The place of psoriatic arthritis in the spondarthritides

The place of psoriatic arthritis in the spondarthritides has been examined in terms of past, present and future aspects. It is concluded that: 1. PsA is a definite entity and separate from rheumatoid arthritis. 2. The spondarthritis concept is universally accepted, although still in an evolving stage. 3. A more definitive picture of the spondarthritides and of PsA itself could arise from a number of new approaches, some entirely novel, some extensions of work already in progress. Avenues of future research that are likely to be fruitful include those involving: more refined clinical studies; further applications of molecular mapping; and, common to both, conceptual advances using mathematical models to provide a more 'three-dimensional' picture.