Introduction
Total joint arthroplasties are some of the most commonly performed procedures in orthopedic surgery and have high success rates. These surgeries can greatly improve a patient’s quality of life.
Even though these procedures generally have positive patient satisfaction rates, the prevalence of several modifiable risk factors can cause increased risk for postoperative complications. The risks associated with smoking, obesity, opioid use, and malnutrition will be discussed in this chapter. With the drastic anticipated increases in rates of arthroplasty in the United States (a 673% predicted increase in primary total knee arthroplasty [TKA] by 2030), knowledge of these risk factors and suggested mitigation practices are essential for identifying potential risks and achieving optimal postoperative results.
Smoking
Risks
Studies have shown that exposure to nicotine and cigarette smoke decreases cutaneous blood flow. The nicotine and carbon monoxide from cigarettes can also hinder cell proliferation and epithelial regeneration. Prospective human trials have suggested that collagen synthesis in patients who smoke more than a pack of cigarettes a day was lower than the collagen synthesis in matched nonsmoking patients. Collagen is a major determinant of tensile strength in healing wounds and thus is an essential factor to consider in the recovery of postoperative joint replacement patients. Because of that, smoking may lead to higher rates of postoperative wound infections.
Effects of Cotinine
Nicotine has several metabolites. The primary one is cotinine, a breakdown product found in the blood, saliva, and urine of smokers. Cotinine is the most commonly used biomarker to test for tobacco exposure and therefore can be used by healthcare providers to test for tobacco usage before total joint arthroplasty procedures. This test can also be used to encourage patients who are smokers to quit by aiding them in monitoring and tracking their smoking consumption.
Cotinine has a half-life of approximately 20 hours and is available as a blood test. Testing cotinine levels before surgical joint procedures can be an effective method to screen for compliance with smoking cessation. Serum cotinine levels of lower than 10 ng/mL should be used as a cutoff consistent with not smoking. However, it is also important to note that these levels vary with race, age, and sex. It is essential to monitor cotinine levels to assess smoking status. It is important to continue to study the relationship between cotinine levels and potential postoperative complications.
Complications
Studies evaluating postoperative outcomes of patients who smoke have demonstrated that smoking can lead to an increase in hospital length of stay, an increase in intensive care unit admissions, greater rates of wound complications, and increased incidence of perioperative joint infections. Metaanalysis studies in rheumatology have evaluated the effects of smoking on total joint arthroplasty. This research has suggested that both current and former smokers are at increased risk for development of complications compared with nonsmokers. These complications include higher rates of reoperation, revision, implant loosening, deep infection, skin necrosis, and mortality ( Fig. 2.1 ).
Cessation
Research has suggested that cessation of smoking before knee arthroplasty surgery can lessen the risk of postoperative infection. Clinical outcome studies have shown that after 4 to 6 weeks of tobacco cessation, metabolic and immune functions begin to recover and normalize. Other studies have suggested that patients who quit tobacco use 4 to 8 weeks before surgery have decreased morbidity and mortality rates compared with current smokers. Although some literature suggests that smoking cessation 4 to 6 weeks before joint arthroplasty surgery can lessen the risks posed by nicotine and other byproducts of smoking, current and former smokers are at greater risk for perioperative complications in comparison with patients who have never smoked.
Smoking cessation is essential for proper wound healing and lowering rates of postoperative complications. Despite targeted efforts to aid patients in stopping smoking before surgery, more than 7% of patients are unsuccessful. An additional 55% of patients who do stop smoking before surgery are unsuccessful in maintaining this cessation 8 years after surgery.
For some patients, especially older adults, the anticipation of surgery itself can serve as a motivating factor for risk-reducing behavioral change and can increase the likelihood of smoking cessation. The need for surgery as a life-improving measure may be the first time a patient seriously considers pursuing an avenue for smoking cessation. Furthermore, smoking cessation for surgery can often serve as a start for long-term smoking cessation. In a study on smoking cessation programs before total joint arthroplasty it was found that 35% (13/37) of patients who quit smoking before surgery were still abstinent 1 year postsurgery.
Total joint arthroplasties have the potential to provide smoking patients with goal-oriented motivation to quit smoking and remain abstinent. For this reason, it is crucial for members of the healthcare team to provide resources, both before and after surgical procedures, to patients who smoke to aid them in establishing and maintaining their smoking cessation. These resources include counseling, pharmacotherapy, acupuncture, hypnosis, or a combination of these therapies. Helping all patients achieve these healthy changes has the potential to drastically improve individual patient outcomes and decrease large-scale risks of complications.
Obesity
The ever-increasing rate of obesity in America today is affecting all sectors of healthcare and poses several risks for detrimental effects for patients pursuing total joint arthroplasty. The Centers for Disease Control and Prevention released a report stating that 54 million obese adults in the United States were affected by osteoarthritis, a common complication of obesity. This number is estimated to rise to approximately 78 million adults by 2040. Preoperative evaluation of surgical risks in total joint arthroplasty patients who are obese is an important period when potential interventions can aid in improving arthroplasty outcomes.
