A bald man with glasses, a light beard, wearing a dark suit, light blue shirt, and striped tie, smiling against a gray background.

John J. Brennan, MD

Total Joint Replacement

John Brennan, MD, received his medical degree from SUNY Health Science Center at Brooklyn after attending college at St. Louis University. He then performed a surgical internship at St. Luke’s-Roosevelt Hospital Center in Manhattan and followed with his orthopedic residency also at St. Luke’s-Roosevelt Hospital Center. During training, he completed rotations at Alfred I. DuPont Children’s Hospital in Delaware, Memorial Sloan-Kettering Cancer Center as well as The Blackrock Clinic in Dublin, Ireland.

Dr. Brennan is board certified in orthopedic surgery and is a member of the American Association of Hip and Knee Surgeons, Medical Society of the State of New York, Suffolk County Medical Society and the Irish-American Orthopedic Society. He also has an extra board certification in sports medicine from the American Board of Orthopedic Surgery. Dr. Brennan merged his practice with Orthopedic Associates of Long Island after being in practice in Southampton since 1999.

East SetauketEast Setauket
RiverheadRiverhead
SouthamptonSouthampton

Patient Testimonials

“If it wasn’t for Dr. Brennan, I wouldn’t be able to enjoy life again at this level. I was in a lot of pain in my right shoulder, losing sleep, and having a lot of trouble just trying to do things that used to be easy. It’s been 8 months since my surgery and I’m playing golf and can’t wait to get back to bowling. The other and maybe the best part of Dr. Brennan is his friendly disposition and desire to help everyone. I can’t possibly thank him and his entire staff enough.”

– LW

Specialties

Two stylized human figures face each other with a ladder-like structure between them on a black background.

Hip

  • Arthritis
  • Hip Replacement
Diagram of a human knee joint showing bones, including femur, tibia, and patella, in a bent position with black background.

Knee

  • Meniscus Tears
  • Cartilage Tears
  • Arthritis
  • Knee Replacement
  • Partial Knee Replacement
  • ACL Tears
Illustration of a shoulder joint, displaying the humerus, scapula, and clavicle with surrounding ligaments and tendons, depicted in white lines on a black background.

Shoulders

  • Rotator Cuff Repair
  • Labrum Repair
  • Dislocation
  • Bone Spurs