Synovial, chondropathic, depositional: the radiological categories of arthritis. A review

The accepted optimum logic frame for complex diagnostic problems is sequential hypothesis testing. The X-ray diagnosis of arthritis has now become sufficiently complex to make this the procedure of choice, but standard classifications of arthritis lack the discriminatory power needed for its effective deployment. This obstacle can be overcome if these standard classifications are replaced by a more discriminant classification based on radiologically identifiable discriminators. This classification divides arthritis into three groups: synovial, chondropathic and depositional. The initial categorization is usually made fairly simply from two or three markers, of which the most important is the site of any erosions present. Once categorized, the subsequent analysis can proceed in an approximately binary manner using the discriminators appropriate for that category. The use of this radiological classification simplifies the diagnostic approach, reduces the workload, and provides the algorithm needed for sequential hypothesis testing.