Einstein Science Reporting for Kids
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8-Oct-2014

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Prosthetic hands and arms that 'belong'



Osseointegrated prosthesis with robust neural control regardless of limb position. This image relates to the paper by Dr. Ortiz Catalan and colleagues.
[Ortiz Catalan et al., Science Translational Medicine, 2014]

Scientists are getting closer to making prosthetic hands and arms look and act like real hands and arms.

Dustin Tyler at Case Western Reserve University and colleagues show that two adult male amputees can perform everyday tasks for over a year (including strenuous outdoor activities such as chopping wood) without problems.

The researchers also developed a way to improve sensory perception in the prosthetic hands, which they tested in the two participants during monthly visits to the lab. For patients, improving sense of touch appears to be a key part of perceiving the prosthetic hand as a natural extension of the body.

During these lab experiments, the research team hooked the participants up to a machine that sent electrical pulses through the prosthetic hand.

After stimulation, the patients reported feeling like they were grasping objects with their own hand, rather than feeling like they were using an external tool.

In a separate study, a different group of researchers show that an artificial arm directly connected to the bone, nerves and muscles of one adult male whose arm was amputated above the elbow functions and feels just a like real arm.

The arm is anchored to the bone in the stump by a metal rod that acts like an artificial extension of the skeleton. The patient used the arm for daily life and work activities, and even occasionally slept with it for over a year with no problems.

This approach appears to work better than skin electrodes, which are more sensitive to cold and heat.

Implanted electrodes are woven under the skin to help stimulate nerves and better control the prosthetic arm.

These human studies show that implanted electrodes are a more precise, reliable way to control prosthetic limbs, and that these can finally be used in bone-anchored implants.

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