Mechanical evaluation of the "Hufner hand" prosthesis

Background: Current body-powered hands have very low acceptance rates. They also require high activation forces. In the past, a high acceptance rate was reported for the then-available Hufner hand, a hand which could be controlled by relatively low activation forces. Objective: The aim of this study was to measure and quantify the mechanical performance of the Hufner hand. Study design: Mechanical evaluation. Methods: Two versions of the Hufner hand were tested using a mechanical test bench. Forces and displacements were measured under four different glove conditions (no glove, leather, polyvinyl chloride (PVC), silicone). The measured results were compared to data from currently available voluntary-closing hands. Results: The Hufner hand required 132-170 Nmm of work and 78-104 N cable force to pinch 15 N. The overall mechanical performance of the Hufner hands is better than currently available body-powered hands. Conclusion: The mechanical performance of the Hufner hand was measured and quantified. Mechanical testing results show that the Hufner hand has better mechanical performance than current body-powered hands. This may have contributed to its reported high acceptance rates. The design of the Hufner hand, combined with data presented in this study, can serve as guidelines for the design of a new generation of body-powered hands.