Erosive osteoarthritis: is it a separate disease entity?

Erosive osteoarthritis (EOA) characteristically involves the hands of middle-aged women. The diagnosis is essentially radiological and depends upon the presence of articular surface erosions. This study investigates whether this radiological feature is a marker of a specific clinical entity. From a series of 500 consecutive patients attending a rheumatology clinic with symptomatic limb joint osteoarthritis, 24 were identified by radiological criteria to have EOA. These were age-sex matched with 24 patients from the same series who presented with osteoarthritis of the hand. Those with EOA had nearly twice as many radiographically abnormal joints in the hands as the controls (274: 144). This was almost entirely due to an increase in distal (134: 68) and proximal (79: 24) interphalangeal joint involvement, 71% of which were erosive. Erosions were found apart from the hands in both elbows of one patient with EOA. Otherwise only minor differences were present between the two groups in terms of distribution and incidence of osteoarthritic changes. There were no distinguishing serological or other clinical differences. This study has demonstrated that erosions in EOA are associated with more severe hand disease but are not apparently a marker of a separate disease entity. EOA appears to be an aggressive acute form of hand osteoarthritis and may represent the hand equivalent of similar forms of osteoarthritis in the shoulder, hip and knee.