Obesity Treatment in Orthopaedic Surgery : JAAOS - Journal of the American Academy of Orthopaedic Surgeons

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Reviews: Review Article

Obesity Treatment in Orthopaedic Surgery

Carreira, Dominic MD; Robison, J. Weston MD; Robison, Susannah RDN, LD; Fitch, Angela MD, FACP, FOMA

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Journal of the American Academy of Orthopaedic Surgeons 30(24):p e1563-e1570, December 15, 2022. | DOI: 10.5435/JAAOS-D-21-01083

Abstract

According to the World Health Organization, obesity is a global health epidemic, which has nearly tripled in prevalence since 1975. Worldwide in 2016, 13% of adults 18 years and older had obesity (body mass index [BMI] ≥ 30 kg/m2) and 39% were overweight (BMI 25.0 to 29.9 kg/m2). In the United States, approximately 35% of adults have obesity and 31% are overweight.1 BMI is a person's weight in kilograms (or pounds) divided by the square of height in meters (or feet). Obesity increases stress throughout the musculoskeletal system and carries a higher risk for the development of osteoarthritis and various other musculoskeletal conditions. Sarcopenic obesity is associated with an increased risk of all-cause mortality, new-onset depression, gastric cancer, insulin resistance, vitamin D deficiency, and inflammation.2 Treatment of sarcopenic obesity includes strength training exercise programs. When patients with obesity undergo orthopaedic procedures, weight loss is a critical aspect to appropriate preoperative counseling and treatment. Weight loss can improve obesity-related comorbidities such as metabolic syndrome, diabetes, cardiovascular disease, and obstructive sleep apnea, which in turn may reduce complications, minimize long-term joint stress, and improve outcomes among patients undergoing orthopaedic procedures.3 The effects of obesity on patients undergoing total joint arthroplasty has been previously described, with reported associations of increased risk of infection, revision, blood loss, venous thromboembolism, and overall costs.2 When initiating care for patients with obesity, surgeons should involve primary care practitioners and refer patients to registered dietitians and other weight loss specialists in an attempt to optimize BMI before scheduling surgery.

The purpose of this article was to provide orthopaedic surgeons with strategies for obesity treatment. The following sections will highlight nutritional quality, caloric reduction, exercise, bariatric surgery, pharmacotherapy, lifestyle, genetics, weight gain prevention, postoperative weight management, endocrine, and orthopaedic outcomes as they relate to weight reduction and obesity treatment. Where indicated, we have provided take away points and action items that will allow orthopaedic surgeons to more easily implement these findings into their practice. In addition, we have created a patient handout that summarizes these points, which is included in the Supplementary Data File, https://links.lww.com/JAAOS/A844.

Nutritional Quality

Although the concept that calories consumed must be lower than calories expended to achieve weight loss is accurate, not all calories are equal in nutritional quality. A study that included over 120,000 participants and spanned over 20 years found weight gain to be associated with increased consumption of lower quality foods such as potato chips, potatoes, sugar-sweetened beverages, unprocessed red meats, and processed red meats. Contrarily, weight loss occurred with increased consumption of high-quality foods such as vegetables, whole grains, fruits, nuts, and yogurt.4 Hall et al in 2019 showed that ultra-processed diets cause excess calorie intake and weight gain in a pivotal inpatient randomized controlled trial of ad libitum food intake.

The Harvard Schools of Public Health and Medicine developed the Healthy Eating Plate to provide the healthiest choices in various food groups. Half of a meal should be composed of nonstarchy vegetables and fruits. Examples of nonstarchy vegetables include asparagus, broccoli, Brussels sprouts, cabbage, cucumbers, peppers, spinach, and squash. One-fourth of the plate should contain whole grains such as brown rice, wild rice, quinoa, and oats. The remaining fourth should include lean proteins such as fish and poultry while limiting intake of red meats high in saturated fat. Healthy oils such as avocado oil and olive oil may be used in moderation. Sugar-sweetened beverages should be avoided.

Nutritional quality in the setting of weight loss may be beneficial to orthopaedic surgery for appropriate protein and other macronutrient intake. Previous studies have shown albumin <3.5 g/dL, total lymphocyte count <1,500 cells/mm3, and/or transferrin level <200 mg/dL to be serum markers of malnutrition and risk factors of wound complications, including surgical site infections.5-7 Nutritional quality is an especially important consideration in patients who are restricting calories to optimize weight reduction before surgery to ensure their macronutrient needs are being met. Despite this link between malnutrition and morbidity after orthopaedic surgery, to the best of our knowledge, there has not been a study to clearly demonstrate that nutritional quality leads to improved outcomes in orthopaedic surgery specifically.

Take Away

Weight loss is promoted through diets rich in vegetables, fruits, lean proteins, and whole grains. When visualizing a plate, half of the plate should be composed of nonstarchy vegetables. The remainder of the plate should be split equally to contain a lean protein source and a whole grain food item.

Action Items

Copies of the Healthy Eating Plate should be available to provide patients a tangible visual to follow. The handout included in the Supplementary Data File, https://links.lww.com/JAAOS/A844, includes a copy with a QR code link.

Caloric Reduction

Caloric restriction is defined as the reduction of daily calorie intake below what is typical for an individual. A well-balanced, calorie-restricted diet is the most commonly prescribed method for weight loss. Daily calories are decreased to allow for fat stores to be used to meet daily energy requirements. A calorie reduction of 500 to 1,000 kcal from one's typical daily consumption should be adequate to meet this goal. In most cases, this equates to an allowance of 1,200 to 1800 kcal daily. The general guideline for caloric restriction is to obtain 50% to 55% of total kcals from carbohydrates, 15% to 25% of total kcals from protein, and no more than 30% of total kcals from fat. However, calorie-restricted diets should be individualized, and vitamin and mineral supplements are typically recommended with caloric restrictions of 1,200 kcal per day for women or 1800 kcal per day for men.8 Consulting with a registered dietitian in the presence of other disease states may be warranted.

Take Away

A well-balanced, calorie-restricted diet is the most commonly prescribed method for weight loss. A calorie reduction of 500 to 1,000 kcals from one's typical daily consumption should be adequate for fat stores to be used in meeting daily energy requirements. This typically equates to a total daily calorie allowance of 1,200 to 1800 kcals.

Action Items

A referral list of local dietitians or nutritionists should be provided to patients with complex medical comorbidities or to those who are interested in best strategizing their dietary changes and weight loss goals. There are a number of smartphone applications that can be used to assist with tracking macronutrients and total caloric intake; these are provided in the handout in the Supplementary Data File, https://links.lww.com/JAAOS/A844.

Exercise

Many patients understand the role of regular exercise for their overall health, and physical activity may play an important role in a weight reduction program. Patients seeking to begin an exercise program may feel overwhelmed by the many options that exist to exercise (gym memberships or popular group fitness classes such as Orangetheory, CrossFit, or Pure Barre). A randomized trial that compared the effects of aerobic exercise with resistance training on total body mass and fat mass in overweight individuals or individuals with obesity found that those individuals who engaged in aerobic exercise reduced total body and fat mass more than those who participated in resistance training alone while those who participated in resistance training increased lean body mass more than those who engaged in aerobic training alone.9 The STRRIDE study demonstrated that an increased amount and intensity of aerobic exercises correlated with the prevention or reduction of visceral and subcutaneous abdominal fat.10 Other studies also have supported the dose-response relation between aerobic exercises and visceral fat reduction. Aquatic exercise programs, such as aquatic jogging or water aerobics, offer a low-impact alternative that patients with joint pain or reduced mobility may find more feasible than walking or jogging on land. Aquatic jogging programs can reduce body fat mass and waist circumference. Aerobic exercises in water is equivalent to aerobic exercises on land regarding body composition assuming that similar duration, intensity, and frequency are used.11 A web-based search of “aquatic physical therapy near me” will typically result in a list of providers in the area.

Patients should be educated that exercise programs that include aerobic activity, regardless of the specific type, will likely improve the chances of long-term weight maintenance. However, although exercise has many positive benefits, the extent of its contribution to weight loss is much less than that of nutritional interventions, with a more important role of weight maintenance. The exercise should be realistically done at least four or five days weekly; consistency is crucial for achieving and maintaining weight loss goals. Most individuals may be able to achieve weight reduction with as little as 30 minutes of walking a day when combined with changes in dietary intake.10

The benefits of exercise go beyond weight reduction. Although there is no literature to the best of our knowledge that directly demonstrates the benefit of exercise as a means for weight loss on outcomes after orthopaedic procedures specifically, exercise remains an important adjunct to dietary changes in weight reduction and weight maintenance strategies for many patients because exercising has positive metabolic effects that extend beyond weight loss alone. For example, many patients with obesity have comorbidities including type 2 diabetes mellitus because those with BMI >35 kg/m2 are 20 times more likely to develop diabetes than those with a BMI between 18.5 and 24.9 kg/m2.12 In patients with obesity and type 2 diabetes, both aerobic exercise and resistance training programs can improve insulin sensitivity and reduce HbA1c.13,14 Additional studies have demonstrated a dose-response relationship between exercise and reduction of central obesity, which is related to metabolic comorbidities often encountered in patients with obesity (ie, cardiovascular disease, diabetes, hypertension).10 One might infer that a link exists between these metabolic improvements and outcomes after orthopaedic procedures. Additional study is needed to compare the various means of weight loss (ie, dietary changes, exercise) in the setting of outcomes after orthopaedic procedures. Possibly, not all vehicles to weight loss are equivalent means to the same end.

In summary, patients should pick an activity that they find tolerable and can complete consistently; for some that may be as simple as walking 30 minutes 5 days per week.

Take Away

Consistent exercise is a beneficial addition to a restricted calorie diet for weight loss and overall health. Aquatic exercise programs, aerobics, and resistance training are all beneficial.

Bariatric Surgery

Bariatric surgery is a viable option for patients with obesity who qualify because of the severity of their disease. According to the American Society for Metabolic and Bariatric Surgery, approximately 256,000 bariatric surgery procedures were conducted in the United States in 2019, which is an increase from 158,000 in 2011. Bariatric surgery has been the most effective and long-lasting treatment modality for patients with Class 3 obesity (body mass index ≥ 40 kg/m2). Patients typically experience most of their weight loss within one to two years after their bariatric surgery, with maintenance of weight loss leading to improvements in conditions related to obesity, including but not limited to type 2 diabetes, hypertension, heart disease, and sleep apnea.15 A 2004 meta-analysis including 136 primary studies and 22,094 patients found that most bariatric surgery patients experienced improvement, if not complete resolution, of their related comorbidities, as given in Table 1.16

Table 1 - Buchwald et al. (2004) demonstrated most bariatric surgery patients experienced improvement of their related comorbidities
Condition Resolved or Improved Resolved
Hypertension 81.8% 65.6%
Obstructive sleep apnea 80.6% 87.9%
Diabetes mellitus 85.4% 76.8%

In addition, patients can be counseled on the risk reduction of certain neoplasms that follow bariatric surgery in some populations. Studies suggest that bariatric surgery improves cancer outcomes in some patients with obesity, with lower incidences of breast and colorectal cancers in the bariatric surgery cohort.17

Potential candidates should be advised of the safety profile for bariatric surgeries, with 30-day mortality rates of those undergoing laparoscopic Roux-en-Y gastric bypass or laparoscopic adjustable gastric banding at 0.3%, with 4.3% of patients experiencing at least one major adverse outcome.18 The inability to use NSAIDs after some bariatric surgical procedures is a long-term limitation in the management of musculoskeletal conditions because there is an association between gastric bypass surgery and marginal ulcerations. However, with gastric sleeve surgery, there are no apparent NSAID-related complications.19

Bariatric surgery is one way to achieve weight loss in patients with morbid obesity who have failed conservative measures. Patients with obesity have been referred for bariatric surgery to meet preoperative BMI parameters (ie, BMI < 40 mg/kg2 before TKA) in hopes of reducing the perioperative risks associated with obesity. However, conflicting evidence exists surrounding preoperative bariatric surgery for weight reduction and postoperative complications in orthopaedic surgery. A recent retrospective cohort demonstrated that those patients who had undergone bariatric surgery before total knee arthroplasty were at increased risk of mortality, pneumonia, and implant failure.20 In this particular report, the authors demonstrated that specific complications were more often associated with specific types of bariatric surgery. Another report demonstrated that those who underwent bariatric surgery before lower extremity total joint arthroplasty had shorter surgical time and length of stay, but did not reduce long-term risks of dislocation, periprosthetic infection, periprosthetic fracture, or revision.21 Another report comparing patients with obesity who received bariatric surgery before total joint arthroplasty of the hip or knee demonstrated a reduced comorbidity burden and reduced complication rate, although this did not lead to a reduction in revision rates.22 Other meta-analyses report that bariatric surgery before hip or knee arthroplasty does not markedly reduce perioperative complications or improve clinical outcomes.23 Future work is needed to further examine the effects of bariatric surgery on outcomes of orthopaedic procedures.

Take Away

Bariatric surgery is a safe and effective method for weight loss in patients with obesity who qualify because of their disease severity.

Action Items

Patients whose BMI is ≥ 40 kg/m2 who have failed to lose weight with diet and exercise should be counseled on the potential benefits of pursuing bariatric surgery. Referral to bariatric surgery is recommended.

Pharmacotherapy

Multiple pharmacotherapeutic options exist for patients desiring weight reduction. Body weight regulation is a complex, multifaceted balance of factors including energy intake, energy expenditure, genetics, environment, and culture. Pharmacotherapeutics typically aim to alter one of three mechanisms of weight regulation: energy intake, nutrient handling, and energy expenditure. Antiobesity medications have been recommended for patients with BMI ≥ 30 kg/m2 or those with BMI ≥ 27 kg/m2 with concomitant obesity-related risk factors or comorbidities, such as type 2 diabetes mellitus, hypertension, hyperlipidemia, coronary heart disease, and sleep apnea.24

Historically, antiobesity medications have had a questionable past track record, with multiple drugs being pulled from the market by the US Food and Drug Administration in the 1990s because of cardiovascular toxicities. One of the more infamous medications that were ultimately removed from the market was ephedra (ma-huang). In addition, the efficacy of many of the available medications has been questioned. A 2005 meta-analysis examining the pharmacologic treatment of obesity demonstrated that the amount of extra weight loss associated with the medications under review was modest, with an average loss of <5 kg at 1 year.25

Weight reduction as small as 5% of body weight can markedly influence obesity-related risk factors such as type 2 diabetes, hypertension, and others. Combination therapy with phentermine and topiramate is the most commonly prescribed antiobesity medication (brand name Qsymia©). This combination therapy demonstrated that 67% were able to lose 5% of their weight versus 17% in the placebo group and 47% of patients were able to lose 10% of their weight versus 7% in the placebo group.26 Other common appetite suppressant medications (anoretic agents) include phentermine, diethylpropion, and topiramate. One of the most studied absorption-altering drugs is orlistat, which promotes weight loss by inhibiting lipase to prevent fat absorption.27

More recent studies show increasing promise for more successful obesity treatment. The STEP 1 trial in NEJM demonstrated that overweight patients or patients with obesity who were treated with weekly subcutaneous semaglutide injections combined with lifestyle modifications lost markedly more weight than those treated with placebo and lifestyle changes alone—with mild-to-moderate adverse effects that were transient.28 In this pivotal study, participants who received semaglutide experienced a mean change in body weight of −14.9% compared with −2.4% in the control group. In addition, these patients had greater improvements in cardiometabolic risk factors and patient-reported physical functioning from baseline than those who received the placebo.28 The FDA has recently approved semaglutide as an antiobesity drug in adults when used in combination with lifestyle changes. Patients should be counseled to consult with their primary care physician to determine what medication profile best suits their needs.

Take away: Although pharmacotherapeutics have historically had questionable efficacy and tolerance profiles, recent studies are promising. Patients should be referred to their primary care physician or an obesity medicine specialist for recommendations.

Action items: Patients should be informed that despite questionable track records of older weight loss medications, newer medications are now available that have proven to be effective adjuncts to weight loss. They should inquire about these medications at their visit with their primary care provider or endocrinologist.

