• Total hip arthroplasty;
  • Obesity;
  • Infection;
  • Sex difference



To evaluate the effect of obesity on the incidence of main complications (infection, dislocation, and revision), functional outcome, and patient satisfaction 5 years after primary total hip arthroplasty (THA), and to determine whether results differ between obese women and men.


We conducted a hospital-based prospective cohort study including patients who underwent primary THA (2,495 hips) between 1996 and 2005. We used rates and rate ratios to compare the incidence of main complications in obese and nonobese patients, and we stratified the data for sex. Functional outcome was measured using the Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index.


The adjusted incidence rate ratio for infection (obese versus nonobese) was 4.4 (95% confidence interval [95% CI] 1.8, 10.8). Obesity substantially increased the infection rate in women (incidence rate ratio comparing obese with nonobese women 16.1; 95% CI 3.4, 75.7), whereas obesity appeared to have no effect in men (incidence rate ratio 1.0; 95% CI 0.2, 5.3). The adjusted incidence rate ratio for dislocation (obese versus nonobese) was 2.4 (95% CI 1.4, 4.2), with a higher rate increase in obese women. A total of 817 patients had a 5-year clinical followup visit. Functional outcome and satisfaction were slightly lower in obese women partly due to higher complication rates. No difference was seen in men.


Primary THA is a successful intervention in obese patients, but physician and patient must be aware of increased complications, particularly in women.