Orthopedic surgeons continue to struggle with the epidemic of patient obesity

Obesity is a widespread, significant and costly problem. The World Health Organization indicates that in 2008, more than 500 million adults worldwide were obese, which the organization defines as having a body mass index of 30 or higher.

The news is just as grim in the United States, where according to 2010 data from the National Health and Nutrition Examination Surveys (NHANES), more than one-third of adults were obese. Among U.S. children and adolescents, roughly 17% were obese, and the obesity rate in this population has nearly tripled since 1980.

There is some good news, however; according to the CDC, obesity and morbid obesity rates decreased from 2003 through 2010 among low-income preschool children.

The cost of managing obesity-related problems is substantial. In 2008, the estimated costs associated with obesity were $147 billion in the United States, up from $78.5 billion in 1998, according to Finkelstein and colleagues. People who were obese incurred medical costs that were $1,429 higher than their nonobese counterparts.

Research by Maradit Kremers and colleagues revealed a link between increasing body mass index (BMI) and longer hospital stays and higher medical costs following total hip arthroplasty (THA). The mean length of stay and direct medical costs were the lowest for patients with a normal BMI. Every five-unit BMI increase beyond 30 kg/m² represented about $500 more in hospital costs; 90-day costs were $900 higher. In revision THA, hospital costs were $800 higher and 90-day costs were $1,500 higher with each five-unit BMI increase.

Obesity puts a significant strain on the entire body, especially the musculoskeletal system, causing damage to knees, hips and the spine and increasing fracture risk. Children are not immune, with obesity putting them at risk for potentially devastating consequences.

In this Cover Story, Orthopedics Today explores the latest data on obesity and its effects on musculoskeletal health, from increased operative times to higher complication rates.

Risk factor for OA

Obesity has a substantial negative effect on the knee joints and hips, increasing the need for total knee arthroplasty (TKA) and THA. “Obesity is a significant risk factor for osteoarthritis of the knees and is a contributing factor in osteoarthritis of the hip,” Thomas P. Schmalzried, MD, medical director of the Joint Replacement Institute in Los Angeles, told Orthopedics Today. “Everyone recognizes that our population demographic is shifting to the upper ages, as the post-war baby boomers are now in their 60s, that has resulted in a substantial increase in the burden of disease and the need for THA and TKA.”

In addition to an increased risk for osteoarthritis (OA), other musculoskeletal problems are linked to obesity.

“There are some studies that suggest that there is an increased risk for meniscal tears or meniscal pathology,” Keith M. Baumgarten, MD, an orthopedic surgeon at the Orthopedic Institute in Sioux Falls, S.D., told Orthopedics Today. Obese patients are at risk for knee dislocations, a high-energy injury usually associated with car accidents and sports injuries. They may even sustain these dislocations from simple falls.

“There are some case reports of patients just walking and having their knee give out on them, actually dislocating their knee, which can be a potentially catastrophic injury,” Baumgarten said.

There is also evidence that increased BMI may put people at risk for low back pain and ankle fractures.

Surgical obstacles

Surgeons face many challenges when operating on obese patients, said Schmalzried, who is the Joint Reconstruction Section Editor for Orthopedics Today. Transferring the obese patient from a gurney to the operating room table is difficult. And then there are exposure issues.

“Bigger people generally need bigger incisions,” Schmalzried said.

“It is a more difficult procedure, and it is going to take longer,” said William M. Mihalko, MD, PhD, professor and JR Hyde Chair of Excellence in biomedical engineering at the University of Tennessee Health Science Center Campbell Clinic, Department of Orthopaedics and Biomedical Engineering. Obese patients require more assistants because, many times, it takes more retractors to get proper exposure. “There are maneuvers and techniques that you can do during surgery so you are not struggling, but in general, this requires a larger incision and more time to gain exposure,” he said.

“Dissections have to be larger,” Baumgarten said. “Operative times are longer, so there is the concomitant risk for medical problems with increased anesthesia time. Surgeries can be more challenging because of the difficulty accessing the joint either with arthroscopic or open surgeries with obese patients compared with patients with more normal BMI.”

