Gout, pseudogout + septic arthritis Flashcards
Differential diagnosis of a single red hot swollen joint
Septic arthritis
Gout
Psuedogout
Reactive arthritis
Haemarthrosis
Investigations of a single swollen joint
Joint aspiration
sent for gram staining, crystal microscopy, culture + antibiotic sensitivities
What is gout?
Inflammatory arthritis related to hyperuricemia
Crystal arthropathy
What is the pathophysiology of gout?
- high blood urine acid levels
- deposition of monosodium urate crystals in joint > inflammation
- results in acute + chronic arthritis, gouty tophi, urate nephropathy + uric acid nephrolithiasis
Risk factors for gout
- male
- > 40 years old
- family history
- obesity
- high purine intake (meat + seafood)
- alcohol (especially beer)
- diuretics
- CVD
- smoking
- diabetes mellitus
- organ transplant
What joints are typically affected by gout?
Base of big toe - MTP joint
Base of thumb - CMC joint
Wrist
Presentation of gout
Acute single hot, red, swollen painful joint
Investigations + diagnosis of gout
- diagnosis made clinically but supported by raised serum urate levels on blood test
- joint aspiration + culture to rule out septic arthritis: raised monosodium urate crystals in gout + no bacterial growth
Describe the aspirated joint fluid in gout
- shows monosodium urate crystals
- needle shaped + negatively birefringement of polarised light
- no bacteria
X-ray features of gout
- maintained joint space
- lytic lesions in bone
- punched out erosions with sclerotic borders + over hanging edges
General prevention of gout
- maintain optimal weight
- regular exercise
- diet modifications
- reduced alcohol intake
- smoking cessation
- maintain fluid intake + avoid dehydration
Treatment of gout
- first line treatment in acute gout: NSAIDs with PPI cover
- second line: colchicine
- third line: oral steroids e.g. prednisone
. - prophylaxis with xanthine oxidase inhibitors > lower uric acid levels: allopurinol, febuxostat
What is first line treatment of gout?
NSAIDs
With PPI cover
Why is colchicine used in gout treatment + why is it only prescribed for a short course?
- for patients who are inappropriate for NSAIDs e..g renal impairment or heart disease
- it can cause abdominal pain + diarrhoea
- dangerous in overdose + can cause multiple organ failure
What is used in prophylaxis of gout?
allopurinol or feboxostat
xanthine oxidase inhibitors > lower uric acid levels
Difference between the crystals deposited in gout + psuedogout
Gout - monosodium urate crystals
Psuedogout - calcium pyrophosphate crystals
Typical presentation of pseudogout
Patient over 65 with rapid onset hot, swollen, stiff + painful knee
What joints does psuedogout affect?
- knee
- shoulders
- hips
- wrists
Describe the joint aspiration fluid in pseudogout
- calcium pyrophosphate crystals
- rhomboid shaped
- positively birefringement of polarised light
- no bacterial joint
X ray features in pseudogout
Chondrocalcinosis: calcium deposits in joint cartilage > thin white line in joint space
LOSS
Management of pseudogout
Symptomatic treatment - often resolves within a few weeks
- NSAIDs + PPI
- colchicine
- steroid injections
- oral steroids
Presentation of septic arthritis
- hot, red, swollen + painful joint
- stiffness
- reduced ROM
- systemic symptoms e.g. fever, lethargy, sepsis
Common bacterial causes of septic arthritis
- staph aureus (most common)
- neisseria gonorrhoea (in sexually active people)
- strep pyogenes
- haemophilus influenzae
- E.coli
When should you suspect gonococcal septic arthritis?
in young sexually active patient with single acutely swollen joint
Treatment of septic arthritis
- abx for 4-6 weeks (IV then oral)
- flucolaxcillin
- clindamyclin if penicillin allergy
- vancomycin if MRSA suspected
Difference in joint aspiration in gout, pseudogout + septic arthritis
- gout: no bacteria, needle shaped crystals, negatively birefringent of polarised light
- pseudogout: no bacteria, rhomboid shaped crystals, positively birefringent of polarised light
- septic arthritis: bacteria present
