Meniscus tear

A 21-year-old man presents to the clinic to be evaluated for right knee pain. The patient was playing basketball three weeks ago when he suddenly pivoted while running and dribbling to the basket and felt pain in the right knee. Since then, he has experienced pain that worsens with running. In addition, he feels like his knee is “catching” and “giving out”. He is otherwise healthy and does not take any medications. Vital signs are within normal limits. Physical examination of the bilateral knees does not demonstrate effusions or deformities When the examiner grasps the patient's thigh and pulls the tibia forward with the knee at 20° of flexion, there is no anterior translation of the tibia or “soft” end-feel. When the examiner attempts to translate the lower leg posteriorly, there is no “soft” end-feel or excessive posterior translation.. There is tenderness to palpation over the medial right joint line. No pain is elicited when the examiner flexes the right knee to maximal flexion beyond 90° and then extends the knee with internal rotation of the tibia and a varus stress. When the examiner returns the knee to maximal flexion and extends the knee with external rotation of the tibia and a valgus stress  pain and clicking are noted. Radiograph of the knee shows no fracture. Which of the following is the most likely diagnosis?