Review Question - QID 108892

A 27-year-old female presents to her primary care physician with a chief complaint of pain in her right lower extremity. The patient states that the pain has gradually worsened over the past month. The patient states that her pain is worsened when she is training. The patient is a business student who does not have any significant past medical history and is currently not on any medications. She admits to having unprotected sex with multiple partners and cannot recall her last menses. She drinks 7 to 10 shots of liquor on the weekends and smokes marijuana occasionally. She recently joined the cross-country team and has been training for an upcoming meet. Her temperature is 99.5°F (37.5°C), pulse is 88/min, blood pressure is 100/70 mmHg, respirations are 10/min, and oxygen saturation is 97% on room air. On physical exam, you note a very pale young woman in no current distress. Pain is localized to the lateral aspect of the knee and is reproduced upon palpation. Flexing and extending the knee results in a snapping sensation over the lateral femoral condyle. Physical exam of the knee, hip, and ankle is otherwise within normal limits. Which of the following is the most likely cause of this patient's symptoms?