MSFinals-2800

A 16-year-old boy comes to the emergency department with a painful knee that started 3 days ago. Upon examination, the patient is stable but has a fever of 38.5ºC. The left knee is red and has limited range of motion. The patient also reports having a severe sore throat 3 weeks ago, which was treated with antibiotics. There are no other symptoms reported. What is the next best course of action for managing this patient?