How Many Joints Can Pseudogout Affect
Pseudogout can affect multiple joints simultaneously and can present with polyarticular involvement affecting 4 or more joints across different joint regions of the body. 1
Joint Distribution in Pseudogout
Pseudogout, also known as calcium pyrophosphate deposition disease (CPPD), commonly affects the following joints:
Most Commonly Affected Joints
- Knee (most frequent site)
- Wrist
- Shoulder
- Ankle 2
Characteristic Joint Involvement
- Radiocarpal joints
- Metacarpophalangeal joints
- Patellofemoral joints
- Atlantoaxial joints 1
Other Potential Sites
- Triangular fibrocartilage of the wrists
- Menisci of the knees
- Symphysis pubis
- Labrum at the pelvis
- Any joint with hyaline cartilage 1, 2
Patterns of Joint Involvement
Pseudogout can present with different patterns of joint involvement:
- Monoarticular - affecting a single joint
- Oligoarticular - affecting 2-3 joints
- Polyarticular - affecting 4 or more joints across different joint regions 1, 3
Research shows that polyarticular disease is common in hospitalized patients with pseudogout, occurring in approximately 42% of cases 3. This is particularly important as polyarticular presentation can sometimes be mistaken for other inflammatory arthritides.
Clinical Significance
The widespread joint involvement in pseudogout has important clinical implications:
- Polyarticular pseudogout can mimic rheumatoid arthritis or septic arthritis 3
- Fever attributable to synovitis is more common in polyarticular (50%) than monoarticular (20%) inflammation 3
- Pseudogout can rarely co-exist with gout in the same joint, complicating diagnosis 4
- Pseudogout can affect the spine, including cervical and thoracic regions, mimicking infection 5
Diagnostic Considerations
When evaluating joint pain that might be pseudogout:
- Radiography should be the initial imaging method, looking for chondrocalcinosis 1, 2
- Ultrasound can detect intra-articular microtophi, echogenic synovial hypertrophy, and the "double contour sign" with 83% sensitivity and 76% specificity 1, 2
- Definitive diagnosis requires joint aspiration and identification of calcium pyrophosphate crystals under polarized light microscopy 2
Associated Conditions
Pseudogout is associated with several metabolic conditions that may influence its presentation:
- Primary hyperparathyroidism (3x higher risk)
- Hemochromatosis
- Hypomagnesemia 2
Understanding the potential for pseudogout to affect multiple joints across different regions of the body is essential for accurate diagnosis and appropriate management, particularly when patients present with widespread joint pain that might be mistaken for other inflammatory conditions.