and reference of original method:

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Introduction
Stroke is a central nervous system disorder that causes the sudden onset of neurologic manifestations. Dysfunction of blood vessels causes corresponding brain lesions in their feeding area. It is categorized into two main subgroups according to its pathogenesis: ischemic stroke and hemorrhagic stroke. The prevalence of ischemic stroke cases is approximately 85% of all stroke patients, and the remaining 15% are intracranial hemorrhages [1] . Disability is a common condition in acute ischemic stroke patients despite standard treatment [2] . As a result, stroke is the leading cause of disability in adults [3] . Thirty-five percent of stroke patients survived with a significant weakness in the legs. They could not regain their lower limb strength to function, and 25 percent needed help in walking [4] . In patients with acute stroke beginning with complete leg paralysis, only 10 percent of them could return to walking without assistance [5] .
Physical therapy (PT) is an essential treatment for stroke patients. This therapy stimulates the recovery of the motor system of the limbs [6] . Several training methods of PT are available, including constraint-induced movement therapy (CIMT), robotic-assisted rehabilitation, virtual reality, and functional electrical stimulation (FES) [7] . Although all methods should help improve weakness in stroke patients, each method's essential keys to success are still regular performance [8] . Some patients were unable to continue rehabilitation due to insufficient physical therapy medical equipment. There is still a matter of physical therapy techniques. In some hospitals, there are insufficient physical therapists for the number of patients. Also, when the patient returns home, he or she has to continue with physical therapy. Some people still have to return to rehab at the hospital. Due to the need to use physical therapy tools, patients have to pay their money to travel to the hospital. Some poor people from remote areas cannot afford the expense of traveling. As a result, patients with these problems do not have physical therapy regularly. Muscle weakness increases. The joints are stuck. Chronic paralysis puts the patient into a bed-bound condition [9] . However, if a device or method encourages the patient to exercise regularly at home or the nearby community hospital, it will reduce costs.
This research project is designed to develop mechanisms that can help restore lower limb muscle strength. We aim to design a device to assist in physical therapy and prevent the recession of lower limb muscles due to muscle weakness and prolonged bed-bound patients with acute stroke. Therefore, we are interested in machine or robotic rehabilitation methods to perform lower limb muscle rehab since in bed. Considering the speed of recovery, tool performance, ease of use should help keep the muscles power, and the patient returns to a routine or the most normal equivalent. We also conducted a comparison study between experimental (lower limb rehabilitation machine) and control (standard treatment) groups for the feasibility of the device use.

Methods
We conducted two steps of developing a DIY Rehabilitation Machine consisting of the prototypes of lower limb rehabilitation machines and the generated machines to collect clinical data.
1. Create a prototype of the lower limb rehabilitation machine.
1.1. We studied literature review, related research, clinical features, and physical therapy using various stroke treatment methods. 1.1.1. We designed the device by SolidWorks program based on the lower limb movement, including hip lifting-up, hip flexion-extension, knee flexion-extension, and ankle dorsiflexionplantarflexion as shown in Fig. 1 . 1.1.2. We calculated motor power and designed a regeneration operation circuit of lower limb muscles. The force was calculated from the three lower limb movement patterns, which consisted hip-knee flexion-extension, (2) hip lifting (bridging), and (3) ankle dorsiflexionplantarflexion of (1). We calculated by determining the extent to which the patient's weight is up to 80 kg and a height of approximately 170 cm. We calculated the force at different lengths and weights by the equation as follows: According to the following three exercises, we calculated the electric motor (EM) power used to construct the device based on the force mentioned above.
Use safety factor (N s ) of 1.5 to account for friction, therefore Therefore, we needed an EM with a torque of about 30 N-m.
(2) hip lifting (Bridging) Calculate the angle at which the hips are raised. θ ( Fig. 4 ): To calculate the moment:  Use safety factor (N s ) of 1.5 times a calculated torque to achieve friction forces in the system, then Therefore, we needed an EM with a torque of about 81 N-m.
(3) ankle dorsiflexion-plantarflexion ( Fig. 5 ) Assume the patient's foot drop about 30 degrees while lying on the bed. Therefore, the angle between the ankle is perpendicular to the foot drop.
Use safety factor (N s ) of 1.5 times a calculated torque to achieve friction forces in the system, therefore Therefore, we needed an EM with a torque of 0.5 N-m.

Clinical data collection methods
It is experimental research. We aimed to test a prototype device in acute stroke patients admitted to Thammasat University Hospital.    Recovery of the lower extremity and modified Rankin Scale before treatment and after twelve weeks of treatment.  The mean and standard deviation in both groups were not statistically significant. Table 1 showed the demographic data of both groups.   , and modified Rankin scale were getting statistically significant improvement when comparing between before and after 12 weeks of treatment in both groups (as shown in Table 3 ).

Discussion
Do-It-Yourself (DIY) medical devices have become widely adopted due to their technological capability. These DIY devices open the chance to get healthcare at home [12] . Rehabilitation at home for stroke patients is becoming popular in either developed or developing countries [13] . Home rehabilitation promotes motivation leading to regular performance, which is the key to improving either physical therapy method [14] . Our DIY rehabilitation device should facilitate regular selfrehabilitation at home. During the COVID-19 pandemic era, many rehabilitation facilities have been shutting down [15] . Furthermore, stroke patients risk getting infected from COVID-19 when they leave home to get physical therapy at the rehabilitation facilities [16] . Our DIY rehabilitation device may become essential for many stroke patients to get adequate physical therapy at home during this distressing COVID-19 pandemic [17] .
We also demonstrated the feasibility and safety of our DIY rehabilitation device. No complication related to the DIY rehabilitation device was found. All ten patients enrolled to use the DIY rehabilitation device can continue regular physical therapy along 12 weeks of treatment. Outcome measurement with the Brunstrom Stage of Motor Recovery (Lower extremity) and modified Rankin scale is trending more remarkable improvement with the DIY rehabilitation device than the regular rehabilitation. However, the improvement is not statistically significant within group. The results showed that the FMA-LE of experimental group was significantly higher than the control group. DIY rehabilitation device is more motivated to practice than traditional physical exercises, and it is a repetitive movement exercise that helps brain plasticity of the brain [18] .
The expense for device assembly is extremely cheap as compared with other methods [18] . It cost only 30,0 0 0 Baht or 1,0 0 0 US Dollars for the materials per device. The local mechanic can easily assembly the device by following the instruction. We plan to create the video clip for device assembly and post it on the Youtube channel or the faculty website.
Our DIY rehabilitation device should be applied in patients with lower limb weakness from other causes rather than ischemic stroke, such as intracerebral hemorrhage, traumatic brain injury, multiple sclerosis, and spinal cord diseases. A clinical trial to prove the benefit of our DIY rehabilitation device is needed to approve its use in routine practice. In the meantime, the device may be a worthy option for stroke patients with lower limb weakness who have limitations to accessing the rehabilitation opportunity.

Declaration of Competing Interest
We declare no conflict of interest.