| Term | Definition |
| Heberden and Bouchard nodes | Clinically defined posterolateral firm/hard swellings. Heberden: distal IPJ; Bouchard: proximal IPJ.Nodes can occur with or without radiological and/or clinical abnormalities characteristics of HOA. |
| Nodal OA | Heberden and/or Bouchard nodes plus underlying IPJ OA, defined clinically and/or radiologically. |
| Non-nodal OA | IPJ OA, defined clinical and/or radiographically, without nodes |
| Erosive OA | Subset of HOA defined radiographically by subchondral erosion, cortical destruction and subsequent reparative change, which may include bony ankylosis. |
| Generalised OA | HOA plus OA at other sites. |
| Thumb base OA | First CMCJ with or without STJ OA |
| Gold standard | The diagnostic reference used for a particular study |
CMCJ, carpometacarpal joint; HOA, hand OA; IPJ, interphalangeal joint; OA, osteoarthritis; STJ, scapho-trapezioid joint.