T&O: Acute Joint Pain Flashcards

1
Q

What are the 4 main differentials for acute onset joint pain?

A
  1. trauma
  2. septic arthritis
  3. gout
  4. pseudogout
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2
Q

Describe the presentations of septic arthritis, gout and pseudogout.

A

Septic arthritis

  • usually affects single large joints, usually knee
  • severe pain, swelling and erythema of joint
  • systemic symptoms: fever, malaise

Gout

  • usually affects 1st metatarsophalangeal joint, midfoot, ankle or knee
  • severe pain, swelling and erythema of joint
  • systemic symptoms: fever, malaise

Pseudogout

  • usually affects knees and wrist, but can affect other joints, inc. MPJ
  • pain (usually milder), swelling and erythema of joint
  • +/- fever
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3
Q

What are the common causative agents of septic arthritis?

A
  • Staphylococcus aureus most commonly

- Can sometimes be caused by gonococcal infections

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4
Q

What is the difference between gout and pseudogout?

A

Gout = arthritis due to deposition of MONOSODIUM URATE CRYSTALS (uric acid exceeds its solubility in blood and precipitates) within joints causing acute inflammation and eventual tissue damage

Pseudogout = inflammation of joints caused by deposition of CALCIUM PYROPHOSPHATE CRYSTALS in (peri)articular tissues.

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5
Q

Suggest risk factors for septic arthritis.

A
  • elderly
  • joint surgery, hip or knee prosthesis
  • prior joint damage, e.g. RA, gout, systemic CT disorders
  • immunodeficiency, e.g. AIDS, DM, steroids
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6
Q

Suggest risk factors for gout.

A
  • male
  • obesity
  • alcohol (>10g/day)
  • thiazide diuretics
  • hypertension, CHD, DM, CKD, high triglycerides
  • diet: meat, seafood
  • chemotherapy
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7
Q

Suggest risk factors for pseudogout.

A
  • elderly
  • dehydration
  • long-term steroids
  • endocrine disorders: hyperparathryoidism, hypothyroidism, acromegaly, etc.
  • surgery or trauma
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8
Q

Which investigations would you perform on a pt with an acutely painful swollen knee?

A
  1. Arthrocentesis (1st line investigation)
    - gram stain
    - culture
    - microscopy - cells and crystals
  2. Bloods (not usua
    - FBC, CRP and ESR: will reveal any widespread inflammatory/infectious process
    - PT and APTT: if arthrocentesis reveals haemarthrosis in absence of sufficient trauma, to screen for coagulopathy
    - rheumatological investigations: rheumatoid factor, anti-CPP antibodies, ANA and other autoantibodies.
  3. Cultures: take swabs of skin lesions, or of throat, urethra, cervix and rectum if gonococcal arthritis is a possibility. Blood cultures should be requested if sepsis suspected.
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9
Q

How would analysis of arthrocentesis fluid help differentiate between septic arthritis, gout and pseudogout?

A
  1. Septic arthritis
    - WCC: 50,000-100,000
    - low glucose
    - high lactate
  2. Gout
    - negatively birefringent, needle-shaped crystals
    - WCC: 5,000-80,000
    - normal glucose
    - normal lactate
  3. Pseudogout
    - positively birefringent, rhomboid crystals
    - WCC: 5,000-80,000
    - normal glucose
    - normal lactate
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10
Q

How would you treat someone with septic arthritis?

A
  1. analgesia and fluids
  2. surgical drainage and lavage of joint
  3. high-dose antibiotics (IV for 2-3 wks then oral for further 4-6 wks)
    - flucloxacillin
    - if MRSA suspected, use vancomycin
    - if gonococcal or gram -ve infection suspected, use ceftriaxone (and treat gonococcal infection)
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11
Q

How would you treat someone with acute gout?

A

Lifestyle changes: weight loss, exercise, diet, alcohol, fluid intake

  1. Ice, rest and elevation
  2. NSAIDs, e.g. diclofenac, naproxen, indometacin
  3. Colchicine (toxic alkaloid)

If NSAIDs/colchicine contra-indicated, corticosteroids can be given.

If no improvement, consider Canakinumab (mAb active as inhibitor of pro-inflammatory IL-1).

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12
Q

How would you treat someone with pseudogout?

A

Unlike gout, there are no specific treatments for the elimination of CPP crystals from the body. Apart from therapy for any underlying cause, treatment is therefore symptomatic.

  • Ice, cool packs, temporary rest.
  • Aspiration of the joint.
  • NSAIDs.
  • Intra-articular steroid injections.
  • Systemic steroids.
  • Colchicine - an alternative if NSAIDs or steroids are contra-indicated.
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