Compared with normal weight and overweight patients, patients with a BMI greater than 40 have an increased risk of medical and surgical complications following total joint arthroplasty, according to study results.
“There is a direct relationship between increasing BMI and increased risk of complications in patients undergoing total joint arthroplasty,” Hasham M. Alvi, MD, an Adult Joint Reconstruction Fellow at Northwestern University, told Orthopedics Today. “The greatest increase in risk of medical and surgical complications is in patients with a BMI [greater than] 40. Additionally, BMI [greater than] 40 conveys an increased risk of return to the operating room and greater length of hospital stay at 30 days of follow-up.”
BMI and complications
Using the American College of Surgeons’ National Surgical Quality Improvement Program database, Alvi and his colleagues stratified 13,250 of 42,867 patients who underwent primary total hip or knee arthroplasty for osteoarthritis into the following five groups based on BMI: healthy weight, overweight, obese class I, obese class II and obese class III. Patients were also matched for gender, age, surgery type and American Society of Anesthesiologists class. 
According to unadjusted analysis of the matched cohorts, patients with a BMI greater than 40 were more likely to experience an overall complication, surgical complication, medical complication and superficial wound infection compared to patients with a normal BMI. Similarly, compared with patients in the overweight group, patients with a BMI greater than 40 were more likely to experience an overall complication, surgical complication, superficial wound complication and deep wound infection.