Case 2

A 22 yo college senior schedules an appointment at the health service because of severe pain in the posterior right thigh for the past 3 days. The pain is 8/10, sharp, and relieved somewhat by lying supine with the knee flexed. It extends from the buttock to the upper border of the popliteal fossa. There are no associated paresthesias or numbness of the perineum or right lower extremity, and bowel and bladder function are normal. The student runs on the intercollegiate cross country team and a week ago completed a 10 mile run through the university's wooded  home course.  She has been in good health and has not had back or leg pain previously. On physical examination with the patient supine there is right thigh pain when the physician grasps the right heel with the knee extended and raises the leg to an angle of 30 degrees above the table (straight leg sign). The pain is diminished by flexing the knee and hip and does not recur with dorsi-flexion of the ankle. There is no pain when the physician raises the opposite (left) leg with the knee extended (crossed straight leg sign). The knee and ankle jerks are 2+ and sensation to pin is normal in both legs. The thigh is tender to palpation.

Which of the following is the most likely diagnosis?

A. Tear of a hamstring muscle

B. Fracture of the femur

C. Herniated lumbar disc

D. Lyme arthritis of the right hip

E. Bakers cyst of the right knee