Calcifying tendinitis: a new concept of its pathogenesis.

To elucidate the pathogenesis of calcifying tendinitis, clinical and morphological investigations were done on 46 surgically treated cases. Contrary to the prevalent concept of degeneration preceding dystrophic calcification, we found no evidence for an active or a healed degenerative process. The affected tendon was transformed into fibrocartilage with a predilection for calcification. The formative phase of calcification was followed in course of time by a resorptive phase during which the deposits were surrounded by phagocytosing cells. There was a concomitant proliferation of vascular channels. We found a significant correlation between severe pain and histological signs of resorption. The pathogenetic mechanism of calcifying tendinitis should be reassessed as a unique disorder of the musculotendinous cuff.