Review Question - QID 219552

A 22-year-old male is involved in a motorcycle accident where he sustained an injury to his right leg. On presentation to the trauma bay, radiographs show a midshaft tibia fracture with a small degree of comminution. The injury is closed and he is neurovascularly intact. He is splinted and taken to surgery the following day for a tibial intramedullary nail. Nine months later, he comes to the clinic with the radiograph seen in Figure A. He still has tenderness about the fracture site but no erythema or swelling. Labs are ordered and are as follows - CRP:5 mg/L (nl <10 mg/L), ESR:10 mm/h (nl <20 mm/h), Vitamin D:51 ng/mL (nl >40 ng/mL). Which of the following is the most likely cause for this patient's problem?