Rehabilitation is critical in this patient population, but can be more difficult. “Conducting the surgery properly is only two-thirds of the story,” said Elena Losina, PhD, associate professor of orthopedic surgery at Brigham and Women’s Hospital in Boston. “It is critical to make sure that the patient will undergo a successful rehabilitation period. People who are morbidly obese may be more likely to need to be rehabilitated in inpatient facilities.”

“There are several studies that suggest there are greater rehabilitation needs, [and that] costs, length of stay after arthroplasties and long-bone injuries [are higher in obese patients],” Baumgarten said.

Influence on surgical outcomes

Obesity has varying effects on surgical outcomes depending on the procedure. “If we are talking about something less invasive and easier to get over like a carpal tunnel release vs. a THA, one is going to be much more effective than the other,” Mihalko said.

Researchers have been studying surgical outcomes related to obesity, particularly after THA and TKA.

“There have been recent studies published from data within the National Surgical Quality Improvement Program (NSQIP) database,” Mihalko said.

Belmont and colleagues used NSQIP data to assess 30-day postoperative complications and mortality after TKA in a national sample of 15,321 patients who underwent unilateral TKA. Their results showed that a BMI greater than 40 was an independent predictor of postoperative complications.

Increased complication rates

Obesity often increases complication rates. In three separate studies, Michael A. Mont, MD, and colleagues studied how obesity, morbid obesity and super obesity influence TKA outcomes. In the first study, Kimona Issa, MD, Mont and colleagues found that obese patients had excellent clinical outcomes at early to midterm follow-up of primary TKA. However, obese patients had significantly higher complication rates and significantly lower mean postoperative UCLA activity scores. Length of hospital stay was similar in both groups.

A literature review by Mont, Mark J. McElroy, MD, and colleagues on TKA outcomes in normal-weight, obese and morbidly obese patients showed that at a mean 5-year follow-up, morbidly obese patients had significantly lower implant survivorship rates compared with obese and nonobese patients. Morbidly obese patients had lower postoperative mean Knee Society objective and function scores than nonobese patients. The complication rate was 9% for nonobese patients, 15% for obese and 22% for morbidly obese patients.

Finally, a comparison of survivorship and complication rates for super-obese patients (minimum BMI of 50 kg/m²) who had undergone primary TKA and nonobese patients yielded no differences in aseptic implant survivorship (94% vs. 98%). Furthermore, Mont, Qais Naziri, MD, and colleagues found that super-obese patients had significantly higher rates of medical and surgical complications (14% vs. 5%). Patients in the super-obese group had lower Knee Society functional scores and smaller gains in flexion arc range of motion.

Similar results have been seen in data on THA. A study by Rajgopal and colleagues showed that although super-obese patients had similar satisfaction scores to those of their obese and normal-weight counterparts, they had a significantly longer length of hospital stay and higher rates of major complications and readmission.

“Sometimes we see that patient satisfaction may not be affected in obese patients, but length of hospital stay for these patients is longer and the resulting functional parameters are lower with hip and knee replacement as your BMI increases from class I to the super obesity ranges,” Mihalko said.

Research in other subspecialties yielded similar findings. Spine Patient Outcomes Research Trial (SPORT) results indicate that obese patients got less clinical benefit from operative and nonoperative management of lumbar disc herniation. In addition, a study on outcomes after total shoulder arthroplasty found that although obesity had no negative effect on short-term shoulder function, the overall physical function of obese and overweight patients did not significantly improve after the procedure.

Risks higher for DVT, SSIs

Obese patients are also at greater risk for deep vein thrombosis (DVT). “No matter what we do, there is always a chance for deep venous thrombosis after a total joint replacement, even if you use prophylaxis and mobilize the patient as quickly as you can,” Mihalko said. “But in larger patients, they tend to be more sedentary. It is the stasis of the patient that increases their risk. The [American Association of Hip and Knee Surgeons] AAHKS has published a consensus statement that included the conclusion that DVT risk is increased in the obese patient”

The rate of surgical site infections is higher in obese patients. “When you have a large, thick layer of subcutaneous tissue, you will have an increased risk for necrosis of some of that fat layer that in turn will result in increased drainage from the incision site,” Mihalko said. “As you increase time of drainage from the incision site … you have a higher risk for surgical site infections.”

