Prosthetic joint infection (PJI) is deemed to be the most serious complication following total hip arthroplasty. Obesity and smoking are known risk factors for PJI. However, the influence of these variables on infection free survival, of septic revision hip arthroplasty, is yet to be explored. The aim of this study was to determine the effect of obesity and smoking on the outcome of two-stage prosthetic exchange surgery.

A consecutive series of 97 hips in 94 patients (69 male, 25 female, mean age 66±12 years), undergoing two-stage revision surgery for hip PJI, were investigated retrospectively, after a mean follow-up of 60 (24–170) months. Survival was estimated using Kaplan-Meyer curves. A multivariate cox-regression model was applied to test for the influence of smoking or obesity (BMI≥30) after adjusting 16 potential patient-dependant variables.

The study hypothesis was that smoking and high BMI are predictors for the failure of septic revision hip arthroplasty. Failure of septic revision hip arthroplasty was defined as failure to eradicate the infection or eradication of the infection but failure to preserve the arthroplasty.

Kaplan-Meier showed a cumulative survival proportion of 80.4%(standard error S.E 4%), of the definitive implant, at 5 years. Obese patients (BMI≥30) and smokers had a significantly lower 5-year survival of 60.9% (S.E 1%) and 50.6% (S.E 1.4%), respectively (p=0.001).

Obesity and smoking are both factors determining infection free survival in two-stage revision hip arthroplasty. Clinicians should be aware of potential complications and anticipate a higher likelihood of conversion to a Girdlestone resection or even amputation in this group of patients.

III, retrospective cohort study.