Kinematic synergies of hand grasps: a comprehensive study on a large publicly available dataset.
Néstor J Jarque-Bou, Alessandro Scano, Manfredo Atzori and 1 others
PMID 31138257WHAT IT FOUND
Healthy adults performing 20 hand grasps showed repeatable coordination patterns, especially finger flexion, wrist and palmar arch, and thumb opposition.
These are a reference for hand rehabilitation and prosthetics, not proof a treatment works.
Key findings
01Twelve synergies were selected to explain at least 80% of the variance across all subjects and grasps.
02Five PCs were extracted in 44 subjects, and six PCs in 33 subjects; the explained variance was 83.06 ± 2.96.
03Only the first three synergies appeared in more than half of the subjects analysed: finger flexion and adduction, palmar arching and wrist flexion, and thumb opposition.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
The paper describes healthy subjects, so it does not show how injured or impaired hands coordinate. The study tested no treatment and reported no clinical outcome, so it cannot tell you whether rehabilitation, gloves or prostheses improve function. The subjects copied movements shown on a screen and were asked to concentrate on mimicking rather than exerting high forces, so the task may not match everyday object handling. The wrist and palmar arch synergy was related to objects located in front of the subject, and the paper says other spatial positions and orientations need study. Signal filtering, calibration, movement replication, grasp choice and clustering choices can change the synergies found.
Declared interests
The supplied text names Ministerio de Economía y Competitividad and Swiss National Science Foundation as funders and gives no further conflict-of-interest statement.
The easy way to misread this
Do not read the 12 synergies as proof that a hand rehabilitation programme works. The study describes coordination patterns in healthy subjects copying movements shown on a screen in a data-glove experiment; it reports no clinical outcome.