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Antonia F. Chen, MD, MBA


Published 10/1/2017
Terry Stanton

Strategies for Preventing TJA Infections

Comprehensive patient optimization is key
Infection is a major cause of failure after total joint arthroplasty (TJA), yet the risk of infection can be minimized through methodical attention to prevention before, during, and after surgery.

During the 2017 annual meeting of the Musculoskeletal Infection Society, Antonia F. Chen, MD, MBA, provided an overview of measures surgeons can take to reduce the risk of infection following TJA procedures.

One of the first issues to be addressed in the patient optimization process is colonization by methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S aureus (MSSA) (Fig. 1). In the preadmissions assessment and testing visit 2 to 6 weeks before surgery, an intranasal swab sample should be obtained. "The key factor is not to just move the swab up and down. You are trying to capture the bacteria there," Dr. Chen said. "Take the swab and dip it in saline. Then, roll it around the nares about five times to really pick up the bacteria. Go up and down the septum. If the patient gets a little uncomfortable, you are doing it right."

In patients who are positive for MRSA/MSSA, Dr. Chen recommends twice-a-day use of intranasal mupirocin 2 percent, although she says this measure is controversial due to potential development of antibiotic resistance. Alternatively, an intranasal povidone-iodine solution can also be used to decrease nasal bacterial colonization on the day of surgery. These patients also should undergo a body wash with chlorhexidine once a day 5 days prior to surgery. On the day of surgery, MRSA-positive patients should receive vancomycin and cefazolin, while those who are MSSA-positive and MRSA-negative should just receive cefazolin.

The benefits of this approach are that it directly reduces S aureus colonization and reduces the likelihood of surgical site infection (SSI) and prosthetic joint infection (PJI). Drawbacks include additional cost, the possibility of missing positive results, and a potential contribution to antibiotic resistance.

Although some centers forgo swabbing altogether and instead give mupirocin to all patients, Dr. Chen said, "We don’t recommend automatically giving everyone mupirocin because there is a potential increased risk of resistance."

Assessment and optimization
Much of patient optimization addresses health and medical conditions and comorbidities. "Obesity looms as a common and significant factor for contributing to SSIs," Dr. Chen said.

"It’s not just a weight issue," she continued. "From a surgical perspective, of course, it’s more difficult to operate in obese patients and there’s poorer wound healing. Additionally, obese patients have increased levels of cytokines, including elevated levels of IL-1β, IL-6, and TNF-α. It creates a milieu that increases the likelihood of infection." Dr. Chen noted that obese mice infected with common oral bacteria had higher bacteria counts and greater alveolar bone loss compared to non-obese mice. "This can translate into greater bacteria count and bone loss in obese human patients," she said.

Dr. Chen’s group practice adheres to strict body mass index (BMI) criteria. "No one with a BMI greater than 40 gets surgery," she said. Patients above the cutoff are required to achieve weight reduction and receive nutritional counseling. "It’s not just about losing a lot of weight," she said. "You don’t want the patient to be malnourished, and they should lose weight in a healthy manner."

Patients should undergo a nutrition assessment (Table 1). Although "we tend to think of malnourished patients as super skinny and sickly," Dr. Chen said, a study from the Rothman Institute found that 42.9 percent of malnourished patients had a BMI greater than 30, and these patients had a significantly higher complication rate, including hematoma formation, infection, and renal and cardiac problems. She recommended that malnourished patients start receiving supplementation, particularly vitamin D and protein supplement, 14 days prior to surgery.

Although the effect of smoking on infection incidence after TJA has not actually been directly demonstrated, Dr. Chen said that "we know that patients who smoke have higher complications." Microvascular constriction caused by smoking leads to insufficient oxygen delivery, which compromises healing.

Dr. Chen’s group practice tests patients for nicotine and cotinine, a metabolite of nicotine, "which predicts smoking within the last week"; levels of <10 ng ml are consistent with smoking cessation. she noted that "patients will say they quit smoking ages ago when it was actually 2 days ago.">

How long before surgery should a patient quit smoking? "If patients can quit smoking 4 to 6 weeks prior to surgery, they can normalize their immune and metabolic function." Dr. Chen said. "When I tell my patients that they need to stop smoking 6 weeks prior to surgery and that I’m going to test them on it, they become invested in their own health."

Alcohol consumption
"You also have to ask every patient about his or her alcohol consumption," Dr. Chen said. "Most people underestimate or understate how much they drink. You need to quantify it." Alcohol misuse has been predicted to result in longer hospital length of stay and higher hospital surgical complications. "Alcohol cessation should begin at least 4 weeks before surgery," she said.

Patients with diabetes "not only have high baseline glucose levels, but the stress of surgery further increases glucose levels," Dr. Chen said. Surgical stress antagonizes insulin, predisposing patients to hyperglycemia, and impairs the ability of leukocytes to stop infection. The result is that patients are at greater risk for infection. Dr. Chen recommends standard glucose monitoring, with a strict hemoglobin A1C criteria of less than 8. "That’s still high," she said. "If patients can maintain glucose under 200, that’s ideal. Strict postoperative control under 140 makes a difference, according to a study we conducted."

