I. Introduction
Measurement of finger joint movement is important in maintaining functional capacity and optimizing ability to adapt quickly to perturbations in manual activities. Measurement of small joint movement is challenging due to the small area, or active range of motion (AROM), over which the measurement takes place. This complexity is compounded when additional characteristics interfere with the normal structure and function of the joint, such as joint deformity due to arthritic conditions or fixed contractures due to neurological impairment. It is also paramount that any measurements that are taken are valid and clinically applicable in order to inform rehabilitation techniques, orthotic, and surgical interventions.