Concise Review Clin Shoulder Elbow 2020;23(4):210-216 https://doi.org/10.5397/cise.2020.00318 eISSN 2288-8721 Diagnosis and treatment of calcific tendinitis of the shoulder Min-Su Kim, In-Woo Kim, Sanghyeon Lee, Sang-Jin Shin Department of Orthopedic Surgery, Ewha Womans University Seoul Hospital, Ewha Womans University College of Medicine, Seoul, Korea Calcific tendinitis is the leading cause of shoulder pain. Among patients with calcific tendinitis, 2.7%–20% are asymptomatic, and 35%–45% of patients whose calcific deposits are inadvertently discovered develop shoulder pain. If symptoms are present, complications such as de- creased range of motion of the shoulder joint should be minimized while managing pain. Patients with acute calcific tendinitis respond well to conservative treatment and rarely require surgery. In contrast, patients with chronic calcific tendinitis often do not respond to conserva- tive treatment and do require surgery. Clinical improvement takes time, even after surgical treatment. This review article summarizes the processes related to the diagnosis and treatment of calcific tendinitis with the aim of helping clinicians choose appropriate treatment op- tions for their patients. Keywords: Calcification; Tendinitis; Shoulder joint; Conservative treatment; Surgical treatment INTRODUCTION and subscapularis tendons, 7% in both the infraspinatus tendon and subacromial bursa, and 3% in the subscapularis tendon [2]. Calcific tendinitis of the shoulder, classified as enthesopathy, is a Diabetes and gout are considered to be risk factors for calcific self-limiting disease characterized by the deposition of calcium tendinitis; however, that possibility has not been fully elucidated. phosphate crystals in the rotator cuff tendons. It most commonly Many patients with calcific tendinitis also have endocrine diseas- occurs between the ages of 30 and 50 and is rare in those older es, and conservative treatment is likely to fail in such cases. In than 70 years. It is approximately twice as likely to occur in wom- addition, stiffness of the shoulder joint, such as frozen shoulder, en as in men, is more common in the right shoulder than in the can occur as a result of chronic shoulder pain. A rotator cuff tear left, and involves both shoulders in 10% of patients [1]. The most is also present in approximately 25% of patients with calcific ten- common site of occurrence is 1.5–2 cm away from the supraspi- dinitis, though such tears tend to be more associated with small natus tendon insertion site on the greater tuberosity. According calcific deposits than with large calcific deposits [3]. The man- to the literature, calcific tendinitis occurs more frequently in agement of calcific tendinitis varies, and whether a patient has some tendons than in others, occurring most often in the supra- pain is an important factor. Treatment options include conserva- spinatus tendon. A previous study reported that 63% of cases oc- tive treatment and surgical intervention, and both options are ef- cur in the supraspinatus tendon, 20% in both the supraspinatus fective when carried out in the appropriate conditions. This arti- Received: November 4, 2020 Accepted: November 16, 2020 Correspondence to: Sang-Jin Shin Department of Orthopedic Surgery, Ewha Womans University Seoul Hospital, Ewha Womans University College of Medicine, 260 Gonghang-daero, Gangseo-gu, Seoul 07804, Korea Tel: +82-2-6956-1656, Fax: +82-2-2642-0349, E-mail: [email protected], ORCID: https://orcid.org/0000-0003-0215-2860 IRB approval: None. Financial support: None. Conflict of interest: None. Copyright© 2020 Korean Shoulder and Elbow Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 210 www.cisejournal.org Clin Shoulder Elbow 2020;23(4):210-216 cle is intended to help clinicians choose the appropriate treat- diseases such as diabetes. Patients with secondary calcific tendi- ment options for patients with calcific tendinitis. nitis often do not respond to conservative treatment, and they require surgical treatment more commonly than patients with ETIOLOGY idiopathic calcific tendinitis. Bosworth [6] classified calcific ten- dinitis based on the size of calcium deposits, with small deposits The etiology of calcific tendinitis of the shoulder remains contro- being less than 0.5 cm, medium deposits being 0.5–1.5 cm, and versial between two theories: degenerative calcification and reac- large deposits being > 1.5 cm. tive calcification. The theory of degenerative calcification was Neer [7] classified four types of calcific tendinitis based on proposed by Codman and Akerson [4] in 1931. It posits that de- pain and calcium