MSRA-1300

A 25-year-old female presents to her GP complaining of pain in her right knee. She is an avid runner and reports that the pain is most noticeable after exercise. She denies any swelling or redness in the joint and has not experienced any locking of the knee. Upon examination, the knee has a full range of motion, but there is sharp pain when palpating the lateral epicondyle of the femur, especially when the knee is flexed at 30 degrees. What is the most probable diagnosis?