Therapeutic electrical stimulation of the lower limb by epimysial electrodes

The problem of inadequate hip stability prevents many patients with head trauma, stroke, or spinal injury from balancing on one limb in order to take a step. There is no adequate orthotic substitute for hip instability, and electrical stimulation with surface electrodes cannot effectively activate the deep hip muscles. This report describes a clinical program in which electrical stimulation via surgically placed electrodes is combined with routine tendon lengthening and transfers and physical therapy. The electrodes are fixed to the epimysium and the leads directed subcutaneously to exit the skin at a common site for attachment to a commercially available stimulator. Preliminary results indicate that functional muscle contractions of the deep hip muscles can be obtained with epimysial electrodes and that stimulation can be used to augment walking ability. The results demonstrate the safety and effectiveness of percutaneous electrical stimulation and contribute to the development of a practical, implanted stimulation system for patients who do not regain hip instability after an upper motor neuron lesion.