Imaging of calcific tendinopathy: natural history, migration patterns, pitfalls, and management: a review

Calcific tendinopathy is characterized by the deposition of calcium hydroxyapatite crystals in various tendons of the body. Terms like calcium tendinitis, tendinosis, and tendinopathy are used interchangeably. Calcific tendinopathy is a common and well-documented ailment in the literature. Although common, the natural history, aetiology, and progression of calcific tendinitis are poorly understood. The treatment options include conservative and interventional measures. However, these measures cannot be applied as a blanket and are often tailored depending on the stage/phase of the disease. Out of the recognized stages of the disease, the resorptive stage causes the utmost symptoms when the calcium is rather soft and unstable. During this stage, the calcium may migrate beyond expected resorption and get deposited in the adjacent tissues contiguous with the calcium focus. The common destinations include bursal migration, intraosseous migration, muscular migration, and other less common migration sites. Such atypical presentations can lead to dilemmas in the diagnosis, prolongation of the diagnostic pathway, unwarranted apprehension, and treatment delay. Radiologists' role in this situation is to correctly recognize the imaging findings of atypical presentations of calcific tendinopathy and prevent unnecessary diagnostic and interventional studies. In this review article, we describe the pathogenic pathway and natural history of calcific tendinopathy from a radiologist's perspective and discuss different migratory patterns of calcium in calcific tendinopathy not only around the shoulder but also in other areas of the body on different imaging modalities. We also show a few examples of mimics and pitfalls on imaging. Finally, we discuss the appropriate management option of this condition.