Researchers have invented a new type of amputation surgery that can help amputees to take better control of their residual muscles and sense where their "phantom limb" is in space.

According to the team, this restored sense of proprioception should translate to better control of prosthetic limbs, as well as a reduction of limb pain. In most amputations, muscle pairs that control the affected joints, such as elbows or ankles, are severed. However, the Massachusetts Institute of Technology (MIT) team has found that reconnecting these muscle pairs, allowing them to retain their normal push-pull relationship, offers people much better sensory feedback. "Through surgical and regenerative techniques that restore natural agonist-antagonist muscle movements, our study shows that persons with an AMI amputation experience a greater phantom joint range of motion, a reduced level of pain, and an increased fidelity of prosthetic limb controllability," said researcher Hugh Herr from MIT.

For the study, to be published in the journal 'Proceedings of the National Academy of Sciences', the research team included 15 patients who received this new type of surgery. This surgery, known as agonist-antagonist myoneural interface (AMI), could control their muscles more precisely than patients with traditional amputations, the team said. The AMI patients also reported feeling more freedom of movement and less pain in their affected limb. The research team has also developed a modified version of the surgery that can be performed on people who have already had a traditional amputation. This process, which they call "regenerative AMI," involves grafting small muscle segments to serve as the agonist and antagonist muscles for an amputated joint.