Bariatric Orthopaedics: Total Hip Arthroplasty in Super-Obese Patients (Those with a BMI of ≥50 kg/m2)

Background: The purpose of this study was to assess the clinical and patient-reported outcomes of primary total hip arthroplasty in super-obese patients (those with a body mass index [BMI] of ≥50 kg/m(2)) compared with a matched group of patients who had a normal BMI (<30 kg/m(2)). A secondary objective was to assess patients' experiences in finding a treating surgeon.

Methods: Forty-eight hips in forty-five patients who had a minimum BMI of 50 kg/m(2) and who had undergone a primary total hip arthroplasty at one of four high-volume institutions between 2001 and 2010 were reviewed. This included twenty-six women and nineteen men who had a mean age of fifty-four years (range, thirty-six to seventy-one years) and who were followed for a mean time of six years (range, four to twelve years). These patients were compared in a 1:3 ratio with a non-obese matched group (those with a BMI of <30 kg/m(2)) of 135 patients who had undergone total hip arthroplasty during the same time period by the same surgeons. The outcomes evaluated included implant survivorship, complication rates, Harris hip scores, 36-item Short-Form (SF)-36 questionnaires, University of California Los Angeles (UCLA) activity scores, and patient experience in finding a treating surgeon.

Results: The super-obese group had a 4.5 times higher odds ratio of undergoing a revision when compared with the matching group (p = 0.06); the overall implant survivorship was 89.6% for the super-obese group and 97.8% for the matching group. The super-obese group also had a significantly higher odds ratio (7.7) of complications compared with the matching group (p = 0.017). The super-obese group also had significantly lower mean values for the Harris hip score (82 points for the super-obese group compared with 91 points for the matched group; p = 0.002), the SF-36 Physical Component Summary score (39 points for the super-obese group and 49 points for the matched group; p = 0.001), the SF-36 Mental Component Summary scores (46 points for the super-obese group and 58 points for the matched group; p = 0.001), and the UCLA activity score (3.9 points for the super-obese group compared with 6.2 points for the matched group; p = 0.001). Compared with the matched group, super-obese patients were evaluated by a larger number of orthopaedic surgeons prior to undergoing total hip arthroplasty.

Conclusions: The clinical and patient-reported outcomes of primary total hip arthroplasty were lower in the super-obese patients. These patients also faced challenges in finding surgeons who would perform their procedure. Super-obese patients may benefit from counseling with their treating surgeon to set realistic expectations with regard to the outcomes of their procedure.