Influence of Fingertip Anthropometry and Anatomy on Mechanical Loads During Grasping

Abstract

Many researchers have investigated the mechanical loads during hand tool use to increase the user performance, satisfaction, and lower the risk of acute and cumulative trauma disorders. While grasping, the mechanical loads are directly transferred to the hand. Rough guidelines of pressure discomfort (PDT) and also pressure-pain threshold (PPT) were provided by previous researchers, where values differ by the subject and the area of the hand. The difference in both limits is between subjects due to the different psychological and physiological factors. In order to understand the physiological aspect of the PDT and PPT difference between subjects, we investigated the influence of the fingertip anthropometry and anatomy on the grasping and the resulting mechanical loads on the fingertip using finite element analysis. Results from the numerical tests have shown significant difference between peak contact pressures as well as the contact pressure distribution between different fingertips. It has been shown that based only on anthropometry the peak contact pressure values and contact pressure distribution cannot be predicted, since geometry of the anatomical structures, especially the bone has significantly higher influence on the peak contact pressure and contact pressure distribution during grasping.