Pseudogout is a crystal arthropathy caused by calcium pyrophosphate crystals. Calcium pyrophosphate crystals are deposited in the joint causing joint problems. It is also known as chondrocalcinosis.
A typically presentation of pseudogout is an older adult with a hot, swollen, stiff, painful knee. Other joints that are commonly affected are the shoulders, wrists and hips.
It can be a chronic condition and affect multiple joints. It can also be asymptomatic and picked up incidentally on an xray of the joint.
In any patient presenting with a hot, painful and swollen joint, septic arthritis needs to be excluded as it is a medical emergency that is joint and life threatening. It tends the be milder in presentation compared with gout and septic arthritis.
To establish a definitive diagnosis the joint needs to be aspirated for synovial fluid.
Aspirated fluid will show:
- No bacterial growth
- Calcium pyrophosphate crystals
- Rhomboid shaped crystals
- Positive birefringent of polarised light
Chondrocalcinosis is the classic xray change in pseudogout. It appears as a thin white line in the middle of the joint space caused by the calcium deposition. This is pathognomonic (diagnostic) of pseudogout.
Other joint xray changes are similar to osteoarthritis. Remember the mnemonic LOSS:
- L – Loss of joint space
- O – Osteophytes
- S – Subarticular sclerosis
- S – Subchondral cysts
Chronic asymptomatic changes found on an xray do not require any action.
Symptoms usually resolve spontaneously over several weeks. Symptomatic management involves:
- Joint aspiration
- Steroid injections
- Oral steroids
Joint washout (arthrocentesis) is an option in severe cases.
Last updated April 2019