The present invention concerns an in vitro process for diagnosing joint disease in a mammal and/or determining the type of joint disease and/or determining the stage of said disease and/or predicting the course of said disease, comprising the following steps: a) depositing a drop of a synovial fluid sample from said mammal onto a flat substrate made of an inorganic material, such as glass; b) drying the drop deposited in step a); c) measuring at least one parameter indicative of the morphological features of the drop dried in step b), whereby a value for said parameter is obtained, and d) comparing each value measured in step c) with a reference value representative of a reference synovial fluid, characterized in that said parameter is selected from (i) the maximum height (H) of the bead formed on the surface of the drop, (ii) the area of the drop and (iii) the surface profile (Z) of the drop.