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Study Design: Experimental trial. Background: The functional performance of currently available body-powered prostheses is unknown. Objective: The goal of this study was to objectively assess and compare the functional performance of three commonly used body-powered upper limb terminal devices. Methods: Twenty-one able-bodied subjects (n=21, age= 22±2) tested three different terminal devices: TRS VC Hook Grip 2S, Otto Bock VO Hand, and Hosmer model 5XA hook, using a prosthesis simulator. All subjects used each terminal device 9 times in two functional tests; the Nine Hole Peg Test (NHPT) and the Box and Blocks Test (BBT). Results: Significant differences were found between the different terminal devices and their scores on the NHPT and the BBT. The Hosmer hook scored best in both tests. The TRS Grip hook 2S scored second best. The Otto Bock hand showed the lowest scores. Conclusions: This study is a first step in the comparison of functional performances of body-powered prostheses. The data can be used as a reference value, to assess the performance of a terminal device or an amputee., BioMedical Engineering, Mechanical, Maritime and Materials Engineering

Study Design: Experimental trial. Background: The functional performance of currently available body-powered prostheses is unknown. Objective: The goal of this study was to objectively assess and compare the functional performance of three commonly used body-powered upper limb terminal devices. Methods: Twenty-one able-bodied subjects (n=21, age= 22±2) tested three different terminal devices: TRS VC Hook Grip 2S, Otto Bock VO Hand, and Hosmer model 5XA hook, using a prosthesis simulator. All subjects used each terminal device 9 times in two functional tests; the Nine Hole Peg Test (NHPT) and the Box and Blocks Test (BBT). Results: Significant differences were found between the different terminal devices and their scores on the NHPT and the BBT. The Hosmer hook scored best in both tests. The TRS Grip hook 2S scored second best. The Otto Bock hand showed the lowest scores. Conclusions: This study is a first step in the comparison of functional performances of body-powered prostheses. The data can be used as a reference value, to assess the performance of a terminal device or an amputee., BioMedical Engineering, Mechanical, Maritime and Materials Engineering

The Delft Institute of Prosthetics and Orthotics has started a research program to develop an improved voluntary closing, body-powered hand prosthesis. Five commercially available voluntary closing terminal devices were mechanically tested: three hands [Hosmer APRL VC hand, Hosmer Soft VC Male hand, Otto Bock 8K24] and two hooks [Hosmer APRL VC hook, TRS Grip 2SS]. The test results serve as a design guideline for future prostheses. A test bench was used to measure activation cable forces and displacements, and the produced pinch forces. The measurements show that the hands require higher activation forces than the hooks and 1.5 to 8 times more mechanical work. The TRS hook requires the smallest activation force (33 N for a 15 N pinch force) and has the lowest energy dissipation (52 Nmm). The Hosmer Soft hand requires the largest activation force (131 N for a 15 N pinch force) and has the highest energy dissipation (1409 Nmm). The main recommendations for future prostheses are the following: (1) Required activation forces should be below the critical muscle force (~18% of maximum), to enable continuous activation without muscle fatigue. (2) Hysteresis of mechanism and glove should be lowered, to increase efficiency and controllability., BioMedical Engineering, Mechanical, Maritime and Materials Engineering

The Delft Institute of Prosthetics and Orthotics has started a research program to develop an improved voluntary closing, body-powered hand prosthesis. Five commercially available voluntary closing terminal devices were mechanically tested: three hands [Hosmer APRL VC hand, Hosmer Soft VC Male hand, Otto Bock 8K24] and two hooks [Hosmer APRL VC hook, TRS Grip 2SS]. The test results serve as a design guideline for future prostheses. A test bench was used to measure activation cable forces and displacements, and the produced pinch forces. The measurements show that the hands require higher activation forces than the hooks and 1.5 to 8 times more mechanical work. The TRS hook requires the smallest activation force (33 N for a 15 N pinch force) and has the lowest energy dissipation (52 Nmm). The Hosmer Soft hand requires the largest activation force (131 N for a 15 N pinch force) and has the highest energy dissipation (1409 Nmm). The main recommendations for future prostheses are the following: (1) Required activation forces should be below the critical muscle force (~18% of maximum), to enable continuous activation without muscle fatigue. (2) Hysteresis of mechanism and glove should be lowered, to increase efficiency and controllability., BioMedical Engineering, Mechanical, Maritime and Materials Engineering