Mechanical evaluation of the "Hüfner hand" prosthesis.
Gerwin Smit
PMID 33834745WHAT IT FOUND
The Hüfner hand requires far less energy to close and pinch than modern body-powered hands.
Its simple design avoids inner gloves that cause friction, offering a model for future prosthetics that could reduce user fatigue.
Key findings
01The Hüfner hand requires significantly less energy to operate than the Otto Bock and APRL hands, with the Otto Bock hand requiring twelve times the energy for closing and pinching.
02The absence of an inner glove in the Hüfner design contributes to its higher mechanical efficiency compared to devices that include one.
03Adding a transmission lever to the Hüfner hand could theoretically lower the activation force to a fatigue-free level for both men and women.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
Only one specimen of each hand type was tested, so variations in production could affect results. The tested hands were new stock, but the age of the original design's components might influence performance compared to modern manufacturing. The proposed lever modification was calculated theoretically and not physically tested. Friction from the proposed lever was not included in the ideal calculations.
The easy way to misread this
Do not assume the Hüfner hand is currently available for clinical use or that adding a lever is a simple retrofit. The study tested historical designs and theoretical modifications; it does not provide evidence that these specific hands can be fitted or that the calculated force reductions will hold up in practice with added friction.