This new surgical procedure could lead to lifelike prosthetic limbs

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Required fields are indicated by an asterisk (*) This new surgical procedure could lead to lifelike prosthetic limbs Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe By Matthew HutsonMay. 31, 2017 , 2:15 PMcenter_img Smart prosthetics such as the one in this rendering could be more responsive after the new surgical technique. Sign up for our daily newsletter Get more great content like this delivered right to you! Country The new technique, developed at the Massachusetts Institute of Technology (MIT) in Cambridge, creates such a pairing for prosthetic joint control. It respects “the fundamental motor unit in biology, two muscles acting in opposition,” says Hugh Herr, a biophysicist at MIT and co-developer of the method.Let’s say you lost your leg above the knee. Surgeons would take two small muscle grafts from somewhere in your body, each a few centimeters long, and suture them together end-to-end to form a linear pair. They would place the pair under the skin near the amputation site. Then they’d suture the two ends to the tissue under the skin, so that when one half of the muscle graft contracts, the other stretches. Finally, they’d connect severed nerve endings to the graft and allow the nerves to grow into it.Once the graft is healthy and connected, the researchers would use electrodes to connect each muscle to a smart prosthetic leg. The severed nerves that would normally tell the ankle to extend, for example, would instead go to one of the grafted muscles, which would contract, sending a signal to the robotic ankle to extend. As the grafted muscle contracts, its mirror opposite would stretch, sending a signal back to the brain. The grafts would receive additional electrical feedback from the smart prosthesis, indicating the ankle joint’s position and force, allowing for finer adjustments. Additional grafts could be added to control other joints in the prosthesis.The new technique, called an agonist­-antagonist myoneural interface, was tested in rodents. The MIT team operated on seven rats, severing muscles and nerves in the back right leg of each. Researchers then grafted on a pair of muscles about 3 centimeters long, connected severed nerves, and let the rats heal for 4 months. When electrodes were attached, the grafted muscles worked in tandem, one contracting and the other stretching. They also emitted electrical signals in proportion to the stimulation. That response suggests that the technique could allow for fine-grained control of a human prosthetic, the researchers report today in Science Robotics. What’s more, inspection under a microscope showed that the grafts healed well and were populated with new nerves and blood vessels and healthy neuromuscular junctions.“This is fairly low-risk. It’s minor surgery,” says Rickard Branemark, an orthopedic surgeon and prosthetics researcher at the University of California, San Francisco. Even without adding a prosthesis, growing severed nerves into muscle grafts could prevent painful neuromas, or abnormal nerve growth. With the new method and a smart prosthesis, “there’s every expectation that the human will feel position, will feel speed, will feel force in the same way that they once felt when they had a limb,” says Herr, who lost his own legs below the knees to frostbite while ice climbing, and is in line to get the procedure. He says they’ll have results from human trials within the next 2 years. Medicine has progressed a lot since the Civil War, but amputations haven’t. Once a limb is sliced off, surgeons wrap muscle around the raw end, bury nerve endings, and often attach a fixed prosthesis that is nowhere near as agile as the flesh-and-blood original. Better robotic limbs are available, but engineers are still figuring out how to attach them to people and give users fine motor control. Now, a team of researchers and clinicians has developed a simple surgical technique that could lead to prosthetics that are almost as responsive as real limbs.“It’s a very clever model,” says Melanie Urbanchek, a muscle physiologist at the University of Michigan in Ann Arbor. “[It makes] use of what the body naturally has to offer.”The biggest barrier to lifelike limbs is that signals can no longer travel in an unbroken path from the brain to the limb and back. Scientists have developed several ways to bridge the gap. The simplest is to place electrodes on remaining muscle near the amputation site. For finer control, doctors can use severed nerves themselves to relay the signals, through electronic attachments. But when they aren’t rejected by nerve tissue, such attachments tend to receive weak signals. A stronger signal comes from attaching nerve endings to small muscle grafts that amplify the signal and relay it using electrodes. But even this method fails to take advantage of a simple biological solution for joint control: the pairing of agonistic and antagonistic muscles. When you contract your biceps to bend your elbow, for example, your triceps on the other side of the joint stretches, providing resistance and feedback. Together, such opposing muscle pairs let you fluidly adjust a limb’s force, position, and speed.last_img

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