X-ray if suspicious for fracture
Plain films or ultrasound can show effusion
If effusion found consider arthrocentesis
Presence of effusion does not rule in or out<unk> synovitis as bilateral effusions can occur in 25% of children
If effusion found consider arthrocentesis
Presence of effusion does not rule in or out<unk> synovitis as bilateral effusions can occur in 25% of children
Must distinguish from septic arthritis<unk> Synovitis favored by:
Temperature <38.5
ESR <20
WBC <12,000
CRP <2
Septic arthritis favored by:
Temperature >38.5
ESR >40
WBC >12,000
CRP >2
severe pain with ROM
Temperature <38.5
ESR <20
WBC <12,000
CRP <2
Temperature >38.5
ESR >40
WBC >12,000
CRP >2
severe pain with ROM
ESR > 40 mm/hr
WBC > 12,000/microliter
Refusal or inability to weight bear on affected joint
Fever 38.5° C or greater
Transient 
Acute rheumatic fever
Sequential 
Developmental dysplasia of hip
SNRI Toxicity
Femur fracture
Quick Sequential 
Juvenile idiopathic arthritis