Crystal Arthropathy

Overview

Crystal arthropathies are a diverse group of disorders characterized by deposition of various minerals in joints and soft tissues leading to inflammation. Four main types of crystal arthropathies:

• Gout: The most common of all the crystal arthropathies, caused by monosodium urate crystal precipitation, and its prevalence appears to be increasing.
• Pseudogout: caused by calcium pyrophosphate dihydrate
• Basic Calcium Phosphate (BCP) Crystal Disease
• Hydroxyapatite crystal deposition disease

Clinical Manifestation

• Typically monoarthritis

Diagnosis

• Synovial fluid analysis – identification of specific crystal types in synovial fluid

Synovial fluid analysis
	Aetiology	Colour and Clarity	WBC (mm³)
Normal	Normal	Clear and transparent	<200
Non-Inflammatory	Osteoarthritis	Yellow and transparent	0 to 2000
Inflammatory	Gout Rheumatoid arthritis	Yellow and traslucent-opaque	2000-100,000
Septic	Bacteria	Yellow/green and opaque	>25,000 – >100,000
Haemorrhage	Trauma	Red and Bloody	200-2000

 

DIFFERENCE BETWEEN GOUT AND PSEUDOGOUT
	Gout	Pseudogout
Aetiology	Build up of uric acid crystal in joints	Build up of calcium pyropohosphate crystals in joints
Diagnosis	Synovial fluid examined under microscopy reveals the presence of uric acid crystals	Synovial fluid examined under microscopy reveals the presence of calcium pyrophosphate crystals
Morphology	Needle shaped	Rhomboidal
Birefringence	Strongly negative	Weakly positive
Acute Treatment	NSAIDs, Colchicine, orticosteroid injection	NSAIDs, Colchicine, corticosteroid injection