Nicholas Senn (1844–1908) was born in Switzerland and was brought by his immigrant parents to Fond du Lac, Wisconsin, as a child. After graduating from the local high school, he taught school for a short time before working as a preceptee with a local physician. He graduated from the Chicago Medical School in 1868 and was an intern at the Cook County Hospital for 18 months before returning to a rural practice in Wisconsin. After six years, he moved to Milwaukee and was on the staff of the Milwaukee Hospital. In 1877 he spent a year studying in Munich with Professor Nussbaum who had visited Lister and was a strong advocate of antiseptic-aseptic surgery. After his return to the United States, he was made Professor of Surgery in the College of Physicians and Surgeons in Chicago, and moved on to become Professor of Surgery at the Rush Medical College in 1888. About this time, his surgical clinic was one of the busiest in the world, and he attracted international students. A man of inexhaustible energy, Senn wrote incessantly, traveled, served as a medical officer in the Spanish-American War, and even found time to serve as President of the American Medical Association in 1897. He was Chairman of the editorial board at the inception of Surgery, Gynecology, and Obstetrics in 1905. Following his death in 1908, his library of 40,000 volumes and 60,000 pamphlets became the nucleus of the great medical reference section of the John Crerar Scientific Library in Chicago.
Senn was the first surgeon to advocate the reduction and nailing of hip fractures on the basis of animal experiments. In this aspect he was far ahead of his time. When this paper was first presented at the meeting of the American Surgical Association on June 1, 1883, its concepts were vigorously opposed by all of his listeners, provoking Senn to say: “Any person who can hit the head of a femur in a cat will certainly not miss it in operating on a human subject.” However, because of this opposition he eschewed nailing his patients with hip fractures and treated them by reduction and immobilization in plaster spicas, a method popularized by Royal Whitman. His emphasis on the importance of the impaction of the fractures after reduction was echoed years later by Cotton.