• College: Yale University, 1988, Post-baccalaureate | Harvard University 1993–1995
  • Medical School: Duke University School of Medicine, 1999
  • Residency: Yale University School of Medicine, 2000–2004
  • Fellowship: Adult Reconstructive Surgery; New England Baptist Hospital, 2004–2005


Frank Ennis, MD, specializes in hip and knee replacement, knee arthroscopy, complex revision arthroplasty of the hip and knee, and treatment of complications from hip fractures. He is fellowship-trained in adult reconstructive surgery. Dr. Ennis is a staff orthopedic surgeon at Greenwich Hospital and was among the first orthopedic surgeons in the New York Metropolitan area to do computer-assisted surgery for total knee replacement. This cutting edge technique uses computerized navigation to guide the surgeon for improved accuracy in joint replacement surgery.

After completing undergraduate studies at Yale University and post-baccalaureate pre-medical studies at Harvard University, Dr. Ennis graduated from Duke University School of Medicine and completed his residency at Yale University Department of Orthopaedic Surgery. Additionally, Dr. Ennis completed Fellowship training in adult reconstructive surgery at New England Baptist Hospital in Boston, MA.

Computer-assisted Joint Replacement

Computer-assisted surgery is the newest generation of technology in joint replacement. Surgeons create a visual map of the knee using a highly-precise image guidance system that allows the surgeon to see beyond the ability of the naked eye. With infrared cameras and digitized images, every aspect of the operation is tracked by computer including instrumentation and positioning of the implant. More precise alignment of the implant leads to better range of motion and long-term results.


  • American Academy of Orthopaedic Surgeons
  • American Association of Hip and Knee Surgeons
  • Connecticut Orthopaedic Society
  • Yale Orthopaedic Association
  • American Board of Orthopaedic Surgery


  • Castle Connolly Top Doctors in NY Metro Area,  2013–2023
  • Connecticut Magazine Best Doctors 2020, 2022
  • Greenwich Magazine Top Doctors in Fairfield Country, 2013–2022
  • Stamford Magazine Top Doctors in Fairfield County,  2013–2022
  • New Canaan/ Darien Magazine Top Doctors in Fairfield County, 2013–2022
  • Westport Magazine Top Doctors in Fairfield County, 2013–2022
Letter from J.O.Patient

“On the first anniversary of the second hip replacement, I wanted to write to formally thank you. I feel great. Play golf regularly. Exercise everyday when I don’t golf. Am strong, and have achieved a much greater range of motion that I ever thought I would. In short, happy all around.”

5 star review on Healthgrades from L.T.Patient

"Dr. Ennis was extremely professional and knowledgeable during all phases of my recent total knee replacement surgery. I would not hesitate to highly recommend his services to anyone in need of hip or knee intervention."

Patient SurveyPatient

"Dr. Ennis and his staff always take good care of me and I have recommended him to several people and all of them have also used him for their hip replacements."