Dr. O'Leary was born in Ireland and graduated medical school from the National University of Ireland at the University College Cork He completed a rotating internship at the L.D.S. Hospital in Salt Lake City, Utah. He completed three years of General Surgical Residency training at Roosevelt Hospital in New York City. He completed his Orthopaedic Residency education at the Hospital for Special Surgery, Cornell Medical Center and subsequently did a Spine Fellowship at the University of Toronto in Canada.

Dr. O'Leary is a fellow of the American Academy of Orthopaedic Surgeons, a fellow of the International College of Surgeons, a fellow of the American College of Surgeons and Board Certified by the American Board of Orthopaedic Surgery. He is currently the Associate Director of Orthopaedic Surgery at Lenox Hill Hospital where he serves as Chief of the Spine Service in that department. Dr. O'Leary is currently an Attending Surgeon at the Hospital for Special Surgery where in the past he has served as Chief of the Spine Service. Dr. O'Leary is currently a member of the Cervical Spine Research Society. the Scoliosis Research Society, and the North American Spinal Society.

Dr. O'Leary's special interest lies in the area of surgical technology and advances in surgical technique. He remains in close contact with his surgical colleagues in Europe and the United States in association with same.