Consider x-rays
Use Ottawa<unk>  Rules for acute<unk>  injuries to determine need for x-rays
Use Ottawa<unk>  Rules for acute<unk>  injuries to determine need for x-rays
Consider x-rays
Consider labs for infectious workup (i.e. septic joint)
CBC
Chemistry
Coags
ESR/CRP
Consider arthrocentesis
CBC
Chemistry
Coags
ESR/CRP
Typically determined by imaging
See following for analysis of synovial fluid, if indicated
>1,100 (prosthetic joint)
>25,000; LR=2.9
>50,000; LR=7.7
>100,000; LR=28
>64% (prosthetic joint)
>90%
Viscosity of synovial fluid may actually be decreased in inflammatory or infectious etiologies, as hyaluronic acid concentrations decrease
The presence of crystals does not rule out septic arthritis; however, the diagnosis is highly unlikely with synovial WBC < 50,000
Ankle pain
Ankle sprain
Flank pain
Ankle dislocation
Hip pain 
Ankle syndesmosis injury
Hip pain
Radiograph-negative ankle injury 