Hip replacement to relieve arthritis pain is considered one of the most effective surgeries in the United States. Over the past decade, improvements in surgical technique, implant design, anesthesia and pain control after surgery have contributed to its success, says Geoffrey Westich, MD, an orthopedic surgeon at Hospital for Special Surgery (HSS) specializing in joint replacement. More than 450,000 total hip replacements are performed each year in the United States, according to the Agency for Healthcare Research and Quality.
One of the most noteworthy advances is what’s known as a “dual mobility” hip replacement, according to Dr. Westrich, who has conducted several studies on the implant. He and colleagues have found that the dual mobility prosthesis reduces the risk of dislocation, one of the most common complications after hip replacement surgery. While the incidence is less than 2% at Hospital for Special Surgery and other major joint replacement centers, it is significantly higher at some other locations.
“Dual mobility” refers to the bearing surface of the implant – where the joint surfaces come together to support one’s body weight. The hip is a ball-and-socket joint, and a hip replacement prosthesis is designed to simulate a human hip joint. Typical components include a stem that inserts into the femur (thigh bone), a ball that replaces the round head of the thigh bone, and a shell that lines the hip socket.
A traditional hip replacement implant contains a ball that moves against a cup, similar to a normal hip. Dual mobility implants provide an additional bearing surface. A large polyethylene plastic ball fits inside a polished metal cup, which is the hip socket component, and an additional smaller metal or ceramic ball is snap-fit within the larger polyethylene ball.
“The dual mobility system was designed to increase range of motion and decrease the risk of a dislocation, which is especially important for active patients who may put more demands on their new hip or patients who are at higher risk of dislocation,” Dr. Westrich explained. Click here to see a video of Dr. Westrich discussing the dual mobility hip replacement.
A study he conducted, which was featured at the virtual annual meeting of the American Academy of Orthopaedic Surgeons last year, evaluated almost 200 hip replacements with the dual mobility implant and found no dislocations at patient follow-up of at least five years.
The study, which compiled data from a national joint replacement registry, looked at outcomes of patients who had a dual mobility hip replacement at HSS and three other hospitals. The mean age was 67, and patient follow-up was from 5 to 7.9 years. X-ray analysis showed no implant loosening, and there were no dislocations.
“In addition to the stability provided by the dual mobility hip replacement, patient-reported outcome measures, including pain and function, also improved, supporting the use of this implant,” Dr. Westrich noted.
Another study by Dr. Westrich found the dual mobility implant to be a good option for patients who needed a revision surgery − a second hip replacement after the original prosthesis wore out or became unstable. The incidence of dislocation after a revision surgery is much higher than after the first hip replacement.
“We found that a revision hip replacement with dual mobility components offered increased stability, lowering the risk of dislocation without compromising hip range of motion,” Dr. Westrich noted. Anyone who would like more information about total joint replacement is invited to visit www.westrichmd.com.
