Grip control and motor coordination with implanted and surface electrodes while grasping with an osseointegrated prosthetic hand.
Enzo Mastinu, Francesco Clemente, Paolo Sassu and 6 others
PMID 30975158WHAT IT FOUND
Implanted electrodes gave three amputees finer grip force control, breaking fewer fragile objects.
However, surface electrodes allowed faster transfers and better timing between grip and lift. The implanted system did not improve overall motor coordination, likely due to a lack of tactile feedback.
Key findings
01Amputees using implanted electrodes broke significantly fewer fragile blocks in a delicate grasping task compared to surface electrodes.
02Surface electrodes resulted in faster task completion and better temporal coordination between grip and load forces than implanted electrodes.
03Implanted electrodes produced more stable grip forces during holding, whereas surface electrodes caused grip force to increase unexpectedly after lifting.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
The study included only three subjects, all of whom were the only available recipients of this specific implant system at the time. Subjects knew which electrode type was active, which may have biased their performance toward the technology they helped test. Statistical significance is limited by the small sample size, and results are presented descriptively. Two subjects had undergone Targeted Muscle Reinnervation (TMR), a surgical procedure that changes how muscles are used for control, which may affect generalizability to amputees without TMR.
Declared interests
The study was funded by Vetenskapsrådet, H2020 European Research Council, and Stiftelsen Promobilia. No commercial conflicts of interest with the prosthetic manufacturers (Integrum AB, Ottobock) were explicitly declared in the funding statement, though the subjects used these specific devices.
The easy way to misread this
Do not assume implanted electrodes are superior for all grasping tasks. While they improved grip force stability, they worsened motor coordination and reduced transfer speed compared to surface electrodes. The benefit depends on whether the patient needs to preserve fragile objects or move quickly.