Hip and knee replacement in the Spanish National Health System

Abstract Purpose To analyze hip and knee arthroplasties and their characteristics in the Spanish National Health System. Materials and methods Using clinical-administrative data gathered in 2005, a nationwide and regional cross-sectional study was performed of the number of discharges of patients subjected to primary and revision total hip (THR) and knee (TKR) arthroplasties. Standardized THR and TKR rates were calculated by age and gender per 10,000 inhabitants analyzing their variability as compared with systematic component of variance (SCV) values. Of each discharge we analyzed gender, age, reason for the procedure, the Charlson comorbidity index (CCI), length of stay, in-hospital mortality and pulmonary thromboembolism (PTE). We also analyzed the work-load entailed by revision surgery on the basis of the number of revision procedures as a percentage of the total number of arthroplasties. Results The rates obtained were 4.3 for THR and 7.3 for TKR, ranging from 2.3 to 10.0 in THR (SCV: 24.4%) and from 4.0 to 12.8 (SCV: 20.6%) in TKR. The majority of patients were older than 65 years. Osteoarthritis was the main reason for surgery with little variability. Generally speaking, the CCI was 0. Median length of stay was 9 days in THR and 8 in TKR. Mortality varied between 0% and 0.9% and PTE between 0% and 0.6%. The percentage of hip revisions was 9.2% and that of knee revisions was 7%. Conclusions Variability in terms of the different rates and patient characteristics could be pointing to differences in the indication criteria. Homogeneous indication criteria should be established and instruments should be developed for assessing the results.