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Orthopedic and Rehabilitation Engineering

Orthopedic and Rehabilitation Engineering - Poster Session E

Poster AA1 - Design and implementation of a Mirror Therapy support system for arm movement recovery

Saturday, October 26, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Stroke is one of the leading causes of death and chronic disability worldwide. There are approximately 12.2M new strokes each year and 101M people are currently living with its effects. Post-stroke, it is estimated that 60-80% of survivors experience motor impairments, with the hand often being more severely impaired compared to the lower. Further only 20% of individuals with upper-limb paralysis regain full function six weeks post-stroke.

Mirror Therapy (MT) is a rehabilitation technique for movement recovery that uses visual feedback to engage the brain's mirror neuron system. In the context of upper limb rehabilitation, MT typically involves hiding the affected limb and using a mirror to reflect the unaffected side, creating an illusion of movement. This activates damaged brain areas, enhancing motor, cognitive, and emotional functions while reducing hemineglect syndrome.

Research indicates that combining MT with robotics may enhance motor recovery through the heightened activation of the motor cortex contralateral to the affected hand. Further, it has been shown that Robotic Mirror Therapy (RMT) can have a positive impact on patient engagement. However, existing robotic devices are expensive, non-intuitive, complex, or require a physical therapist for operation. In Low-and-Middle-Income Countries (LMICs), where stroke incidence is increasing and healthcare resources are scarce, there is also a critical need for affordable robotic rehabilitation solutions, bridging the gap created by expensive and inaccessible technologies.

To address this problem, we aim to design, manufacture, and test a cost-effective, portable, and easy-to-use RMT device for upper limb rehabilitation, focusing on elbow flexion and extension.

Materials and

Methods:  The robotic mirror therapy device (RMTD) has two components: one attached to the user’s unaffected side and the other to the affected side. The structure attached to the unaffected side serves as the input and consists of a platform connected to a timing belt pulley system. This platform is manually driven by the user, with a rotary encoder attached to the pulley system to precisely measure movement, direction and distance traveled. The side of the RMTD attached to the affected side consists of a carriage mounted to a lead screw linear actuator. Limit switches are included in both structures for safety, and all components are connected to a power supply. An STM32F411 microcontroller manages the device, interfacing with a computer that stores time and value data for both arms and includes a Graphic User Interface (GUI) for user interaction in a game-like mode.
The system operates in two phases: the start-up stage ensures both arms are positioned at the origin, and the rehabilitation stage, where the unaffected arm executes movements at various speeds and amplitudes as directed by the GUI, while the affected arm mirrors these movements in real-time.

Initially, we evaluated the bandwidth of the system. The GUI was used to assess the device’s performance across a range of motion with various frequencies. The movement's amplitude was adjusted to 14.8 cm, and the back-and-forth movements were evaluated at 0.01, 0.025, 0.05 0.075 and 0.1 Hz. Data points from the trajectories of both arms were plotted over time and compared.

Results, Conclusions, and Discussions: This project successfully designed, implemented, and manufactured a device that aids in MT to foster improved motor function, focusing on elbow extension and flexion. The resulting device is made from 3D-printed materials and simple electronics, featuring a graphic user interface to provide visual feedback. The structure measures approximately, 10 ± 0.05 cm by 65 ± 0.05 cm by 16.2 ± 0.05 cm and has total weight of 2.41 ± 0.001 kg. The manufacturing cost is approximately $163. Lastly, after conducting the mentioned tests, the arms were able to travel a back-and-forth distance of 29.6 cm at a maximum frequency of 0.05 Hz, translating to a maximum speed of 4.65 cm/s with minimal delay.

We analyzed several existing robotic systems for upper-limb rehabilitation that aim to provide a cost-effective, portable alternative for post-stroke rehabilitation, each tailored for different movements. Building on these advancements, our contribution introduces a device with a low cost, compact and lightweight design, and ease of assembly, making it scalable and portable for underserved areas. Furthermore, its 3D-printed components allow for customization to meet individual needs.

Future efforts will focus on testing the GUI to assess patient autonomy and engagement, evaluating the device's use and adoption in various settings such as physical therapy facilities, hospitals, and in-home use, and refining the device’s performance. Potential upgrades include switching to a DC motor for increased speed and adding a joystick and servo motor for more complex movements such as wrist rehabilitation.
In order to validate and enhance the device's functionality, feedback from therapists and patients, registration as a Class I medical device, and human studies are necessary. Successful validation will pave the way for manufacturing and commercialization.

In summary, this prototype advances the development of scalable and accessible rehabilitation technology for stroke recovery. By combining MT principles with robotic automation, it aims to improve motor function and patient engagement, making effective rehabilitation more accessible. Future studies should refine this prototype, validate it through trials, and expand its capabilities to include more upper-limb movements.

Acknowledgements (Optional):  I would like to extend my heartfelt gratitude to my two advisors, Professor Pedro Malagón and Professor Quentin Sanders. Your knowledge, patience, feedback, and motivation have been indispensable for the development of this thesis. I hope this collaboration between George Mason University and Universidad Politécnica de Madrid (UPM) does not end here and continues to open new doors and projects together. Additionally, this project would not have been possible without the support from UPM through the scholarship ’Beca de Colaboracion para Departamentos’, which financed part of this research.