Review Question - QID 108523

A 14-year-old male basketball player presents to his pediatrician with right knee pain. He reports that he has experienced intermittent right knee pain localized to an area just inferior to his patella. He is fully ambulatory and has not experienced any knee instability. He recently increased the frequency of basketball practice from once per week to three times per week. On exam, his right tibial tubercle is visibly enlarged and tender to palpation. He has full range of motion of his knee. Resisted right knee extension elicits pain while resisted knee flexion is not painful. Lachman’s test and the posterior drawer test are both negative. A lateral radiograph of the patient’s right knee is shown (See Figure A). What is the most likely underlying cause of this patient’s knee pain?