Early arthritis signs and symptoms revisited-is synovitis what we are assessing?

Classic signs of joint inflammation at physical examination of patients with rheumatoid arthritis (RA) are joint swelling and joint tenderness. In the hand, additional characteristic signs include a positive squeeze test, reduced grip strength, and incomplete fist closure. Typical symptoms that are presumed to be inflammatory are pain and morning stiffness. Traditionally, these signs and symptoms have been thought to reflect underlying synovitis, ie, inflammation of the intra-articular synovial lining. Over the past 15 years, however, we have recognised the involvement of other inflamed tissues, such as tenosynovitis and osteitis, and more recently, interosseous tendon inflammation in the hand, and intermetatarsal bursitis in the forefoot. The question now arises as to whether the signs and symptoms observed during clinical assessment of RA are purely driven by synovitis, or if, and to what extent, they can be explained by other inflamed tissues. Therefore, we have summarised the current literature to explain which inflamed tissues contribute to the clinical characteristics in early arthritis, as well as during the at-risk stage of clinically suspect arthralgia. We found that signs and symptoms are not only explained by synovitis, but also by inflammation of tendon sheaths and intermetatarsal bursae. Among these different inflamed tissues, tenosynovitis most frequently contributed to classic clinical characteristics. Other inflamed tissues, eg, interosseous tendon inflammation and intermetatarsal bursitis, seemed to have a smaller contribution. Together, the findings provide a revisited but advanced understanding of early arthritis signs and symptoms: they arise not only from synovitis, but also from various inflamed tissues.