➢ Malnutrition is common in orthopaedic patients and can have negative effects on outcomes, as studied in the hip fracture and arthroplasty population.
➢ Malnutrition can be stratified according to etiology (i.e., chronic disease, acute injury or illness, and starvation).
➢ History-taking and physical examination, combined with simple laboratory tests such as a complete blood cell count with differential, prealbumin, albumin, and transferrin, can help aid in the diagnosis.
➢ A multidisciplinary approach may help provide the best nutritional interventions for orthopaedic patients.
➢ Malnutrition is not limited to cachectic patients only: obese patients may also be malnourished and benefit from nutritional interventions.
Malnutrition in orthopaedic patients, a condition that is overlooked and understudied, has substantial effects on outcomes1-6. Underweight and malnourished elderly patients are at risk of experiencing reduced well-being and autonomy as well as increased mortality as compared with their counterparts of normal weight7. Malnutrition may be simply defined as an imbalance of energy, protein, and nutrients leading to functional and compositional adverse effects on the body8,9. By this definition, as much as 15% of ambulatory and 65% of hospitalized patients are malnourished10. Without adequate nutrition, orthopaedic patients are more susceptible to infections, slower healing rates, and sarcopenia (reduced lean body mass and muscle function)8. Stratifying malnutrition on the basis of etiology (e.g., “starvation-related,” “chronic disease-related,” and “acute injury or illness-related”) facilitates the formation of a more clinically relevant definition11. In starvation, the primary problem is reduced intake, possibly due to socioeconomic factors or secondary to anorexia6. With chronic disease and acute injury, increases in resting energy expenditure and protein requirements due to the inflammatory response contribute to malnourishment7.
The new etiology-based approach to the diagnosis of malnutrition recognizes the importance of the inflammatory state on skeletal muscle catabolism that is partially cytokine-mediated12. A well-nourished orthopaedic patient who presents with severe trauma or who is suffering from a postoperative wound infection may develop malnutrition. The acute inflammatory response leads to rapid loss of lean body mass with even greater loss of weight if nutritional intake is poor. In contrast, an inflammatory condition associated with a chronic disease such as diabetes or an underlying kidney injury may cause loss of muscle mass and function over a period of months to years. The response to nutritional intervention is dependent on resolution of the underlying disease. An elderly patient who sustains a hip fracture may suffer from starvation-related malnutrition, often due to suboptimal nutrient intake associated with poor access to food, depression, or social isolation. These patients are commonly diagnosed with acute injury-related malnutrition coupled with preexisting starvation-related malnutrition.
Nutritional Basic Science
Proper nutrition provides adequate substrates for energy metabolism, essential cofactors, signaling molecules, and electrolytes. The basal energy expenditure for an average healthy adult man is approximately 20 kcal/kg/day, amounting to about 1600 kcal/day. Normal daily activity increases this expenditure to 30 to 40 kcal/kg/day, with a resultant total daily energy expenditure of approximately 2400 to 3600 kcal/day. Decreased oral intake due to surgical precautions or the anorexic sequelae of disease combined with the metabolic effects of stress, inflammation, increased catabolism, and decreased anabolism lead to nutritional disorders in surgical patients13.
The effects of inflammatory stress on nutritional requirements cannot be overstated. Inflammation, through an interplay between the central nervous system, endocrine system, and inflammatory mediators, causes systemic responses. The increased release of catecholamine and cortisol promote gluconeogenesis, peripheral lipolysis, and proteolysis to mobilize energy stores. The resulting hypermetabolic state is characterized by increased caloric expenditure, temperature, glucose flux, and protein catabolism, with decreased androgens and growth hormones14. Increases in metabolism correlate to severity of injury; for instance, patients who have sustained multiple fractures, severe infections, or third-degree burns have a greater hypermetabolic change than that experienced by patients in the postoperative period after an elective operation15. A combination of increased metabolic demand and reduced intake places these patients with severe injuries at a very high risk of experiencing malnutrition. A previously well-nourished individual or even an obese patient may suffer rapid loss of lean body mass due to injury, with or without adequate food intake. This situation is frequently overlooked when identification of nutritional risk and assessment of nutritional status are not routinely considered.
