Factors influencing regional variability in the rate of total knee arthroplasty

Background and purposeGeographic variations in knee arthroplasty have been detected through international surveys. We aim to investigate in this study the influence of aging index, health budget, and number of orthopedic surgeons in the regional variations of the primary and revision TKA rate in a single European country, Spain.Material and methodsInpatient database of knee arthroplasty procedures for years 1997 to 2010 was obtained from the Spanish Ministry of Health, including 393,714 primaries and 37,037 revisions, segregated for each of the 17 regional health services in Spain. Crude and adjusted rates (direct method with total Spanish population per year) were calculated and used as dependent variables. Aging index, regional health budget, and number of orthopedic surgeons per region were used as independent variables in a Kruskal-Wallis test and a negative binomial regression analysis model.Results and conclusionsWith a mean crude rate for Spain of 76 primary TKA and 7 revision surgeries per 105 population and year, the mean adjusted rate per region oscillated between 702 and 27 primary TKA and 87 and 3 revisions per 105. A model was adjusted confirming the influence of aging index, health budget, and number of surgeons, but regional variations remained partly unexplained by these factors.