Preoperative and Perioperative Medical Management

Vignesh K. Alamanda, MD

Bryan D. Springer, MD

This chapter acquaints the reader with an approach to the patient undergoing knee replacement and describes strategies for modifying both preoperative and perioperative risk factors that can help minimize the risk of periprosthetic joint infection.

SCOPE OF PROBLEM

Periprosthetic joint infection (PJI) remains a significant, expensive and morbid complication of total knee arthroplasty (TKA). It has a measurable impact on all parties involved including the patient, surgeon, as well as the healthcare system.¹ PJI is projected to have an economic burden in excess of 1.62 billion dollars by the year 2020.² This is especially important to address since estimates currently project large increases in demand for total knee arthroplasties. By the year 2030, the demand for total knee arthroplasties is projected to grow by 673%.³ The demand for revisions will also follow a similar trend.³

The incidence of deep periprosthetic infection after primary total hip and knee replacements has been reported in the literature to range anywhere from 0.5% to 2%.¹,⁴ In examining total knee revision procedures, Bozic et al showed that infection was the leading cause of revisions comprising 25% of all failures in TKA.⁵ Other studies have also reported infection to be an important reason for patients undergoing revision in the total knee population with rates ranging from 33% to 38%.⁶,⁷ Kurtz et al have also shown that infection is on the rise as a reason for revisions and will continue to be the dominant reason for revisions.⁸,⁹ The Centers for Disease Control and Prevention (CDC) provided new guidelines that had important updates and additional recommendations for the prevention of surgical site infections. However, as noted by Parvizi et al, the lack of evidence in many of the areas prevents it from being a comprehensive guide.¹⁰

Thus, it is important that we attempt to further understand and minimize the risk factors in both the preoperative and perioperative settings which can play a role in the development of PJI. In particular, modifiable risk factors from the patient perspective can help with decreasing the overall risk of developing a PJI.

PATIENT MODIFIABLE RISK FACTORS

Diabetes Mellitus

Diabetes has been associated with increased risk of surgical site infection in a variety of surgical procedures.¹¹,¹² Additionally, the incidence of diabetes is continuing to rise in the United States.¹³ Diabetes has been shown to be a positive predictor of PJI in multiple studies. Analysis of these studies has shown diabetes to increase the odds ratio by 2.28 times in one of the largest series (Table 48-1).

Hemoglobin A1c (Hgb A1c) is frequently used as a marker of long-term glycemic control and may take 3 months to change. Patients with optimal glycemic control should have Hgb A1C levels less than 7.0. Hgb A1c has frequently been used a routine screening test as it is a simple test which allows the provider to gain insight of the patient’s glycemic control over the past 3 months.²¹,²² However, it appears that perioperative glucose levels have an increased ability to predict PJI as opposed to Hgb A1c alone.²³,²⁴

Surgical stress increases the production of hormones that antagonize insulin and predisposes patients to hyperglycemia. In particular, perioperative glycemic control needs to be strictly enforced as surgical stress-related postoperative hyperglycemia, even in patients without a diagnosis of diabetes, has been found to be an independent risk factor for the development of surgical site
infection in a dose-related relationship.²⁵,²⁶,²⁷ Thus, it is recommended that blood glucose levels be maintained between 110 and 180 mg/dL in the perioperative period to help minimize the risks associated with hyperglycemia. This can be achieved with frequent blood sugar checks and initiation of diabetic management protocols in the postoperative period. Alternatively, other markers such as serum fructosamine have also been proposed to serve as an adjunct to measuring glycemic control.²⁸

TABLE 48-1 Diabetes and Periprosthetic Joint Infection

Authors	Sample Size	OR (Confidence Interval)
Jamsen et al¹⁴	7181	2.3 (1.1-4.7)
Wu et al¹⁵	297	5.47 (1.77-16.97)
Lee et al¹⁶	1133	6.07(1.43-25.75)
Bozic et al¹⁷	8301	1.19(1.06-1.34)
Yang et al¹⁸	110, 923	1.61 (1.38-1.88)
Kunutsor et al¹⁹	512,508	1.74 (1.45-2.09)
Marchant et al²⁰	751, 340	2.28 (1.36-3.81)
Stryker et al²¹	1702	3.75 (1.25-11.22)

Obesity

Similar to diabetes, the prevalence of obesity has also significantly increased. Obesity has been shown to significantly contribute to a higher rate of osteoarthritis and eventual increased use of arthroplasty.²⁹ While studies have shown that patient satisfaction and functional improvement in the obese patient population are similar to the nonobese group, obese patients are, nonetheless, at higher risk of postoperative complications, specifically PJI.³⁰ Multiple studies have correlated increased body mass index (BMI) with increased rates of wound infection³¹,³²,³³ (Table 48-2).

