Is calcific peritendinitis at the humeral head with reduced range of motion secondary to pain a form of shoulder tendinitis or a different condition?

Calcific Peritendinitis is a Distinct Entity from Classic Tendinitis

Calcific peritendinitis at the humeral head represents a specific pathologic process distinct from typical shoulder tendinitis, characterized by calcium hydroxyapatite crystal deposition in the peritendinous tissues rather than inflammatory or degenerative changes within the tendon itself. 1

Key Distinguishing Features

Pathophysiology Differences

• Calcific peritendinitis involves pathologic deposition of calcium hydroxyapatite crystals in the rotator cuff tendons and surrounding tissues, not inflammatory tendon degeneration 2
• Classic tendinitis (tendinopathy) involves collagen fiber degeneration, disorientation, and fiber separation without calcium deposition 1
• The ACR explicitly categorizes calcific tendinitis separately from acute traumatic shoulder conditions and addresses it under chronic shoulder pain protocols 1

Clinical Presentation Distinctions

• Calcific peritendinitis can present as either a chronic self-limiting process or acute painful episodes (acute calcific tendinitis) with severe pain and restricted range of motion 3, 2
• The acute phase occurs when calcium deposits rupture into the subacromial bursa, causing intense inflammatory response 4
• Classic tendinitis presents with insidious onset of load-related pain that worsens with activity, typically without the dramatic acute flare-ups seen in calcific disease 1

Diagnostic Approach

Imaging Characteristics

• Plain radiographs readily identify calcific deposits as homogeneous soft-tissue densities adjacent to the humeral head, following the course of affected tendons 5
• The calcium deposits appear as distinct radiodense lesions on X-ray, which is pathognomonic for calcific tendinitis and not seen in standard tendinopathy 5, 2
• Ultrasound demonstrates hyperechoic foci with posterior acoustic shadowing, representing calcium deposits, plus associated tendon thickening and decreased echogenicity 4, 2
• MRI may show the calcific deposits but can occasionally mimic aggressive processes like infection or neoplasm, making radiographs more specific for diagnosis 2

Clinical Examination Pearls

• Both conditions may demonstrate painful arc during abduction (70-120 degrees) and positive impingement signs (Hawkins' 92% sensitive, Neer's 88% sensitive) 6, 7
• However, calcific peritendinitis often presents with more severe acute pain episodes and may have 2.7%-20% asymptomatic cases discovered incidentally 3
• The presence of radiographically visible calcium deposits definitively distinguishes calcific disease from pure tendinopathy 5, 2

Management Implications

Treatment Differs Significantly

Acute calcific tendinitis:

• Responds well to conservative management including NSAIDs, rest, and physical therapy 3
• Ultrasound-guided percutaneous needle aspiration/lavage is highly effective for eliminating calcifications, with significant improvement in Constant Shoulder Scores (mean 28.6 to 81.4 after single treatment) 4
• Intrabursal steroid infiltration combined with lavage provides superior outcomes 4

Chronic calcific tendinitis:

• Often requires surgical intervention when conservative treatment fails 3
• Arthroscopic removal of calcium deposits with multiple punctures of the calcific spot shows satisfactory results in 94% of cases at 2-year follow-up 8

Standard tendinopathy:

• Managed primarily with relative rest, progressive strengthening of rotator cuff and scapular stabilizers, and addressing biomechanical factors 1, 9
• Surgery reserved only for cases failing 3-6 months of conservative therapy 1

Critical Clinical Pitfall

• Do not assume all shoulder pain with reduced range of motion is simple tendinitis - always obtain plain radiographs as initial imaging to identify calcific deposits, which fundamentally change the treatment approach 1, 6
• Pretreatment MRI should evaluate for associated impingement syndrome, as its presence predicts incomplete response to first treatment and need for repeat intervention 4
• Approximately 35-45% of patients with incidentally discovered calcific deposits will develop symptomatic shoulder pain requiring intervention 3