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Hydroxyapatite Deposition Disease (HADD), also known as calcific tendinitis is a crystal-induced arthropathy caused by the deposition of basic calcium phosphate (BCP) crystals, primarily hydroxyapatite, in tendons, bursae, joints, or periarticular tissues.
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| Feature | Description |
|---|---|
| Crystal Type | Basic calcium phosphate (BCP) — mainly hydroxyapatite |
| Site of deposition | Tendons (esp. rotator cuff), periarticular tissues, bursae, joints |
| Pathogenesis | Local trauma, ischemia → necrosis → dystrophic calcification |
| Cellular response | Inflammatory reaction during crystal resorptive phase |
| Aspect | Description |
|---|---|
| Typical age | 30–60 years |
| Common site | Shoulder (supraspinatus tendon) > hip, elbow, wrist, knee |
| Symptoms | Acute localized pain, swelling, restricted motion |
| Phases | Formative → Resting → Resorptive (most painful) |
| Chronic form | May present as ‣ (joint destruction) |
Common sites of HADD and involvement:
| Region | Common Structures Affected |
|---|---|
| Shoulder | Supraspinatus > infraspinatus, subscapularis |
| Hip | Gluteus medius/minimus tendons |
| Knee | Quadriceps or popliteus tendon |
| Wrist | Flexor carpi ulnaris |
| Elbow | Common extensor or flexor tendon |
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Calcific tendinitis appears as a calcific density near tendon insertions, especially around the rotator cuff tendons
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| Modality | Imaging features |
|---|---|
| XR | • Formative: Homogeneous, well-defined, round/ovoid calcification near tendon |
| • Resting: Dense, stable calcific deposit | |
| • Resorptive: Ill-defined, fluffy, amorphous calcification; may migrate | |
| US | • Echogenic focus: Bright, well-defined or shadowing lesion in tendon |
| • Resorptive phase: Fragmented or liquified appearance, with Doppler signal | |
| • Soft-tissue inflammation: Bursal fluid, hyperemia on color Doppler | |
| MR | • T1: Low signal intensity |
| • T2: Variable: hypo- to hyperintense depending on phase | |
| • Bursal reaction: Subdeltoid bursitis, edema, synovial thickening | |
| • Tendon involvement: May show intratendinous edema, partial tear |
A-E AP internal rotation radiograph of the shoulder (A) shows well-defined, amorphous soft tissue calcification projecting over the posterior aspect of the greater tuberosity (formative/resting stage). Another AP shoulder radiograph (B) shows an ill-defined calcific deposit overlying the greater tuberosity (resorptive stage). Coronal PD-weighted fat-saturated MRI (C) of the right knee demonstrates focus of low signal intensity posterolaterally, interposed between femoral origin of the fibular collateral ligament and femoral origin of the lateral gastrocnemius with extensive reactive deep soft tissue edema. Axial (D) and sagittal (E) CT of the cervical neck shows coarse calcifications interior to the anterior arch of C1 and anterior to the dens of C2, consistent with HADD of the longus coli muscle
Patel, J., Tai, R., Sereni, C. et al. Hydroxyapatite deposition disease, an overlooked differential diagnosis in the emergency department: a case series and review of literature. Emerg Radiol 31, 229–238 (2024). https://doi.org/10.1007/s10140-024-02212-6