Obesity: An increasing problem for orthopedists

Data indicate that the prevalence of obesity in the United States is increasing in adults and children. According to the most recent data from the National Health and Nutrition Examination Survey, 66.5% of men and women 20 years and older in the United States are overweight and almost 32% are obese. Being overweight or obese has been reported to increase the risk of orthopedic complaints such as osteoarthritis, tendinosis, bursitis, overuse syndromes and surgical complications.

During the gait cycle, obese individuals have been noted to take shorter steps, walk slower, have increased step width, increased Q angles, increased hip abduction angles, more abducted foot angles, and increased out-toeing. Some of these differences, such as the increased step width, slower stride and a more abducted foot position may be simply an effort to increase stability. Many of the gait changes such as an increased Q angle and increased step width may also be attributed to thick thighs.

Obesity may even be more prevalent in an orthopedic practice than in the general population. It is for this reason, that orthopedic surgeons should be able to effectively identify obesity, initiate appropriate referrals and assist in obesity education.

Carol C. Frey, MD
Moderator

Round Table Participants Moderator Carol C. Frey, MD Fellowship Director, West Coast Sports Medicine Foundation Director, Foot & Ankle Surgery Assistant Clinical Professor, UCLA Manhattan Beach, California Sajida Ahad, MD Senior Fellow Center for Videoendoscopic Surgery University of Washington Seattle, Wash. Brant K. Oelschlager, MD Associate Professor Director, Center for Videoendoscopic Surgery Director, Swallowing Center Director, Bariatric Surgery Department of Surgery University of Washington Seattle, Wash. George A. Bray, MD Boyd Professor and Chief, Division of Clinical Obesity and Metabolism Pennington Center Louisiana State University Baton Rouge, La. Michael S. Pinzur, MD Professor, Department of Orthopedic Surgery and Rehabilitation Loyola University Health System Maywood, Ill.

Carol C. Frey, MD: What is the best way to diagnose obesity?

Sajida Ahad, MD, and Brant K. Oelschlager, MD: Obesity is excessive adipose tissue in the body. Obesity is a worldwide epidemic. It is well recognized that obesity is a major risk factor for development of chronic diseases all of which cause mortality. There is disagreement among experts regarding true measure of obesity. However all agree that excess adiposity contributes to metabolic syndrome seen in obese individuals.

The presence of excess abdominal fat is recognized as an independent predictor of higher risk of chronic diseases and morbidity.

Body fat can be measured by different methods. These can be density based, ie, hydrodensitometry, air displacement plethysmograpgy; imaging, MRI, CT scans, dual energy X-ray absorptiometry or DXA; bioelectric impedance testing; and anthropometric measures, skin-fold thickness, waist circumference (WC), waist-to-hip ratio, or body mass index (BMI).

Hydrodensitometry or underwater weighing is often described as the gold standard among the plethora of tests. It is based on buoyancy law that objects denser than water will sink. The subject is required to exhale when submerged underwater, therefore this test requires a high degree of water confidence and is not suitable for all populations. Additionally if the tank is not at floor level, accessibility may be restricted for the very obese, elderly and disabled populations.

CT and MRI are expensive to use and involve radiation exposure. DXA involves less radiation exposure, however, it is expensive. Hydrodensitometry and all imaging modalities are limited to research settings.

Bioelectric impedance use conductors to measure impedance of subject’s body to low, safe current. This is considered a less accurate method; however the current analyzers are inexpensive and portable making them more user-friendly in field and population studies.

George A. Bray, MD: The first step is to obtain an accurate height and weight and then calculate the BMI (weight in kilograms divided by the square of the height in meters = kg/m²). Normal range is 18.5 to 24.9. Overweight is 25 to 29.9, and obesity is greater than 30. The second step is to measure waist circumference. This criterion has been agreed on by the U.S. Government and the World Health Organization (WHO). The second step is to measure waist circumference. Your waist is too large in a man if the circumference is above 40 inches, and in a woman above 35 inches.

Frey: Do you routinely get height and weight measurements or BMI on your patients?

Michael S. Pinzur, MD: We routinely obtain height, weight and BMI values on our patients. Interestingly, we looked at the BMI of patients undergoing surgery for complex Charcot foot deformity. In this series of patients, published in 2007, 54% had open wounds with osteomyelitis at the time of surgery. The average BMI in this group was 38.3.

