Why hip replacements may fail

SAN FRANCISCO, Jan. 7 (UPI) -- U.S. researchers say the most common reason for total hip replacements failing is not surface wear, as previously thought.

Researchers at the University of California, San Francisco, finds the most common reasons for patients needing subsequent hip replacement surgery include dislocation or loosening of the implant and infection such as staph infections either around the time of surgery or later in the bloodstream.

The researchers analyzed data from about 50,000 patients who had to have their hip replacements revised in the United States between Oct. 1, 2005, and Dec. 31, 2006.

"The reason why this study is important is because up until now it has been believed that the most common reason why hip replacements fail is because the bearing surface wears out. We found that other problems -- including dislocation, implant loosening and infection -- may be even more common causes of hip replacement failure," study lead investigator Dr. Kevin Bozic said in a statement.

"This suggests that in addition to research aimed at developing better implants, we also need to direct new research efforts to improve care in those three areas."

The findings are published in The Journal of Bone and Joint Surgery.