Overweight and Obese Patients Require Total Hip and Total Knee Arthroplasty at a Younger Age.

Osteoarthritis (OA) of the hip and knee is associated with obesity but the exact effect remains unknown. The aim of this study was to investigate the independent association between the age at which total hip (THA) and knee arthroplasty (TKA) are required for end-stage severe OA according to body mass index (BMI) category. A retrospective study of 3,699 patients undergoing primary THR and 4,740 patients undergoing a primary TKA for the treatment of end-stage OA. Patient demographics, BMI, comorbidity, social deprivation, Short form 12 and Western Ontario and McMaster Universities OA Index score pre-operatively were collected. Linear regression analysis identified that there was an earlier age at which THA and TKA were performed with increasing obesity BMI category compared with normal-weight patients when adjusting for confounding variables. Using the normal weight category as the reference group overweight (0.9 years [95% confidence interval, CI] 0.0-1.8) and obese patients in class 1 (3.1 years, 95% CI 2.1-4.2), 2 (5.2 years, 95% CI 3.7-6.7), and 3 (7.4 years, 95% CI 5.0-9.8) required their THA at a significantly (p ≤ 0.04) earlier age. Again, using normal weight category as the reference group overweight (2.1 years, 95% CI 1.3-2.9) and obese patients in class 1 (4.7 years, 95% CI 3.8-5.6), 2 (6.7 years, 95% CI 5.6- 7.7) and 3 (10.5 years, 95% CI 8.9-12.1) required their TKA at a significantly (p < 0.001) earlier age. Overweight and obese patients required their THA and TKA at a significantly younger age. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:348-355, 2020.