Crystal Arthropathy (pseudogout)

Question 1

Definition

Answer 1

Arthritis associated with deposition of calcium pyrophosphate dihydrate (CPPD) crystals in the joint cartilage

Question 2

Aetiology

Answer 2

• CPPD crystal formation is initiated in cartilage located near the surface of
chondrocytes
• It is linked with excessive calcium pyrophosphate production
• This abundance of calcium pyrophoshpate leads to the formation of CPPD crystals
• Shedding of crystals in to the joint cavity leads to acute arthritis
• Most causes of joint damage predispose to pseudogout (e.g. osteoarthritis, trauma)

• Rarer conditions that increase the risk of pseudogout:
o Haemochromatosis
o Hyperparathyroidism
o Hypomagnesaemia
o Hypophosphatasia

Question 3

Precipitating factors

Answer 3

o Intercurrent illness
o Surgery
o Local trauma

Question 4

Epidemiology

Answer 4

• 2 x more common in WOMEN

* More common in the ELDERLY

Question 5

Presenting symptoms

Answer 5

• Acute Arthritis
o Painful
o Swollen Joint (e.g. knee, ankle, shoulder, elbow, wrist)

• Chronic Arthropathy
o Pain
o Stiffness
o Functional impairment

• Uncommon Presentations
o Tendonitis
o Tenosynovitis
o Bursitis

Question 6

Signs on physical examination (acute)

Answer 6

• Acute Arthritis

o Red
o Hot
o Tender
o Restricted range of movement
o Fever

Question 7

Signs on physical examination (chronic)

Answer 7

• Chronic Arthropathy

o Similar to osteoarthritis
o Bony swelling
o Crepitus
o Deformity
o Restriction of movement

Question 8

Investigations (bloods)

Answer 8

o High WCC in acute attacks
o High ESR
o Blood culture - to exclude septic arthritis

Question 9

Investigations (joint aspiration)

Answer 9

o Rhomboid, brick-shaped crystals
o POSITIVE birefringence
o Culture or Gram-staining to exclude septic arthritis

Question 10

Investigations (joint radiograph)

Answer 10

o Chondrocalcinosis

o Signs of osteoarthritis:
• Loss of joint space
• Osteophytes
• Subchondral cysts
• Sclerosis