Clinically
Unwell / irritable
Fever
Not feeding
Unable to weight bear / limp
Knee pain
Examination
Fever
Limited / painful ROM
Hip held flexed and externally rotated
- maximises volume of capsule
Lab tests
WCC > 12 000
ESR > 40
CRP > 10
Blood cultures
Joint Aspiration
- Innoculate directly into culture bottles to increase yield of fastidious organisms eg Kingella
- WCC >50 with >80% PMN suggestive
Xray
May demonstate hip subluxation
Ultrasound
Confirms hip effusion
MRI
Can be useful
- identifies proximal femoral osteomyelitis
Issue
- requires GA usually
Kocher Criteria
Kocher MS et al. Differentiating between septic arthritis and transient synovitis of the hip in children : an evidenced-based clinical prediction algorithim. JBJS (Am). 81 (12): 1662 - 70.
- Criteria :
ESR > 40
WCC > 12
Fever >38.5
Inability to weight-bear
- Risk of Septic Arthritis - 0/4 - .2% ; 1/4 3%; 2/4 40%; 3/4 93% ; 4/4 99%
Pathology
Staph aureus most common; MRSA increasingly common
Group B Strep
Kingella Kingae (fastidious organism; increasingly common in < 3 years)
Gonococcus (Sexually active adolescents)
Operative Management
Indications
- raised inflammatory markers
- fever
- ultrasound with effusion
Technique
No antibiotics unless positive blood culture
Smith Petersen approach
- remove window of capsule
- washout +++
- don't close capsule
- leave in drain
Drill proximal femoral metaphysis / femoral neck
- diagnose / decompress osteomyelitis
MUA
- ensure hip is stable
- may require posteroperative spica if unstable
Post operative
Antibiotics
- broad spectrum initially
- targetted antibiotics with positive culture
- IV until child well and inflammatory markers normalised
- oral until 6 weeks
TWB 6/52
Xray follow up minimum 2 years
- AVN
- chondrolysis
- physeal arrest
- subluxation / dislocation