Frey: Is BMI meant to be used as a means of classifying individuals as having normal body composition?

Ahad and Oelschlager: BMI has been adapted by the insurance industry for risk stratification as well as used in numerous studies to evaluate and treat obesity. BMI varies with age as it increases from birth to 1 year and then decreases until 6 years of age and then increases again. This makes BMI a difficult measure to interpret in adolescence and children.

“… there is hard medical evidence that obesity increases the risk for developing diabetic foot morbidity, lower extremity amputation and premature death.” — Michael S. Pinzur, MD

Populations tend to vary in the relative percentage of fat in relation to total body mass. This means that ethnically different individuals with the same BMI will have different fat and lean mass and therefore different health implications. Also, since BMI is related to height it will vary according to sex and age.

Despite these limitations BMI has served as an important measure of obesity both for research and clinical practice. It is an easily obtainable measure both by clinical personnel and individuals. Another commonly used anthropometric measure that correlates highly with BMI is WC. It is positively correlated with abdominal and overall fat content and is not greatly influenced by height. Potential errors can stem from incorrectly positioning the tape and specific defined anatomic landmarks should be used to measure WC.

Bray: BMI is the criterion for diagnosing obesity. Like other criteria — hemoglobin, uric acid, white blood cell counts, etc, we have upper limits of normal. When someone exceeds these limits the physician and his staff should pursue the problem as appropriate. When the BMI is > 30 and the individual is not an active athlete, it is almost always a good marker for obesity and the associated risks.

Frey: How many of your patients would you estimate are actually obese?

Pinzur: I think that this should be broken down by patient subgroups. At least two-thirds of the diabetic population that I see are obese, most being morbidly obese. More than two-thirds of the patients with posterior tibial tendon insufficiency (adult acquired flatfoot) are obese. Interestingly with this population, “flat feet” are common.

The vast majority of patients who come to surgery are morbidly obese. And in those patients who might respond to custom foot orthoses, the results are better in smaller-sized individuals. In addition, the materials that are used in orthosis fabrication are better suited for nonobese individuals.

Cushioned orthotics cannot be used in obese individuals as they wear out or are mechanically unable to withstand the subsequent forces applied.

These two populations stand out to me as being heavily “weighted” by obesity, vs. the traumatic and sports populations, which seem to be more evenly distributed.

Frey: Are orthopedists missing opportunities for diagnosing and treating obesity-related complaints?

Bray: It would be worthwhile for the physician, or more likely his or her well-trained staff to review the patient’s weight and its relation to orthopedic problems like osteoarthritis (OA).

Pinzur: There are several problems with this line of thinking. It may be too late to institute early interventions which would combine dietary change and exercise. By the time the patient gets to the orthopedic surgeon, the disease process might preclude meaningful exercise.

Most orthopedic surgeons say that patients don’t listen, or get offended when they advise weight loss. In fact, patients fully understand that they are obese and that weight loss would help. They also understand that smoking is detrimental to their cardiovascular system, yet they continue smoking. There are psychological or behavioral issues at play that are beyond the scope of an orthopedic surgeon.

We also cannot put this responsibility on the primary care physician. Every specialist speaks to groups of primary care physicians, pontificating that their problem is the most important problem in the work. They advise that the most important responsibility of the primary care physician is to screen patients for the specialist’s area of interest, and only refer patients that will require surgery. If the primary care physician followed the wishes of each of the specialists who speak to them, they would spend their entire practice screening for specialist disease and not be able to care for the patient.

This is a societal issue, and must be approached in the schools with education and exercise programs, in the workplace with programs to promote healthy living, and in the community.

Frey: Every pound of body weight places 4 to 8 pounds of stress on the lower extremity during weightbearing activity, and most people take 5,000 to 10,000 steps a day. Does that translate into significantly more wear and tear on the lower extremity joints in heavy people?

Pinzur: Absolutely, and there is hard medical evidence that obesity increases the risk for developing diabetic foot morbidity, lower extremity amputation and premature death. In 2005, we reported the relationship between BMI and hospital admission with a primary or secondary diabetic foot comorbidity. The mean BMI in this group was 31 with 35% of the population having a BMI over 30.

