Crystal arthropathies

Question 1

What are crystal arthropathies?

Answer 1

A group of joint diseases caused by deposition of crystals in joints

Question 2

Basic pathology of crystal arthropathies

Answer 2

Deposition of crystals in joints. Neutrophils ingest the crystals and degranulate, releasing enzymes that damage the joint.

Question 3

Define gout

Answer 3

Monosodium urate crystals deposited in joints, causing painful inflammation. Usually in metatarsophalangeal joint in big toe.

Question 4

Epidemiology of gout

Answer 4

1. More common in men
2. Rises in post-menopausal women
3. Acute attack: cold, sepsis, dehydration, drugs, trauma

Question 5

Causes of gout (reduced urate excretion)

Answer 5

1. Elderly
2. Men
3. Post-menopausal women
4. HTN
5. Diuretics
6. Impaired renal function
7. Anti-hypertensives
8. Aspirin

Question 6

Causes of gout (increased urate production)

Answer 6

1. Dietary (sweeteners, alcohol, red meat, seafood)
2. Genetic disorders
3. Psoriasis
4. Drugs (e.g warfarin)

Question 7

Signs and symptoms of gout

Answer 7

1. Red, tender, hot, painful joints (mainly big toe)
2. Tophi (large deposits of urate causing chalky, onion-like appearance, nodules)
3. Florid synovitis

Question 8

Diagnosis of gout

Answer 8

1. Polarised light microscopy of synovial fluid after joint fluid aspiration: negatively bifringent needle urate crystals
2. Serum urate: can be raised or normal
3. Tophi confirm diagnosis

Question 9

Management of gout

Answer 9

1. Aim to get urate < 300umol/L
2. Allopurinol (long term)
3. NSAIDs/colchicine
4. Steroids can be used
5. Rest and elevate joint, ice packs

Question 10

Prevention of gout

Answer 10

1. Lose weight
2. Avoid prolonged fasts
3. Avoid alcohol
4. Avoid purine-rich meats
5. Avoid low-dose aspirin

Question 11

Complications of gout

Answer 11

1. Increased risk of HTN
2. Increased risk of CVD
3. Renal disease
4. T2DM

Question 12

Define pseudogout

Answer 12

Deposition of calcium pyrophosphate crystals in joints, causing inflammation. Typically in knees and wrists

Question 13

Epidemiology of pseudogout

Answer 13

1. Elderly

2. More common in women

Question 14

Precipitants of pseudogout

Answer 14

1. Dehydration
2. Direct trauma
3. Steroids
4. Surgery
5. Blood transfusion
6. Diabetes
7. High magnesium

Question 15

Signs and symptoms of pseudogout

Answer 15

1. Acute attack: sudden and severe pain associated with redness, tenderness + low grade fever
2. Stiffness, swelling, heat, painful joints long term
3. Polyarticular - knees, wrists, knuckles, hips, shoulders, elbows, ankles, toes
4. Pain worsens with movement

Question 16

Investigations for pseudogout

Answer 16

1. Polarised light microscopy of synovial fluid after needle aspiration: weakly positive birefringent rhomboid-shaped crystals
2. X-ray - soft tissue calcium deposition

Question 17

Management of pseudogout

Answer 17

1. Acute: analgesia, physio, intra-articular steroid injections, NSAIDs/colchicine, and joint aspiration
2. Methotrexate/hydroxychloroquine for chronic
3. Synovectomy surgery