Neuroprosthetics of the upper extremity--clinical application in spinal cord injury and future perspectives.

Within the last couple of years, partial restoration of lost motor functions in a larger number of spinal cord injured patients has become possible by the introduction of neuroprostheses into the clinical environment. The Freehand system in particular is the first implantable neuroprosthesis from which a certain group of tetraplegic patients with stable shoulder function, but missing or weak grasp and hold function of the hand do benefit. The system is based on the combination of electrical stimulation and operative tendon transfers and thus represents a multicomponent concept for long-term restoration of the grasp function. The crucial prerequisites for successful use of an implantable neuroprosthesis are the right indication, careful preoperative muscle stimulation, differentiated planning of the surgery and functional training adopted to the individual residual functions. After successful completion of an extensive rehabilitation program, patients are able to use the system for activities of daily living without the need for special additional aids, which enhances their quality of life and independency. In order to extend the group of potential users of neuroprostheses in the future, new technological developments will have to take into account that nowadays the majority of spinal cord injured patients suffer from an incomplete lesion of the spinal cord. For these particular patients who still possess residual functions, modular, "naturally" controllable systems for supporting these functions are needed rather than complex systems to substitute them.