Hand anthropometrics from radiograms of Italian women: A population-specific ergonomic design procedure

To design a comfortable hand support, the population-specific morphological characteristics of human hands must be known. Surface and bone anthropometric data from 177 radiograms of the left hands of an unselected sample of 87 subjects (training set) belonging to the Italian, female population (age 58 ± 12) were collected. Hand Length (HL) and Hand Width (HW) were respectively 172 ± 8 mm and 81 ± 4 mm; Hand Bone Length (HBL) was 179 ± 8 mm. A separate validation set consisting of 25 radiograms from 25 patients belonging to the same population was also collected. Bone and surface measurements were compared to validate the relationships proposed by Kong et al. Their approach applied to the validation set resulted in errors between 3.1% and 8.7%, which is almost as accurate (low bias) but somewhat less precise (higher mean errors) than what found by Kong et al. on their own sample belonging to the Korean population. Two methods were developed to predict the positions of the Metacarpo-phalangeal joints of the Index, Middle, and Ring fingers with reference to the Index-Middle interdigital crotch: method PM, based on the population mean, and method PR, which also considers the Hand Width. The overall average estimation error for method PM is 1.87 mm, while for method PR it is 1.69 mm. Method PR compared to method PM improves the precision by up to 32% in the x direction and 3% in the y direction. Based on these results, a 3D CAD hand model representing the target population was developed, which can be used for the design of population-specific ergonomic medical devices.