Calcifying Tendinitis of the Shoulder: Advances in Imaging and Management Taco Gosens, MD, PhD, and Dirk-Jan Hofstee, MD Corresponding author Taco Gosens, MD, PhD Department of Orthopedics and Traumatology, St. Elisabeth Hos- pital, Hilvarenbeekseweg 60, 5022 GC Tilburg, The Netherlands. E-mail: t.gosens@elisabeth.nl Current Rheumatology Reports 2009, 11: 129–134 Current Medicine Group LLC ISSN 1523-3774 Copyright © 2009 by Current Medicine Group LLC Calcifying tendonitis of the shoulder is a common, acute or chronic, painful disorder characterized by calci icat ions in the rotator cuff tendons. A natural cycle exists during which the tendon repairs itself. In chronic calci ic tendonitis, however, this cycle is blocked at one of the healing stages. Because chronic presentation with exacerbations is usual, initial treatment should be conservative, including rest, physical therapy, nonsteroidal anti-inl am- matory drugs, and, in later stages, subacromial ini ltrat ion with corticosteroids. Surgery is recom- mended when conservative treatment fails. This article discusses advances in imaging and medi- cal, physical, and surgical management, as well as current evidence for the treatment of calcifying tendonitis of the shoulder. Introduction Calcifying tendonitis of the shoulder is a common, acute or chronic, painful disorder characterized by cal- ci ications in rotator cuff tendons. The calci ic material consists of a collection of calcium hydroxyapatite in crys- talline or amorphous form. Material may occasionally excite a surrounding acute inlammatory response when the entire mass assumes sterile chemical abscess charac- teristics. What initiates this sudden change? The trauma effect is uncertain, but minor traumatic episodes may change the characteristics of an existing, symptomless calci ic deposit, and therefore produce acute symptoms. Calcifying tendonitis may also be related to mechani- cal irritation by deposits when the arm is abducted and deposits impinge on the acromion (hence the popularity of subacromial decompression, such as open or endo- scopic anterolateral acromionectomy). Past As early as 1892, Duplay [1] recognized the subacro- mial–subdeltoid bursa as a source of painful shoulders. He described the condition as scapulohumeral periar- thritis, later also called Duplay’s disease. Painter [2] irst mentioned calciications in 1907. Since then, various nomenclature for the same condition has been used, includ- ing calciic tendonitis or tendinitis, calcareous bursitis, calcifying tendinopathy, and others. In Europe, the term tendinosis is used, whereas in North America tendonitis or tendinitis are more common terms. Codman [3] mentioned the intratendinous origin of calciications in his classic text- book: “The deposits do not arise in the bursa itself, but in the tendons beneath it.” In 1912, Wrede [4] described the disease, including pathologic changes in the tendon: “The cells resemble more and more chondrocytes, meanwhile the iber arrangement of the tendon is lost.” Calci ications in the shoulder most commonly occur in the supraspinatus tendon (51%–90%) and least commonly in the subscapularis tendon (3%). The supraspinatus tendon is 2 to 3 cm long and traverses the subacromial compartment, which is rigidly limited by the coracoacro- mial arch above and the humeral head below. Codman [3] noted that diseases in the supraspinatus tendon tend to occur in a speci ic area of the tendon, or “about half an inch proximal to the insertion.” He called this area the critical portion and later the critical zone. Microangio- graphic and histologic examination studies by Rothman and Parke [5] showed that the critical zone is markedly undervascularized. The articular side of the supraspinatus tendon especially underilled, regardless of the posi- tion of the arm [6]. These critical zones also exist in the infraspinatus and subscapularis tendons, as well as in the supraspinatus tendon. Present The etiology of calcifying tendinitis remains largely unknown. The condition may be related to hypovascular- ity-induced ibrosis and necrosis within the tendon with subsequent degeneration [7]. The disorder has four stages [8,9]. The irst stage, or precalciic stage, involves ibro- cartilaginous metaplasia within the tendon. This is usually one centimeter medial to the insertion of the supraspinatus