U.S. Army Dr. (Maj.) Rasel Rana, McDonald Army Health Center chief of orthopedic surgery, performs a knee surgery in the MCAHC operating room at Fort Eustis, Va., March 13, 2013. Orthopedics is the branch of medicine focused on conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat musculoskeletal trauma, sports-related injuries, degenerative diseases, infections, tumors and congenital disorders. (U.S. Air Force photo by Airman 1st Class R. Alex Durbin/Released)