Introduction
Pseudogout is a form of microcrystal synovitis caused by the deposition of calcium pyrophosphate dihydrate crystals in the synovium. For this reason, it is now more correctly termed calcium pyrophosphate crystal deposition (CPPD) disease.
Epidemiology
- Incidence: 10.00 cases per 100,000 person-years
- Peak incidence: 70+ years
- Sex ratio: 1:1
| Condition | Relative incidence |
|---|---|
| Osteoarthritis of the knee | 75.00 |
| Gout | 15.50 |
| Septic arthritis in adults | 1.30 |
| Pseudogout | 1 |
| Reactive arthritis | 0.50 |
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Aetiology
Risk factors
- haemochromatosis
- hyperparathyroidism
- acromegaly
- low magnesium, low phosphate
- Wilson's disease
Clinical features
Features
- knee, wrist and shoulders most commonly affected
- joint aspiration: weakly-positively birefringent rhomboid-shaped crystals
- x-ray: chondrocalcinosis
- in the knee this can be seen as linear calcifications of the meniscus and articular cartilage
Management
Management
- aspiration of joint fluid, to exclude septic arthritis
- NSAIDs or intra-articular, intra-muscular or oral steroids as for gout