Risks
The risks of having obesity-related complications are greater when combined with joint disease, because this combination can lead to greater pain and increased disability. This presents a specific challenge for orthopedic surgical healthcare teams as positive lifestyle changes and increases in physical activity are difficult to implement when patients are suffering from these negative effects of obesity and osteoarthritis.
It is important to recognize that patients with obesity often have multiple comorbidities, such as coronary artery disease, metabolic syndrome, hypertension, hyperlipidemia, and diabetes mellitus, which increase their risks of postoperative complications and increased lengths of stay. Patients with obesity also have higher rates of postoperative infections and wound complications.
Complications
The mean body mass index (BMI) for patients undergoing arthroplasty in the United States is 33. Patients with obesity (defined as a BMI value ≥30) who pursue TKA have high rates of complications. Patients who are morbidly obese have even greater complications compared with their counterparts who have lower BMI but still have obesity. Thus it is suggested that the risk of complications increases with increased BMI, a trend supported by research demonstrating that increased postoperative complication rates exist at a threshold of BMI >30; these complication rates were even greater in populations with a BMI >40. Predicted causes for these drastically increased complication rates in patients who have BMI >40 are an increase in subcutaneous fat and a greater amount of dead space contributing to seeding of bacteria, which predisposes patients to infection.
Patients with obesity also have unique complications. For example, avulsions of the medial collateral ligament are seen more frequently in this patient population. However, weight and BMI are not the only predictive measures of complications. Distribution of body fat may also be an important factor in determining wound healing and infection risk in knee arthroplasty patients. The prevalence of diabetes, which is an independent risk factor for increased risk of infection postoperatively, is higher in patient populations with obesity.
Prior studies have suggested that the most prevalent complications in patient populations with obesity are venous thromboembolism (VTE) and renal insufficiency. Although there are increased rates of pulmonary embolism in patients with obesity, there is no observed trend of increasing rates with increasing BMI. One hypothesized reason for this correlation is that patients with obesity may be slower to mobilize after surgery, and immobility is a risk factor for VTE. Researchers speculate that rates of renal insufficiency are increased in patients with obesity due to the use of angiotensin II receptor blockers or angiotensin-converting-enzyme inhibitors, drugs that are commonly used in the treatment of hypertension and, if used chronically, can lead to acute kidney injury.
In comparing patient populations with obesity with patients who do not have obesity patients with obesity were suggested to have increased rates of infection, VTE, renal injury, and subsequent unplanned returns to the operating room. In stratifying populations with obesity further, it was noted that patient populations who were morbidly obese had markedly increased risks of postoperative complications compared with other groups with obesity. In considering total joint arthroplasty for patients with obesity morbid obesity should be addressed preoperatively. Several studies have researched the utility of bariatric surgery to decrease a patient’s BMI and its effects on outcomes, but this is a risky and controversial approach and the definitive results about the reduction in complications remain uncertain.
Patients who have a BMI >30 have been found to have higher wound complication rates and higher hospital readmission and revision surgery rates than patients with BMI <30. Additionally, a retrospective study suggested that a BMI of >40 was a risk factor for developing periprosthetic joint infection after total hip arthroplasty (THA). This finding was supported by a metaanalysis showing that patients with obesity have higher infection rates and significantly higher rates of revision surgery than patients who are not obese. Furthermore, hospital readmission rates for patients with BMI >40 are almost double those of patients who are not obese.
Metabolic Syndrome
When considering patients with obesity, it is imperative to remember that not all patients are the same. Patients who have obesity can sometimes also meet the criteria for metabolic syndrome, which is defined as having a BMI that meets the criteria for obesity (BMI ≥30 kg/m 2 ) and two of the following conditions: hyperlipidemia, hypertriglyceridemia, hypertension, or diabetes. Metabolic syndrome arises from insulin resistance and can lead to many postsurgical complications. Fig. 2.2 shows metabolic syndrome components versus total complication rates and suggests that a diagnosis of metabolic syndrome greatly increases chances for postsurgical complications.
Obesity Reduction Approach
In looking at the drastically increased rates of complications in patient populations with obesity, it is imperative for healthcare teams to encourage these patients to lose weight before surgery. However, several studies have suggested that it is difficult for patients with obesity to lose weight before surgery. Overall, very few patients with obesity can maintain weight loss, even after undergoing total joint arthroplasty. To lessen the risks of postoperative complications, healthcare teams should provide patients with resources for weight loss, counsel them appropriately before surgery, and aid them in the creation of a weight reduction plan preoperatively.
