Every effort should be made to aspirate involved joints to exclude a septic joint if diagnosis is uncertain. Involve the on-site orthopedic team or radiology for ultrasound-guided aspiration if necessary. Record the color, viscosity, and turbidity. Perform microscopy for cell count, differential, and Gram stain (Microbiology); polarizing microscopy for crystals (Histopathology lab); and culture.
About
- Pseudogout syndrome, first described by Kohn and colleagues in 1962, is a cause of acute painful joints, often in older patients.
- Results from calcium pyrophosphate dihydrate (CPPD) crystal deposition in connective tissues or joint cartilage.
- Commonly affects knee cartilage (hyaline cartilage and menisci), wrist (triangular fibrocartilage), and pelvis (symphysis pubis).
Aetiology
- CPPD crystals deposit in articular cartilage and periarticular tissue.
- Increased ATP breakdown in joints leads to excess inorganic pyrophosphate, often due to aging, genetic factors, or both.
- CPPD is a common condition with increased prevalence with age across all races.
Associations
- Haemochromatosis
- Hypothyroidism
- Hyperparathyroidism
- Haemophilia
- Wilson's disease
- Bartter syndrome
- Hypomagnesaemia
- Ochronosis
- Amyloidosis
Chondrocalcinosis: Calcification of the Cartilage
Clinical Features
- Acutely inflamed, tender joint due to cartilage calcification
- Typically affects large joints
- Characterized by hot, tender, red, and swollen joints
- More common in middle-aged or elderly patients
- Commonly affects hips, knees, or wrists and can persist for months
- In young patients, it may be associated with conditions like haemochromatosis, hyperparathyroidism, Wilson's disease, or alkaptonuria
Investigations
- FBC with differential, ESR, and CRP (often elevated)
- U&E, calcium levels to check for primary hyperparathyroidism
- Ferritin to exclude haemochromatosis
- Blood cultures x3
- X-ray: Chondrocalcinosis shows as linear calcification in hyaline cartilage or fibrocartilage
- Joint aspirate: Polarizing light microscopy for calcium pyrophosphate crystals (rhomboid-shaped and positive birefringence)
Differential Diagnosis
- Gout vs. Pseudogout: Pseudogout attacks may take longer to reach peak intensity and last up to 3 months. Large joints are often affected, and the inflammation can involve one or more joints.
- Pseudogout may coexist with gout in 20% of CPPD patients who have hyperuricaemia.
Management
- Management of CPPD-related arthropathy can be challenging due to patient characteristics, diagnostic uncertainty, and lack of effective crystal-reducing treatments.
- Acute Attack Management:
- Admit if septic arthritis is suspected. Rest, elevate the limb, and provide analgesia.
- Joint aspiration if infection is suspected to confirm diagnosis.
- NSAIDs: First-line treatment, but avoid in elderly/CKD patients. Consider adding a short-term PPI.
- Colchicine: Often 0.5 mg BD for several days to prevent or control flares.
- Prednisolone: 10-15 mg PO for up to a week for refractory cases.
- Chronic Inflammatory Arthritis:
- Hydroxychloroquine
- Methotrexate
- Prophylaxis:
- Colchicine for recurrent attacks
- NSAIDs with a PPI if appropriate