Incision site fat thickness and 90-day complications for direct anterior and posterior approach total hip arthroplasty.

Background: Defining the distribution of subcutaneous fat around the hip in relation to different approaches for total hip arthroplasty (THA) may lead to a better understanding of the relationship between obesity and complications. The purpose of this study was to: (1) describe the intraoperative thickness of subcutaneous fat at the incision site for direct anterior (DAA) and posterior approaches (PA) for THA; and (2) examine the relationship between fat thickness and 90-day postoperative complications.

Methods: Intraoperative fat measurements were obtained at the anterior incision site (AT-IS) of the DAA ( = 60) and the lateral incision site (LT-IS) of the PA ( = 64). Lateral hip fat thickness was measured from preoperative anteroposterior pelvis radiographs (LT-XR). Body mass index (BMI), sex, age, and 90-day complications were collected retrospectively.

Results: Patients within the same demographic groupings had significantly more fat laterally than anteriorly, between 9.6 mm and 17.96 mm. Return to the OR was significantly associated with BMI, AT-IS, and LT-IS. Wound complications were significantly associated with AT-IS. Periprosthetic joint infection (PJI) was significantly associated with BMI and LT-IS. No outcome variables were associated with LT-XR, approach, sex, or age. LT-XR was strongly correlated with AT-IS and LT-IS.

Conclusions: Regardless of BMI, sex, or age more soft tissue was encountered with a PA compared to a DAA. General adiposity was associated with return to the OR. Excess incisional fat was associated with wound complications following a DAA and PJI after a PA. LT-XR and clinical examination near the proposed incision, may provide helpful data in making preoperative risk assessments.