Part 1.
Laura played midfielder and was team captain on an intercollegiate soccer team at a Midwestern Division III college. It was the final game of the conference tournament—one that was billed as “win and go the NCAA tournament or lose and go home” game.

It was late in the second half and Laura was dribbling the ball towards the goal when she pivoted on her left foot and passed the ball to a teammate, who ultimately scored. As she was pivoting on her left foot she felt a pop and tearing sensation in her lateral left leg just at and below the left knee. She hobbled for the next few minutes until a substitution could be made and she could be examined by the team's athletic trainer.

When questioned by the trainer (and subsequently verified by game films) Laura denied any physical contact with another player.

Examination results, as noted by team trainer, were as follows:

• Palpation of the left lower extremity demonstrated no tenderness or pain in any portion of the left thigh.
• Palpation of the calf elicited tenderness along the length of the fibula; no swelling was noted
• Anterior and lateral muscle groups were supple.
• Lachman test, pivot shift, reverse pivot shift, clunk and Losee tests were all inconclusive
• No pain with passive movement of the ankle.
• Distal neurovascular function was intact, including sensation.
• X-rays of the tibia and fibula were normal.

What is your diagnosis of the patient?