An osseointegrated human-machine gateway for long-term sensory feedback and motor control of artificial limbs

An osseointegrated interface allowed long-term stable and bidirectional communication between robotic prostheses and implanted neuromuscular electrodes for intuitive control with sensory feedback in one patient. A Bone-Anchored Arm Prosthetic An artificial limb should not only anatomically resemble its original counterpart but also function and feel just like it. Currently available prosthetic limbs allow for basic functions—closing a door or taking a step—but they often do not support fine-motor control or sensory perception. Ortiz-Catalan and coauthors describe a first-in-human trial of a bone-anchored (osseointegrated) upper-arm prosthetic that attached directly to the bone, nerves, and muscles of the remaining limb. The patient was followed for 1 year, demonstrating finer motor control (grasping, for example, an egg without breaking it) and a greater range of motion (touching toes and reaching arm overhead) compared with a conventional socket prosthesis with surface electrodes. Direct electrical stimulation of the peripheral nerves also provided the patient a sense of touch. The study was in only one patient, thus preventing quantification of improvement, which may vary depending on the amount of soft tissue and scar tissue remaining in the stump. Nevertheless, osseointegration could revolutionize the field of neuroprosthetics, giving patients more intuitive control and more freedom of movement. A major challenge since the invention of implantable devices has been a reliable and long-term stable transcutaneous communication. In the case of prosthetic limbs, existing neuromuscular interfaces have been unable to address this challenge and provide direct and intuitive neural control. Although prosthetic hardware and decoding algorithms are readily available, there is still a lack of appropriate and stable physiological signals for controlling the devices. We developed a percutaneous osseointegrated (bone-anchored) interface that allows for permanent and unlimited bidirectional communication with the human body. With this interface, an artificial limb can be chronically driven by implanted electrodes in the peripheral nerves and muscles of an amputee, outside of controlled environments and during activities of daily living, thus reducing disability and improving quality of life. We demonstrate in one subject, for more than 1 year, that implanted electrodes provide a more precise and reliable control than surface electrodes, regardless of limb position and environmental conditions, and with less effort. Furthermore, long-term stable myoelectric pattern recognition and appropriate sensory feedback elicited via neurostimulation was demonstrated. The opportunity to chronically record and stimulate the neuromuscular system allows for the implementation of intuitive control and naturally perceived sensory feedback, as well as opportunities for the prediction of complex limb motions and better understanding of sensory perception. The permanent bidirectional interface presented here is a critical step toward more natural limb replacement, by combining stable attachment with permanent and reliable human-machine communication.