Early Surgical Complications of Total Hip Arthroplasty in Patients With Morbid Obesity: Propensity-Matched Cohort Study of 3683 Patients

BACKGROUND: The aim of this study is to determine whether the high risk of surgical complications within 1 year of total hip arthroplasty (THA) is due to associated comorbidities or morbid obesity alone as measured by body mass index (BMI ≥ 40 kg/m²). METHODS: Population-based retrospective cohort study was conducted of all adults in Ontario undergoing primary THA for osteoarthritis (2012-2018). All patients were followed for 1 year. Outcomes were compared among matched groups (hypertension, diabetes, chronic obstructive pulmonary disease, frailty, congestive heart failure, coronary artery disease, asthma, and Charlson score). Primary outcome measure was major surgical complications within 1 year (composite of deep infection requiring surgery, dislocation requiring closed or open reduction, and revision surgery). RESULTS: A total of 3683 patients with morbid obesity were matched and had a significantly greater risk of major complications within 1-year (132 [3.6%] vs 54 [1.5%]; hazard ratio [HR] 2.54, 95% confidence interval [CI]; 1.98-3.25). This included greater risk for deep infection requiring surgery (100 [2.8%] vs 26 [0.7%]; HR 3.85, 95% CI; 2.70-45.48) and revision arthroplasty (86 [2.4%] vs 34 [0.9%]; HR 2.61, 95% CI; 1.92-3.55). Operative time was also longer with a median 116 (99-138) vs 102 (87-121) minutes. There were no significant differences in hospital stay, cost of acute care episode, or medical complications. CONCLUSION: Patients' large body habitus seems to contribute to the increased risk of surgical complications within 1-year of THA. Future research is needed to identify ways of mitigating surgical complications such as centralizing care for this complex group of patients in specialist centers.