A team of researchers at the University of Texas at Dallas and the Southwestern Medical Center, Dallas, conducted a study to determine the optimal operation of body-powered transradial prostheses so that the activation force is minimized and the grip force is maximized. The researchers note that because using a body-powered prosthesis requires large muscle forces and great concentration by the user, which can lead to discomfort, muscle fatigue, and skin breakdown, establishing the optimal operation of such a prosthesis to mitigate these drawbacks is clinically meaningful.
In the study, a computer-controlled robotic amputee simulator capable of rapidly testing multiple elbow, shoulder, and scapular combinations of the residual human arm was constructed. It was fitted with a transradial prosthesis and used to systematically test multiple configurations. The researchers found that increased shoulder flexion, scapular abduction, elbow extension, and the placement of the prosthesis’ ring harness near the C7 vertebra correlate with higher gripper operation efficiency, which they defined as the ratio of grip force to cable tension. These findings led them to conclude that force transmission efficiency is closely related to body posture configuration.
According to the authors, the results suggest that clinicians should place the ring harness inferior and to the sound side of the C7 vertebra to maximize grip efficiency. Additionally, the results may help clinicians better instruct patients in body posture during prosthesis operation to minimize strain.
The study was published online July 28 in Prosthetics and Orthotics International.
