Dual Mobility Hip Implant Reduces Risk of Dislocation

A new study shows that modular dual mobility (DM) hip implants could reduce the risk of dislocation in patients who need revision surgery.

Researchers at the Hospital for Special Surgery (HSS, New York, NY, USA) and other joint replacement centers in the United States conducted a study involving 370 patients (average 65.8 years of age) who underwent revision hip replacement with a DM implant between April 2011 and April 2017. Clinical, radiographic, and patient reported-outcome information were collected for all patients; but to be included in the final report, patients needed to be seen for follow-up for at least two years after their surgery.

The results revealed that surgery with the DM implant resulted in a very low rate of instability for the revision patients (2.9%), with good functional improvement and a low rate of reoperation. According to the researchers, there was a clear benefit provided by the DM implant in the first few years following revision surgery. The study was presented at the annual meeting of the American Association of Hip and Knee Surgeons, held during November 2017 in Dallas (TX, USA).

“Although the concept of dual mobility was originally developed in France in the 1970s, the technology is relatively new in the United States,” said senior author Geoffrey Westrich, MD, research director of the adult reconstruction and joint replacement service at HSS. “Our study found that the newer technology with modular dual mobility components offered increased stability, lowering the risk of dislocation, without compromising hip range of motion in patients having a revision surgery.”

A hip replacement implant is a ball-and-socket mechanism, designed to simulate a human hip joint and mimic its movement. Typical components include a stem that inserts into the femur, a ball that replaces the head of the thighbone, and a shell that lines the hip socket. The concept of DM refers to the bearing surface of the implant; DM provide two areas of motion within the artificial socket, instead of one, thus improving the range of movement and reducing the risk of dislocation.

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Hospital for Special Surgery