Pseudogout - Crystal arthropathies

Pseudogout

Definition

A crystal arthropathy resulting from calcium pyrophos-phate dihydrate (CPPD) deposition in the joints.

Aetiology/pathophysiology

CPPD crystal formation occurs in cartilage located near chondrocytes. It is suggested that excessive cartilage pyrophosphate production leads to local crystal formation. Crystals are thought to enter the joint cavity after being shed from the cartilage in which they have formed.

Clinical features

Chondrocalcinosis may be detected on X-ray in cartilage without joint disease. Acute joint inflammation resembles gout most commonly affecting the knee and other large joints.

Investigation

Examination of the joint fluid will demonstrate positively birefringent crystals.

Management

The pain of pseudogout is relieved by nonsteroidal anti-inflammatory drugs, aspiration of synovial fluid and intra-articular steroid injection.