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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Septic arthritis and osteomyelitis

Paediatrics and child health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Suspected septic joint with sepsis

A febrile child with severe joint pain, non-weight-bearing, painful passive movement and abnormal perfusion may have destructive septic arthritis with bacteraemia.

Action: Use ABCDE and paediatric sepsis care, obtain blood cultures and urgent blood tests when this does not delay treatment, give age- and risk-appropriate intravenous antibiotics and contact orthopaedics immediately for aspiration and drainage. Keep fasting for likely theatre while maintaining glucose, analgesia and circulation.

Synopsis

Recognise haematogenous bone and joint infection before cartilage, physis or blood supply is damaged, obtain high-yield cultures and MRI or ultrasound promptly and combine age-appropriate intravenous antibiotics with urgent aspiration, drainage and safe response-guided oral transition.

  • Septic arthritis is an orthopaedic emergency because purulent pressure and inflammation rapidly damage cartilage and blood supply; osteomyelitis can form subperiosteal or intraosseous abscess and injure the growth plate.
  • Suspect infection in any febrile child with new non-weight-bearing, pseudoparalysis, severe joint pain, focal bony tenderness or painful restriction, especially infants who may show only irritability or poor feeding.
  • Use sepsis ABCDE and contact paediatrics and orthopaedics immediately. Obtain blood cultures before antibiotics when this causes no delay; give prompt intravenous therapy if the child is septic or transfer is prolonged.
  • Full blood count, CRP and ESR support and monitor the diagnosis, but normal values early, in young infants or with Kingella infection do not safely exclude disease.
  • Plain radiographs assess fracture and baseline bone but are commonly normal early. Ultrasound detects a joint effusion and guides aspiration; MRI is preferred for osteomyelitis, pelvic infection, abscess and multifocal disease.
  • Joint aspiration provides cell count, Gram stain, culture and molecular tests, but a negative culture after prior antibiotics does not exclude septic arthritis.
  • Begin age- and risk-specific intravenous antibiotics covering Staphylococcus aureus through the local antimicrobial pathway; extend for neonates, MRSA risk, sickle cell disease, immunocompromise or penetrating injury.
  • Drain a septic joint urgently by aspiration, arthroscopy or open washout as selected by site, organism, response and surgical team; antibiotics alone are not reliable source control for a pressurised infected joint.
  • Switch to oral treatment only when the child is clinically improving, afebrile, able to take medicine, blood culture and organism issues are addressed and CRP is falling, with a documented total course and follow-up owner.
  • Persistent fever, rising CRP, ongoing bacteremia or pain after 48 to 72 hours requires repeat examination and imaging for abscess, adjacent joint infection, endocarditis, resistant organism or another diagnosis.

Key red flags

Shock, altered consciousness or organ dysfunction with bone or joint pain requires immediate sepsis treatment.

A painful immobile hip is time critical because pressure can compromise femoral-head blood supply.

Pseudoparalysis in a neonate or infant may be the only sign of osteoarticular infection.

Back pain with weakness, bladder change or epidural collection features requires urgent spinal MRI and specialist care.

Persistent bacteraemia, murmur or multiple painful sites suggests endocarditis or metastatic infection.

Sickle cell disease changes the organism differential and requires Gram-negative and Salmonella-aware antimicrobial advice.

Failure to improve after 48 to 72 hours suggests undrained abscess, resistant organism, thrombosis or alternative diagnosis.

Septic deterioration

Shock, altered consciousness, rapidly worsening pain or organ dysfunction requires immediate antibiotics and critical-care support.

Investigation priorities

01
First-line blood cultures and inflammatory profileFirst stepFirst line

Obtain organism and baseline full blood count, CRP, ESR and organ function before antibiotics when safe.

02
Preferred MRI with appropriate contrastPreferred

Map osteomyelitis, pelvic or spinal infection, abscess, pyomyositis and adjacent-joint involvement.

Management branches

Initial emergencyCulture and treat without harmful delay

A child is febrile, non-weight-bearing or has severe joint or focal bone pain with infection concern.

  1. Use ABCDE, give analgesia, obtain blood cultures and baseline tests and call orthopaedics and paediatrics immediately.
  2. Start IV antistaphylococcal treatment through the age- and risk-specific local pathway, adding broader coverage where indicated.
  3. Keep fasting for possible theatre and arrange ultrasound for joint fluid or MRI for bone, pelvis, spine and abscess questions.
Oral transitionSwitch only after objective improvement

The child is stable, afebrile and improving after source control and intravenous treatment.

  1. Confirm pain, weight bearing or limb use and CRP are improving and organism, susceptibilities and abscess issues are addressed.
  2. Choose a reliably absorbed active oral formulation the child can take and document total duration and missed-dose advice.
  3. Arrange orthopaedic and paediatric review for recurrence, range, gait, growth and limb-length complications.

Key medicines

Empirical intravenous antistaphylococcal therapyUse the current local paediatric bone-and-joint regimen at the exact weight-based BNFC dose and frequency, commonly IV flucloxacillin with additional age-, sepsis-, Gram-negative- or MRSA-directed coverage when risk requires it.Obtain cultures first only when this is immediate, review allergy and renal or hepatic function, and broaden for neonates, sickle cell disease, immunocompromise or penetrating injury.
Targeted oral step-down antibioticSelect an active high-bioavailability oral agent at the exact current child weight-based dose after clinical and CRP improvement; define total course individually from site, source control, organism, bacteraemia and complications.Do not switch for convenience alone, confirm formulation can be taken and absorbed, and extend or reassess for MRSA, abscess, spine, neonate or slow response.
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • BSAC paediatric bone and joint pathwayUK diagnosis, imaging, cultures, empirical therapy, source control, oral switch and non-response guidance.
  • NICE NG254 managing suspected sepsisCurrent under-16 cultures, time-critical antimicrobial treatment, fluid, monitoring and critical-care escalation.
  • NICE NG195 neonatal infectionAge-specific neonatal infection recognition, cultures and empirical antibiotic principles.
  • BNF for ChildrenCurrent intravenous and oral antimicrobial child doses, formulations, monitoring and contraindications.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom