Super-obese patients are associated with significant infection burden after total hip arthroplasty

Over ⅓ of the population in the United State is obese (body mass index [BMI] >30 kg/m²), with an increasing proportion being morbidly obese (BMI >40 kg/m²). As the obesity rate climbs, an increasing number have entered the super-obese category (BMI >50 kg/m²), theoretically increasing risk for complications after total hip arthroplasty (THA). This study compared complications in non-obese, obese, morbidly obese, and super-obese patients undergoing THA. We specifically assessed: (1) 1- and 2-year peri-prosthetic joint infection (PJI) rates; (2) complication rates; as well as (3) 1- and 2-year revision rates.

A database review identified patients undergoing primary THA from 01 January 2010 to 31 December 2019. Patients were stratified based on the presence of International Classification of Diseases, 9th and 10th revision diagnosis codes of non-obese (BMI <30 kg/m²) (n = 8680), obese (BMI <40 kg/m²) (n = 12,443), morbidly obese (BMI <50 kg/m²) (n = 5250), and super-obese (BMI >50 kg/m²) (n = 814) prior to THA. Complication rates at 90 days, 1 year, and 2 years were compared across groups.

At all time points, super-obese patients were associated with higher rates of PJI, even when compared to morbidly obese patients. Complications such as sepsis, venous thrombo-embolism, and revision surgeries were found in higher numbers in super-obese as well as morbidly obese patients, compared to obese and non-obese patients.

This study provides large-scale analyses demonstrating the association between super-obese and morbidly obese patients and higher infection rates, as well as complications, following THA. Importantly, the association of PJI is highest among super-obese patients, even when compared to morbidly obese patients. Attaining a BMI <40 kg/m² prior to surgery may be an important goal discussed with patients to lower the chance of postoperative infections.