Do the Long-Term Functional Outcomes and Revision Rates of Total Hip Arthroplasty in Obese and Morbidly Obese Patients Justify Restricting Their Access to Surgery?

Background: A prospective observational study with retrospective analysis of the data was carried out on 8,089 patients who underwent total hip arthroplasty (THA) at a single elective center between January 1, 2006, and November 30, 2022. Our aim was to examine whether obesity and morbid obesity have an effect on long-term clinical outcomes and revision rates.

Methods: The patients were divided into three groups: non-obese (body mass index (BMI) < 30), obese (BMI 30 to < 40), and morbidly obese (BMI ≥ 40). Our primary outcomes were the mean change in Oxford Hip Score (OHS) and Western Ontario and McMaster's Universities Osteoarthritis Index (WOMAC) up to 10 years to assess the long-term clinical benefit of surgery. The secondary outcomes measured were the rate of revisions up to 10 years, rate/100 component years, time between primary THA and revision, reasons for revision (aseptic loosening, deep infection, dislocation, fractured femur), mean skin-to-skin time, American Society of Anesthesiologist Classification, and the 90-day mortality rate. The BMI data were not available for 1,130 patients (13.97%).

Results: There was no difference in the absolute at 10 years and mean change in OHS and WOMAC up to 10 years between the groups. There was no difference in the absolute revision rate between the groups, although the obese and morbidly obese groups did have a higher rate of revision/100 component years and can expect a shorter time interval between THA and revision surgery compared to the non-obese groups. We did not find any significant association between obesity and the reasons for revision surgery, with the exception of fractured femur in the non-obese group.

Conclusion: The long-term functional outcomes and revision rates of THA do not justify restricting access to surgery on the basis of BMI.