The authors say anatomical differences between men and women may account for the differing implant failure rates. Specifically, women typically have to be fitted with smaller implants, including a smaller femoral head, due to their smaller size and this may increase the rate of dislocation. Researchers are also looking into the role that bone density may play in implant failure."Our study will allow patients to make more informed decisions when discussing hip replacements with their physicians," said Inacio. "It is important that patients and physicians work together to identify potential risks and customize a care plan best suited for the patient." In 2010, Kaiser Permanente added a patient risk calculator to the organization's electronic health record system. This tool helps physicians estimate the patient's unique probability of device failure, as well as other risks associated with joint replacements. Examining these risk factors allows the physician and patient to make personalized treatment decisions. According to the Agency for Healthcare Research and Quality, more than 285,000 total hip replacements are performed each year in the United States. The primary reason people require a total hip replacement is osteoarthritis, a serious and painful joint disease that places severe limits on daily activity and quality of life. Approximately 26 percent of women in the United States were diagnosed with osteoarthritis in 2010, compared to 18 percent of men, according to the Centers for Disease Control and Prevention. This study was made possible by Kaiser Permanente's Total Joint Replacement Registry, which now has more than 160,000 total joint arthroplasty procedures registered. Since its inception in 2001, Kaiser Permanente's registry has helped health care providers identify clinical best practices, evaluate and monitor patient outcomes and risk factors associated with revision surgeries, and assess the clinical effectiveness of implants. Developed in association with Kaiser Permanente's surgeons, the registry's data is collected prospectively through standardized documentation by surgeons and supplemented by the organization's electronic health records.