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Crystal Deposition Disorders
HA Deposition Disease

HA Deposition Disease

Crystalline Calcium Hydroxyapatitie [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
  - Pelligrini-Steiner Lesion

Chronic Destructive Arthritis

HA crystals found in association 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

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