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Septic Arthritis

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Other Names

  • Infectious Arthritis
  • Bacterial Arthritis
  • Infected Joint


  • This page refers to septic arthritis (SA) of all joints



  • Estimated case fatality rate of 11%[1]
  • More than 50% of cases involve the knee (need citation)
  • Incidence ranges widely, between 4 and 29 cases per 100,000 person-years [2]


  • Etiology
    • Bacteremia and hematogenous spread most common[3]
    • Direct inoculation from trauma, surgery
    • Local contiguous spread such as osteomyelitis
  • Etiology
    • Penetrating trauma can seed the joint, causing SA[4]
  • Affected joint
    • 60% of cases involve the hip, knee[5]
    • In 22% of cases, more than one joint is affected (oligo- or poly-articular)[6]
    • Axial joints (sternoclavicular, sacroiliac, etc) more commonly seen in patients with IVDA[7]
  • Effects on joint
    • Irreversible cartilage destruction begins as early as 8 hours


  • Staphylococci aureus, streptococcus pyogenes (group A)
    • Account for up to 91% of cases[8]
  • Gram negative organisms (E. coli, klebsiella, enterobacter)
    • More common in older adults, immunocompromised patients
  • Neisseria Gonorrhea
    • Accounts for about 20%, seen in young sexually active adults, may have associated dermatitis
    • Tenosynovial, seen in hands, wrists and ankles
    • Associated with terminal complement deficiency
  • Propionibacterium acnes
    • Can be seen following shoulder surgery
  • Sickle Cell Disease
    • Consider Salmonella or Streptococcus pneumoniae
  • Bartonella henselae
    • Associated with HIV
  • Eikenella corrodens
    • Seen in human bites
  • Fungal/candida
    • Consider in immunocompromised host
  • Cat or dog bite
    • Typically hands, fingers
    • Bugs: Pasteurella multocida or Capnocytophaga species
  • Mycobacterium marinum
    • Seen in small joints such as hand, fingers.
    • Associated with cleaning fish tank[9]
  • Brucella species
    • Associated with consumption of unpasteurized dairy products[10]
    • Often monoarticular, affects sacroiliac joint
  • Pseudomonas aeruginosa
    • Associated with IV drug abuse (IVDA), nail through shoe
  • Coccidioides immitis
    • Regional: Southwestern United States, Central and South America
    • Patients typically have a primary respiratory illness, knee most commonly affected
  • Blastomyces dermatitidis
    • Found in soil, dust containing decomposed wood
    • Regional: north-central and southern United States
    • Monoarticular: knee, ankle, or elbow
  • Systemic Lupus Erythematosus
    • Consider: N. gonorrhoeae, Proteus species, Salmonella species

Risk Factors

Differential Diagnosis

Clinical Features

  • History
    • Classically, patients will present with a hot, swollen and tender joint
    • Range of motion is restricted
    • Duration of symptoms is typically <2 weeks
      • Longer more insidious presentations can be seen with low virulence organisms, tuberculosis, prosthesis infection[14]
    • Large joints are more commonly affected than small joints
    • Constitutional symptoms (sensitivity): fever (57%), chills (27%), or rigors (19%)[15]
    • When septic arthritis is a consideration, risk factors should be careful considered
  • Physical Exam
    • Important to distinguish peri-articular (i.e. prepatellar bursitis) vs intra-articular
    • Inspection: erythema, effusion, extremity in position of comfort
    • Palpation: warmth, tenderness
    • ROM: restricted
    • Gait: unable to ambulate or bear weight
  • Special Tests


