The reported incidence of elbow involvement in rheumatoid arthritis varies widely, ranging from 10% to 70%. A study by Freyberg (1968) showed the incidence to be 34%. Synovitis and erosion affect the humeroulnar joint (the olec-ranon fossa and trochlear notch) and humeroradial joint. Pinhole scans in the early stage show increased uptake localized to the humer-oulnar joint and peripheral bones, which are osteopenic (Fig. 10.16). The finding has a strong resemblance to similar change in early rheumatoid arthritis of the wrist (Fig. 10.12). Chronic active rheumatoid arthritis reveals diffuse tracer accumulation in the whole elbow including the olecranon fossa and notch, the coronoid fossa, the radial fossa, and the proximal radioulnar joint (Fig. 10.17). The eccentric uptake is considered to indicate erosions in the periarticular bones that are exposed by pannus with typical changes occurring in the radial head, the coronoid process, and the distal humerus (Foster et al. 1980).
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