deposits. Their first type is characterized by generative changes of the tendon accumulate with age, leading to pain caused by chemical irritation as a result of the calcium de- decreased distribution of blood vessels and reduced local oxy- posits. The second type involves pain caused by increased local genation of the tissue, which in turn produces hypoxia, thinning pressure within the tissue as it swells. The third type causes im- and tearing of the tendon, necrosis, and eventually calcification. pingement-like pain through bursal thickening and irritation by However, that theory cannot explain why calcific tendinitis has a prominent calcium deposits. The fourth type reflects pain caused peak incidence in patients aged 50 years or why it is a self-limit- by chronic stiffness of the glenohumeral joint, such as frozen ing disease. In 1997, Uhthoff and Loehr [5] proposed the theory shoulder. of reactive calcification, a series of processes that occur in precal- Many classifications have been attempted based on the mor- cific, calcific, and postcalcific stages. Among them, the calcific phology of the calcific deposits as observed in simple radiogra- stage consists of formative, resting, and resorptive phases. In the phy. In 1961, DePalma and Kruper [1] classified two types of cal- precalcific stage, tenocytes change into chondrocytes, a process cium deposits on radiography. Type 1 has a fluffy shape with an called metaplasia, and fibrocartilaginous transformation occurs ill-defined margin and mainly appears in the resorptive phase of within the tendon. In the formative phase of the calcific stage, the calcific stage, in which patients complain of acute pain. This calcium deposits form and increase in size. Calcium deposition disease state is acute calcific tendinitis. Type 2 has homogenously then stops at the resting phase of the calcific stage. During the re- dense calcium deposits with a well-defined margin, and most pa- sorptive phase of the calcific stage, calcific deposits are absorbed tients with this type have little or no pain. These deposits appear by cell-mediated phagocytosis, which is performed by cells such in the formative or resting phase of the calcific stage, and they re- as macrophages and giant cells. Acute pain is mainly present in flect subacute or chronic calcific tendinitis. this phase. In the postcalcific stage, the spaces remaining in the The French Arthroscopic Society classification divides calcific tissue where calcium deposits were absorbed is replaced by gran- tendinitis into four types based on the morphology of calcium ular tissue, and remodeling occurs. Calcific tendinitis eventually deposits on radiology [8]. Type A calcium deposits show dense, progresses to bursitis and inflammatory synovitis caused by homogenous, and sharp contours; type B deposits show dense, chemical irritation due to the calcific deposits. Chemical furun- segmented, and sharp contours; type C shows heterogeneous and cles are formed by swelling and increased local pressure in the soft contours; and type D shows dystrophic calcification at the tissue. Thickening of the bursa causes collisions in the subacro- insertion of the rotator cuff tendon. Loew et al. [9] classified mial space. All of these processes produce various forms of three types of calcific tendinitis based on the pattern of calcium shoulder pain. deposits observed on magnetic resonance imaging (MRI). Type A appears as a dense, uniform, and well-defined single deposit; CLASSIFICATIONS type B is uniform and well-defined with two or more deposits; and type C appears as heterogeneous, widely spread, and ill-de- Calcific tendinitis is classified as acute (within 2 weeks), subacute fined deposits. (3 to 8 weeks), and chronic (more than 3 weeks), according to the duration of clinical symptoms [1]. Depending on the degree CLINICAL EVALUATION of invasion, calcium deposits are classified as localized or dif- fused. The diffused form is usually more painful and persists for Calcific tendinitis is diagnosed through patient history, physical a longer time than the localized form. Idiopathic calcific tendini- examination, and imaging examination. Among patients with tis, type I, is not accompanied by endocrine disease, whereas sec- calcific tendinitis, 2.7%–20% are asymptomatic, and 35%–45% of ondary calcific tendinitis, type II, is accompanied by endocrine patients whose calcific deposits are discovered inadvertently on https://doi.org/10.5397/cise.2020.00318 211 Min-Su Kim, et al. Appropriate treatment options for calcific tendinitis simple radiographs develop symptoms [10,11]. The formative phase. In the resorptive phase, on the other