Table 1.

Traditional model for rheumatoid arthritis (RA) based mainly on radiographic findings and modern concepts emerging from magnetic resonance imaging in RA

	Traditional paradigms for RA	Modern imaging paradigms
Erosions	A relatively late feature	Present in the majority at clinical presentation
Synovitis and damage	Synovitis not necessarily linked to damage – uncoupling	Linear link between synovitis with damage
Erosion mechanism	Immunologically mediated or autonomously by synovial fibroblasts	Major biomechanical contribution – such factors may mechanically uncouple synovitis from damage.
Cutting edge of erosions	Synovial fibroblasts and osteoclasts destroy tissue from outside in.	Recognition that magnetic resonance imaging bone oedema represents a diffuse osteitis – at least some of erosive process occurs within the bone.
Synovitis locations	Considered as diffuse	Regional variations within and between joints
Pathophysiological perspective	Erosion formation and cartilage pannus junction key to understanding RA	Erosion and pannus are inevitable and predictable consequences of chronic synovitis, RA being the most common cause.