Severely Obese Patients Have a Higher Risk of Infection After Direct Anterior Approach Total Hip Arthroplasty.

Background: The orthopedic literature documents that obesity can place patients at increased risk for complications. This is the first study to document the increased risk of infection in obese patients after direct anterior approach (DAA) primary total hip arthroplasty (THA).

Methods: We retrospectively evaluated 1621 consecutive primary THAs performed with a DAA. Patients were stratified by body mass index <35 kg/m(2) (group 1) or ≥35 kg/m(2) (group 2). Rates of postoperative infection requiring revision, superficial wound dehiscence, return to the operating room, and total wound complications were compared. There were 1417 cases in group 1 and 204 in group 2.

Results: Five cases in each group had a deep infection, resulting in a significantly higher rate in group 2 (0.35% vs 2.5%, P = .0044, relative risk = 7.1). Superficial wound dehiscence was diagnosed in 13 (0.92%) THA in group 1 and 4 (1.96%) in group 2 (P = .256). The all-cause reoperation rate was 0.92% and 3.43% in each group, respectively (P = .008). The total rate of all studied complications was 1.27% compared to 4.41% (P = .0040, relative risk = 3.5).

Conclusion: This is the first study to report on significantly increased rates of postoperative infection requiring revision in patients with body mass index ≥35 kg/m(2) after anterior approach hip arthroplasty. We believe it is the combination of immune dysfunction and proximity of the anterior incision to the inguinal crease and genitalia with overlying abdominal pannus that contributes to this risk. Further studies comparing other surgical approaches in obese patients are needed to determine if this complication is truly attributable to the DAA alone.