A Review Paper A Bariatric Surgery Primer for Orthopedic Surgeons Jessica G. Kingsberg, MD, Alan A. Halpern, MD, and Brian C. Hill, MD of the pathophysiology associated with bariatric surgery can Abstract assist orthopedic surgeons in optimizing medical and surgical Increasing numbers of patients who have undergone management of patients’ musculoskeletal issues. bariatric surgery are now presenting to orthopedic sur- geons for elective arthroplasties. In addition, orthope- Bariatric Surgery dic surgeons themselves are referring more patients Surgically induced weight loss works by reducing quantity of for consideration of bariatric surgery in anticipation of food consumed and absorption of calories. Jejunoileal bypass, future elective procedures. Although the full effects one of the first procedures used, significantly decreased the of bariatric surgery on metabolism are not yet known, absorptive area for nutrients, which led to complications such 4 the altered digestion associated with these surgeries as diarrhea, cirrhosis, and nephrolithiasis. This surgery is no poses several issues for orthopedic surgeons. longer performed, and current procedures try to minimize 5 In this article, we address 3 aspects of care of this the risks of malabsorption. class of patient: review of the most commonly per- The 2 types of bariatric surgeries now available in the Unit- formed procedures and their metabolic consequenc- ed States are gastroplasty and gastric bypass, both of which 6 es; suggested preoperative assessment of bariatric are performed laparoscopically. Gastroplasties are purely re- patients for any conditions that should be corrected strictive procedures, which reduce stomach volume. In gastric before surgery; and evaluation of outcomes of elective banding, the most common gastroplasty, a silicone band is procedures performed after bariatric surgery.AJO Aware- placed around the proximal stomach to create a 15-mL pouch ness of the unique characteristics of this group of pa- in the cardia. Sleeve gastrectomy also reduces stomach vol- tients helps minimize the potential for complications of ume, to about 25%, by stapling along the greater curvature. In both procedures, consumed calories are restricted, but the planned orthopedic surgeries. gastrointestinal tract is left in continuity, and essential nutri- ents are properly absorbed.7 However, failure rates are higher, and weight loss more variable, than with gastric bypass pro- n estimated 220,000 bariatric surgeries are per- cedures.8 formed annually in the United States and Canada, Gastric bypass uses both restriction and malabsorption to ADOand 344,221 procedures NOT worldwide.1 Not only are increase weightCOPY loss.7 A gastric pouch (15-30 mL) is created orthopedic surgeons seeing more patients who have had bar- by stapling across the cardia of the stomach. The jejunum is iatric surgery, they are also referring morbidly obese patients then divided, and the distal portion of the divided jejunum to bariatric surgeons before elective procedures.2 Patients with anastomosed to the small proximal stomach pouch. This cre- body mass index (BMI) over 40 kg/m2 are candidates for sur- ates the roux limb where food passes. The duodenum is ex- gical treatment of obesity. Comorbid conditions directly re- cluded, and the proximal portion of the jejunum is attached to lated to obesity, including diabetes, respiratory insufficiency, the roux limb to provide a conduit for biliary and pancreatic and pseudotumor cerebri, decrease the BMI of eligibility to digestive secretions. Weight loss is caused by both reduction 35 kg/m2. Other considerations are failure of nonsurgical in stomach size and malabsorption of calories owing to the weight-loss methods, such as dietary programs for weight diversion of digestive enzymes and the decrease in absorptive reduction, behavioral modification programs, and phar- surface area. Only 28% of ingested fat and 57% of ingested macotherapy. Patients’ psychological stability is extremely protein are absorbed9 (Table 1). important given the rigorous dietary changes required after surgery.3 Although weight-loss surgery can eliminate many Metabolic Consequences of the complications of obesity, bariatric patients even with Nutrient deficiencies are seen more often in the malabsorp- weight loss have increased operative and postoperative risks, tive procedures; however, patients with restrictive procedures likely because of alterations in nutrient absorption. Knowledge may have poor eating habits and are therefore also at risk.10 Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article. www.amjorthopedics.com January 2016 The American Journal of Orthopedics® E1 A Bariatric Surgery Primer for Orthopedic Surgeons In fact, many