Monoarthritis

Question 1

What causes gout?

Answer 1

Crystal arthropathy from excess uric acid.
Excess uric acid crystallises and deposits in the soft tissues and joints.
On microscopy you see monosodium urate crystals which are needle-like and negatively befringent under plane polarised light.

Question 2

Gout-symptoms

Answer 2

Severe pain, swelling and erythema in a joint, 70% in the 1st MTP- great toe. Can also be ankle, wrist etc.
If in >1 joint - polyarticular gout.
Acute episodes reach intensity within 12 hours.

Question 3

Gout- investigations

Answer 3

Joint aspiration and crystal microscopy.
Take a serum uric acid level 4-6 weeks later.
XR may show rat-bite erosions.

Question 4

Gout- management

Answer 4

NSAIDs or colchicine.
High dose until 1-2 days after symptoms settle. Prescribe PPI for gastric protection.
Colchicine has a slower onset and may cause GI upset

Consider steroids if the other 2 are CI.

Offer allopurinol to start 2 weeks after an acute attack/ Continued allopurinol use if already taking.
Side effects: bone marrow supression

Lifestyle advice.
Thiazides can be a precipitating drug.

Question 5

What is pseudogout?

Answer 5

Crystal arthropathy from calcium pyrophosphate deposition. (CPPD)
Can be asymptomatic, or in acute or chronic presentations.
Seen in the elderly, if in < 60 years suspect: haemochromatosis, hyperparathyroidism, familial CPPD disorder or acromegaly.

Question 6

Pseudogout- symptoms

Answer 6

Acute severe joint inflammation, pain, redness and swelling.
Usually asymmetrical.
Larger peripheral joints affected than in gout - knees, shoulders

Question 7

Pseudogout- investigations

Answer 7

Joint aspiration and crystal microscopy- small rhomboid CPPD crystals with weak positive befringence.
Rule out septic arthritis.
XR- cartilage calcification on meniscus of knee, white lines of chondrocalcinosis.

Question 8

Pseudogout- management

Answer 8

NSAIDS, or colchicine.

Oral steroids/intraarticular steroid injections