Review Question - QID 218658

A 15-year-old female high school soccer player presents to your clinic with right knee pain, stating she had a collision with an opponent one week ago where she twisted the knee and felt it "pop out of place". She is currently using crutches to get around. On examination, she has a large effusion and tenderness to palpation over the medial femoral epicondyle and medial patellar facet. There is no joint line tenderness. Lachman and posterior drawer testing are stable, and there is no varus/valgus laxity at 0/30°. McMurray and Thessaly testing do not cause pain. Her patella translates two quadrants with apprehension near the final endpoint. A radiograph is seen in Figure A. What is the next best step?