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 was to determine whether the high risk of surgical complications within one 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 of all adults in Ontario undergoing primary THA for osteoarthritis (2012-2018). All patients were followed for one year. Outcomes were compared amongst 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 one year (composite of deep infection requiring surgery, dislocation requiring closed or open reduction, or revision surgery).

Results — A total of 3,635 patients with morbid obesity were matched and had a significantly greater risk of major complications within a year (132 [3.6%] vs. 54 [1.5%]; HR 2.54 [95% 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.

Conclusions — Patients’ large body habitus seem 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 centres.