A 55-year-old woman presented with acute pain in the right shoulder (while attempting to pick up a dumbbell) for 2 days. Upon physical examination, she had markedly restricted external rotation of the arm along with painful abduction. The anteroposterior radiograph (Figure 1) of the right shoulder showed amorphous periarticular calcifi cations just lateral to the greater tuberosity. The ultrasound (US) image of the right shoulder disclosed nodular and homogenously echogenic calcifi c deposits at the rotator interval (Figure 2). Distally, the calcifi cation extended along the anterior aspect of the bicipital groove. Faint distal shadowing was observed in the proximal aspect of the calcium deposits. Diffuse synovial hypertrophy was seen in the subacromial-subdeltoid (SASD) bursa (Figures 3 and 4). On the short-axis view, the calcifi cation was located between the thickened SASD bursa and the long head of the biceps tendon. Considerable edema was seen in the peribursal fat plane. Power Doppler imaging did not demonstrate any signifi cant vascularity in this region. Mild effusion was seen in the biceps tendon sheath. Posterior fi bers of the underlying supraspinatus tendon appeared mildly hypoechoic. Her serum uric acid levels were within normal limits. She was diagnosed with calcifi c tendinitis of the rotator cuff with extrusion of calcium in the peri-SASD bursal fat planes. The patient was managed conservatively with anti-inflammatory medications and a shoulder sling.

The incidence of calcific tendinitis in adults ranges from 2.7% to 20.0% [1]. The incidence is higher in women compared to men. This condition most commonly presents in individuals between 30 and 50 years of age [2]. As far as calcifi cation in the shoulder is concerned, the supraspinatus is the most commonly involved tendon, followed by infraspinatus and subscapularis tendons [3]. Small linear calcifications in the peri-insertional fibers of subscapularis tendon are not an uncommon finding, though.

The exact etiology of this disorder is not yet completely understood. It is postulated that hypoxia within the tendons results in necrosis of tenocytes and fibrocartilaginous metaplasia followed by calcium deposition [4-6]. As described by Uhthoff and Loehr [6], the pathogenesis of calcific tendinitis is classified into three stages: (1) pre-calcific stage, (2) calcific stage, and (3) post-calcific stage. Intratendinous fibrocartilaginous metaplasia occurs in the precalcific stage. The calcific stage is divided into the formative and resorptive phases. The resorptive phase is characterized by local inflammation, an increase in vascularity and edema, resulting in intense shoulder pain. Granulation tissue gradually replaces intratendinous calcium in the postcalcific stage, which may last for months.

The US morphology of periarticular calcium deposits is classified into three types [3]:

(1) Type I: Calcific foci have dense calcium and show considerable distal shadowing.

(2) Type II: These calcific foci appear echogenic and show mild distal shadowing.

(3) Type III: Calcific foci appear mildly echogenic and barely show any distal shadowing.

Extrusion of intratendinous calcium into the adjacent structures is an uncommon complication [7]. Superiorly, the calcium may migrate into the SASD bursa or the peribursal fat. Inferiorly, intraosseous migration may occur in the greater tuberosity. Migration of calcium in the periarticular structures results in considerable exacerbation of patient’s pain. Calcium deposits with Type II and Type III morphology have soft inconsistency and are more likely to migrate into the surrounding structures.

US is an excellent imaging modality to evaluate shoulder pain. It can help differentiate calcific tendinitis from rotator cuff tear, isolated SASD bursitis, and frozen shoulder. As far as calcific tendinitis is concerned, US can help not only identify calcium deposits, their exact location and dimensions, but also in image-guided therapeutic interventions. In absence of an obviously identifiable calcification deposit on US, presence of edema in the peribursal fat planes can help identify a possible periarticular calcium deposit.

The treatment options for calcific tendinitis are broadly classified as conservative and surgical. Conservative management includes non-steroidal anti-inflammatory drugs, US-guided injection of steroids in the SASD bursa, US-guided needling of periarticular calcium deposit, US-guided calcium barbotage, and extracorporeal shock wave lithotripsy. Owing to the increased effectiveness of the conservative measures and better patient acceptability, the role of surgical management in calcific tendinitis has significantly reduced.

Figure 1. Periarticular Soft Tissue Calcification
Anteroposterior radiograph demonstrates periarticular soft tissue calcification (open arrow) along the lateral aspect of the greater tu-berosity.

Figure 2. Soft Calcium Deposit
Short-axis ultrasound image at the level of proximal bicipital groove shows the soft calcium deposit (asterisks) between the
subacromial subdeltoid bursa (open arrows) and the long head of biceps (arrow).
Abbreviations: GT, greater tuberosity; LT, lesser tuberosity.

Figure 3. Homogenously Echogenic Calcium Deposits
Short-axis ultrasound image shows homogenously echogenic calcium deposit (asterisk) at the level of rotator interval. Diffuse synovial hypertrophy is also noticed in the subacromial-subdeltoid bursa
(open arrows).
Abbreviations: GT, greater tuberosity; LT, lesser tuberosity.

Figure 4. Calcification
Long-axis image of ultrasound at the level of proximal bicipital groove shows the calcification (asterisk) located anterior to the long head of biceps (white arrow). Open arrow shows edema in the peribursal fat.