Suspected septic arthritis (native joint)
Hot, swollen, painful joint. A normal temperature, blood count or CRP does not exclude it.
All Pathways
Orthopedic SurgeryEmergency
Septic Arthritis Management (SANJO Guidelines)
Septic Arthritis Management (SANJO Guidelines): Suspected septic arthritis (native joint) → Sepsis or septic shock: IV antibiotics now, do not wait for ...
Pathway Overview
25 steps
Algorithm Steps
25 total
01Start 02Warning Sepsis or septic shock: IV antibiotics now, do not wait for aspiration
Take 2 sets of blood cultures first if this causes no delay.
- Give IV antibiotics at once; use sepsis-pathway doses
- Aspirate the joint as soon as possible after that
- Urgent orthopaedic review: surgical washout without delay
03Warning Prosthetic joint or ACL graft: this pathway does not apply
This pathway is for native joints. Refer urgently to orthopaedics.
- Prosthetic joint: urgent orthopaedic referral; use a prosthetic joint infection pathway
- After ACL reconstruction: arthroscopic washout is the first treatment
- Other implant in or near the joint: orthopaedic advice before treatment
04Action Clinical assessment
No history or examination finding confirms or excludes septic arthritis.
- Acute joint pain, swelling, warmth; painful, limited movement
- Cannot bear weight or use the limb (child: limp or refuses to use the limb)
- Fever may be absent, especially in older or immunosuppressed patients
- Look for a source: skin infection, injection site, urinary tract
- Gonococcal clues: sexually active, pustular skin lesions, tenosynovitis, several joints
- Symptoms for weeks to months: think of TB arthritis
- Other causes: gout, pseudogout, reactive arthritis, trauma; child: transient synovitis, acute rheumatic fever
05Action Risk factors that raise suspicion
None of these is needed for the diagnosis.
- Age over 80 years
- Diabetes mellitus
- Rheumatoid arthritis
- Recent joint surgery or joint injection
- Prosthetic joint (see warning above)
- Immunosuppression
- Injecting drug use
- Skin infection
06Action Urgent joint aspiration (before antibiotics unless septic)
Do not delay it for imaging. Child: aspirate with the orthopaedic team, but do not delay antibiotics for it.
- Strict aseptic technique; do not pass the needle through an abscess or, if possible, through cellulitis
- Priority if fluid is scarce: Gram stain and culture, then WBC count with differential, then crystals
- Send at least 1 mL in a sterile tube for culture; put leftover fluid into blood culture bottles
- Drain as much fluid as possible
- Hip, sacroiliac or other deep joint, or dry tap: ultrasound, fluoroscopy or CT guidance
- Do not inject saline to increase the culture yield
- Synovial lactate and glucose may add information
07Action Blood tests and imaging
No blood test confirms or excludes septic arthritis.
- Blood cultures: 2 sets (aerobic and anaerobic bottle each) before antibiotics
- FBC, CRP (baseline to track response), urea, electrolytes and creatinine (for antibiotic doses)
- Suspected gonococcal infection: NAAT and gonococcal culture (ask for it by name) from urethra or cervix, throat and rectum; synovial fluid for gonococcal NAAT and culture
- X-ray: baseline; shows fracture, osteomyelitis, arthritis or implants
- Ultrasound: confirms an effusion and guides aspiration
- MRI: sacroiliac joint, or suspected nearby osteomyelitis or abscess
08Warning Synovial results cannot exclude septic arthritis
A low WBC count, crystals or a negative Gram stain do not rule it out. Start antibiotics without waiting for results.
- WBC over 50,000 cells/µL suggests infection; under 25,000 cells/µL lowers the chance but does not exclude it
- Crystals do not exclude infection: gout or pseudogout can coexist with it
- Cutoffs may not apply if immunosuppressed; the Gram stain is often negative
09Warning Tropical northern Australia: think of melioidosis
Wet season, diabetes, hazardous alcohol use, chronic kidney or lung disease. Flucloxacillin and cefazolin do not treat it.
- Suspected melioidosis, or gram-negative bacilli on Gram stain: meropenem 1 g IV 8-hourly (adult); child 25 mg/kg (max 1 g) IV 8-hourly
- Get infectious diseases (ID) advice
- Tell the laboratory that melioidosis is possible
10Decision Child (under 18 years)?
Children need different doses, Kingella kingae cover under 5 years and a different surgical approach.
- If Yes
- Child
11Action Child: IV cefazolin as soon as cultures are taken
Do not delay antibiotics for aspiration. Cefazolin covers S. aureus and Kingella kingae (under 5 years).
