Comprehending finger flexor tendon pulley system using a computational analysis

Abstract

Existing prosthetic/orthotic designs are rarely based on kinetostatics of a biological nger, especially its tendon-pulley system (TPS) which helps render a set of extraordinary functionalities. Studies on computational models or cadaver experiments do exist. However, they provide little information on TPS con gurations that lead to lower tendon tension, bowstringing, and pulley stresses, all of which a biological nger may be employing after all. A priori knowledge of such con gurations and associated trade-o s is helpful not only from the design viewpoint of, say, an exoskeleton but also for surgical reconstruction procedures. We present a parametric study to determine optimal TPS con gurations for the exor mechanism. A compliant, exure-based computational model is developed and simulated using the pseudo rigid body method, with various combinations of pulley/tendon attachment point locations, pulley heights, and widths. Deductions are drawn from the data collected to recommend the most suitable con guration. Many aspects of the biological TPS con guration are explained through the presented analysis. We reckon that the analytical approach herein will be useful in arriving at customized (optimized) hand exoskeletal designs.