Crystal Arthropathy Flashcards
Define crystal arthropathy
Gout: overproduction or reduced renal excretion of uric acid
-> hyperuricaemia -> deposition of monosodium urate
crystals in the joints, soft tissues and kidneys -> acute
inflammatory arthritis, tophi, renal disease and urolithiasis
Pseudogout: deposition of calcium pyrophosphate
dihydrate crystals in joint cartilage
What are the causes/risk factors of gout?
• ↑ dietary urate intake (seafood, meat, alcohol/beer)
• ↑ purine turnover e.g. lymphoma, leukaemia, polycythaemia rubra vera, psoriasis
• Drugs e.g. CANT LEAP – ciclosporin, alcohol, nicotinic acid, thiazides, loop diuretics,
ethambutol, aspirin, pyrazinamide
• Renal dysfunction
What are the causes/risk factors of pseudogout?
Excessive chondrocyte pyrophosphate production -> local calcium pyrophosphate
supersaturation and crystal formation -> shedding of crystals into joint
• Joint damage e.g. osteoarthritis, trauma
• Haemochromatosis
• Hyperparathyroidism
• Hypomagnesaemia
• Hypophosphataemia
What are the symptoms of gout?
Acute: • Severe sudden onset pain – monoarticular (usually in 1st MTP) • Precipitated by trauma, infection, alcohol, starvation
Chronic: • Joint stiffness/ swelling • Polyarticular pain • Painful tophi (extensor surface joints) • symptoms of renal calculi
What are the symptoms of pseudogout?
Acute: • Painful swollen joint e.g. knee, ankle, shoulder, elbow, wrist • Fever, malaise
Chronic (mimics osteoarthritis): • Pain • Stiffness • Functional impairment
uncommen presentations:
- tendonitis
- tenosynovitis
- bursitis
What are the signs of gout?
Joint tendereness
What are the signs of pseudogout?
Acute:
• Red, hot, tender
joint
• Restricted ROM
Chronic: • Bony swelling • Crepitus • Deformity e.g. varus
What investigations are carried out for crystal arthropathies?
• Synovial fluid aspiration
- Monosodium urate crystals – needle shaped and –vely birefringent
- CPPD crystals – rhomboid and +vely birefringent
