Osteoarthritis also affects the manubriosternal joint, which is one of the largest fibrocartilagi-nous articulations. Degenerative arthritis mainly involves the central portion of the articular fibrocartilage with resultant articular narrowing and periarticular eburnation.
Radiographically, the manubriosternal joint shows diffuse or partial narrowing with irregular sclerosis of the subchondral bones. Occasionally, the joint may be totally closed (Fig. 9.30A). Conventional or computed tomography is extremely useful for a definitive demonstration of the joint. Pinhole scintigraphy shows intense tracer uptake that fills up the joint, spreading to the lower manubrium and upper gladiolus (Fig. 9.31). It is to be mentioned that the tracer uptake in manubriosternal osteoarthritis is maximal in the central portion of the joint (Figs. 9.30B and 9.31).
Radiographic manifestations include periar-ticular bone erosions, joint space narrowing, eburnation, and osteophytosis. Understandably, these changes are mild or even dubious in the early stage (Fig. 9.28A). In general, the sternal facet is affected more prominently than the clavicular facet whose fibrocartilaginous layer is thicker. More often than not, chondro-lysis and bone erosion may be disguised as
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