The research conducted at Hospital for Special Surgery in New York has implications for hospital staff scheduling surgeries, operating room utilization and personnel staffing, and also raises the question of whether knee replacements should be reimbursed based on time.
"When we schedule surgery, the body mass index is never considered," said Geoffrey Westrich, lead author of the study.
"If I have four or five knee replacements in a day, they will just put them on the OR schedule but they don't look at whether a person is heavy or obese class II or obese class III.
"What this study shows is that the utilization is greatly increased. If you have a 20 percent greater utilization for someone who is obese and if you multiply that by five or six knee replacements over the course of a day, at the end of the day the operating room staff could be finishing up two hours later.
"In many cases, the hospital has to pay the staff overtime which greatly increases hospital expenditures," Westrich said.
Obesity causes a variety of health problems, including an increased need for total knee arthroplasty (TKA) or knee replacement surgery-extra weight puts extra stress on knees.
The investigators retrospectively reviewed a consecutive series of 454 TKAs conducted by one surgeon at HSS between 2005 and 2009. They categorized patients into groups based on the World Health Organization classification of body mass index.
The investigators then correlated weight with five factors: anesthesia induction time, tourniquet time, time spent surgically closing the knee after completing the procedure, total surgery time, and total amount of time spent in the operating room.
The investigators found that as BMI increased, so did the time it took to perform all parts of the surgery.
In patients who were a healthy weight, the overall room time was two hours and increased as weight category increased; for obese class III patients (>40 kg/m2), it was two hours and 24 minutes, a difference that was 20 pc greater and highly statistically significant.
In comparing normal weight to obese class III patients, the times were also greater for obese patients in total room time, surgery time, tourniquet time, anesthesia time and closure time.
The study has been presented at the American Academy of Orthopaedic Surgeons annual meeting, held Feb. 15-19 in San Diego, Calif. (ANI)