Three-year-old Reuven Kirshner plays pattycake with his nurse, Sarah Parks, during a recent chemotherapy session at St. Louis Children’s Hospital. Reuven had a rare bone cancer called Ewing’s sarcoma that required removal of about two-thirds of his humerus, or the top part of the bone in his left arm. Douglas J. McDonald, M.D., professor and chief of orthopaedic oncology, and Martin I. Boyer, M.D., associate professor of orthopaedic surgery, headed a team that transplanted Reuven’s fibula from his shin into his arm. Reuven is now able to use his arm.