Jack Farr, MD, Voluntary Professor of Orthopedic Surgery, Indiana University School of Medicine; Director, Cartilage Restoration Center of Indiana; and OrthoIndy Sports Medicine Fellowship Director, OrthoIndy and Indiana Orthopedic Hospital, Greenwood, IN, USAAndreas H. Gomoll, MD, Assistant Professor of Orthopedic Surgery, Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Chestnut Hill, MA, USA