Grip control and motor coordination with implanted and surface electrodes while grasping with an osseointegrated prosthetic hand

• Published in: Journal of neuroengineering and rehabilitation Vol. 16; no. 1; pp. 49 - 10
• Main Authors: Mastinu, Enzo, Clemente, Francesco, Sassu, Paolo, Aszmann, Oskar, Brånemark, Rickard, Håkansson, Bo, Controzzi, Marco, Cipriani, Christian, Ortiz-Catalan, Max
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 11.04.2019; BioMed Central; BMC
• Subjects: Amputation; Amputees; Artificial Limbs; auditory feedback; Communications systems; Controllability; controlled study; Eggs; Electrodes; Electrodes, Implanted; Electromyography; Electromyography (EMG); Electromyography - instrumentation; Electromyography - methods; Epimysial; experimental locomotor activity test; Extremities (Anatomy); Feedback; Feedback, Sensory; Female; Grasping; Grip force; hand grip; Hand Strength; Health aspects; human; Humans; Implanted electrodes; Implanted electrodes (biology); limb amputation; Male; Motor ability; motor coordination; Motor task performance; Motors; Myoelectricity; Neurophysiology; Orthopaedics; Ortopedi; osseointegrated prosthetic hand; Osseointegration; osseoperceptive feedback; Pattern recognition; pick and lift test; priority journal; Prostheses; Prostheses and implants; Prosthetic control; Prosthetics; Psychomotor Performance - physiology; Reproducibility of Results; Sensory feedback; Sensory integration; Stability; Technology; transhumeral amputation; Transplants & implants; virtual eggs test; visual feedback; Visual perception; Germany; Prosthetic control; Epimysial; Osseointegration; Implanted electrodes; Electromyography (EMG)
• ISSN: 1743-0003; 1743-0003
• DOI: 10.1186/s12984-019-0511-2

Replacement of a lost limb by an artificial substitute is not yet ideal. Resolution and coordination of motor control approximating that of a biological limb could dramatically improve the functionality of prosthetic devices, and thus reduce the gap towards a suitable limb replacement. In this study, we investigated the control resolution and coordination exhibited by subjects with transhumeral amputation who were implanted with epimysial electrodes and an osseointegrated interface that provides bidirectional communication in addition to skeletal attachment (e-OPRA Implant System). We assessed control resolution and coordination in the context of routine and delicate grasping using the Pick and Lift and the Virtual Eggs Tests. Performance when utilizing implanted electrodes was compared with the standard-of-care technology for myoelectric prostheses, namely surface electrodes. Results showed that implanted electrodes provide superior controllability over the prosthetic terminal device compared to conventional surface electrodes. Significant improvements were found in the control of the grip force and its reliability during object transfer. However, these improvements failed to increase motor coordination, and surprisingly decreased the temporal correlation between grip and load forces observed with surface electrodes. We found that despite being more functional and reliable, prosthetic control via implanted electrodes still depended highly on visual feedback. Our findings indicate that incidental sensory feedback (visual, auditory, and osseoperceptive in this case) is insufficient for restoring natural grasp behavior in amputees, and support the idea that supplemental tactile sensory feedback is needed to learn and maintain the motor tasks internal model, which could ultimately restore natural grasp behavior in subjects using prosthetic hands.