A 21-year-old male collegiate basketball player presents with 1 year of left lower leg pain. The pain is worse with activity and the leg is tender to palpation. He denies constitutional symptoms, and conservative treatment has failed to provide relief. He denies recent trauma, but did sustain a severe ankle sprain 7 years ago. Radiograph, bone scan, and CT scans are shown in Figures A-D. What is the next most appropriate step in management?