Review Question - QID 4455

A 9-year-old boy was placed in a short leg splint in an emergency department after twisting his ankle during recess. He presents 10 days later with increasing pain and fevers up to 39 degrees C over the last 3 days. The splint is removed revealing intact skin integrity with notable swelling and erythema overlying the distal fibula. Lab results include a C-reactive protein level of 12mg/L (normal 0-3.2 mg/L), erythrocyte sedimentation rate of 38mm/h (normal 0-20mm/h) and a white blood cell count of 12.3 K/mm3(normal 4.3 -11.4 K/mm3). Radiographs are included in Figures A and B. MRI images include T1, T2 and post-contrast in Figures C-E, respectively. What is next step in management?