Morbid obesity: a significant risk factor for failure of two-stage revision total hip arthroplasty for infection

Morbid obesity (BMI [body mass index], ≥40 kg/m2) is associated with a higher risk of complications, including infection and implant failure, following primary total hip arthroplasty. The purpose of this study was to compare the results of two-stage revision total hip arthroplasty for infection in a morbidly obese patient cohort (BMI, ≥40 kg/m2) and nonobese patients (BMI, <30 kg/m2).

Using an institutional total joint registry, we reviewed the medical records of 653 patients treated with two-stage revision total hip arthroplasty for periprosthetic joint infection over a twenty-year period (1987 to 2007). Patients were stratified according to preoperative BMI. Thirty-three patients (fourteen male and nineteen female) with a BMI of ≥40 kg/m2 were identified. These patients were matched 1:2 with a cohort of sixty-six patients (twenty-eight male and thirty-eight female) of the same sex and similar age (91% within two years) who were not obese (BMI, <30 kg/m2). All patients had a minimum of five years of clinical follow-up (mean, 8.1 years in the morbidly obese group and 10.3 years in the nonobese group).

Compared with nonobese patients, morbidly obese patients had significantly greater rates of reinfection (18% compared with 2%, p<0.005), revision (42% compared with 11%, p<0.001) and reoperation for any reason (61% compared with 12%, p<0.001). Prior to surgery, the mean Harris Hip Score had been 50.6 in the morbidly obese group and 48.8 in the nonobese group, and these scores improved significantly in both groups postoperatively (p<0.01).

Morbidly obese patients have markedly elevated risks of reinfection, reoperation, and component resection as well as poorer intermediate-term clinical outcome scores compared with nonobese patients following revision total hip arthroplasty for periprosthetic joint infection.