Joint Infections and Osteomyelitis¶

Ally Glover

Background:¶

If high concern for septic arthritis, engage Ortho before ID. Needs arthrocentesis ± wash out.
ESR/CRP are helpful but nonspecific in diagnosing bone/joint infections

Septic arthritis: erythema, effusion, limited ROM and pain with passive and active ROM
Osteomyelitis: often underlying a wound (diabetic foot ulcer, sacral decubitus ulcer) but may be hematogenous as well; probe to bone positivity is diagnostic for osteomyelitis

CBC (leukocytosis), ESR, CRP
Blood cultures
Imaging: start with X-ray → if radiograph is negative for osteo, cannot rule out, need to get MRI. Very helpful if it’s picked up on X-ray though due to specificity
Fluid studies & gram stain results from synovial fluid if concerned for septic arthritis: usually WBC > 20,000 cells/ microL

If pt is sick, don’t wait for culture data to start empiric antibiotics
- Gram positives: empiric coverage with vancomycin until ID and sensitivities; MRSA nares being negative does not rule out MRSA skin/soft tissue infection
- Gram negatives: empiric coverage with ceftriaxone or cefepime if concerned for Pseudomonas.
If concern for septic arthritis, consult Ortho, hold AC
If a pt has a foot wound with underlying osteomyelitis, talk to Podiatry/Ortho for deep tissue biopsy. If clinically stable, hold abx.
- IR and CT/US guided procedures don’t really do bone biopsies, so talk to surgical specialty first
Osteomyelitis abx duration: usually 6 weeks, but can do PO antibiotics based on susceptibilities, ID follow up
Septic arthritis abx duration: usually 3-4 weeks

Septic arthritis mimic: gout / CPPD → obtain crystal analysis with synovial studies
Less common causes of septic arthritis: gonococcal, Lyme disease (order serologies if suspicion is high)