QUESTIONS In case of Heberden's nodes the osteoarthritis starts with a so called tidemark flaking as a reaction to a subchondral ossification. The question was, if a differentiation in relation to a control group by an objective score is possible. METHODS 218 finger joints from 56 cadavers were investigated morphologically (score). RESULTS The osteoarthritis starts with a subchondral ossification. At this time the surface of the cartilage is not destroyed yet. Reactive tidemark flaking is the beginning of the general degradation. In relation to a control group a significant differentiation by a histological score is possible. CONCLUSIONS In case of Heberden's nodes the osteoarthritis starts with the subchondral ossification. Because Heberden's nodes are the specific manifestation of the Generalized Osteoarthritis on the distal finger joints, further studies have to assess, if the same pathogenetic mechanism can be seen in osteoarthritis of the large joints.