Crystal Arthritis: Pseudogout (Copycat Disease) Flashcards
Defintion
Form of inflammatory arthritis caused by deposition of calcium pyrophosphate crystals in the synovium
Epidemiology
Increasing age >65
FEMALE
Risk factors
Diabetes
Previous joint trauma
Hyperparathyroidism
Haemochromatosis
Acromegaly
Wilson’s disease
Hypomagnesaemia
Hypophosphatemia
Aetiology
Calcium pyrophosphate crystal deposition
- knee, shoulder, and wrist being most commonly affected
Pathophysiology
Deposition of calcium pyrophosphate crystals is thought to trigger synovitis, with the knee, shoulder + wrist being most commonly affected
Acute - mainly affects larger joints in the elderly and is usually spontaneous but can be provoked by illness, surgery or trauma.
Chronic - inflammatory RA - like = symmetrical polyarthritis + synovitis
Signs
Joint erythema, pain, erythema, and swelling
Hot, swollen, painful, joint with stiffness
- knee
- shoulders
- wrists
- hips
Chronic condition and affects multiple joints. It can also be asymptomatic + picked up incidentally on X-ray of the joint
Symptoms
Rapid onset severe joint pain: knee, shoulder and wrist are most commonly affected
Joint stiffness
Diagnosis
GOLD STANDARD = Joint aspiration:
- weakly positive birefringent rhomboid-shaped crystals under polarised microscopy
- no bacterial growth
Joint X-ray:
- Chondrocalcinosis (not diagnostic) = thin white line in the middle of the joint space
- Other similar to OA
Investigating underlying cause: (younger people)
- Serum bone profile + PTH
- Iron studies
- Serum Mg2+
Treatment
Pseudogout is treated only acutely
- Anti-inflammatory: NSAIDs or colchicine, particularly in polyarticular disease
- Corticosteroid: intra-articular steroids can be used in monoarticular disease or systemic steroids in polyarticular disease
Joint replacement: only indicated in chronic, recurrent cases with severe joint degeneration