In addition, obese people are far more likely to develop diabetes. At any point in time, 3% to 4% of the diabetic population will have a foot ulcer, 15% will have one during their lifetime and 85% of the 60,000 lower extremity amputations yearly in the United States are preceded by a diabetic foot ulcer. My colleagues and I in 1993 as well as Reiber et al in 1998 published data showing that diabetic foot ulcers precede lower extremity amputation in 85% of patients. If a diabetic undergoes a below-knee amputation, the 2-year mortality is 36%.

Frey: How safe are the surgical options for the obese patient, such as the lap-band procedure and should we suggest any procedure to the severely obese patient before performing a total joint replacement?

Ahad and Oelschlager: Laparoscopic adjustable gastric band (LAGB) is very popular bariatric operation both in the United States and worldwide. It has an effective, safe profile in addition to being adjustable and removable if needed. Studies have reported 40% to 60% excess weight loss at 3 to 5 years after LAGB placement. The mortality rate reported ranges from 0% to 0.51%. Major complications are uncommon and include band slippage, 2.3% to 12.5%; erosion 0.1% to 2.8%; port complications; and stoma obstruction, 0.2% to 1.6%.

The resultant weight loss is associated with remission of type 2 diabetes, improvement in dyslipidemia, lower blood pressure, resolution or improvement in sleep apnea, improved fertility, and improvements in other aspects of quality of life.

Obesity is considered to be a mechanical risk factor for OA with the knee joints especially susceptible. There is evidence in the literature that supports a correlation between obesity and complications after joint replacement surgery including being a specific risk factor for joint infection. The increased morbidity seen in obese patients undergoing weight-loss surgery therefore calls for attempts at weight reduction prior to undergoing joint replacement surgery. However preoperative weight reduction through increased physical activity is difficult to achieve in patients who are already limited by pain and joint mobility.

Additionally traditional methods of weight loss through dietary restrictions are slow and frustrating for patients. These patients can therefore benefit from bariatric procedure performed prior to undergoing a joint replacement surgery. One study reported on 20 hip and knee arthroplasties in patients after undergoing bariatric surgery first. The cumulative Knee Society score improved from a mean of 103.6 to 148.9 while the Harris hip score increased to 67.5 from 40 preoperatively.

Bray: In experienced hands the laparoscopic bariatric procedures carry low risk. If the patient falls into a category where this is a consideration, they should consult an institution that has a skilled bariatric surgical team.

Frey: How far should an orthopedic surgeon go in treating obesity in a patient?

Bray: Since most orthopedic surgeons are not trained in managing weight problems, my advice would be that they refer patients who need help to an endocrinologist or internist.

Pinzur: The orthopedist has several responsibilities. These include:

• A simple explanation that their obesity impacts on their medical/orthopedic problem and that weight loss might provide a reduction or elimination of symptoms. This should be accomplished without admonishing or embarrassing the patient.
• Patients should be advised to discuss these issues with their primary care physician in order to establish a safe treatment strategy.
• If weight loss is not an option, surgery should be addressed, with the understanding that the outcomes might not be as favorable and the risk of perioperative morbidity is likely increased.

Frey: Is OA simply a result of increased biomechanical stress on the joints?

Bray: The presence of OA in the hands as well as knees and feet of overweight people suggests a more complex problem to which wear and tear are adding. Weight loss will benefit OA in all locations, so this would clearly be the course of action, even though we don’t fully understand the relation of weight to the OA, particularly in the hands.

Pinzur: No. As we all know, there are a lot of thin people with OA, as well as morbidly obese individuals with no evidence of it. I think morbid obesity is a mechanical factor that can negatively impact on abnormal biomechanical structures.

Nonobese individuals are more able to tolerate minor abnormalities, while morbidly obese individuals will see longitudinal progression of deformity and degeneration of the mechanical structures.

Frey: The American College of Rheumatology recommends the nonpharmacologic treatment of OA to include patient education and weight loss. Does weight loss help because it takes some load off of the joints or because it may have some effect on the systemic underpinnings of OA?

