As you may or may not be aware of is many post-stroke patients improve their walking abilities significantly during rehabilitation, but their hand function remains underdeveloped. Scientists are continually asking themselves how to help stroke patients recover their hand function and, in turn, their quality of life. But how can they help patients regain control over the intricate muscle, tendon, and joint interaction? Researchers in the US have just come a step closer to figuring this out. Focusing on task-oriented practice in addition to general training, they developed a glove that can stimulate the muscle and tendon movements, providing artificial feedback that can result in real improvements.
This new technique is known as biomimetic hand exotendon (BiomHED). And it could compensate for the reduced capacity of impaired hand muscles to produce movements and achieve substantial goals such as increasing overall functionality.
In this study, the researchers looked at the effect of artificial feedback from the BiomHED from muscles and tendons within the hand observing manual dexterity and function. The researchers believe that patients can benefit from this type of feedback because it accounts for muscle activation. Therefore, it can yield better results than treatment that only focuses on movements.
How does BiomHED differ from traditional hand rehabilitation?
Hand rehabilitation efforts typically have focused on movements, stimulating and aggravating abnormal muscle activation. Researchers have already developed a substantial number of assistive robotic devices to perform joint-based training exercise for the hand, mainly helping the hand to open and close. This approach forces the muscles to move instead of targeting the underlying cause of functional impairment. In the hands, however, many muscles can contribute to the motion of a single joint in a relatively complicated manner. Previous robotic systems have proven inadequate in replicating the dynamic process of joint coordination within the hand.
The biomimetic hand exotendon device (BiomHED) applies forces to tendons that mimic a “normal” situation. It is a kind of glove with 3D-printed plastic compartments. These compartments route cables that mimic muscle tendons on both sides of the hand and around the wrist. Velcro secures the device to the hand. So, tension applied to these cables makes it feel like muscles are contracting. There is no discomfort or pain associated with the device’s use.
This study examined 12 subjects – 5 men and 7 women between 22 and 26 years of age. The patients produced a constant force with their fingers opening their hand, or in the extension direction. They were assisted and not assisted in this movement in two different ways. While they performed the force production, researchers measured the activity of several muscles.
The researchers showed that assisting the hand with these artificial tendons changes the activity of muscles while the patients extend the fingers. But the effect was different for different muscles, which indicates a change in coordination between these sets of muscles. Subjects found it possible to use the minimal amount of force necessary to complete a given task. This is great news since after a stroke a lot of muscle activity is “wasted”. There is much more contraction than necessary due to spasms and poor muscle control.
What does this mean for your therapy?
The BiomHED explores muscle activation-based therapy, matching the required assistance to the muscle. This new technique provides a therapeutic solution that will improve muscle activation patterns and ultimately reduce the debilitating impairment. The researchers’ bottom line: training stroke patients with this device assisted muscles and tendons in the hands. They felt it could offset reduced capacity of impaired muscles.
The device is still a prototype. It is therefore not available as a therapy option yet. However, it is essential to know that this cutting edge technology is on the horizon and could be available to you in the near future.
The lead author of this study was Sang Wook Lee, Department of Biomedical Engineering, Catholic University of America, Washington, USA.