* Differential

* Traumatic causes: non-accidental trauma, fracture, dislocation, sprain, strain, tendonitis, osgood schlatter

* Non-traumatic causes: septic arthritis, transient synovitis, osteomyelitis, SCFE, LCP disease, rheumatologic disease, bony tumors

* Work-up

* XRay

* Labs to evaluate for septic arthritis – CBC BMP ESR CRP

* Kocher Criteria

* Non-weight bearing

* Fever >38.5C

* ESR >40

* WBC >12

* Kocher Criteria Statistics

* 0 points: 0.2% (or 2% in prospective studies)

* 1 point: 3% (or 9% in prospective studies)

* 2 points: 40%

* 3 points:93%

* 4 points: 99%

* Septic Arthritis DX

* >50,000 WBC

* Age 0-3mo : group B strep

* Age 3mo – 12 years: Staph Aureus

* Age 12-18 years: Gonorrhea

* Sickle Cell Disease: Salmonella