The present study is focused on a group of arthropathies that may have very similar bone manifestations (rheumatoid arthritis, ankylosing spondylitis, reactive arthritis, psoriatic arthritis, osteoarthritis and diffuse idiopathic skeletal hyperostosis), which makes it more difficult to diagnose them in human remains from archaeological contexts. A stepwise recording form was designed in order to improve the identification and differential diagnosis of these pathological conditions in bone remains, particularly in joint manifestations of the spine, pelvis, hands, feet and other limb joints. This recording form was applied in the analysis of two medieval individuals from the Basque Country (Spain) who presented very severe arthropathic manifestations. The use of this recording form allowed the researchers the diagnosis of ankylosing spondylitis in one of them and diffuse idiopathic skeletal hyperostosis in the other.This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (GCL2016-79093/P), and grants from the Basque Government to Research Groups of the Basque University System (IT1138-16). We are grateful to Mikel Neira, Director of the archaeological intervention in the medieval necropolis of San Miguel de Erenozar for the archaeological data. Besides, the Institutions that granted permission for human remains study, including the Government of the Basque Country (Cultural Heritage Dept.) and the Archaeology Museum of Bizkaia
