Control of a Six Degree of Freedom Prosthetic Arm After Targeted Muscle Reinnervation Surgery

Miller LA, Lipschutz RD, Stubblefield KA, Lock BA, Huang H, Williams III TW, Weir RF, Kuiken TA. Control of a six degree of freedom prosthetic arm after targeted muscle reinnervation surgery.ObjectivesTo fit and evaluate the control of a complex prosthesis for a shoulder disarticulation-level amputee with targeted muscle reinnervation.DesignOne participant who had targeted muscle reinnervation surgery was fitted with an advanced prosthesis and his use of this device was compared with the device that he used in the home setting.SettingThe experiments were completed within a laboratory setting.ParticipantThe first recipient of targeted muscle reinnervation: a bilateral shoulder disarticulation-level amputee.InterventionsTwo years after surgery, the subject was fitted with a 6 degree of freedom (DOF) prosthesis (shoulder flexion, humeral rotation, elbow flexion, wrist rotation, wrist flexion, and hand control). Control of this device was compared with that of his commercially available 3-DOF system (elbow, wrist rotation, and powered hook terminal device).Main Outcome MeasureIn order to assess performance, movement analysis and timed movement tasks were executed.ResultsThe subject was able to independently operate all 6 arm functions with good control. He could simultaneously operate 2 DOF of several different joint combinations with relative ease. He operated up to 4 DOF simultaneously, but with poor control. Work space was markedly increased and some timed tasks were faster with the 6-DOF system.ConclusionsThis proof-of-concept study shows that advances in control of shoulder disarticulation-level prostheses can improve the quality of movement. Additional control sources may spur the development of more advanced and complex componentry for these amputees.