Pinzur: I keep going back to diabetes, because the evidence is available in diabetes associated morbidity. The longitudinal care of the diabetic foot involves patient education and therapeutic footwear. Obese patients cannot get access to see their feet, so they often have significant delays in the awareness of foot wounds or infections. Therapeutic footwear used to protect diabetic feet, and avoid ulcers and amputations, are predicated on the use of cushioned pressure-dissipating materials. Since the presence of obesity impairs the mechanical properties of these very durable materials, I would suspect that it would do the same to biologic tissue.

It appears to be simple common sense that the applied forces to cartilage and bony deformities are increased with obesity. At the same time, orthotic efforts to support or accommodate these deformities are greatly impaired in the presence of obesity.

Frey: Outcomes data support the significant positive effect of weight loss in obese patients with OA. A Framingham Knee OA Study found that older women who lost about 5 kg decreased their risk of OA by 50%. Another study found that obese woman decreased their symptoms of OA in direct proportion to the amount of weight lost.

Frey: Do overweight patients have poorer outcomes related to quality of life and satisfaction with surgery than normal-weight patients?

Pinzur: Yes. Morbidly obese individuals are functionally restricted without the presence of deformity. Once you add deformity, the disability and functional limitation is exponentially increased.

Frey: What is new for the treatment of obesity?

Ahad and Oelschlager: Sleeve gastrectomy is another restrictive procedure used to decrease the size of the stomach. Excess weight loss is reported to be around 50% at 1 year. Advantages include reduced risk of malabsorption and no dumping.

Gastric pacing is not available outside trials in United States. It is thought that it alters the level of ghrelin and therefore mimics satiety.

Rimonabant (approved in Europe only) is a CB1 receptor blocker, and works as an appetite suppressant. Side effects occur in 6% of patients treated and include depression, anxiety, agitation and irritability.

Bray: We would all like to see agents that will produce more weight loss. However, we should remember that the current treatments of diet, exercise, lifestyle changes and medications can all delay the onset of major health problems with only modest weight loss of 5% or more. Thus we should look on the positive side of what we can do for patients until the day comes when we can do more.

Frey: Dr. Pinzur, are there any other points that your research has shown that might help the orthopedic surgeon manage the obese patient?

Pinzur: Obesity compounds the disability of musculoskeletal disease and limits the patient’s potential to participate in weight-loss programs that will enhance their functional outcomes.

Correcting deformity in a morbidly obese individual will allow that individual to participate in exercise programs to help them lose weight.

While not always true, certain obese individuals will lose an appreciable amount of weight following correction of deformity. This is accomplished by their new found ability to participate in aerobic weight loss programs.

For more information:

• Sajida Ahad, MD, and Brant K. Oelschlager, MD, can be reached at University of Washington, 1959 NE Pacific St., Box 356410, Seattle, WA 98195; 206-543-3518; e-mail: sahad@siumed.edu or brant@u.washington.edu.
• George A. Bray, MD, can be reached at 6400 Perkins Road, Baton Rouge, LA 70808; 225-763-2500; e-mail: George.Bray@pbrc.edu.
• Carol Frey, MD, can be reached at 1200 Rosecrans Ave., Suite. 208, Manhattan Beach, CA 90266; 310-990-5253; e-mail: footfreymd@aol.com.
• Michael S. Pinzur, MD, can be reached at Loyola University Health System, 2160 South First Ave., Maywood, Illinois 60153; 708-216-4993; e-mail: mpinzu1@lumc.edu.

References:

• Pinzur, MS, Freeland, R, Juknelis, D. The Association between Body Mass Index and Diabetic Foot Disorders. Foot Ankle Int. 2005;26: 375-377.
• Pinzur, MS, Gottschalk, F, Smith, D, et al. Functional Outcome of Below-Knee Amputation in Peripheral Vascular Insufficiency. Clin Orthop Relat Res. 1993;286:247-249.
• Pinzur, MS. Neutral Ring Fixation for High Risk Non-Plantigrade Charcot Midfoot Deformity. Foot Ankle Int. 2007;28:961-966.
• Reiber, GE, Lipsky, BA, Gibbons, GW. The Burden of Diabetic Foot Ulcers. Am. J. Surg. 1998;176:5S-10S.