Trauma, infection, burn, and surgery induce acute-phase protein production, mainly in the liver (Table I)12. Type-I proteins are induced by interleukin-1 (IL-1)-like cytokines, while Type-II proteins are induced by interleukin-6 (IL-6) and similar cytokines12. Acute-phase proteins restore body homeostasis through individual functions. This increased production of acute-phase proteins exacts a concomitant toll on the body’s nutritional status, resulting in loss of lean body mass.
Malnutrition and Bone Health
Calcium, Phosphorus, and Vitamin D
Nutritional status has profound effects on bone health. The daily calcium requirement for all adults (i.e., age nineteen through fifty) is 1000 mg16 (Table II). Beginning at the age of fifty-one years in women and seventy-one years in men, the requirement increases to 1200 mg. The intake requirements for vitamin D are more complicated, as they are secondary to dietary intake and synthesis by the skin from exposure to sunlight16. The dietary reference intake of vitamin D for all persons (ages one through seventy years) is 600 International Units (IU)16. At age seventy-one, this increases to 800 IU. Increased dietary protein intake has been associated with increases in both intestinal calcium absorption and calciuria, without any known effect on net calcium balance17.
Vitamin D plays an integral role in the mineralization of bone. Frank deficiency leads to rickets in children and osteomalacia in adults, both characterized by bone pain, proximal muscle weakness, and increased risk of fractures18. However, less pronounced vitamin-D insufficiency is a global problem, with 50% of the North American elderly population and two-thirds of the rest of the world having blood levels of vitamin D that are below the minimum level recommended for bone health (20 ng/mL or 50 nmol/L)19,20. Many experts advocate for a higher level of 30 ng/mL or 75 nmol/L to be used as the standard for sufficiency, of which 70% of the U.S. population falls short20,21. Vitamin D levels below this cutoff have been associated with lower bone density, increased risk of fractures, lower lean body mass in athletes, decreased muscle strength, increased risk of falls in the elderly, and numerous non-orthopaedic health issues20,22,23. A study comparing 448 patients with hip fractures and a control group of 1091 patients, all of whom underwent elective total knee or hip replacement, showed that there was a significantly higher rate of vitamin-D insufficiency (<30 ng/mL) in the patients who had sustained a hip fracture (65.8% versus 54.0%, p < 0.05)24. Except for some fatty fish products, vitamin D amounts are too low in normal foods, and even too low in most fortified foods and over-the-counter supplements to have much population-wide benefit20. Although vitamin D can be formed in the skin by exposure to ultraviolet light, prolonged exposure to sunlight is not recommended because of skin aging and an increased risk of the development of skin cancer20. Currently, 2000 IU or 50 μg of vitamin D per day is considered the upper limit of safe intake, and many experts, including the National Osteoporosis Foundation, recommend aggressive supplementation with at least 800 to 1000 IU daily in patients who are older than fifty years of age and have insufficient levels of vitamin D25.
There are no studies in the literature directly evaluating the role of antioxidants in the nutritional treatment of orthopaedic patients. In the nutrition, surgery, and critical care literature, conflicting data have been reported as favorable versus potential adverse outcomes associated with immune-enhanced diets. The most recent, large-scale international trial of glutamine and antioxidant supplementation of enteral and parenteral nutrition concluded that early provision of these components did not improve outcomes in critically ill patients and that glutamine was associated with increased in-hospital and six-month mortality in patients with multiple-organ failure26. At the current time, addition of antioxidants to nutritional regimens should be approached with caution.
The results from a large cohort study showed that protein intake was inversely related to risk of hip fracture, with the greatest risk reduction in the subjects who were in the highest quartile of daily animal protein intake27. Although some studies report very high protein diets (greater than 2.0 g/kg) combined with low dietary calcium intake (less than 600 mg/day) should be avoided28, a meta-analysis found no detrimental effects of high protein intake on the incidence of hip fracture29. Twenty grams of additional daily protein intake in patients who sustained a hip fracture resulted in improved clinical outcomes and muscle strength, less bone mineral loss on the contralateral femur, and a trend toward fewer vertebral fractures as compared with those in controls in a randomized, double-blinded trial30.
