The present invention relates to a surface neuroprosthetic device for muscle stimulation.
Movement impairment in a limb can result from a number of neurological or orthopedic pathological conditions. Activation of selected muscles of the limb by functional electrical stimulation (FES) to generate controlled movements has been used, both as a therapeutic modality and for the improvement or restoration of activities of daily living (ADL) or functional restoration.
Devices based on surface electrical stimulation which have been developed for activating specific body sites include the dropfoot system, which activates the ankle joint, modifying hemiplegic gait; hybrid FES-orthosis systems for restoring gait in spinal cord-injured patients, and systems for therapeutic activation and functional restoration of the hand, such as the Handmaster, described in U.S. Pat. No. 5,330,516 (Nathan). Other prior art devices are described in U.S. Pat. No. 5,562,707 (Prochazka); U.S. Pat. Nos. 4,580,569 and 4,558,704 (both to Petrofsky). Use of these devices requires them to be placed on the body limb and to be removed, possibly once or several times, each day. One of the main barriers to widespread use of surface neuroprostheses has been the lengthy time and high level of expertise required to position the electrode array and to hold the electrodes on the limb surface. This is generally carried out by the patient himself, who suffers from neurological or orthopedic deficits. A hemiplegic patient, having the use of only one hand, will often be required to don and doff the neuroprosthesis by himself. Quadriplegic users may be able to don or doff the neuroprosthesis, or may require assistance.
The soft tissue of the paralyzed or plegic limb is highly flexible and mobile. Mechanical interaction between the limb and the device during the donning of the neuroprosthesis can result in geometric distortion of the limb's soft tissue. This problem should be addressed, as neuroprostheses are intended to be worn for several hours each day.