New Metal on Metal Hip Replacement Lowers Dislocation Risk

Mount Sinai Hospital’s Rubin Institute for Advanced Orthopedics (RIAO) is the only center in Maryland to offer two of the newest generations of metal on metal hip replacement prostheses with a larger hip-ball design: the Conserve(r) Total Femoral Head and the Conserve(r) Plus. Both designs offer patients who qualify for the procedure several advantages over the traditional total hip replacement.

“The difference is that the larger hip-ball, or femoral head, more closely mimics one’s own natural hip design,” said Michael Mont, M.D., co-director of the RIAO’s Center for Joint Preservation and Replacement. “The natural adult hip-ball ranges in diameter from about 36mm to 55mm. The traditional total hip replacement uses a hip-ball that is roughly the diameter of a nickel, or about 26mm to 28mm. The Conserve(r) Total Femoral Head and the Conserve(r) Plus implants employ a much larger ball of up to 54mm, allowing for a closer match to the natural hip anatomy.”

The advantages of larger-head implants include greater range of motion and reduced risk of dislocation because of the greater surface area of the hip-ball. They are also known for a more natural feeling joint and normal gait (walking) characteristics. In regard to the Conserve(r) Plus, another advantage includes bone preservation because this implant requires minimal invasion into the hip-ball and neck, known as the femoral canal.

“Younger patients with problems like severe arthritis or avascular necrosis, a disease that causes the bone to die, are opting for hip replacements to get their active lives back. These two hip designs help them do that. Our list of satisfied patients for these hip procedures includes surfers, ballet dancers, karate instructors, tennis players and ski champions,” said Gracia Etienne, M.D., Ph.D., a specialist in complex joint replacement at the Center.

A recent study done at the Wasserman Gait Laboratory at the RIAO found that the gait characteristics of patients with the Conserve(r) Plus more closely resembled normal hips than the patients who had traditional hip replacements. “Standard hips never return to normal gait patterns, whereas with these new devices they do. I have never seen hips perform this well or this early. This technology may help people lead a more normal and active lifestyle longer,” said Anil Bhave, P.T., director of the Gait Laboratory. This study was presented in New York City at the National Wright Medical Users Meeting in September 2002.

The traditional hip replacement prosthesis is composed of metal and a plastic insert. The plastic is known to wear down slowly over time, and in some cases, can cause osteolysis, or joint infection, to the affected hip joint. These newer implants are made completely of metal and may reduce the wear and risk factor associated with traditional hip replacements.

The Conserve(r) Total Femoral Head is FDA approved and has recently been made available in California and in Maryland at Sinai’s RIAO. The Conserve(r) Plus is currently part of an FDA investigational study for which the RIAO is one of six test sites in the United States. The Conserve(r) Plus is not commercially available in the United States. Drs. Mont and Etienne have performed close to 200 hip surgeries using the Conserve(r) Plus.

Sinai Hospital has the fastest growing orthopedic program in the state of Maryland. With regard to hip implants, Sinai’s fastest growing patient populations are ages 40 to 49 and 50 to 59. According to the American Academy of Orthopedic Surgery, over 168,000 people in the United States undergo hip replacement surgery every year.

1 Star2 Stars3 Stars4 Stars5 Stars (94 votes, average: 3.45 out of 5)

Leave a Reply