With minor variation, the following is an extremely common sequence of events. A man notices slowly worsening nagging knee pain that persists over months. He sees an orthopedist who examines him and orders an MRI. The MRI shows a tear in the medial meniscus. (The lateral and medial menisci are the cartilage pads that cushion the knee joint.) Pain medicine and physical therapy are prescribed but the pain persists. So the orthopedist recommends surgery and performs an arthroscopic partial meni...