Dr. Milton C. Cobey, 73, a retired physician and a former head of the orthopedic surgery department at Georgetown University Hospital, died of congestive heart failure Jan. 4 at his home in Washington. He also maintained a home in Welcome, Md.

Dr. Cobey practiced medicine in Washington for 36 years before retiring in 1975. During his career, he had been senior orthopedic surgeon at Children's Hospital. He directed the orthopedic service and training program at D.C. General Hospital from 1940 to 1962.

He was head of the research laboratory in orthopedic surgery at Georgetown from 1947 to 1962. His research included work on the development of a waterproof plaster, an injectable bone glue, and a plastic implant for arthritic joints.

Dr. Cobey was a past president of both the Association of Bone and Joint Surgeons and the Washington Medical and Surgical Society. He was a fellow of the American College of Physicians and Surgeons. Other professional memberships included the American Fracture Association and the D.C. Rheumatism Society.

He chaired the medical committees of two presidential inaugurations.

He had been a member of St. Alban's Episcopal Church in Washington and was a member of Durham Parish in Nanjemoy, Md., at the time of his death.

Dr. Cobey was a native of Frostburg, Md. He earned undergraduate and medical degrees at Duke University. He completed his internship and his residency in orthopedic surgery at Johns Hopkins Hospital in Baltimore. He served with the Army Air Forces during World War II, attaining the rank of lieutenant colonel.

Survivors include his wife, Dr. Fredericka Rainey Cobey of Washington and Friendship; a son, Dr. James Carpinter Cobey of Washington; two daughters, Fredericka Blackwell Cobey of Mill Valley, Calif., and Elizabeth Earle Cobey of San Jose, Calif., a brother, Judge James Alexander Cobey of Pasadena, Calif., and three grandchildren.