Arthrocentesis and Synovial Fluid Analysis

  • Arthrocentesis of the affected joint should be performed promptly
    • Gold standard for diagnostic evaluation
  • Synovial fluid labs which should routinely be ordered when evaluating for SA
    • Culture and gram stain
    • Culture
    • Cell count
    • Protein and glucose
    • Crystal analysis
    • Synovial lactate
  • General
  • Gram stain
    • Only positive in 50% of cases
  • Culture
    • More sensitive than gram stain alone
    • Neisseria Gonnorrhea organisms do not culture well
    • Strongly consider injecting synovial fluid into blood culture bottles
  • Synovial white cell count
    • Coutlakis et al: >50,000/mm3: 47% of cases; >100,000/mm3: 76% of cases[16]
    • < 50,000/mm3 have a low likelihood of infection, but it is not entirely excluded
    • >1,100/mm3 in prosthetic joint is considered SA
    • PMN > 90% often seen
    • Low WBC seen with: gonococcal disease, peripheral leukopenia, or joint replacement[17]
  • Glucose
    • Reportedly less than 60% of normal
    • Diagnostic value has been called into question[18]
  • Crystal analysis
    • SA can co-exist with crystal arthropathies, presence of crystals does not exclude SA[19]
  • PCR
    • May be useful to isolate uncommon organisms


  • WBC
    • Typically elevated with left shift
    • Bands may be present
  • ESR (erythrocyte sedimentation rate)
    • Typically elevated, can be normal
    • Can trend with treatment
  • CRP (C reactive protein)
    • Typically elevated, can be normal, more useful than ESR
    • Can trend with treatment
  • Blood culture
    • Positive in 25-50% of patients with SA[20]
  • No evidence for diagnostic value
    • Tumour necrosis factor a </ref name="ref1">
    • Interleukin 6
    • Interleukin 8

Saline Load Test

  • Can be used to determine if wound communicates with joint
    • 175 mL is 99% sensitive (need citation)


  • Obtain radiographs of affected joint
    • Mainly useful to exclude other pathology
  • Potential findings
    • Joint space widening
    • Effusion
    • Periarticular osteopenia


  • Helpful to confirm presence or absence of joint effusion
    • Useful to guide arthrocentesis


  • Potential findings
    • Joint effusion
    • Involvement of bone (osteomyelitis)


  • No formal classification system
    • Sometimes broken down into Nongonococcal and gonococcal arthritis



  • Outcomes
    • Delay in care can lead to irreversible joint destruction, disability[21]
    • Up to 1/3 of patients have severe morbidity (amputation, arthrodesis, prosthetic surgery, severe functional deterioration) depending on risk factors[22]
  • Predictors of poor prognosis[22]
    • Older age
    • Pre-existing joint disease
    • Presence of synthetic material within the joint
  • Post antibiotics
    • Patients with S. aureus SA regain 46% - 50% of their baseline joint function[23]
    • Patients with Pneumococcal SA regain 95% of their baseline joint function


  • Antibiotic therapy
    • Broad coverage early
    • Tapered to organisms found on culture, gram stain
  • Antibiotic choices
    • Gram positive: vancomycin
    • Gram negative cocci: ceftriaxone
    • Gram negative rods: Ceftazidime (Fortaz), cefepime (Maxipime), piperacillin/tazobactam (Zosyn), or carbapenems
    • Negative gram stain: Vancomycin plus either ceftazidime or an aminoglycoside


  • Indications
    • Virtually all cases
  • Technique
    • Irrigation and drainage of the joint

