The Effect of Obesity on Fluoroscopy-Assisted Direct Anterior Approach Total Hip Arthroplasty.

BACKGROUND Obesity has been considered a relative contraindication to performing a direct anterior approach total hip arthroplasty (DAA-THA) since it is hypothesized to lead to component malpositioning and poor outcomes. Fluoroscopy-assisted DAA-THA has been reported to diminish variability in acetabular component positioning. However, fluoroscopy-assisted DAA-THA in the obese patients has not been well described. We report on a single surgeon consecutive series of fluoroscopy-assisted primary DAA-THA's examining the radiographic and perioperative outcomes in obese patients. METHODS A retrospective review was conducted of 509 consecutive unilateral fluoroscopy-assisted DAA-THAs on a specialized orthopaedic table performed by a single surgeon. All patients were divided into three cohorts according to their body mass index (BMI): Group I (< 30 kg/ m2 ), Group II (≥ 30 to < 35 kg/m2 ), and Group III (≥ 35 kg/ m2 ). Perioperative parameters, outcome scores (EuroQol 5 Dimension and hip disability and osteoarthritis outcome scores), and radiographs were comparatively assessed. Cup position was determined using Widmer's method. RESULTS A total of 492 DAA-THAs (minimum follow-up: 2.1 years) with appropriate radiographs were analyzed. Of which 356 (72.2%) were in Group I (average: 25.1 kg/m2 ), 105 (21.3%) in Group II (average: 32 kg/m2 ), and 31 (6.5%) in Group III (average: 38.6 kg/m2 ). There were no differences in any parameters between Group II and III. Group I differed in average age and included more female patients than Groups II and III. There was a statistically significant difference in cup anteversion between all groups with average measurements of 20.8°, 19.5°, and 17.6°, respectively. No other differences were identified in radiographic parameters or postoperative outcomes. CONCLUSIONS There were no clinically relevant differences in component positioning or perioperative parameters between obese and non-obese patients. We do not consider a BMI ≥ 30 kg/m2 to be a contraindication for fluoroscopyassisted DAA-THA when performed by a surgeon experienced in the technique.