Definition and Pathogenesis

CPPD disease is characterized by acute and chronic inflammatory joint disease, usually affecting older individuals. The knee and other large joints are most commonly affected. Calcium deposits in articular cartilage (chondrocalcinosis) may be seen radiographically; these are not always associated with symptoms.

CPPD is most often idiopathic but can be associated with other conditions (Table 167-1 Conditions Associated with Calcium Pyrophosphate Crystal Deposition Disease).

Crystals are thought not to form in synovial fluid but are probably shed from articular cartilage into joint space, where they are phagocytosed by neutrophils and incite an inflammatory response.

Clinical Manifestations

• Acute CPPD arthritis (“pseudogout”): knee is most frequently involved, but polyarticular in two-thirds of cases; involved joint is erythematous, swollen, warm, and painful. Most pts have evidence of chondrocalcinosis.
• Chronic arthropathy: progressive degenerative changes in multiple joints; can resemble osteoarthritis (OA). Joint distribution may suggest CPPD with common sites including knee, wrist, metacarpophalangeal (MCP), hips, and shoulders.
• Symmetric proliferative synovitis: seen in familial forms with early onset; clinically similar to RA.
• Intervertebral disk and ligament calcification
• Spinal stenosis

Diagnosis

• Synovial fluid analysis-demonstration of CPPD crystals that appear as short blunt rods, rhomboids, and cuboids with weak positive birefringence by polarizing microscopy.
• Radiographs may demonstrate chondrocalcinosis and degenerative changes (joint space narrowing, subchondral sclerosis/cysts).
• Secondary causes of CPPD deposition disease should be considered in pts <50 years old.