- Cefazolin 50 mg/kg (max 2 g) IV 8-hourly
- Under 3 months: paediatric ID advice now; also cover gram-negative bacteria and group B streptococcus
- Unvaccinated: also cover H. influenzae and S. pneumoniae (paediatric ID advice)
- Sickle cell disease: also cover Salmonella (paediatric ID advice)
- MRSA risk or penicillin allergy: local guideline or paediatric ID advice; vancomycin or clindamycin alone does not cover Kingella kingae
- Tropical north: see melioidosis warning above
- Suspected gonococcal infection: ceftriaxone 50 mg/kg (max 2 g) IV daily if 45 kg or less, 1 g IV daily if over 45 kg, for 7 days; child protection and sexual health advice. Neonate: paediatric ID advice; no ceftriaxone if premature, jaundiced or on IV calcium
- Stop antibiotics only if another diagnosis is confirmed (senior decision)
12Action Child: orthopaedic team now; aspirate and wash out the joint
Hip: emergency orthopaedic review, because the blood supply to the femoral head is at risk.
- Septic arthritis needs urgent aspiration, with or without arthrotomy and washout
- After aspiration and irrigation, orthopaedics may choose a conservative approach
- Surgery if symptoms for more than 5 days, MRSA or another hard-to-treat organism, or no progress after 2-3 aspirations
- Young infant: arthrotomy may be needed
13Action Child: oral switch when improving (often after 2-3 days IV)
Switch when afebrile, clinically better and inflammatory markers are falling.
- Cefalexin 45 mg/kg (max 1.5 g) orally 8-hourly
- Total course usually 2-3 weeks for uncomplicated septic arthritis
- Osteomyelitis, unusual site or resistant organism: longer course; paediatric ID advice
- Not improving: orthopaedic review for washout; paediatric ID advice
- Resistant organism, S. aureus in blood cultures, under 3 months or immunocompromised: paediatric ID advice
14Outcome Child: discharge when well and using the limb
Afebrile, markers improving, weight bearing, tolerating oral antibiotics. Return at once if fever or worse.
If No- Adult
15Action Adult: empiric IV antibiotics straight after aspiration and blood cultures
Do not wait for cell count or Gram stain. Check allergy, past flucloxacillin jaundice (do not give it again) and kidney function (adjust cefazolin and vancomycin).
- No penicillin allergy: flucloxacillin 2 g IV 6-hourly
- Non-severe penicillin allergy: cefazolin 2 g IV 8-hourly
- Severe penicillin allergy: vancomycin IV; loading dose, then dose by levels and kidney function (local protocol)
- MRSA risk (known MRSA; northern Australia or other high-rate area): add vancomycin IV
- Gram-negative bacilli on Gram stain, or older age, immunosuppression or urinary source: add ceftriaxone 2 g IV daily (severe beta-lactam allergy: ID advice for a non-beta-lactam option)
- Injecting drug use or recent hospital care: ceftriaxone may miss Pseudomonas; get ID advice
- Suspected gonococcal infection: ceftriaxone 1 g IV daily (see gonococcal step)
- Also taking paracetamol: flucloxacillin can cause high anion gap metabolic acidosis; monitor
16Decision Another diagnosis confirmed and septic arthritis unlikely?
Senior review of Gram stain, cell count, crystals and clinical course.
- If Yes
- Other diagnosis confirmed
17Outcome Other diagnosis confirmed: antibiotics may be stopped; follow cultures
Follow cultures to the final result (5-7 days). Joint worse: re-aspirate and restart antibiotics. No steroid injection into the joint until cultures are negative.
If No- Septic arthritis possible
18Action Septic arthritis possible: drain the joint; orthopaedic review now
Sepsis: surgical washout without delay. No sepsis: surgery may wait up to 24 h only if the joint is aspirated and irrigated, antibiotics have started and an experienced surgeon will operate.
- Large joint (hip, knee, shoulder) or joint damage: surgical washout is recommended
- Arthroscopic washout for most early disease (Gächter stage I-III); open arthrotomy for adhesions, cartilage or bone damage (stage III-IV)
- Hip: surgical drainage; the blood supply to the femoral head is at risk
- Small accessible joint without sepsis, if orthopaedics agree: repeat needle aspiration when fluid reaccumulates; no improvement: surgical washout
- At surgery: send synovial biopsies for culture and histology
- Delay beyond 24-48 h increases the need for repeat washout
19Action Culture results: targeted antibiotics
Narrow to the organism and its susceptibilities. Get ID advice for resistant or unusual organisms.