Rehab and Return to Play


  • Needs to be updated
    • Likely no formal rehabilitation guidelines

Return to Play

  • Needs to be updated
    • Likely no formal return to play guidelines


See Also


  1. Gupta MN, Sturrock RD, Field M. A prospective 2-year study of 75 patients with adult-onset septic arthritis. Rheumatology (Oxford) 2001;40:24–30.
  2. Mathews CJ, Weston VC, Jones A, Field M, Coakley G. Bacterial septic arthritis in adults. Lancet. 2010;375(9717):846–855....
  3. Ross JJ, Saltzman CL, Carling P, Shapiro DS. Pneumococcal septic arthritis: review of 190 cases. Clin Infect Dis. 2003;36(3):319–327.
  4. Brook I, Frazier EH. Anaerobic osteomyelitis and arthritis in a military hospital: a 10-year experience. Am J Med 1993;94:21–8.
  5. Rosenthal J, Bole GG, Robinson WD. Acute nongonococcal infectious arthritis. Evaluation of risk factors, therapy, and outcome. Arthritis Rheum 1980;23:889–97.
  6. Dubost JJ, Fis I, Denis P, Lopitaux R, Soubrier M, Ristori JM, et al. Polyarticular septic arthritis. Medicine (Baltimore) 1993;72:296–310.
  7. Goldenberg DL. Bacterial arthritis. In: Ruddy S, Harris ED, Sledge CB, Kelley WN, eds. Kelley's Textbook of Rheumatology. 6th ed. Philadelphia, Pa.: Saunders; 2001:1469–1483.
  8. Ryan MJ, Kavanagh R, Wall PG, Hazleman BL. Bacterial joint infections in England and Wales: analysis of bacterial isolates over a four year period. Br J Rheumatol 1997;36:370–3.
  9. Gardam M, Lim S. Mycobacterial osteomyelitis and arthritis. Infect Dis Clin North Am. 2005;19(4):819–830.
  10. Ohl CA. Infectious arthritis of native joints. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa.: Churchill Livingstone; 2010:1443–1456.
  11. Kaandorp CJ, Van Schaardenburg D, Krijnen P, Habbema JD, van de Laar MA. Risk factors for septic arthritis in patients with joint disease. A prospective study. Arthritis Rheum. 1995;38(12):1819–1825.
  12. Le Dantec L, Maury F, Flipo RM, et al. Peripheral pyogenic arthritis. A study of one hundred seventy-nine cases. Rev Rhum Engl Ed. 1996;63(2):103–110.
  13. Meijers KA, Dijkmans BA, Hermans J, van den Broek PJ, Cats A. Nongonococcal infectious arthritis: a retrospective study. J Infect 1987;14:13–20.
  14. Gupta MN, Sturrock RD, Field M. Prospective comparative study of patients with culture proven and high suspicion of adult onset septic arthritis. Ann Rheum Dis 2003;62:327–31.
  15. Margaretten ME, Kohlwes J, Moore D, Bent S. Does this adult patient have septic arthritis? JAMA. 2007;297(13):1478–1488.
  16. Coutlakis PJ. In:, Roberts WN, Wise CM, eds. Another look at synovial fluid leukocytosis and infection. J Clin Rheumatol 2002;8:67–71.
  17. Shmerling RH, Delbanco TL, Tosteson AN, Trentham DE. Synovial fluid tests. What should be ordered? JAMA. 1990;264(8):1009–1014.
  18. Soderquist B, Jones I, Fredlund H, Vikerfors T. Bacterial or crystal-associated arthritis? Discriminating ability of serum inflammatory markers. Scand J Infect Dis 1998;30:591–6.
  19. Yu KH, Luo SF, Liou LB, et al. Concomitant septic and gouty arthritis—an analysis of 30 cases. Rheumatology (Oxford). 2003;42(9):1062–1066.
  20. Bockenstedt LK. Infectious disorders: Lyme disease. In: Klippel JH, Stone JH, Crofford LJ, White PH, eds. Primer on the Rheumatic Diseases. 13th ed. New York, NY: Springer; 2008:282–289.
  21. Weston VC, Jones AC, Bradbury N, Fawthrop F, Doherty M. Clinical features and outcome of septic arthritis in a single UK health district 1982–1991. Ann Rheum Dis 1999;58:214–9.
  22. 22.0 22.1 Kaandorp CJ, Krijnen P, Moens HJ, Habbema JD, van Schaardenburg D. The outcome of bacterial arthritis: a prospective community-based study. Arthritis Rheum. 1997;40(5):884–892.
  23. Weston VC, Jones AC, Bradbury N, Fawthrop F, Doherty M. Clinical features and outcome of septic arthritis in a single UK Health District 1982–1991. Ann Rheum Dis. 1999;58(4):214–219.
Created by:
John Kiel on 13 June 2019 10:36:20
Last edited:
25 January 2024 20:25:58