Septic Arthritis Management (SANJO Guidelines)

Algorithm Steps

1. ▶

   Start

   Suspected Septic Arthritis

   Acute monoarthritis - consider infectious until proven otherwise

   1. ●

      Action

      Clinical Assessment

      History, exam, and risk factors

      • Acute onset joint pain, swelling, warmth
      • Inability to bear weight (lower extremity)
      • Fever (may be absent in elderly/immunocompromised)
      • Limited ROM due to pain
      • Risk factors: RA, DM, recent surgery, prosthesis, IV drug use
      1. ●

         Action

         High-Risk Features

         Increase suspicion for septic arthritis

         • Age >80 years
         • Diabetes mellitus
         • Rheumatoid arthritis
         • Recent joint surgery or injection
         • Prosthetic joint
         • Immunosuppression
         • IV drug use
         • Skin infection
      2. ●

         Action

         Urgent Joint Aspiration

         MANDATORY - Do not delay for imaging

         • Sterile technique
         • Send for: Cell count + differential, Gram stain, Culture
         • Crystal analysis (rule out gout/pseudogout)
         • Lactate, glucose (if available)
         • Aspirate as much fluid as possible
         1. ◆

            Decision

            Synovial Fluid Analysis

            Interpret results

            • WBC >50,000/µL with >90% PMNs: Highly suggestive
            • WBC 25,000-50,000: Possible septic arthritis
            • WBC <25,000: Less likely but does not exclude
            • Gram stain positive in ~50%
            • Culture positive in 70-90%
            1. ●

               Action

               Empiric IV Antibiotics

               Start immediately after cultures obtained

               • Cover S. aureus (most common pathogen)
               • Vancomycin 15-20mg/kg IV q8-12h (if MRSA risk)
               • OR Flucloxacillin 2g IV q6h / Cefazolin 2g IV q8h (if MSSA likely)
               • Add Gram-negative coverage if: elderly, immunocompromised, GU source
               • Ceftriaxone 2g IV daily if gonococcal suspected (young, sexually active)
               1. ◆

                  Decision

                  Drainage Method

                  Joint must be adequately drained

                  1. ●

                     Action

                     Serial Needle Aspiration

                     Option for accessible joints

                     • Repeat daily until effusion resolves
                     • Appropriate for knee, shoulder, ankle
                     • May be inadequate if loculated
                     • Monitor WBC count improvement
                     1. ●

                        Action

                        Pathogen-Directed Therapy

                        Narrow antibiotics when culture results available

                        • S. aureus: Flucloxacillin or Vancomycin (MRSA)
                        • Streptococcus: Penicillin or Ceftriaxone
                        • Gonococcus: Ceftriaxone 1g IV → PO switch
                        • Gram-negative: Ciprofloxacin or Ceftriaxone
                        • Duration: 1-2 weeks IV, then 2-4 weeks oral (SANJO)
                        1. ●

                           Action

                           Monitoring & Follow-up

                           Assess treatment response

                           • Clinical improvement within 48-72h expected
                           • CRP should decline
                           • Repeat aspiration if effusion recurs
                           • Physical therapy when acute phase resolves
                           • Total treatment: 3-6 weeks (1-2wk IV + 2-4wk PO)
                           1. ✓

                              Outcome

                              Infection Resolved

                              Begin rehabilitation

                           2. ⚠

                              Warning

                              Complications

                              Joint destruction, osteomyelitis, sepsis

                              • Cartilage damage and arthritis
                              • Osteomyelitis extension
                              • AVN (especially hip)
                              • Systemic sepsis
                  2. ●

                     Action

                     Surgical Drainage/Washout

                     Preferred for hip, difficult joints, or failed aspiration

                     • Arthroscopic washout: Less invasive
                     • Open arthrotomy: For complex cases
                     • Mandatory for hip (especially pediatric)
                     • If loculated fluid or debris
                     • If no improvement with serial aspiration
                     • May need repeat washout
                  3. ⚠

                     Warning

                     ⚠️ Hip Septic Arthritis

                     Surgical emergency

                     • Urgent surgical drainage required
                     • Blood supply to femoral head at risk
                     • Pediatric hip: Emergency surgery within hours
                     • Kocher criteria guide pediatric workup
         2. ●

            Action

            Additional Studies

            Blood tests and imaging

            • CBC, CRP, ESR (elevated but nonspecific)
            • Blood cultures (positive in 50%)
            • X-ray: May be normal early, rule out osteomyelitis
            • MRI: If adjacent osteomyelitis suspected
            • Ultrasound: Guide aspiration, detect effusion