HA Deposition Disease

• Crystalline Calcium Hydroxyapatite [Ca10(PO4)6(OH)2]
  • Normal component of bone
• Deposition can be
  • Dystrophic
  • Metastatic
• Dystrophic usually onto damaged connective tissue
  • Tendon/ ligament
  • Damaged cartilage
• Metastatic with
  • Hypercalcaemia
  • Hyperphosphataemia

Pathology

• Deposit around chondrocytes & into avascular portion of connective tissue
• Crystals grow by accretion
  • Early on – like cream
  • Later – like chalk
• Can be inert or surrounded by inflammatory reaction
• Crystal shedding into joint causes synovitis
• Can be complicated by rapidly destructive erosive arthritis (rare)

Clinical Features

• Two syndromes

Acute or Subacute Periarthritis

• Most common
• Patient 30-50 yo
• Painful around large joint
• Usually shoulder or knee
• Not intra-articular
• After minor trauma
• Warm & swollen tendon/ ligament
  • Examples
    • Calcific Tendonitis Cuff
    • Pellegrini-Steiner Lesion

Chronic Destructive Arthritis

• HA crystals found in association with chronic erosive arthritis
• Milwaukee shoulder
  • Destructive arthropathy seen in shoulder with cuff arthropathy
  • Whether related to HA unknown
• Also seen
  • Hip & Knee

Investigations

• Crystal too small (< 1um) to be seen with light microscopy
• Hence will not see on aspiration
• Periarthritis seen as calcification in tendon
  • Especially rotator cuff
• Chronic HA arthritis doesn’t show on XR as well as CPPD

Management

• Nonoperative
  • Periarthritis
    • RICE
    • NSAID
    • Steroids in joint
• Operative
  • Periarthritis
    • May need HA surgical removal
  • Chronic Arthritis
    • Treat as Osteoarthritis
    • Early arthroplasty if rapid bone destruction

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