Lifestyle

Long-term lifestyle changes are often needed to initiate and maintain weight loss for many patients; however, initiating long-term changes to activity and eating behavior can be quite difficult. Regarding weight loss monitoring, studies have shown that daily self-weighing improves weight loss and adoption of weight control behaviors, with higher frequency associated with greater weight loss.29

Comprehensive lifestyle modification programs in groups have been effective at achieving and maintaining weight loss. These group therapies typically involve weekly meetings for the first 6 months, followed by meetings every two weeks for the second 6 months, with registered dietitians, psychologists, exercise specialists, and other health professionals. Group sessions can be more effective and less expensive than individual sessions. These sessions are designed to give participants the motivation to maintain weight control behaviors, such as consistent exercise, caloric reduction with periodic food intake recording, and weight loss monitoring. These behaviors mirror those practiced by participants in the National Weight Control Registry.30 With advances in technology, patients may stay connected with their peers through applications on their smartphones and tablets that are designed to promote social interaction and accountability.

Take Away

Lifestyle modifications along with community support are effective, especially when elements of inspiration and accountability are incorporated.

Genetics

The development of obesity also has a genetic component. An international study of 53 pairs of monozygotic twins demonstrated that 50 to 70% variance in the body mass index is attributable to genetic differences.31 Although rare monogenic forms of obesity exist, most often obesity results from a polygenic component combined with environmental factors.32 A recent genome-wide association study (GWAS) of approximately 700,000 individuals of European ancestry revealed 941 single nucleotide polymorphisms (SNPs) associated with body mass index. Multiple studies have linked the FTO gene as a main contributor to obesity in the European population.32

Although consistency and adherence to lifestyle modification is a major determinant of successful weight loss, there is some variability between individuals in weight loss response, with genetics serving as a factor.

Weight Gain Prevention

Unfortunately, it is common for individuals who have successfully met their weight loss goals to regain the lost weight. Caloric requirements for weight maintenance after weight reduction are approximately 25% lower than the original weight. The National Weight Control Registry (NWCR) was developed to determine key factors in successful long-term weight loss. The NWCR currently tracks over 10,000 individuals who have lost notable weight over the long term. In general, the NWCR participants have reported eating breakfast every day, assessing weight at least once per week, watching less than 10 hours of television per week, and exercising an average of 1 hour per day. The chances of long-term success in weight maintenance increase after individuals have been able to maintain weight loss for 2 to 5 years.30 The addition of pharmacotherapy to lifestyle changes increases successful weight maintenance when the pharmacotherapy is continued. Like any chronic disease with multiple causes, long-term treatment with medication often is warranted.

Take Away

The following habits have helped promote weight maintenance: eating breakfast daily, weighing in at least weekly, watching television less than 10 hours per week, and exercising an average of 1 hour daily. Addition of pharmacotherapy to lifestyle behaviors improves weight maintenance.

Action Items

Patients should be provided information on the National Weight Control Registry program so that they can read about others’ success stories and join if interested. The link to the website is attached with the handout in the Supplementary Data File, https://links.lww.com/JAAOS/A844.

Postoperative Weight Management

Although many patients may hope to lose weight after improving their mobility postoperatively, several studies have demonstrated this weight loss not to occur. There have been several studies examining patient factors on postoperative weight change.33,34 Ast et al33 reported in their review of 3,893 total hip arthroplasties and 3,036 total knee arthroplasties that most patients maintained their body mass index after their surgeries. In their review, female sex, greater BMI, and total knee arthroplasty were significant predictors of weight loss postoperatively (P < 0.05). In addition, a higher preoperative functional level was significantly associated with a lower likelihood of weight gain at two-year follow-up (P < 0.05).34 These findings are consistent with other studies of joint arthroplasty surgery, with lower preoperative BMI and young age being associated with weight gain postoperatively.34 In addition, it has been reported that female patients are more likely to lose weight postoperatively. Most patients with obesity do not lose weight after hip or knee arthroplasty, which reinforces the need for preoperative counseling and weight reduction strategic planning.

