In a recent article in Arthritis Research and Therapy, authors noted the significant relationship between obesity, as defined by a body mass index greater than 30 and the risk of developing arthritis requiring hip and knee replacement. Many countries around the world have Joint Replacement Registries, which track the number of procedures, trends, and their use, the age and gender of patients, and failure rates of various procedures and implants. Unfortunately, the United States does not have such a Joint Registry, though work is underway to try an implement one. These can be extremely effective tools for monitoring the results of specific implants and procedures. Data from the Australian Joint Registry indicates the seven year cumulative revision rate for conventional total hip replacement is 3.4% and for resurfacing procedures 4.6%. The revision rate for resurfacing procedures is affected by age with those patients less than 55 years having a 2.5% revision rate at four years compared to patients over age 55 who had a revision rate of 9.7%. The revision rate for females is significantly higher 7.0% at five years compared to males at 2.5%. Joint Registries from Sweden, Finland, Australia, and other countries, have provided valuable information with regard in trends of joint replacement and the incidence of success and failure of various procedures.