Stethopedia | Approach

Approach to

Arthritis

Confirm true synovitis and tap any hot joint before antibiotics, then sort by synovial fluid and joint pattern. A WBC <50 ×10⁹/L does not exclude infection (gonococcal, prosthetic joint, immunosuppressed).

  1. Painful, swollen joint(s)
  2. Confirm synovitis; count joints; tap any effusion: cells, Gram stain, culture, crystals1,10
  3. Could this be a septic joint?

Possible septic joint: tap before antibiotics1,2

  • Acute hot, swollen joint(s)
  • Older age, DM, RA, prosthesis, skin infection
  • Fever in only 57%: absence doesn't exclude
  • Gram stain positive or WBC >50 ×10⁹/L
  • Pustules and tenosynovitis: gonococcal
  • Crystals seen but patient looks septic

→ Joint and blood cultures, IV antibiotics, ortho to drain10,11

Then: synovial WBC and joint pattern?

CausesCluesWorkupManagement

Septic

  • S. aureus > strep > gram-negatives
  • Gonococcal (DGI)
  • Prosthetic joint infection: ortho/ID10
  • Mono (knee ~50%); >1 joint in ~20%10
  • PMN ≥90% (LR 3.4)1
  • Lower WBC: DGI, PJI, immunosupp.10,11,12
  • Gram stain, culture; blood cultures ×2
  • GC NAAT: urine, throat, rectum
  • X-ray; CT or MRI if deep joint10
  • Cefazolin + ceftriaxone ± vancomycin (MRSA)11
  • Drain: serial taps or washout10,11
  • 3–4 wk; 2 wk if hand/wrist washout9,10

Crystal

  • Gout (monosodium urate)
  • CPPD (pseudogout)
  • 1st MTP; peaks within 24 h; tophi3
  • Diuretics, alcohol, CKD, meat, seafood
  • Older; knee or wrist; chondrocalcinosis
  • Needles, negatively birefringent: gout
  • Rhomboids, positively birefringent: CPPD
  • Culture anyway: 1.5% also septic2
  • Colchicine, NSAID or steroid (oral/IA)4
  • Tophi/≥2 flares/y: allopurinol, <360 µmol/L4
  • CPPD, 1–2 joints: aspirate, IA steroid7

Inflammatory

  • Rheumatoid arthritis
  • SpA: psoriatic, reactive, IBD, axial
  • Viral (parvovirus, HBV, HCV), Lyme, SLE
  • Morning stiffness >30 min10
  • Symmetric MCP, PIP, wrist, MTP: RA5
  • Dactylitis, psoriasis, uveitis, GU/GI: SpA
  • RF, anti-CCP, ESR/CRP; hand/foot X-ray5
  • HLA-B27, SI imaging; GC/chlamydia NAAT10
  • Parvo IgM, HBV, HCV, HIV, Lyme; ANA10
  • NSAID or short prednisone course10
  • Early rheum; methotrexate for RA6
  • Reactive: treat GU infection10

Noninflammatory

  • Osteoarthritis
  • Fracture, hemarthrosis
  • AVN, internal derangement
  • Age >45, bony swelling, stiff <30 min
  • Trauma or anticoagulant: bloody tap
  • Locking or giving way: mechanical
  • X-ray: joint space loss, osteophytes
  • MRI if AVN or derangement suspected
  • Bloody tap: X-ray for fracture; INR, CBC
  • Exercise, weight loss, tai chi8
  • Topical or oral NSAID; IA steroid8
  • Hemarthrosis: hold anticoagulant; ortho

Can't-miss cause Superscripts link to the references below.

References

  1. Margaretten ME, Kohlwes J, Moore D, Bent S. Does this adult patient have septic arthritis? JAMA. 2007;297:1478–1488. PubMed 17405973
  2. Shah K, Spear J, Nathanson LA, et al. Does the presence of crystal arthritis rule out septic arthritis? J Emerg Med. 2007;32:23–26. PubMed 17239729
  3. Neogi T, Jansen TL, Dalbeth N, et al. 2015 gout classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Ann Rheum Dis. 2015;74:1789–1798. PubMed 26359487
  4. FitzGerald JD, Dalbeth N, Mikuls T, et al. 2020 American College of Rheumatology guideline for the management of gout. Arthritis Care Res (Hoboken). 2020;72:744–760. PubMed 32391934
  5. Aletaha D, Neogi T, Silman AJ, et al. 2010 rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum. 2010;62:2569–2581. PubMed 20872595
  6. Fraenkel L, Bathon JM, England BR, et al. 2021 American College of Rheumatology guideline for the treatment of rheumatoid arthritis. Arthritis Care Res (Hoboken). 2021;73:924–939. PubMed 34101387
  7. Zhang W, Doherty M, Pascual E, et al. EULAR recommendations for calcium pyrophosphate deposition. Part II: management. Ann Rheum Dis. 2011;70:571–575. PubMed 21257614
  8. Kolasinski SL, Neogi T, Hochberg MC, et al. 2019 American College of Rheumatology/Arthritis Foundation guideline for the management of osteoarthritis of the hand, hip, and knee. Arthritis Care Res (Hoboken). 2020;72:149–162. PubMed 31908149
  9. Gjika E, Beaulieu JY, Vakalopoulos K, et al. Two weeks versus four weeks of antibiotic therapy after surgical drainage for native joint bacterial arthritis: a prospective, randomised, non-inferiority trial. Ann Rheum Dis. 2019;78:1114–1121. PubMed 30992295
  10. Hendrickson M, Savoie M. Approach to rheumatologic disease; Arthritis. In: Gay E, Levy N, eds. Department of Medicine Housestaff Manual, 30th ed. 2024:169–171.
  11. Ravn C, Neyt J, Benito N, et al. Guideline for management of septic arthritis in native joints (SANJO). J Bone Jt Infect. 2023;8:29–37. PubMed 36756304
  12. McNally M, Sousa R, Wouthuyzen-Bakker M, et al. The EBJIS definition of periprosthetic joint infection. Bone Joint J. 2021;103-B:18–25. PubMed 33380199

For education only; not a substitute for clinical judgment or local protocols. Where sources differ, the flowchart follows the current guideline.

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