Surgical Implications of Soft Tissue Depth in Primary Total Hip Arthroplasty

Background: Morbid obesity has been identified as a risk factor for complications in total hip arthroplasty (THA). However, the impact of the adipose tissue distribution near the surgical site has not been adequately studied. We aimed to characterize the complication rates associated with varying soft tissue depth around the operative hip as measured on plain films. Methods: We performed a retrospective review of primary THAs at our institution from 2009 to 2020. A total of 106 patients met inclusion criteria. Propensity score matching was used to match the patients that required reoperation (n=13) to a cohort of those that did not (n=33) based upon demographics, BMI, and age. Four standardized measurements were taken, and statistical analyses were performed to determine if complication differences existed between cohorts. Results: There was no statistical difference between the non-reoperation cohort or the reoperation cohort in age (65.0 vs. 65.4, P =0.462) or BMI (39.4 vs. 40.9, P =0.108). There was no significant difference between the two cohorts for all four measurements ( P =0.296, P =0.369, P =0.463, P =0.321). A subgroup analysis of patients with BMI ≥40 (n=23) demonstrated that individuals in the reoperation cohort had a higher value of measurements 3 and 4 (237.2 vs. 274.6, P =0.041; 236.5 vs. 284.1, P =0.015). Conclusions: A standardized measurement of thigh width on an AP pelvis plain film may help surgeons identify a subset of patients (BMI ≥40) at elevated risk for complication in primary THA.