To achieve better outcomes in obese patients, Mihalko recommends certain preoperative actions, starting with good hemoglobin A1C control. “Hemoglobin A1C of seven or less is definitely a way to optimize the patient as well as to assure their cholesterol levels and triglyceride levels are optimized and maintaining better control of their blood pressure. These comorbidities are all associated with the metabolic syndrome that has been linked to poor orthopedic outcomes as well” he said.

Weight loss before surgery

“If you look at forces across the knee and the knee cap, when you ambulate, there is a linear increase of force across the knee,” Baumgarten said. “If you drop weight, it is not just a one-to-one reduction in the forces across the knee. There is a significant reduction in the biomechanical aspects of how the joints function with weight loss. There is significantly better quality of life.”

Some surgeons and hospitals have instituted “obesity protocols,” which identify patients who have reached a certain BMI level that deems them unsuitable for elective orthopedic surgery.

“In our hospital, I am more concerned about the general metabolic syndrome that is associated with obesity,” Schmalzried said. “People tend to be malnourished, have low protein, low albumin, low total lymphocyte counts. They may have concomitant heart disease or lung disease.

“We have a protocol where every patient gets seen by the same internist and the internist assesses their general health,” Schmalzried continued. “There are some of those people who are obese and of poor enough general health that we do not think they are good surgical candidates.”

Effects on the growing skeleton

In addition to the complications that obesity causes in adults and related to surgery, it can have significant and sometimes devastating effects on a child’s musculoskeletal system, said Steven L. Frick, MD, chairman of the department of orthopedics at Nemours Children’s Hospital in Orlando, Fla.

The primary issue is the effect of obesity on the angular alignment of the lower extremities, according to Frick, most commonly severe bowing of the knees or Blount’s disease.

“This is related to putting too much weight and too much force on the growth plates,” Frick continued. “If you think about growth plates as the weak link in the musculoskeletal system, they are the part of the skeleton that is the most likely to fail or deform if you put too much force on it.”

A second common problem is slipped capital femoral epiphysis (SCFE), which has a clear correlation to obesity, Frick said. SCFE is “clearly directly related to obesity and weight to the point that when we see children of normal weight who have that problem, we investigate to see if they have some other endocrine problem that would affect their growth plate; we rarely see SCFE in children who are not overweight.”

SCFE can result in a significant loss of anatomy. An unstable SCFE can permanently damage the blood supply to the ball of the proximal femur and lead to horrible arthritis, which is crippling and lifelong,” Frick said. Milder forms of SCFE can result in limited function, limb shortening and a loss of mobility that could lead to early arthritis.

Higher fracture rates

In addition, children who are obese have higher fracture rates than their nonobese counterparts, according to Frick.

A study by Seeley and colleagues demonstrated that obese children were more likely to sustain complex supracondylar humeral fractures compared with nonobese children, they were more likely to sustain these fractures from a fall on an outstretched hand, and they had more postoperative complications.

Just like their adult counterparts, obese children are difficult to treat, and they are more likely to have complications like wound healing and infections, Frick said.

“[Obesity] diminishes our ability as pediatric orthopedic surgeons to effectively treat pediatric orthopedic conditions because our treatments — casting, bracing or surgery — are less effective because the child is obese,” Frick said. “It is harder to cast fractures because the child is obese. It is harder to brace children who have spinal deformities because you cannot push the spine with the brace because there is so much fat in the way.”

This patient population group also has a higher incidence of medical problems, such as sleep apnea.

“Some children who are obese could have significant anesthetic issues after relatively minor orthopedic procedures if their airway is obstructed because of their obesity,” Frick said.

Strain on the health care system

The problem of obesity continues to impact the orthopedic specialty.

“The average weight and BMI of average Americans continues to rise,” Schmalzried said.

“We all know that obesity is growing, but it is not growing at similar rates among different population groups,” Losina said. “The greatest increase in obesity prevalence is seen, unfortunately, in minorities … particularly black women.”

This growing obese population will strain an already burdened health care system. “Obese patients will require more care,” Baumgarten said. “With increased pain and pathology associated with an elevated body mass index, the management of the increased complications is going to be more difficult.”

