T&O: Acute Joint Pain Flashcards
What are the 4 main differentials for acute onset joint pain?
- trauma
- septic arthritis
- gout
- pseudogout
Describe the presentations of septic arthritis, gout and pseudogout.
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
What are the common causative agents of septic arthritis?
- Staphylococcus aureus most commonly
- Can sometimes be caused by gonococcal infections
What is the difference between gout and pseudogout?
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.
Suggest risk factors for septic arthritis.
- elderly
- joint surgery, hip or knee prosthesis
- prior joint damage, e.g. RA, gout, systemic CT disorders
- immunodeficiency, e.g. AIDS, DM, steroids
Suggest risk factors for gout.
- male
- obesity
- alcohol (>10g/day)
- thiazide diuretics
- hypertension, CHD, DM, CKD, high triglycerides
- diet: meat, seafood
- chemotherapy
Suggest risk factors for pseudogout.
- elderly
- dehydration
- long-term steroids
- endocrine disorders: hyperparathryoidism, hypothyroidism, acromegaly, etc.
- surgery or trauma
Which investigations would you perform on a pt with an acutely painful swollen knee?
- Arthrocentesis (1st line investigation)
- gram stain
- culture
- microscopy - cells and crystals - 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. - 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.
How would analysis of arthrocentesis fluid help differentiate between septic arthritis, gout and pseudogout?
- Septic arthritis
- WCC: 50,000-100,000
- low glucose
- high lactate - Gout
- negatively birefringent, needle-shaped crystals
- WCC: 5,000-80,000
- normal glucose
- normal lactate - Pseudogout
- positively birefringent, rhomboid crystals
- WCC: 5,000-80,000
- normal glucose
- normal lactate
How would you treat someone with septic arthritis?
- analgesia and fluids
- surgical drainage and lavage of joint
- 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)
How would you treat someone with acute gout?
Lifestyle changes: weight loss, exercise, diet, alcohol, fluid intake
- Ice, rest and elevation
- NSAIDs, e.g. diclofenac, naproxen, indometacin
- 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).
How would you treat someone with pseudogout?
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.
