The relationship between bariatric surgery and risk of hip or knee replacement in severe osteoarthritis is obesity class-specific.

Background: In patients with osteoarthritis, bariatric surgery is associated with diminished joint pain and improved functionality.

Objectives: To evaluate the relationship between the risk of total joint replacement (TJR) and the fact of having undergone bariatric surgery (yes or no) in people living with obesity.

Settings: Data from the French National Hospitals Database.

Methods: This case-control study was conducted to identify hospitalizations for TJR. The main exposure of interest was having undergone (or not) a bariatric surgery procedure between January 2017 and December 2021. After a 6-month run-in phase, data on hospitalizations for the first TJR (i.e., hip or knee) from July 2017 to December 2023 were classified by obesity class and surgical type.

Results: One hundred sixty thousand seven hundred seventy-three patients who had undergone bariatric surgery (mean age: 40.8 years, 79.5% females) and 160,773 matched controls were identified. The most frequent surgical technique was sleeve gastrectomy (72.2%), followed by gastric bypass (27.8%). The average follow-up was 4.7 years. An increase in the overall risk of TJR, with a hazard ratio (HR) of 1.09 (95% confidence interval [CI], 1.03-1.15), was observed. Depending on obesity class, patients with body mass index (BMI) < 40 kg/m² had a lower risk of TJR (HR: 5.85; 95% CI: .78-.93), whereas a higher risk was observed in patients with BMI ≥40 kg/m² (HR: 5 1.25; 95% CI: 1.16-1.34).

Conclusions: In France, hospitalizations for TJR following bariatric surgery were associated with an increase of 25% in patients with BMI ≥ 40 kg/m², whereas it was associated with a decrease of 15% in patients with BMI < 40 kg/m².