- MSSA: flucloxacillin 2 g IV 6-hourly (non-severe penicillin allergy: cefazolin 2 g IV 8-hourly)
- MRSA: vancomycin IV (local AUC-guided protocol); ID advice
- S. aureus in blood cultures: manage as S. aureus bacteraemia (ID advice, repeat blood cultures, echocardiography); longer course
- Streptococcus: benzylpenicillin or ceftriaxone, by susceptibility
- Gram-negative bacilli: by susceptibility; ID advice
- Culture negative: ask for synovial PCR and longer culture (10-14 days); think of TB; ID advice
- Gonococcus: see next step
20Action Gonococcal arthritis: ceftriaxone plus azithromycin; STI tests; partners
Pregnant: no doxycycline; get sexual health advice. Headache, neck stiffness or new murmur: look for meningitis or endocarditis (higher dose, longer course; ID advice).
- Ceftriaxone 1 g IV or IM every 24 h
- Plus azithromycin 1 g orally once (Australian dual therapy against resistance)
- After 24-48 h of clear improvement: oral switch guided by susceptibility; total at least 7 days
- Chlamydia not excluded (not pregnant): doxycycline 100 mg orally twice daily for 7 days
- Get sexual health or ID advice on the local regimen
- Test for other STIs; partner notification; notify the state or territory health department
21Action Review daily: is treatment working?
Check pain, swelling, fever, joint function, blood WBC and CRP.
- Falling CRP supports a response
- Repeat aspiration if the effusion returns or progress is poor
- Mobilise as soon as infection is controlled and drains are out
22Decision Improving (joint signs better, WBC and CRP falling)?
Signs of failure: persistent pain or swelling, pus, fever, worse joint function, CRP not falling.
- If Yes
- Improving
23Action Improving: oral switch and total duration
Set the total duration with ID advice. Longer if bacteraemia, osteomyelitis or slow response.
- Switch to oral when fever, joint signs, WBC and CRP improve; choose a drug with good oral absorption and joint penetration
- SANJO: IV usually 1-2 weeks, then oral 2-4 weeks
- After surgical washout, 2 weeks of targeted therapy was as good as 4 weeks in one adult RCT (mostly hand and wrist)
- Gonococcal: at least 7 days in total
24Outcome Infection resolved: rehabilitation
Physiotherapy to restore movement. Review for joint damage.
If No- Not improving
25Warning Not improving: treatment failure
Repeat washout. Look for an abscess, osteomyelitis or a missed organism.
- Urgent orthopaedic review for repeat washout or open debridement
- MRI or CT for periarticular abscess or osteomyelitis
- Review cultures and antibiotics with ID; think of TB, fungi or resistant organisms
Guideline Source
EBJIS/ESSKA guideline for management of septic arthritis in native joints (SANJO), 2023
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Not for prosthetic joint infection or joint implants: refer to orthopaedics
- Antibiotic choice depends on local resistance (for example MRSA and melioidosis in northern Australia); follow local guidelines such as eTG
- Adult IV and oral durations rest on low-certainty evidence; set the duration with ID advice
- TB and fungal arthritis are not covered in detail
Contraindicated Populations
Prosthetic joint infection (use a prosthetic joint infection pathway)
Applicable Regions
AUUSEU
AU: Empiric choices follow Therapeutic Guidelines (eTG) style: flucloxacillin first line. MRSA rates are high in northern Australia (NT: about 40% of S. aureus bloodstream infections). In tropical northern Australia, consider melioidosis. Children: RCH Melbourne bone and joint infection guideline.
Version 2Next review: 2027-09-30
Next steps
Finish the workflow by opening the most relevant calculator, then convert the session into a live account when you are ready.
Related Resources
Frequently Asked Questions
What is the Septic Arthritis Management (SANJO Guidelines)?
The Septic Arthritis Management (SANJO Guidelines) is a emergency clinical algorithm for Orthopedic Surgery. It provides a structured decision tree to guide clinical decision-making, based on EBJIS/ESSKA guideline for management of septic arthritis in native joints (SANJO), 2023.
What guideline is the Septic Arthritis Management (SANJO Guidelines) based on?
This algorithm is based on EBJIS/ESSKA guideline for management of septic arthritis in native joints (SANJO), 2023 (DOI: 10.5194/jbji-8-29-2023).
What are the limitations of the Septic Arthritis Management (SANJO Guidelines)?
Known limitations include: Not for prosthetic joint infection or joint implants: refer to orthopaedics; Antibiotic choice depends on local resistance (for example MRSA and melioidosis in northern Australia); follow local guidelines such as eTG; Adult IV and oral durations rest on low-certainty evidence; set the duration with ID advice; TB and fungal arthritis are not covered in detail. Individual patient factors may require deviation from these recommendations.
Get AI-Powered Analysis Alongside This Algorithm
In AttendMe.ai, the Septic Arthritis Management (SANJO Guidelines) appears automatically when your clinical question matches — alongside evidence from 3M+ peer-reviewed articles.
Try AttendMe Free