Opioids
The opioid epidemic in the United States is linked with injuries and deaths from medications. To decrease rates of postoperative opioid drug abuse, improved patient and provider education is essential. Multidepartmental research suggests that from 67% to 86% of postoperative patients have access to excessive narcotics from initial prescription, and 92% to 96% of these patients report a lack of information or instruction on how to dispose of unused narcotics. Closing this communication gap between providers and patients and better explaining narcotic disposal options can aid in decreasing the prevalence of narcotic abuse.
Preoperative Testing
Preoperative pain threshold testing has proven to be an objective, simple, reliable, and safe method to help anticipate outpatient narcotic needs in surgical patients. The results of this preoperative sensory test can aid physicians in creating a postoperative medication plan and can aid patients in discontinuing their opioid use postoperatively. A prospective study suggested a significant negative correlation between the results of preoperative pain threshold testing and outpatient narcotic consumption, demonstrating that the higher a patient’s measured pain tolerance, the less need there is for narcotic use postoperatively. This information can aid healthcare teams in developing postoperative plans that are tailored specifically for individual patients, thus reducing overprescribing and lessening the potential for abuse, diversion, addiction, or overdose.
Preoperative Opioid Management
Increased rates of opioid use because of increased prescribing have made it very common for patients who have chronic pain to use opioids. This has created a large population of people who consume opioids daily. A large population of patients undergoing surgical procedures are prior chronic prescription opioid users, and these patients require high opioid dose increases after surgery that can persist long into their postoperative care.
To improve patient outcomes, it is recommended that opioid-using patient populations be identified and counseled. Prior studies have suggested that minimizing use of preoperative opioids decreases postoperative risks. Therefore it is imperative for healthcare teams to have discussions regarding opioid dose tapering or cessation before joint surgeries, a practice that is not commonplace. Patients should be educated regarding techniques other than opioid use that can maintain adequate pain control. This practice is especially important in chronic pain patient populations, as prior research suggests that preoperative opioid reduction is protective against adverse postoperative outcomes. The recommendation for care of opioid-using patients is a combination of psychological and opioid screening through a multidisciplinary approach that includes tapering opioid use preoperatively and closely monitoring opioid use postoperatively. It is essential for healthcare teams to establish a pain management system with nonopioid protocols for pain control in these patients.
Nutrition
Effects of Malnutrition
Studies have suggested that rates of malnutrition in arthroplasty patients can be as high as 26%, and these high rates of malnutrition can lead to decreased immune system function. In a review of patients who had THAs the preoperative presence of malnutrition contributed to joint infection.
Malnutrition in various studies has been defined as serum albumin levels <3.5 or an absolute lymphocyte count <1500, whereas other studies have used other markers such as transferrin or prealbumin. However, these values have been questioned in several studies. In a consensus agreement reached through a series of meetings held at the American Society for Enteral and Parenteral Nutrition and European Society for Parenteral and Enteral Nutrition congresses, malnutrition was classified into three groups: starvation-related, chronic disease–related, and acute injury– or disease state–related groups. The classification of malnutrition based on etiology simplifies the issue and also helps determine appropriate management strategies.
Nutritional factors play a crucial role in regulating metabolic pathways and immune system functions. Various nutritional factors that have been identified as playing a role in patients undergoing arthroplasty include serum albumin, serum iron/transferrin, vitamin D, serum zinc, and adiposity.
Role of Vitamins
Vitamin D insufficiency in surgical patients has been associated with increased postoperative pain and increased risk of periprosthetic infections. Prior research has suggested that the prevalence of patients who have levels of vitamin D lower than 20 ng/mL is 41%. In patients who had undergone elective joint arthroplasty procedures prevalence of vitamin D deficiency in patients who had periprosthetic fractures was about 66%. The prevalence of vitamin D–deficient patients who had arthroplasties was approximately 54%. Studies on patients who had hip arthroplasties for osteoarthritis have suggested that increased levels of 25-hydroxy-vitamin D in male patients were associated with a 25% increase in need for arthroplasty. Screening and correcting for low vitamin D levels can prove to be instrumental in lessening pain and infection risks associated with joint arthroplasty procedures.
Although vitamin D has a well-recognized role in bone health, it also plays an important role in innate immunity. The immunomodulatory actions of vitamin D are well recognized and are a key factor in innate and adaptive immunity and immunity modulation. Vitamin D may improve outcomes by reducing local and systemic inflammatory responses as a result of modulating cytokine responses and reducing toll-like receptor activation. It also stimulates expression of potent antimicrobial peptides, such as cathelicidin and beta-defensin 2.
Similarly, vitamin C has been identified as an important nutritional variable. Vitamin C has well-recognized antioxidant properties and has been used in arthroplasty to prevent systemic inflammatory response syndrome. It is also known to have immunostimulant, antibacterial, and antiviral properties and has been advocated for the reduction of regional pain syndrome.
