In paraplegic subjects who had functional transection of the spinal cord
at a level between the fourth and the eleventh thoracic vertebra,
independent reciprocal walking was achieved with the use of a portable
microprocessor-controlled stimulator that electrically activated the
muscles through percutaneous intramuscular wire electrodes. The electrodes
were implanted, by means of hypodermic needles, in the flexors, extensors,
abductors, and adductors of the hip; the extensors of the knee; and the
plantar flexors and dorsiflexors of the ankle. The subjects had strong,
selective, and reproducible muscular contractions that increased in
strength during the twenty-two to forty-four months (average, thirty-two
months) of training with the regimen. A basic pattern of stimulation was
adapted for each individual; each step was initiated by the subject using a
hand-operated switch. The subjects progressed to the use of a walker for
support, and two of them were able to walk using axillary crutches. Three
subjects were able to climb stairs.