Action items: Based on total hip and knee arthroplasty outcomes related to weight loss, patients should be educated that although it is possible to lose weight after surgery, studies have shown that many patients do not lose weight afterward. This information may help patients develop appropriate expectations and strategies for weight loss before and after surgery.

Endocrine

A number of endocrine abnormalities exist that are associated with obesity. Type 2 diabetes, thyroid disease, polycystic ovarian disease (PCOS), fatty liver disease, and hypogonadism in men (low testosterone) are all associated with obesity. In patients with obesity and type 2 diabetes, providers may consider limiting weight-promoting medications such as insulin and sulfonylureas and replacing them with weight loss–promoting medications such as GLP-1, SGLT-2, and metformin.35 Patients with obesity should be screened for thyroid abnormalities so that deficiency can be replaced to normal levels. Although thyroid hormone replacement has not shown any consistent weight loss benefit, it is reasonable that hormone replacement therapies may enhance patients' energy and mood. Patients with improved energy and mood may be more likely to adhere to lifestyle changes, resulting in weight loss over time. PCOS is diagnosed clinically, and treating PCOS does not typically result in weight loss.36 Although these obesity-associated endocrine abnormalities may warrant personalized treatment modalities from endocrine specialists, none of the specialized treatments have been proven to be superior to treating the obesity through medication, surgery, diet, and lifestyle changes. Patients should be referred to their primary care physicians or endocrine specialists for optimized, specialized treatment modalities geared toward their specific condition; however, fundamentally, their obesity must be addressed first and foremost.

Take Away

While endocrinopathies should be noted and optimized, treatment remains best directed toward obesity itself.

Orthopaedic Outcomes

Obesity is associated with several medical comorbidities, including diabetes, pulmonary disease, cardiovascular disease, and obstructive sleep apnea. These comorbidities place patients with obesity at an increased risk of perioperative complications, including venous thromboembolism, pulmonary embolism, and surgical site infection.2 Biomechanical analysis work has shown that obesity can result in higher THA dislocation rates.37 Uncontrolled diabetes has been shown to increase risk of surgical site infection. In a retrospective review of 6,108 patients who underwent primary hip or knee arthroplasty and those with BMI > 50 were 21 times more likely to develop a deep infection postoperatively.38 Although the common comorbidities of obesity account for many of the perioperative risk factors, simple obesity in the absence of other comorbidities has been demonstrated to be an independent risk factor of venous thromboembolism and pulmonary embolism. As such, it is recommended that chemical and/or mechanical DVT prophylaxis be used in these patients.39

Implant survivorship at 5 years after TKA is markedly reduced in patients with Class 3 obesity compared with patients without obesity.40 Consequently, some authors suggested that total hip or knee arthroplasty in patients with BMI ≥ 40 should consider being delayed until some weight loss has been achieved.40 However, multiple studies have demonstrated that overweight individuals and individuals with obesity have similar clinical outcomes after total hip and knee arthroplasty.40

The effect of obesity on outcomes in patients undergoing orthopaedic procedures has been well described. However, there is no evidence to support an optimal preoperative duration for nonsurgical weight reduction strategies before orthopaedic surgery. In addition, there is limited literature supporting a minimum amount of clinically meaningful weight reduction to optimize outcomes after orthopaedic procedures. A retrospective review demonstrated that patients with BMI > 40 kg/m2 who lost ≥ 20 pounds before TKA were associated with shorter length of stay and fewer discharges to a facility, but not in those who lost five or 10 pounds.41 However, the literature remains somewhat ambiguous regarding preoperative weight reduction on postoperative outcomes after orthopaedic procedures. Literature exists demonstrating an “obesity paradox” in joint arthroplasty, whereby patients with obesity have lower mortality and/or complications after these procedures.42,43 There are also reports supporting the notion that notable preoperative weight reduction can result in postoperative rebound weight gain and inferior outcomes after orthopaedic procedures.44,45 Additional research in this area is needed to help direct patients establish realistic goals.

Conclusion

Obesity is a complex, multifaceted disease with high prevalence. This review should not be considered exhaustive but rather is intended to provide busy orthopaedic surgeons with an updated review of the current best literature on how to best help treat their population of patients who are overweight or have obesity.

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