Septic, Crystal and Reactive Arthritis Flashcards
What are the causes of acute monoarthritis?
- infection
- crystal (gout, calcium pyrophosphate)
- reactive (inflammation)
- haemoarthrosis (bleeding into joint)
- systemic rheumatic condition
- trauma
Describe the clinical features of acute monoarthritis
- inflammation signs (redness, heat, discomfort, swelling)
- +/- fever (can be dampened if patient is on certain drugs)
- +/- leucocytosis, raised CRP (can be blunted)
- be aware of atypical presentations
What is the most important thing to remember about acute monoarthritis?
acute monoarthritis is septic until proven otherwise (negative aspirate)
What are the risk factors for septic arthritis?
- previous arthritis
- trauma
- diabetes mellitus (esp if poorly controlled)
- immunosuppression
- bacteraemia (eg. self-catheterising/changing catheters)
- sickle cell anaemia
- prosthetic joint
Describe the pathogenesis of septic arthritis
- bacteria enter joint and deposit in synovial lining
- most common by haematogenous spread (can also by local invasion/ inoculation)
- rapid entry into synovial fluid (due to limited host response)
- good environment for pathogen due to lack of basement membrane and close relationship to blood vessels
Describe the features of septic arthritis
- > 60
- on average 4 joints (knee, elbow, shoulder and hip)
- commonly RA (without fever or leucocytosis)
- blood/synovial fluid culture (both effective)
- staph and strep most common pathogens
- poor prognosis (1/3 mortality)
What is the management for septic arthritis?
- joint aspiration (to reduce burden and washout joint)
- antibiotic therapy
- surgical intervention (if not responding after 48hrs of therapy - consult orthopaedics)
List the risk factors for gout
Non-modifiable: age, male, race, genetic factors, impaired renal function
Modifiable: obesity, alcohol, high-purine diet (meat and seafood), fructose corn syrup, medications
What medications can put you at risk for gout?
- aspirin (reduces UA excretion which can lead to progressive accumulation)
- diuretics
- cyclosporin
- pyrazinamide and ethambutol
- nicotinic acid
When can a diagnosis of gout be made on clinical suspicion?
- typical presentation of podagra
- history of gout flares or hyperuricaemia
- raised sUA between attacks
What differentials should you keep in mind when considering a diagnosis of gout?
- septic arthritis
- CPPD
What are the goals of gout treatment?
Acute attacks: relieve pain and reduce inflammation
- cold-packs, NSAIDs/colchicine/corticosteroids
Long-term: prevent attacks and joint damage and eliminate top (crystals)
List the urate lowering therapies
- allopurinol (100mg then increase every 4w until target)
- febuxostat (80mg, can go to 120mg in 4w if not target)
What are the important features of reactive arthritis?
- serum-negative for rheumatoid factor
- associated with HLA-B27
- tends to develop soon after an infection
- no viable organism (not septic arthritis)
Describe the clinical features of reactive arthritis
- acute (2-6 weeks post infection)
- warm, swollen, tender joints (commonly lower limb)
- systemically unwell (inflammatory markers raised + malaise)
- arthritis, conjunctivitis and urethritis
- most will resolve but can recur
