Hip Replacement Outcome May Be Genetic
Serious complications are more common with certain variations
 (HealthDay News) -- Whether hip replacement surgery is successful in the long run might be predetermined by a person's genes.
According to British researchers, people with variations in a gene dubbed MMP-1 are about three times more likely to have a serious complication called aseptic loosening within 10 years of their surgery. In aseptic loosening, the artificial joint loosens, and the surrounding bone starts to dissolve.
Additionally, people with variations in their vitamin D receptor gene were about twice as likely to experience deep infections and dissolving bone, the researchers found.
"There are unknown biological factors involved in these problems," Dr. Mark H. Gonzalez, a professor of orthopedic surgery at the University of Illinois , told HealthDay . "This study shows an association between aseptic loosening and MMP-1 . This is a very interesting association, and an understanding of this association may allow us to identify patients who are at risk for aseptic loosening."
The finding may not change surgical practices right away, said Dr. Samuel J. Chmell, an associate professor of orthopedic surgery at the University of Illinois , but "eventually such genetic factors will have to be taken into account in our surgical planning."
Neither Gonzalez nor Chmell was involved with the research.
For the study, researchers from the Centre for Integrated Genomic Medical Research at the University of Manchester compared genetic variations in 312 people who underwent hip replacement surgery. Slightly more than half had difficulty with their hip replacement in the 10 years after surgery, according to the study, which was published in the Annals of the Rheumatic Diseases .
Of those who had problems, 91 experienced aseptic loosening and 71 had a serious deep infection. The researchers tested for three different genetic variations: MMP-1 , interleukin 6 and the vitamin D receptor. Only interleukin 6 did not seem to affect hip replacement outcomes.
The findings could help doctors determine who might not be a good candidate for surgery, and it might also help in the choice of prosthetic materials -- metal on polyethylene, metal on metal or ceramic on ceramic, Gonzalez said. "It may also allow us to proactively intervene pharmacologically to treat at-risk patients," he said.
Osteoarthritis is the most common reason for hip replacement surgery, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. The best candidates for the surgery, according to the institute, are people in generally good health, regardless of their age. The main reasons people cite for deciding to have the surgery include the desire to reduce pain, improve mobility and have a better quality of life.
Alternatives to hip replacement include pain-relieving medications, topical analgesics and, occasionally, corticosteroids. Exercise might also help improve joint function, according to the institute.
On the Web
To learn more about hip replacement, visit the American Academy of Orthopaedic Surgeons.
SOURCES:
HealthDay News ; Mark H. Gonzalez, M.D., professor and head of orthopedic surgery, University of Illinois at Chicago; Samuel J. Chmell, M.D., associate professor of orthopedic surgery, University of Illinois at Chicago; March 15, 2007, Annals of the Rheumatic Diseases ; National Institute of Arthritis and Musculoskeletal and Skin Diseases (www.niams.nih.gov)
Author:
Serena Gordon
Publication Date:
April 30, 2008
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