Osteopenia, Osteoporosis, and Osteomalacia
Osteoporosis is defined as low bone mass, deterioration of osseous microarchitecture, and increased bone fragility with risk of fracture31. The clinical definition is a dual x-ray absorptiometry T-score of −2.5 or less in the lumbar spine, entire hip, or femoral neck as compared with the mean score of young women32. Osteoporosis affects nearly 75 million people globally25, and of postmenopausal white women in the U.S., 30% are osteoporotic and 54% are osteopenic33. After the age of eighty years, the incidence of osteoporosis increases to 70% and the incidence of osteopenia decreases to 27%33. Although age is the greatest risk factor for osteoporosis34, nutrition, exercise, and genetics are all important components in its development35-37. No studies to date have related malnutrition to the development of fragility fractures in elderly patients. However, in patients with anorexia nervosa, malnutrition results in decreased peak bone mineral density with an implied increased risk in fragility fractures over time36. Osteomalacia refers to generalized softening of bone, most frequently caused by vitamin-D deficiency and characterized by poorly mineralized bone38.
The impact of osteoporosis on the risk of fracture and subsequent mortality of a patient is striking. The National Osteoporosis Foundation estimates that, in the U.S., half of Caucasian women will experience an osteoporosis-related “fragility fracture” within their lifetime, as will one in five U.S. men25. African Americans and other races in the United States may be at a lower risk of developing osteoporosis, but they have the same fracture risk once they become osteoporotic25. Fragility fractures to the wrist are common and lead to disability and reduced quality of life without influencing mortality, whereas hip fractures are associated with increased risk of death from pulmonary embolisms, pneumonia, cardiac and cerebrovascular events, and deconditioning39. In 1109 patients over the age of sixty-five years who were cognitively intact and ambulatory prior to sustaining a nonpathologic hip fracture, the mortality rate was 11.9% in the year following the fracture, with the mortality risk returning to that of the standard population at three years40. Age appears to be an important factor, as a twenty-two-year follow-up study on 766 Swedish women sustaining hip fractures reported that the one-year mortality rate was 7% for those who were younger than seventy-five years, 21% for those who were from seventy-five to eighty-four years old, and 33% for those who were eighty-five years of age or older41. Men who sustain hip fractures are twice as likely to die as their female counterparts42, and only about one-half of these men will return to their previous level of mobility and independence43.
Obesity and Sarcopenia
Although the common perception of a malnourished patient is one who is cachectic and elderly, many obese patients may also be malnourished or at risk of becoming malnourished. Sarcopenic obesity is the age-related loss of muscle function with concurrent obesity44. In a study of 180 obese patients undergoing knee and hip arthroplasty, all patients were insufficient in both vitamin D levels and protein levels on the basis of low prealbumin levels, which responded to supplementation during the rehabilitation period45. The avoidance of prolonged bed rest and the routine assessment of performance status and function, such as the hand-grip strength test, the stair-climbing test, and the six-minute walk test, can be helpful in the evaluation or monitoring of sarcopenia.
Following orthopaedic surgery, diabetes is a well-known risk factor for complications such as surgical site infection, poor functional outcomes and increased revision rates after arthroplasty, and delayed wound-healing46,47. In a prospectively collected registry of 4234 total knee arthroplasty patients, diabetic patients had increased odds ratios for complications and moderate-to-severe limitations in activities of daily living at both two and five years after surgery48. Diabetic patients had a higher rate of complications (thirty-nine, 17.6%) than did patients in the control group (eighteen, 8.1%) in a case-control study of 222 diabetic patients undergoing total knee arthroplasty46. Control of blood glucose and achievement of euglycemia is one of the most important interventions for the avoidance of diabetes-related infectious complications in patients recovering from surgery, injury, or illness49,50.
Malnutrition and Outcomes in Orthopaedic Patients
A direct correlation between poor nutritional status and outcomes is difficult to discern due to confounding factors, difficulties in study design, and the ethical issues of withholding nutrition from patients. Prior to the establishment of the consensus guidelines to diagnose and characterize malnutrition11, there was great variability in the parameters used to indicate nutritional risk, and many studies in which a high incidence of malnutrition was cited were based on the presence of hypoalbuminemia, making comparison of historical studies difficult. Jensen et al. prospectively studied 129 orthopaedic patients after determining nutritional status by anthropometric, biochemical, and skin-antigen testing methods2. The authors compared the differences between a group of patients who were scheduled to have major elective orthopaedic surgery (including total hip arthroplasty) and a group of orthopaedic trauma patients. The patients were followed for several weeks, beginning five days after the injury. Trauma and major surgery resulted in the highest incidence of malnutrition (58.6%), and suboptimal nutrition was correlated with an increased risk of complications, including sepsis, wound-healing complications, and pulmonary complications. Malnutrition was attributed to injury-induced anorexia as well as the catabolic response to infection or injury, although causation could not be determined. No pre-injury nutritional parameters could be collected on the trauma population.
