 A large number of instruments exists to assess upper limb prosthetic function. However, they differ substantially in terms of psychometric properties and content. Furthermore, there is no gold standard and nearly every single center uses a unique set of instruments. This fact prevents the linking of the commonly small due to the limited number of patients in each center data sets of different centers and makes comparisons between different fittings or treatment protocols difficult. To generate accepted evidence, we need large data sets with similar outcomes. With remarkable progress made in prosthetic research and rehabilitation in the recent years, the need to evaluate the impact of this intervention on daily life, including productivity, self-care and leisure becomes increasingly relevant. Moreover, self-reported instruments and observation-based instruments exist, but there is a lack of data if, for example, the self-reported instrument which is easier and less health-professionals-time-consuming to perform could replace a performance or observation-based instrument. 