Anemia—hemoglobin, <12 g dl in women,><13 g dl in men—should also be addressed preoperatively. patients with hemoglobin hematocrit><10 30 should be referred to their primary care physician or to a hematologist for workup of the primary cause, which may be nutritional deficiency (iron, vitamin b12, folate), chronic renal insufficiency, or inflammatory disease.>

Simple iron deficiency should be treated with supplements, either orally (325 mg 3 times a day for 3 to 5 weeks before surgery) or intravenously for fast action, as may be needed in the trauma setting for a hip fracture patient. Constipation may be a side effect of iron therapy, so a laxative may be indicated.

Dr. Chen also addressed the use of epoetin for use in anemic patients. The mechanism is that of human erythropoietin, stimulating bone marrow and increasing red blood cell production. Epoetin has been used as a blood doping agent by athletes; medically it may serve as a substitute for transfusion in Jehovah’s Witness patients and others. It is approved by the U.S. Food and Drug Administration (FDA) for use in anemic patients. "It’s FDA approved, but it is expensive and very hard to get preapproval from insurance companies," Dr. Chen observed. Epoetin carries a Black Box warning for possible effects including cardiovascular events and increased risk of tumor progression or recurrence.

Rheumatoid arthritis
In discussing the protocol for patients taking medication for rheumatoid arthritis (RA), Dr. Chen noted that earlier this year, the American College of Rheumatology and the American Association of Knee and Hip Surgeons (AAHKS) issued a set of recommendations for medication management in RA patients undergoing joint replacement ("AAHKS and Rheumatologists Team Up to Issue TJA Guideline," AAOS Now, September 2017). The guideline may challenge the protocol many clinicians may be following, as it recommends continuing the use of drugs commonly taken by patients with inflammatory rheumatoid diseases—such as methotrexate—while specifying a dosing plan for withholding biologic medications prior to surgery and timing a procedure at the end of a dosing cycle for such drugs instead of withholding them for a longer period.

"The guidelines have been eye-opening because we were all taught that if you have any kind of immunotherapy, it should be stopped prior to surgery," Dr. Chen said. "Yet many of these drugs, including methotrexate, can be continued. However, the clearance physician may not know about the recommendations and will tell patients to stop taking it. The tradeoff is between a flare and a decrease in infection."

The recommendation states: "Withhold all current biologic agents prior to surgery in patients undergoing elective total hip arthroplasty and total knee arthroplasty, and plan the surgery at the end of the dosing cycle for that specific medication." Dr. Chen noted that the recommendation regarding glucocorticoids—to continue the current daily dose in adult patients receiving ≤ 20 mg, rather than administering a perioperative supraphysiologic "stress dose"— may receive pushback from anesthesiologists.

Antonia F. Chen, MD, MBA
Fig. 1 Algorithm for MRSA/MSSA screening.
Courtesy of Antonia F. Chen, MD, MBA

Attention to the impact depression and mental health have on infections and failures in TJA has increased. "Patients who are depressed have a depressed immune response, similar to that seen with obesity," Dr. Chen said. "Depression impacts not only outcomes, but also infection." 

The biologic association between depression and inflammation, with affected patients demonstrating higher levels of functional allelic variants, "can lead to dissatisfaction, higher rates of infection, and revisions," Dr. Chen said. "Counsel these patients about their expectations—tell them that their hips and knees are not going to be 20 years old again." Treatment may include cognitive behavioral therapy, psychotherapy, medication, and possibly, electroconvulsive therapy.

Surgery and afterward
The use of perioperative antibiotics, at least in regard to duration, is controversial, Dr. Chen noted, although their administration is mandated by the Joint Commission Surgical Care Improvement Project (SCIP) guidelines. "At least one dose should be administered prior to surgery," she said. In her practice, cefazolin is given to all patients without a confirmed cefazolin allergy. "Patients who merely had a rash to penicillin at 6 months may not actually be allergic to cefazolin and may benefit from cefazolin administration," she said.

In preparing the patient for surgery, clipping hair has been shown to reduce SSI risk. For antimicrobial solutions, "the choice of prep is up to you, but one that is alcohol-based is ideal." She noted that maintaining normothermia "is useful in our cold operating rooms, and for reducing the use of transfusion." With regards to transfusions, she said, "we no longer have patients donate blood beforehand and sparingly transfuse blood after surgery." Administration of tranexamic acid may reduce transfusions.

Draping should be done so that the surgical site is the only open area. Laminar flow is a controversial topic, but a policy to minimize operating room traffic is not, Dr. Chen said. "We try to limit the number of people who walk into the operating room and the number of things that come into the operating room, like cell phones."

