Lateral displacement of the proximal femur due to synovial exudate and inflammation can also be seen in the early stages. Late findings include periostitis, periarticular osteoporosis, and dislocation of the femoral head. Ultrasound is the most effective study in demonstrating the presence of a joint effusion acutely. Radionuclide bone scanning can be helpful in the early stages, but the definitive diagnostic tool remains isolation and identification of the organism by hip aspiration. The most common etiologic organism is Staphylococcus aureus.
Hematogenous spread is more common in children than in adults.
The treatment for septic arthritis of the hip includes intravenous antibiotics and immediate surgical incision and drainage of the hip, followed by a period of immobilization. Antibiotics should be continued for at least 4-6 weeks, depending on the sensitivities of the organism and the patient's clinical status. The initial choice of antibiotics should take into account the most common etiologies of septic arthritis. In the case presented above, cefuroxime was used to cover streptococci and staph aureus. However, given the growing frequency of methicillin resistant staph aureus, empirically starting vancomycin pending culture results and antibiotic sensitivities may be justified as well.