Another prospective cohort study found increased wound infections in 109 orthopaedic patients with protein-calorie malnutrition51.Gherini et al. reported delayed wound-healing in association with thirty-four (33%) of 103 total hip arthroplasty procedures, which correlated with lower preoperative serum transferrin levels in those patients as compared with patients who had uneventful wound-healing52. Delayed wound-healing occurred with higher frequency in patients who underwent bilateral total hip arthroplasty, likely due to the additional stress of having a larger surgical procedure. In another study, malnourished patients (determined on the basis of weight loss, triceps skinfold thickness, and serum albumin and prealbumin levels) were more likely to have impaired wound-healing, more medical complications (including cardiac-related complications), and longer hospitalization after lower-extremity amputation3. Of 490 patients with hip fracture, 18% (eighty-seven patients) were found to be malnourished on the basis of serum albumin levels, and 57% (280 patients) were found to be malnourished on the basis of total lymphocyte count4. Decreased albumin correlated with increased length of stay and in-hospital mortality, but neither albumin nor lymphocyte counts predicted complications. In 213 patients undergoing total knee arthroplasty, there were eleven infections (5.16%) and a significant inverse relationship between triceps skin thickness and infection rate (p = 0.012)6.
Assessment of Malnutrition
To reduce poor surgical outcomes associated with malnutrition, a specific and sensitive method for identifying at-risk patients and initiating appropriate nutritional support is necessary. The assessment ideally begins before surgery, by reviewing the patient’s history and performing a physical examination and nutritional screening (Fig. 1). The risk of developing malnutrition is increased in elderly, obese, pediatric, joint replacement, oncology, traumatic injury, spinal pathology, and “female athlete triad” (osteoporosis, disordered eating, and amenorrhea) patients53. The surgeon may inquire about usual food intake and about recent involuntary weight loss of more than 10% of body weight. In addition, to estimate fat and lean body mass, the surgeon may measure the triceps skinfold thickness and the arm-muscle circumference54. The adequacy of nutritional intake can be determined with use of a twenty-four-hour recall of meals, food frequency lists, or a food diary. Skipped meals or a diet that lacks entire food groups may signal correctable nutritional intake deficiencies. Clinical scoring systems, including the six-question Mini Nutritional Assessment Short Form (MNA-SF, Nestlé Nutrition Institute) (Fig. 2), can be used to assign a numerical value to these queries to define a threshold for malnutrition. The MNA has proven to be an accurate predictor of wound complications in the elderly, specifically after orthopaedic surgery55.
Determining lean body mass and nutritional status is especially important for elderly patients. Physical examination findings may include overt muscle-wasting and fat-wasting, especially near the temporal bone region, orbital region, clavicle, shoulders, interosseous muscles of the hands and feet, scapula, thigh, and calf. Decreasing muscle mass and physiologic stress from surgery may result in protein malnutrition, a major risk factor for mortality56. Serum albumin measurement may aid in assessing operative risk, but it is a nonspecific indicator of malnutrition4,57,58. Because production of constitutive proteins such as albumin are downregulated during the acute-phase response, serum albumin levels may not correlate with nutritional status in preoperative patients with severe physiologic stress54. A low preoperative total lymphocyte count has been correlated with other indicators of poor nutrition and increases the likelihood of delayed wound-healing and wound infections postoperatively4,55. In essence, a few pointed screening questions and the findings from the physical examination can help determine the nutritional status of patients both preoperatively and postoperatively, whereas serum markers such as albumin and total lymphocyte count may only be of benefit preoperatively and in the absence of other causes of an acute-phase reaction.
In a prospective evaluation of 2161 patients undergoing total joint arthroplasty, the authors identified 184 malnourished patients (8.5%) on the basis of serum levels of albumin or transferrin8. In comparison with patients with normal laboratory values, malnourished patients had an increased rate of complications, with twenty-two (12%) of the 184 patients experiencing complications. Seventy-nine (43%) of the 184 malnourished patients were obese, contrary to the common perception that malnourished patients appear thin and cachectic.