Role of Zinc and Lymphocytes
A prospective research study suggested that the presence of low zinc levels in preoperative arthroplasty patients was correlated with delayed and poor wound healing. This study also suggested a significant correlation between lymphocyte counts <1500 and delayed wound healing in THA patients. Patients should be screened for zinc levels before surgery, and healthcare teams should use a cutoff value of <95 mg/dL to determine which patients should have supplemental zinc before surgery.
Role of Albumin
Protein deficiency causes atrophy of lymphoid organs. This atrophy affects several immune functions such as lymphocyte proliferation, antibody responses, interleukin-2 (IL-2), interferon-gamma, and delayed-type hypersensitivity reactions. In a later study 49,603 primary THA or TKA patients were retrospectively reviewed using the American College of Surgeons National Surgical Quality Improvement Project database. Hypoalbuminemia was identified in 4.0% of cases and was associated with a 2-fold increase in the rate of surgical site infection. This study also demonstrated independent associations between hypoalbuminemia and increased risk of pneumonia, prolonged hospital length of stay, and readmission.
Identification of At-Risk Patients
Obesity, low BMI, prior gastric bypass, malabsorption states, and hypermetabolic states can increase risks. Referral to a bariatric center for counseling and potential surgical management of obesity may be appropriate in certain cases. However, some forms of bariatric surgery may lead to malabsorption, and monitoring and supplementation are important in these patients. Routine preoperative laboratory studies should include a complete blood count with differential to identify anemia and quantify absolute lymphocyte count. A reticulocyte count is also helpful to determine marrow response to anemia. Serum albumin and transferrin levels and a hemoglobin A1C should be obtained. Optimization of anemia can include iron, vitamin C, and folate supplementation. Patients who have a preoperative hemoglobin <11 g/dL should have additional tests to determine the etiology. Screening for vitamin D deficiency may also be useful.
Preoperative Malnutrition Screenings and Recommendations
For patients undergoing surgical procedures, various malnutrition screening tools are available. The most common serological markers are serum albumin levels <35 mg/dL, lymphocyte counts <1500, and transferrin levels <200. Anthropometric measures and nutritional screening tools have also been described in orthopedic literature as tools for screening. Although anthropometric measures have been useful for nutritional screening, there are no established cutoff values, and their usefulness has been limited.
Correction of Malnutrition in Elective Arthroplasty Patients
Protein supplementation for patients who have protein deficiency can be accomplished with nutritional shakes, with a target intake of 1 g/kg daily. Oral nutritional supplements should be enriched with immune-modulating substances, including arginine, omega-3 fatty acids, and nucleotides.
Simple interventions can include iron supplementation (324 mg per oral three times daily for 3 to 4 weeks) and vitamin C (500 mg per oral daily) to aid iron absorption and collagen cross-linking, which aids wound healing. Zinc (11 mg per oral daily) can also aid in wound healing. Additionally, vitamin D supplementation of 25 mcg daily is recommended for routine maintenance. Patients with vitamin D levels <20 ng/mL should be given greater supplementation with 1250 mcg weekly for 8 weeks followed by maintenance doses of 37.5 to 50 mcg daily with yearly vitamin D level monitoring. Levels between 20 and 30 ng/dL should be treated with daily vitamin D supplementation of 125 mcg for 3 to 6 months followed by retesting.
Conclusion
In approaching joint arthroplasty procedures, evaluation of risk factors is just as important, if not more important, than the quality of the surgery itself. Good surgical outcomes start with good patient selection. The risks and benefits of joint arthroplasty should be carefully weighed in high-risk patients, and surgery should be delayed until appropriate medical optimization has been achieved. Following the famous saying, “Good surgeons know how to operate, better surgeons know when to operate, and the best surgeons know when not to operate,” the need for an objective assessment of the likelihood of adverse patient outcomes caused by patient risk factors cannot be overemphasized.
It is essential for healthcare teams to prescreen patients for the four major modifiable risk factors discussed in this chapter: smoking, obesity, opioid abuse, and malnutrition. Teams should have discussions with patients and their families regarding how lifestyle changes, that can be made preoperatively, can lead to better outcomes, more effective healing, and lower complication rates.
Curbing patient expectations is another crucial component of surgery, as patients seeking joint arthroplasties today are younger, better educated, living longer, and have higher expectations. Unrealistic expectations can have a profound effect on surgical outcomes, leading to frustration, dissatisfaction, and unnecessary resource utilization. Communication and transparency, outlining clear and achievable goals, are necessary for correcting unrealistic expectations before surgery. Today, more than ever, we are challenged to provide efficient, high-quality, patient-centered care. Ensuring good outcomes should be a top priority, not just from a financial standpoint but also as a moral obligation. We should strive to be leaders in the face of challenges, using innovation and integrity to produce the best results and advance our profession.
