Dual-Mobility Total Hip Arthroplasty in Patients with Obesity, Morbid Obesity and Super-Obesity: Medium-Term Outcomes of a Series of 180 Hips.

Background: Obesity has been consistently proven to be associated with an increased risk of dislocation following total hip arthroplasty (THA). As the prevalence of obesity continues to rise globally, it is of vital importance to minimise risks, including dislocation rates, in these patients undergoing THA. Methods: We describe a series of patients with obesity, morbid obesity (BMI ≥ 40) and super-obesity (BMI ≥ 50) undergoing THA at our institution over a 10-year period using a dual-mobility acetabular cup. The dislocation rate and all-cause revision rate were used as primary outcome measures. Patient-reported outcomes (PROMS) were assessed using the Oxford hip score (OHS) and VAS score. We assessed for differences in PROMS after grouping patients into BMI ranges of 30-34.9, 35-39.9, 40-49.9 and > 50. Results: A total of 180 dual-mobility THAs in 162 patients were included of which 36 hips had BMI ≥ 40 and 8 hips had BMI ≥ 50. The mean age was 64.2 (29-88) years and the mean follow-up period was 52.1 months (13-122 months). The all-cause revision rate was 2.2% and no patient had a post-operative dislocation. The survivorship of the acetabular component was 100% with the maximum follow-up being 10.1 years. The mean OHS was 43.82 ± 3.29 (30-48) and the mean VAS for pain from the hip was 0.94 ± 1.34 (0-8). No significant difference in PROMS was found between the four BMI ranges. Conclusion: Our results indicate excellent mid-term survivorship, and improvement over traditional dislocation rates in high BMI patients with a dual-mobility THA.