Obesity predisposes patients to higher surgical times with increased surgical dissections needed to gain exposure. Additionally, the poor vascularization of adipose tissue further compounds this problem. A workgroup of the American Association of Hip and Knee Surgeons (AAHKS) evidence-based committee came up with a consensus opinion that consideration should be given to delaying total joint arthroplasty in a patient with a BMI > 40, especially when associated with other comorbid conditions, such as poorly controlled diabetes or malnutrition.²⁹

Additionally, surgeons should also have an index of suspicion for metabolic syndrome in those with obesity. Metabolic syndrome is composed of a cluster of conditions arising from insulin resistance that impairs normal leukocyte function. It is defined as having a BMI >30 kg/m² with central obesity, as well as two of the following: hyperlipidemia, hyperglyceridemia, hypertension, or diabetes.³⁸ Zmistowski et al have shown increased risk of PJI (14.3% vs. 0.8%) in those with uncontrolled metabolic syndrome compared to those with controlled disease/healthy cohort.³⁹ Thus, patients with obesity should also be screened to ensure that they do not have other features that define metabolic syndrome. Patients with obesity or metabolic syndrome should have their elective TKA delayed till their BMI <40 and should be directed appropriately such as being referred to a dietician in order to accomplish that goal.

TABLE 48-2 Obesity and Periprosthetic Joint Infection

Authors	Sample Size	OR (Confidence Interval)
Kunutsor et al¹⁹	512,508	3.68 (2.25-6.01)
Jamsen et al¹⁴	7181	6.4 (1.7-24.6)
Everhart et al³⁴	1, 875	5.28 (1.38-17.1)
Maoz et al³⁵	4078	4.13 (1.3-12.88)
Jung et al³⁶	9, 481	1.94 (0.63-5.70)
George et al³⁷	150,934	2.14 (1.48-3.1)

Malnutrition

An often underappreciated facet of obesity involves malnutrition or so-called paradoxical malnutrition in obese patients that have high-caloric but nutritionally poor diets. A prospective study evaluating the role of malnutrition in total joint arthroplasty found that malnutrition was present in 42.9% of obese patients.⁴⁰ Additionally, the geriatric population, patients with gastrointestinal problems, patients with a history of alcohol abuse, and those with cancer are also at increased risk of malnutrition. Multiple studies have implicated malnutrition as a contributing factor in increasing the risk of a PJI.⁴¹,⁴² Specifically, patients with malnutrition were found to have five to seven times greater risk of developing a major wound complication.⁴³ Malnutrition has also been associated with increased risks of infection after undergoing revision total joint arthroplasty.⁴⁴ Similarly, Bohl et al have also reported increased odds of PJI for patients with malnutrition.⁴⁵

Simple and immediately available laboratory tests can help to identify patients at risk for malnutrition. These include a total lymphocyte count of less than 1500 cells/mm³, a serum albumin of less than 3.5 g/dL, or a transferrin level of less than 200 mg/dL.⁴¹ Patients with preoperative malnutrition should be encouraged to work with a dietician to improve their nutritional intake and help prepare them for the catabolic demands required in the postsurgical period.

Smoking

Smoking, and its primary offending component, nicotine, has been associated with microvascular constriction and decreased oxygen delivery to tissues.⁴⁶,⁴⁷ In particular when analyzing the effects of smoking on total joint arthroplasty, Duchman et al reported increased risk of wound complication with both current as well as former smokers in a large national database study with current smokers having higher rate of wound complications than former smokers.⁴⁸,⁴⁹ Additional studies have also corroborated the deleterious effects of smoking as it pertains to PJI⁵⁰ (Table 48-3).

It has been shown that a smoking cessation program can help decrease complications associated with the use of nicotine even if it is introduced as late as 4 weeks before
surgery.⁵³ Thus, it is our recommendation that patient undergoing total joint arthroplasty has a minimum period of 4 weeks of smoking cessation prior to their surgery. Smoking cessation can be confirmed via easily available laboratory test, the serum cotinine assay (normal value of ≤10 ng/d).⁵⁴

TABLE 48-3 Smoking and Periprosthetic Joint Infection

Authors	Sample Size	OR (Confidence Interval)
Singh et al⁵¹	33, 336	1.41(1.16-1.72)
Singh⁵²	1185	3.42 (0.69-16.85)
Duchman et al⁴⁸	78,191	1.47 (1.21-1.78)
Teng et al⁵⁰	8,181	3.71 (1.86-7.41)