In order to formulate and institute a nutritional plan, the orthopaedic surgeon may choose a multidisciplinary approach that includes primary care physicians, physician-nutrition specialists, and registered dieticians to assist with the management of the patient (Fig. 1). It is important to estimate the total caloric needs of the patient as well as determine the optimal combination of macronutrients and micronutrients. Injury and stress increase a patient’s resting metabolic rate and the degree of protein catabolism54. Nutritional support must provide appropriate energy and nutrients for the patient’s metabolic state54. The best method to determine energy expenditure, indirect calorimetry, is often unavailable, so many predictive equations exist. The resting metabolic rate of a nonstressed patient can be approximated on the basis of age, sex, height, and weight with use of the Harris-Benedict equation59. The resting metabolic rate can then be multiplied by an empirically derived stress factor—based on the patient’s level of physiologic stress and typically ranging from 1.2 to 1.6—to arrive at a caloric goal54. Typically, patients should receive 25 to 30 kcal/kg/day unless the patient has abnormal losses (e.g., protein-losing enteropathy or continuous venovenous hemodialysis) or increased requirements (e.g., as a result of burns or an open abdomen)54.
The patient’s response must be monitored, followed by continual adjustments. Measurement of the serum level of prealbumin and/or transferrin is preferred to that of albumin because of the relatively shorter half-life of those markers, yet no serum protein marker has been found to be reliable in the setting of an acute-phase reaction54. A more dependable method of evaluation is to aim for a positive nitrogen balance as assessed with use of a formula comparing protein intake to the level of urinary urea nitrogen54.
Considerations for selection of the route of feeding include the goals of therapy, the ability of the patient to eat, the gastrointestinal function, and the expected duration of therapy (Fig. 1). Supportive or supplemental nutritional therapy often is provided to previously well-nourished patients who are unable or unwilling to spontaneously eat enough food to meet their increased nutrient or metabolic demands. If patients are able to tolerate oral feedings, they are counseled to increase their caloric intake by using milkshakes or commercially available oral nutritional supplements. The registered dietitian can greatly assist the patient and family in selecting appropriate supplements. We also encourage the use of food from home or a favorite restaurant because it frequently is more acceptable to patients than is institutional food. Malnourished patients who are about to undergo surgery can also benefit from dietary counseling, oral nutritional supplementation, and small meals with frequent snacks to enhance their food intake. In some instances, patients can receive supplemental nutritional support through nighttime tube feeding.
The dictum “if the gut works, use it” holds true. Although all attempts should be made to feed patients by the oral route, if this method is inadequate or unsuccessful, enteral nutrition becomes the preferred feeding modality for patients who have functioning gastrointestinal tracts. Total parenteral nutrition is the appropriate choice for patients in whom tube feedings have failed or in whom there is diminished gastrointestinal function due to underlying disease, surgery, or effects of therapy (such as radiation or chemotherapy).
Several trials have attempted to supplement nutrition in orthopaedic patients to determine the effect on outcomes. A randomized controlled trial evaluated the effect of nightly nasogastric tube feedings to supplement oral intake in malnourished patients who were being treated for a hip fracture1. The patients considered “very thin” trended toward lower mortality with supplemental feedings, but this result did not reach significance (death occurred in five [21.7%] of twenty-three in the control group versus two [8.0%] of twenty-five in the tube-fed group; p > 0.1). These patients also demonstrated decreased time to independent mobility. Patients with lower oral intake during the day were supplemented with nightly tube feedings, but only ninety-five (78%) of the 122 patients tolerated the nasogastric tube feedings. In a case-control study of supplemental nutrition (enteral or parenteral) in patients undergoing transtibial amputation for occlusive arterial disease, the authors reported increased healing of the amputation site in twenty-six (81%) of thirty-two patients with supplemental nutrition compared with thirteen (41%) of thirty-two patients with no perioperative nutritional intervention60. There was a nonsignificant reduction in mortality of nine deaths (28%) in thirty-two patients with supplemental nutrition as compared with fourteen (44%) of thirty-two control patients60. A pilot study of nightly enteral tube feedings in elderly patients with acute hip fractures did not demonstrate improved postoperative survival or reduced complications with supplementation61. The role of nightly supplemental nasogastric feeding is unclear due to poor patient tolerance and inconsistent results.
