During the Civil War, Dr. Hodgen was appointed to the rank of Surgeon General of the State of Missouri in 1862. When Dr. McDowell sided with the Confederacy, Dr. Hodgen transferred his allegiance to the St. Louis Medical College where he served as the Chair of Physiology (1862-1868) and Dean of the College (1865-1882). In addition to his administrative duties at the St. Louis Medical College, Dr. Hodgen also taught clinical surgery at City Hospital from 1864-1882 and was a surgeon at St. Luke's Hospital.
Dr. Hodgen was a member of the St. Louis Board of Health from 1867-1871, President of the St. Louis Medical Society in 1872, Chairman of the Surgical Section of the American Medical Association in 1873, president of the Missouri State Medical Association in 1874, a member of the International Medical Congress in 1876 and 1881, one of the founders of the American Surgical Association, and President of the American Medical Association in 1881.
Dr. Hodgen's literary work consisted largely in contributions to medical journals. He edited the chapters on injuries to the chest and injuries of the abdomen in the American edition of A System of Surgery edited by Timothy Holmes. Some of his papers were on the surgery of shock, nerve sections for neuralgia, fractures, and thigh and skin grafting. Among the many surgical appliances devised by him are a wire suspension splint, a cradle splint, a snare for the for the removal of urethral calculi, a surgeon's reel and artery forceps, and a simple siphon and stomach pump.