Research ArticleMEDICAL ROBOTS

Long-term implant of intramuscular sensors and nerve transfers for wireless control of robotic arms in above-elbow amputees

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Science Robotics  17 Jul 2019:
Vol. 4, Issue 32, eaaw6306
DOI: 10.1126/scirobotics.aaw6306
  • Fig. 1 Implants and magnetic coil.

    (A) X-ray of patient II with five IMES sensors implanted. (B) X-ray of patient II with telemetry socket (magnetic coil laminated within the socket) and the prosthetic device.

  • Fig. 2 Learning curves for SHAP, CPRT, BBT, and AC during the rehabilitation when using IMES for control.

  • Fig. 3 Schematic drawing of the IMES sensor.

  • Fig. 4 Patient I wearing the IMES system.

  • Fig. 5 Schematic signal pathway.

    To perform a specific motion of the prosthetic arm, the patient is thinking of this movement (1). This creates an impulse along the responsible nerve (2) and leads to a contraction of a specific muscle belly (3). The produced EMG signal is then recorded, rectified, and integrated within the IMES sensor (4). Via telemetry using a magnetic coil around the stump, these signals are transferred to the control unit, and forward telemetry is used to transmit power and configuration settings to the sensors (5). Within the belt-worn control unit, the preprocessed rectified EMG data (6) of the IMES are sent to the prosthesis (7), and the desired movement of the prosthetic device is performed (8).

  • Table 1 TMR nerve transfer matrix for the above-elbow level of amputation.

    Targeted musclesNervesProsthetic functionInnervation
    M. biceps caput longumN. musculocutaneousElbow flexionOriginal
    M. biceps caput breveN. ulnarisHand closeTransferred
    M. brachialisN. medianusPronationTransferred
    M. triceps caput longum/medialeN. radialisElbow extensionOriginal
    M. triceps caput lateraleSplit ramus prof. N. radialisHand openTransferred
    M. brachioradialisSplit ramus prof. N. radialisSupinationTransferred
  • Table 2 Functional outcome using SHAP, BBT, CPRT, and AC.

    NA, not available.

    PatientSHAPBBTCPRTAC
    PreIMESSurfacePreIMESSurfacePreIMESSurfaceIMESSurface
    139452712121186.982643.332.832.33
    23644239103.3349.3842.06NA2.952.22
    32452452156.67117.0014.6737.5832.33
    Mean33.0047.0031.677.6712.337.0084.4527.5840.462.932.29
    SD7.944.3211.725.132.523.8533.8813.764.070.090.06
  • Table 3 Patient demographics.

    PatientAge at
    amputation
    Side of
    amputation
    Dominant
    hand before
    amputation
    Years from
    amputation
    to surgery
    Follow-up
    from surgery
    (years)
    Time from
    surgery to
    evaluation
    (years)
    Nature of lossNumber of
    IMES
    implanted
    115.92RightRight1.083.003.00Traffic accident6
    231.42LeftRight1.502.752.00Motorcycle accident5
    347.17RightRight0.502.501.92Machine accident6
    31.501.032.752.31
    15.630.500.250.60

Supplementary Materials

  • Supplementary Materials

    The PDF file includes:

    • Legends for movies S1 and S2

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). SHAP and CPRT of patient II.
    • Movie S2 (.mp4 format). Accuracy test of patient III with six myosignals and surface electrodes compared with implanted electrodes.

    Files in this Data Supplement:

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