After-Hours Urgent Ortho Care is now available in Wilton, Monday to Friday from 4:00 pm to 7:00 pm and Saturdays from 12:00 to 4:00 pm. Walk-ins welcome.

Frank A. Ennis, MD

Located In

Greenwich, Harrison


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. 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.

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.

  • Commercial Plans (Including APCN Plus, We do not accept regular APCN)
  • Managed Medicare
Anthem Blue Cross Blue Shield of CT
  • Commercial and Exchange
  • Managed Medicare
Blue Cross Blue Shield (Plans Outside CT)
  • Cards with the “PPO” inside the suitcase logo
CarePartners of Connecticut
  • Managed Medicare (HMO/PPO)
  • Commercial, MetroNY, and LocalPlus
  • Cigna+Oscar, Cigna+MVP (CT Locations Only)
  • Commercial and Exchange (Except “Value” Network)
  • Managed Medicare
Connecticut Medicaid
Connecticut State Workers’ Compensation
  • Emblem Commercial and Exchange (Except for Millennium and Enhanced Care Prime Networks)
  • Managed Medicare (VIP Prime, Bold, Reserve)
Harvard Pilgrim
  • Through United Shared Services – ONS Harrison location only.
Medicare (Including Railroad Medicare)
  • Liberty and Freedom Plans
UHC/NYSHIP/NY Government Empire Plan
United Healthcare
  • All Commercial Plans (Except Indemnity and Compass)
  • Managed Medicare

Orthopaedic & Neurosurgery Specialists (ONS) accepts most major insurance plans. Please see the list of accepted insurance plans above and confirm that ONS participates with your plan prior to scheduling an appointment. Certain insurance plans are limited to specific regions and physicians. If you have additional questions, please call our offices at (203) 869-1145 ext. 279 and our team will be happy to provide additional information.


Fellowship in Adult Reconstructive Surgery: New England Baptist Hospital

Medical School

Duke University School of Medicine


Yale University School of Medicine


Undergraduate: Yale University

Post-baccalaureate: Harvard University

  • American Board of Orthopaedic Surgery: Orthopaedic Surgery Board Certification

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

  • Castle Connolly Top Doctors in NY Metro Area, 2013–Present
  • Connecticut Magazine Best Doctors, 2020, 2022
  • Greenwich Magazine Top Doctors in Fairfield Country, 2013–Present
  • New Canaan/ Darien Magazine Top Doctors in Fairfield County, 2013–Present
  • Stamford Magazine Top Doctors in Fairfield County, 2013–Present
  • Westport Magazine Top Doctors in Fairfield County, 2013–Present
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