patients have nutritional deficiencies predating dures because of decreased dietary intake from intolerance. their bariatric surgery, as obesity creates a chronic inflamma- Malabsorptive procedures also decrease pepsinogen secretion tory state that leads to anemia of chronic disease. Schweiger and reduce the intestinal absorption surface. and colleagues11 assessed the nutritional status of bariatric sur- gery candidates and noted a high incidence of iron and folic Considerations for Orthopedic Surgeons acid deficiencies with corresponding anemia. They concluded Wound Healing these deficiencies stemmed from calorie-dense diets high in Much of our knowledge of the effects of bariatric surgery on carbohydrates and fats. Although patients may improve their skin and wound healing has been gleaned from samples ob- diet after surgery with concomitant nutritional counseling, tained from patients during abdominoplasty or other body- deficiencies in iron, calcium, vitamin 12B , folate, and vitamin contouring procedures. These samples have all shown a decrease D are common12 (Table 2). in hydroxyproline, the major constituent of collagen and the Iron deficiency continues after bariatric surgery because main factor in determining the tensile strength of a wound.19 dietary iron must be converted to its absorbable form by hy- D’Ettorre and colleagues20 performed biopsies of abdominal drochloric acid secreted from the stomach. As stomach vol- Table 1. Weight-Loss Surgery Options ume is reduced, there is a cor- responding decrease in acid Restrictive Malabsorptive secretion. The result is that Options Gastric banding Roux-en-Y iron deficiency occurs in both Gastrectomy restrictive and malabsorptive procedures.13 Moreover, with Mechanisms Decreases size of stomach Decreases size of stomach the diversion from the duo- Decreases area of absorption denum and the proximal je- Amount of weight loss expected Unpredictable Predictable junum in bypass surgery, the main areas of absorption are Advantages Easier to reverse More weight loss Decreased risk of metabolic deficiency excluded.10 Patients may re- quire intravenous therapy for Nutrient deficiencies Rare Common iron-deficiency anemia—or AJO oral supplementation com- bined with ascorbic acid to increase stomach acidity. Table 2. Comparison of Gastroplasty and Gastric As calcium is absorbed mainly in the duodenum and the Bypass Procedures jejunum, patients who undergo malabsorptive procedures can Gastroplasty Gastric Bypass absorb only 20% of the amount ingested.14 Restrictive pro- cedures do not have the same effect on calcium absorption; Type Restrictive Malabsorptive however, patients may have reduced dietary lactose intake and Metabolic deficiencies Iron Iron be at risk for deficiency. Vitamin B12 Vitamin B12 DOA study by Ducloux and colleaguesNOT15 found that 96% of COPYProtein Protein bariatric surgery patients had vitamin D deficiency before the Calcium procedure. After malabsorptive procedures, the decrease in Vitamin D bile salts leads to an inability to break down fat-soluble vi- Orthopedic complications Wound healing Wound healing tamins and to uncoordinated mixing of food and bile secre- Osteopenia tions.16 Restrictive procedures do not carry this risk, though many patients still require supplementation because of their underlying deficiency. skin before and after biliopancreatic diversion and noted that The decrease in stomach size causes a decrease in intrinsic tissue proteins, including hydroxyproline, were significantly factor from parietal cells, with subsequent inability to appro- reduced. Histologic examination revealed disorganized dermal priately transport vitamin B12. Exclusion of the duodenum elastic and collagen fibers. In addition, all patients involved in also eliminates the site of absorption; therefore, B12 should the study had wound-healing problems, with delayed healing be replaced orally.11 Megaloblastic anemia is a rarely reported of 25 days, compared with 12 days in nonbariatric patients. 17,18 sequela. Folate deficiency is less common because it can Deficiencies in vitamins B12, D, and E, as well as folate and total take place in the entire intestine after surgery, even though tissue protein, were implicated as causative factors. absorption occurs primarily in the proximal portion of the small intestine.10 Effects on Bone Protein deficiency can result in loss of muscle mass and Malabsorptive procedures decrease bone mineral density subsequent muscle weakness, edema, and anomalies of the (BMD) through their effects on calcium and vitamin D. BMD skin, mucosa, and nails.12 It is seen after both types of proce- is also decreased because these procedures lower levels of E2 The American Journal of Orthopedics® January 2016