Career
He returned to Nobleville to help his father in his clinic and worked there for two years. In 1843, he partnered with his brothers-in-law to form an iron foundry business named Irwin & Agnew. The business failed in 1846 leaving him in debt and he returned to the practice of medicine in Cochranville, Pennsylvania. He wanted to focus on surgery and acquired cadavers from Philadelphia to practice his dissection technique.
He caused a scandal in town when he left the used cadavers in a nearby pond to allow eels to consume the soft tissue and leave the skeletons for medical use. He was asked to leave Cochranville and moved to Philadelphia after it was revealed that eels sold in town for human consumption were sourced from that pond.
In 1852, he purchased the Philadelphia School of Anatomy for $600 and taught there for ten years. In 1854, he worked as a surgeon in the Philadelphia General Hospital and founded the pathological museum. He managed the pathological museum until 1867 when he transferred responsibility to William Pepper. He became the demonstrator of anatomy and assistant lecturer on clinical surgery at The University of Pennsylvania.
In June 1862 he worked as acting assistant surgeon In the United States Army at Satterlee General Hospital and the Hestonville Military Hospital in West Philadelphia. His contract expired in October 1862 and he was assigned as Surgeon of Volunteers. He was consulting surgeon to a staff of 47 resident physicians at the Mower General Hospital, in the Chestnut Hill neighborhood of Philadelphia. After the Battle of Gettysburg, he traveled to field hospitals near the battlefield and administered care, including to General Winfield Scott Hancock. This was his first experience with military surgery and an emerging medical field due to the proliferation of gunshot wounds and injuries and diseases due to military activities of the American Civil War. The depth of experience he obtained during the war burnished his reputation as one of the top surgeons in the United States and an expert on gunshot wounds.
In 1863, he founded the Philadelphia School of Operative Surgery and worked as a surgeon at Wills Eye Hospital. In 1864, he was appointed surgeon at Pennsylvania Hospital and in 1867, surgeon to Orthopedic Hospital.
At the University of Pennsylvania, he was appointed professor of clinical surgery in 1870; professor of principles and practices of surgery in 1871; and professor emeritus of surgery and honorary professor of clinical surgery in 1889. He was elected as a member of the American Philosophical Society in 1872. He served as president of the Philadelphia County Medical Society in 1870, the Pennsylvania State Society in 1877, the Philadelphia Academy of Surgery in 1888, and the American Surgical Association in 1888. He served as manager of the Philadelphia House of Refuge for thirty-three years and served on the board of directors of the Philadelphia Dental College and the Franklin Institute. He was elected president of the College of Physicians of Philadelphia in 1890.
Agnew was the chief surgeon in attendance after the shooting of President James A. Garfield. He performed several operations on Garfield to attempt to remove the assassins bullet and prevent infection but the surgeries were unsuccessful.
He published 100 journal articles and several publications on surgery including The Principles and Practice of Surgery, which covered his medical experience of fifty years.