For some, their excess weight will mean limited access to care.

“One of the things that we are concerned about is that different providers, hospitals, surgeons and accountable care organizations in the future will be held financially responsible for complications such as infection or deep vein thrombosis,” Schmalzried said. “That may influence access to care for obese patients. … Based on the fact that obese patients are at increased risk for short-term complications, I could see circumstances where the health care system would be increasingly concerned about doing elective surgery on these people.” – by Colleen Owens

How will the increasing number of obese patients affect the future of health care?

Beyond the dollar amount

While currently living in an era of unprecedented rates of obesity — now considered to be a worldwide epidemic — the mean body mass index (BMI) of the population has increased globally since 1980, with adults in the United States demonstrating an overall prevalence of 68% for being overweight and 33.8% for being obese. Obesity is well-associated with an increased incidence of major diseases such as diabetes, cardiovascular disease, asthma and most cancers — problems that will only get worse as more of the population becomes overweight.

“Three factors are thought to be responsible for the increasing burden of treating obesity; increase in the number of people that are obese, the increasing cost of treatments specific to obesity-related illnesses and the demographic shift in the population with a trend for older individuals to be obese,” Kenneth E. Thorpe, PhD, of Emory University wrote in Health Affairs. To put the scope of the problem in perspective, it is estimated that by 2018, the direct costs of obesity at a national level is projected to be $1,425 per person, increasing from $361 today, according to Thorpe.

The cost of obesity, however, goes well beyond consideration of the dollar. The burden of obesity-related disease will be seen across all disciplines, having significant impact on disability as well as quality and longevity of life. We will see profound, direct impacts of obesity in our field of musculoskeletal care, and to say that the effects of obesity on the future of health care will be significant would merely be an understatement and a gross underestimation of the true nature and burden of this problem.

Jonathan T. Bravman, MD, is an assistant professor and director of sports medicine research at the University of Colorado in Denver.
Disclosure: Bravman is a consultant to Smith & Nephew and receives fellowship support from DePuy Mitek, Stryker and Smith & Nephew.

Huge economic burden

The obesity rates that exist in the United States are already significantly impacting the health of our citizens in epidemic proportions. The current and future projected health care costs related to obesity will place an increasingly huge burden on the U.S. economy. This problem will be even more significant in the future unless we can institute significant changes in individual behavior, including levels of exercise and diet changes.

Obesity has also increased to an alarming incidence among our youth. The potential number of years these overweight children will be living with obesity will promote future ongoing health problems and costs.

The obesity epidemic is the largest single health challenge — but it can potentially be prevented and treated. It will involve significant individual behavior modification with concomitant reductions in physical inactivity and unhealthy diet. This will require individual discipline and accountability for each person’s health care and maintenance.

The United States cannot afford the trajectory we are on, and it should not continue to support obesity without changing the education of these patients, introducing prevention programs and placing requirements for individual behavior that do not result in limitless funding.

As an orthopedic surgeon, I found the most satisfaction from treating patients who wanted me to help them get better and achieve their best outcomes. These patients sought to control and contribute to their individual health. As a rule, they had healthy lifestyles prior to seeing me and participated actively in their recovery. Contrast this with the patients who just wanted to be fixed and were not actively involved in their maximum recovery. Those patients often offered excuses for their inability to exercise and control their diets. Their potential outcomes were often compromised. I would occasionally ask these patients how much they thought carrying a 50-pound backpack while walking upstairs or playing tennis would increase their knee pain. While they all understood that carrying extra weight could increase their pain and limit their function, less than 10% of my patients could lose 10 pounds or more when asked. Those who did lose weight often regained it in the next few years. The patients who lost 80 pounds to 100 pounds almost always had bariatric surgery.

Obesity is a complex issue. Obesity and its associated health care needs require us to make changes to solve it. Physicians must continue to educate people, with the involvement of a supporting team of providers such as nutritionists and our health care institutions.

Douglas W. Jackson, MD, is Chief Medical Editor Emeritus of Orthopedics Today.
Disclosure: Jackson has no relevant financial disclosures.