What can we learn from the synovium in early rheumatoid arthritis?

Rheumatoid arthritis (RA) affects approximately 1% of the population and is a chronic inflammatory joint disease resulting in joint destruction, increased morbidity and mortality. Although the aetiology of this disease is unknown, the pivotal role played by cytokines and degradative enzymes in mediating inflammation and joint destruction, particularly early in the disease process, has been the focus of recent literature and will be the focus of this review. Up until recently, studies on early RA were limited as there was an inherent delay in patients reaching the rheumatologist's care and initial diagnostic confusion may have compounded these problems. In particular, the observation that early intervention improves outcome, has driven the study of early RA. It is difficult to define early RA but most studies have defined this as disease duration of less than 12 months from symptom onset. Clearly, it is important to study the synovial membrane in early disease, in particular to try and answer the important questions: (1) What are the earliest changes to occur in the RA synovium? (2) Can we distinguish RA on the basis of synovial membrane pathology? (3) Can synovial immunopathology predict outcome? (4) What is the role of arthroscopic biopsy in early RA?