Knee replacement surgeries take more time, are more costly in overweight individuals

Feb 18, 2011

Knee replacement surgery takes far more time to conduct in overweight and obese patients than in normal weight patients, according to recent research at Hospital for Special Surgery in New York. The study will be presented at the American Academy of Orthopaedic Surgeons annual meeting, held Feb. 15-19 in San Diego, Calif. The study 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 is never considered," said Geoffrey Westrich, M.D., an adult reconstruction and joint replacement surgeon and co-director of Joint Replacement Research at Hospital for Special Surgery who led 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 staff could be finishing up two hours later. In many cases, the hospital has to pay the staff overtime which greatly increases hospital expenditures."

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. Researchers at Hospital for Special Surgery wondered whether weight might impact the time it took to perform a knee replacement. "Intuitively, one would think that as people get heavier, knee replacement surgery may be more difficult and more time consuming because the fatty tissue makes surgery more difficult," Dr. Westrich said. "Now that we have collected data on the different stages of knee replacement surgery, we wanted to use the objective data to determine if there was an increase in the time of surgery based on a patient's weight and whether we could correlate a patient's weight or BMI with the different steps of ."

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: normal weight 18.5-25 kg/m2, overweight 25-30 kg/m2, obese class I 30-35 kg/m2, obese class II 35-40 kg/m2, and obese class III >40 kg/m2. 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 tourniquet time is measured from the time of the initial incision, includes the time it takes to implant the knee prosthesis, and ends when the bone cement is hard. The closure time is not included in the tourniquet time.

The investigators found that as BMI increased, so did the time it took to perform all parts of the surgery. "As BMI increased, surgery times progressively increased," Dr. Westrich said. 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, it was two hours and 24 minutes, a difference that was 20 % 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 (24 minutes, P<0.01), surgery time (16 minutes, p<0.01), tourniquet time (7.5 minutes, p<0.01), anesthesia time (4.5 minutes, p=0.005) and closure time (8 minutes, p<0.01).

Obesity is a growing epidemic in the United States with currently 71 percent of individuals over the age of 60 classified as obese. While the number of obese people has grown, so has the number of TKAs performed—between 2000 and 2004, there was a 53 percent increase in the number of TKAs conducted in the United States. Dr. Westrich said that, in this study, seventy percent of his patients were classified as overweight or obese I, II, III and 50 percent were obese class I, II, III. The number of obese people being scheduled for TKAs will likely increase.

"Before this particular study, we knew that when people are heavier, we knew the surgery could be more challenging but we never had objective data to support it," Dr. Westrich said. "Hospitals should not only take into account the type of surgery and its complexity, but also the patient's body mass index when appropriately allocating OR time."

Explore further: Experts call for higher exam pass marks to close performance gap between international and UK medical graduates

Provided by Hospital for Special Surgery

not rated yet
add to favorites email to friend print save as pdf

Related Stories

No justification for denying obese patients knee replacements

Jul 24, 2008

There is no justification for denying obese patients knee replacement surgery: They benefit almost as much as anyone else from the procedure, concludes a small study published ahead of print in the Annals of the Rheumatic Di ...

2 knee replacements may be better than 1

Feb 17, 2011

Replacing both knees in one surgery, or simultaneous total knee replacement (TKR) was associated with significantly fewer prosthetic joint infections as well as other revision knee operations within one year after surgery, ...

Recommended for you

Obese British man in court fight for surgery

Jul 11, 2011

A British man weighing 22 stone (139 kilograms, 306 pounds) launched a court appeal Monday against a decision to refuse him state-funded obesity surgery because he is not fat enough.

2008 crisis spurred rise in suicides in Europe

Jul 08, 2011

The financial crisis that began to hit Europe in mid-2008 reversed a steady, years-long fall in suicides among people of working age, according to a letter published on Friday by The Lancet.

New food labels dished up to keep Europe healthy

Jul 06, 2011

A groundbreaking deal on compulsory new food labels Wednesday is set to give Europeans clear information on the nutritional and energy content of products, as well as country of origin.

Overweight men have poorer sperm count

Jul 04, 2011

Overweight or obese men, like their female counterparts, have a lower chance of becoming a parent, according to a comparison of sperm quality presented at a European fertility meeting Monday.

User comments : 0

More news stories

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Study says we're over the hill at 24

(Medical Xpress)—It's a hard pill to swallow, but if you're over 24 years of age you've already reached your peak in terms of your cognitive motor performance, according to a new Simon Fraser University study.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Health care site flagged in Heartbleed review

People with accounts on the enrollment website for President Barack Obama's signature health care law are being told to change their passwords following an administration-wide review of the government's vulnerability to the ...