Septic Arthritis — Management Pathway

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

🎓 Want to practice? Do a case challenge with this pathway → (get a case, choose management step by step, scored).

Full pathway

1. [Decision] High suspicion?
   Acute hot swollen painful joint — does arthrocentesis support it? (Acute mono/oligo-arthritis with redness, heat, swelling, restricted motion ± fever (systemic symptoms are insensitive). Staph aureus is most common (>80% of non-gonococcal); risk factors = prosthetic joint, pre-existing joint disease (RA), immunosuppression, IVDU, diabetes, recent procedure. Serology/imaging cannot exclude it — arthrocentesis is required.)
   • Synovial fluid supports / high clinical suspicion → High suspicion → antibiotics + drainage
   • Low probability, other arthritis → Low probability
2. [End] Low probability
   Send synovial fluid for cell count + differential, Gram stain, culture and crystals — differentiate crystal arthritis (gout/pseudogout; crystals do not exclude coexisting infection), reactive/RA, etc.; if it cannot be reliably excluded, admit as septic arthritis on empiric antibiotics until cultures return.
3. [End] High suspicion → antibiotics + drainage
   Synovial fluid supportive (WBC often >50,000/mm³, PMN-predominant; not a hard cutoff, Gram stain insensitive, crystals do not exclude) or high clinical suspicion: 1) empiric IV antibiotics after aspiration — cover Gram-positives including MRSA (vancomycin); add Gram-negative cover (a third-generation cephalosporin) in high-risk/elderly/immunosuppressed, add anti-pseudomonal cover for IVDU; de-escalate per Gram stain/culture. 2) Joint drainage and decompression (repeated aspiration/arthroscopy/open washout, orthopedics consult; surgery for hip/prosthetic joint/hemodynamic instability). Course ~4 weeks (longer for prosthetic joints).

Source guidelines & references

• AAFP diagnosis and treatment of septic arthritis

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

Other pathways