When finishing the procedure, Dr. Chen said her team "takes a package of sterile betadine, injects it into a liter of saline and irrigates the site." The use of polymyxin and bacitracin in the irrigation solution is controversial, she said. "I personally do not use them in my irrigation solution; it’s not necessary to add more antibiotics, but some individuals do." Other controversial areas of infection prevention include the use of vancomycin powder, which is used in spine surgery, and antibiotic cement.

After closure, the wound should be watertight. "The worst thing to do is to leave the wound open with a poor closure," Dr. Chen said. In her practice, all patients get a watertight dressing (Aquacel; ConvaTec) that is silver-impregnated and completely seals the area. "Patients love it. They can shower over it and keep it on for 7 days."

In summarizing strategies to prevent infection in TJA patients, Dr. Chen advised taking the following measures:

  • Optimize patients with modifiable risk factors prior to surgery.
  • Work with other specialists to improve patient conditions (eg, nutritionists, endocrinologists, primary care physicians, hematologists, etc.).
  • Institute intraoperative prevention of PJI.

Dr. Chen has a consulting arrangement with ConvaTec, which sponsored the MSIS symposium "Optimizing Patients Before, During, and After Surgery."

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org.

Bottom Line

  • Careful patient optimization is a key measure for preventing infection after total joint arthroplasty.
  • In screening for MRSA/MSSA, swabbing technique should be thorough; patients testing positive should undergo chlorhexidine body wash and receive antibiotics as described.
  • TJA candidates should be assessed for a variety of health measures and comorbidities, including obesity, smoking, alcohol consumption, diabetes, anemia, nutrition, rheumatoid arthritis, and mental health.
  • Pre-, intra- and postoperative measures as described, including hair clipping, antibiotics, proper draping, and wound closure and watertight dressing, should be performed.

The Rothman Institute study
Huang R, Greenky M, Kerr GJ, Austin MS, Parvizi J: The effect of malnutrition on patients undergoing elective joint arthroplasty. J Arthroplasty 2013;28(8 Suppl):21-24.

Poster abstract on glucose levels
Poster presented at the 2016 Annual Meeting of the American Association of Hip and Knee Surgeons

Post-operative Blood Glucose Levels Predicts PJI after Primary Total Joint Arthroplasty

Michael M. Kheir, MD; Timothy L. Tan, MD; Matthew Kheir, BS; Mitchell G. Maltenfort, PhD; Antonia F. Chen, MD, MBA

Perioperative hyperglycemia has many etiologies including medication, impaired glucose tolerance, uncontrolled diabetes mellitus (DM), or stress, the latter of which is common to post-surgical patients. Our study aims to investigate if post-operative day 1 (POD1) blood glucose level is associated with complications, including periprosthetic joint infection (PJI), after total joint arthroplasty (TJA) and to determine a threshold for glycemic control that surgeons should strive for during a patient’s hospital stay.

A single-institution retrospective review was conducted on 24,857 primary TJAs performed from 2001-2015. Demographics, Elixhauser comorbidities, laboratory values, complications and readmissions were collected. POD1 morning blood glucose levels were utilized and correlated with PJI, as defined by the Musculoskeletal Infection Society criteria. The Wald test was used to determine the influence of covariates on complication rate. An alpha level of 0.05 was used to determine statistical significance.

The rate of PJI significantly increased linearly from blood glucose levels of 115 mg/dL onwards. We determined that blood glucose (OR 1.004, 95% CI: 1.001-1.006, p=0.001), male gender (OR 1.480, 95% CI: 1.185-1.848, p=0.001), body mass index (OR 1.049, 95% CI: 1.033-1.065, p<0.001), operative time (or 1.004, 95% ci: 1.001-1.007, p="0.006)," length of stay (or 1.059, 95% ci: 1.038-1.080, p><0.001), post-operative hematocrit (or 0.751, 95% ci: 0.621-0.909, p="0.003)," peripheral vascular disease (or 1.942, 95% ci: 1.042-3.617, p="0.037)," liver disease (or 2.576, 95% ci: 1.344-4.935, p="0.004)," rheumatic disease (or 1.991, 95% ci: 1.266-3.132, p="0.003)," and alcohol abuse (or 2.588, 95% ci: 1.096-6.110, p="0.030)" were associated with pji. the youden index was used to determine an optimal blood glucose threshold of 132 mg dl to reduce the likelihood of pji.>

The PJI rate in the entire cohort was 1.59% (1.46% in non-diabetics compared to 2.39% in diabetics, p=0.001). Diabetics did not have an association between blood glucose level and PJI (OR 1.002, 95% CI: 0.998-1.006, p=0.331), although there was a linear trend for postoperative glucose predicting PJI.

The relationship between POD1 blood glucose levels and PJI increased linearly, with an optimal cut off of 132 mg/dL. Immediate and strict post-operative glycemic control is critical in reducing post-operative complications, and we demonstrate that even mild hyperglycemia is significantly associated with PJI.

Higher POD1 blood glucose levels is significantly associated with PJI and the rate of PJI