Overnight fasting to prevent aspiration of gastric contents remains the dogma for preoperative elective surgical patients since the advent of ether for anesthesia nearly 150 years ago62. In a prospective study of 292 patients undergoing elective and emergent general, gynecologic, vascular, and orthopaedic surgery, the mean fasting time exceeded the often-quoted six to eight hours for solid food, with emergent patients fasting for a median of 17.8 hours63. A Cochrane Review of thirty-eight randomized, controlled trials found no increased risk of aspiration, vomiting, or morbidity in patients who followed a shortened, fluid-fasting state as compared with the standard “nil per os” after midnight64. Additionally, patients who consumed water preoperatively had significantly lower gastric volume intraoperatively than did those who fasted64. These patients were healthy adults who were not considered to be at an increased risk of aspiration or regurgitation during anesthesia. There are limited data on the perception of the patient with regard to well-being (i.e., thirst, hunger, anxiety, or nausea).
Recent literature suggests that the fasted state leads to increased insulin resistance, lipolysis, and muscle breakdown, leading to a reduction in muscle mass65,66. Another study attributes increased complications and hospitalizations to increased insulin resistance67. One method to counteract postoperative insulin resistance is with an infusion of dextrose and insulin68 or more simply, a hypo-osmolar, carbohydrate-rich beverage (50 kcal/100 mL) given two to three hours before surgery69. In fourteen elective colorectal surgical patients, those receiving a carbohydrate-rich beverage in the evening and two hours prior to anesthesia had less reduction in insulin sensitivity and fat oxidation postoperatively when compared with a fasting control group70. In a small, randomized, double-blinded, placebo-controlled trial of fifteen patients undergoing total hip arthroplasty, postoperative insulin resistance was attenuated as a result of preoperative oral carbohydrate loading as compared with the result obtained with placebo69. The gastric transit time of this 400-mL beverage was well under the three-hour window prior to surgery in patients without concomitant gastric motility or reflux issues. There are no long-term outcomes to date with this preoperative regimen.
The benefits of preoperative carbohydrate-rich beverages have been questioned, possibly due to the volume of liquid ingested rather than the carbohydrate content. Sixty patients having total hip arthroplasty were randomized to preoperative fasting, 800 mL of tap water two hours prior to surgery, or an 800-mL carbohydrate drink the evening before surgery and another 400 mL two hours prior to surgery71. There was no significant difference in glucose clearance, insulin sensitivity, or postoperative complications between the three groups71. Because of inconsistent results between studies, a beneficial role for preoperative oral feeding in orthopaedic patients has not been confirmed.
Postoperative feeding regimens have become a target for nutritional interventions in surgical patients, although the literature is very limited in orthopaedic patients. One obstacle to early postoperative feeding is the risk of aspiration, particularly in patients with an acute change in mental status upon waking from anesthesia72. In both gynecological and abdominal surgery, randomized controlled trials have demonstrated the safe elimination of the clear liquid diet following surgery, opting instead for early advancement to the more nutritious, self-selected, regular diet73,74. Although patients experienced more nausea and vomiting in the early regular diet group, these studies demonstrated no deleterious effects of early feeding. Clinical examination of the patient should drive the decision to permit early advancement to regular feeding; for a postoperative patient without abdominal distension, nausea, or vomiting, progressing through a clear liquid diet as tolerated is unnecessary and calorically deficient72.
Malnutrition is a prevalent and important factor in the care of orthopaedic patients. After screening for malnutrition in their patients, contemporary orthopaedic surgeons may choose a multidisciplinary approach to establish a treatment plan suited to the individual patient. Basic history-taking, including food intake combined with physical examination of the patient, can help in the diagnosis of malnutrition. Laboratory tests, including a total lymphocyte count and the assessment of albumin, prealbumin, and transferrin levels, may assist in the diagnosis but can be unreliable in the setting of trauma or perioperatively with the release of acute-phase proteins.
The authors thank Jorge Albina, MD, for his help with the background and editing of this manuscript.
Source of Funding: No funding was received for the preparation of this manuscript.
Investigation performed at Rhode Island Hospital, Providence, Rhode Island
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, no author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
- Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated