Intraoperative Evaluation of the Spiral Nerve Cuff Electrode for a Standing Neuroprosthesis

Evaluation of the spiral nerve cuff electrode on the proximal femoral nerve for a standing neuroprosthesis was performed intraoperatively in 4 subjects. The mean stimulation threshold was 17.7 plusmn 12 nC, similar to stimulation thresholds in upper extremity nerves. The femoral nerve was found to have an oblong cross section with an average width of 9 mm and height of 1-2 mm. In all 4 subjects where data was recorded, selective activation of at least one hip flexor (rectus femoris or sartorius) was possible. For a standing neuroprosthesis, knee extension without hip flexion is desired. A more selective electrode is needed for this application.