[Diagnosis of early arthritis]

The diagnosis of early arthritis is often difficult even though it is an important issue. A step-by-step clinical examination is necessary to make the diagnosis of "joint emergency": an infection must be suspected when fever is associated with arthritis. Then, classification of early arthritis will be carried on with a special attention to rheumatoid arthritis when the rheumatism is persistent and erosive. However, arthritis might be undifferentiated for several months to years; such an explanation should be given to the patient. A tight follow-up is necessary.