7. Infectious Arthritis Flashcards
Septic arthritis is always associated with what? More likely to appear in what joints with what quality?
Inflammation or true arthritis (not just arthralgia, which is pain in and around the joint) More likely to appear in a joint previously afflicted with another form of arthritis.
Septic Arthritis: what are the culprits for ACUTE presentation?
Bacterial (usually gram neg) or viral. Anaerobes are uncommon
Septic Arthritis: what are the culprits for CHRONIC presentation?
Lyme, Mycobacterial, fungal, filarial, bacterial (gonococcal, meningiococcal)
What organism is the most common agent?
Staph Aureus because it expresses receptors found in joints, and it is part of normal skin flora. Opportunities to spread from minor wounds
What is the pathophysiology of Septic (infectious) arthritis? In otherwords, how does this hapepn?
Synovial tissue is vascularized, susceptible to being seeded by bacteria –> bacterial toxins induce leukocytes and chondrocytes to produce proteases, which are destructive to cartilage
clinical presentation: how many joints? feels better in resting position or with movement? systemic sx?
- abrupt onset
- usually MONOarticular, may be pauci (2-3 joints)
- discomfort in Resting position**
- May have low fever, rigors
which joints are typically affected?
- weight bearing joints like KNEE, hip, ankle
- for bedridden patients, still weight-bearing joints, but that may mean sternoclavicular, collarbone, shoulder
findings on physical exam?
- redness, swelling, warmth
- bulge sign, floating patella (“ballottement”)
- decr ROM
- tender proximal lymph nodes
- source of infection (but may not be present)
best method for diagnosis?
Arthrocentesis is crucial
The following findings on Arthrocentesis indicate what?
- PMNs
- blood
- crystals
- protein
- low glucose
- PMNs -> infection
- blood -> trauma
- crystals -> gout, pseudogout
- high protein -> infection
- low glucose -> infection
Beyond arthrocentesis, other methods of dx?
-Technetium bone scan (cellulitis v septic arthritis v osteomyelitis) -peripheral blood leukocytes -ESR -culture Arthrocentesis is best!
You suspect septic arthritis: what do you do first?
aspirate that joint FAST: outcome depends on early dx and treatment!
Synovial fluid analysis of Normal joint: what is cell count? appearance of fluid? amount of protein? glucose?
0-200
translucent
protein < 3
glucose 80-100
Synovial fluid analysis of OA or trauma joint: what is cell count? appearance of fluid? amount of protein? glucose?
200-2000
translucent
protein < 3
glucose 80-100
Synovial fluid analysis of RLA, SLE, gout joint: what is cell count? appearance of fluid? amount of protein? glucose?
2000-30000 opaque protein > 3 glucose < 60
Synovial fluid analysis of septic joint: what is cell count? appearance of fluid? amount of protein? glucose?
This is disgusting fluid
75,000 + 90% PMNs
opaque + pus
protein > 3
glucose < 60
Epidemiology for septic arthritis?
peak incidence is bimodal: childhood and old age, predominantly males
what factors predispose the elderly to septic arthritis?
chronic arthritis, systemic disease, immune deficiency, prosthetic joints, underlying RA
what factors predispose younger pts to septic arthritis?
trauma, IVDU
what is the major cause of septic arthritis in sexually active pts under 30? what pattern does it follow?
Neisseria gonorrhoeae –> migrating polyarthritis, inflammation that follows tendon sheaths. may not have GU symptoms. May also settle into one or two joints. That sucks. We had a conference case on this…