About Infection & Total Joint Replacement

How often does it occur?

Infection is a rare, but devastating complication following total joint replacement surgery. It occurs in 1–3 percent of patients nationally, though our most recent review of infection data at the University of Utah Center for Hip and Knee Reconstruction showed an infection rate better than the national average at 0.5 percent (as of 2013).

Who is at risk?

As mentioned above, these infections are rare. Not everyone will get them. However, certain patients are at higher risk than others. The greatest risk factors for infection are obesity, poorly controlled diabetes, and smoking. Some of these are modifiable risk factors, though, meaning you can decrease your risk by improving these conditions.

To measure your body fat (and possible obesity) based on your height and weight, calculate your body mass index (BMI) using a BMI calculator.

There are other risk factors for infection. Patients with prior surgeries at a surgical site have scar tissue and altered tissue planes that may delay healing and lead to infection. Patients that have a history of prior infections are also at increased risk. Poor nutrition, anemia, liver disease, kidney disease, or other health issues are also risk factors.

Finally, patients who have certain bacteria that live on them routinely, such as resistant staph (MRSA), may be able to decrease their infection risk by identification through screening and subsequent decolonization (see below).

We screen all patients undergoing joint replacement surgery for their nutrition status, bacterial colonization, kidney and liver function, protein status, and for the possibility of anemia. All patients receive these tests because we can’t predict who may have some of these issues that they or their primary care doctors were unaware of.

Given the significance of infection after joint replacement, all patients are considered to be at risk. We try to minimize the risk of complications by identifying patients at risk and optimizing their health status before they undergo the surgery.

Why does it occur?

Infections generally occur due to bacteria that live on/in/around us. All of us have bacteria that live on our skin, in our nose, and in our intestines. During surgery, we clean the skin and maintain a sterile environment around the surgical site to remove bacteria from the area.

Patients also receive antibiotics immediately before and for 24 hours after surgery. However, bacteria can find their way in through a surgical incision. Bacteria can also get to a surgical site through the blood stream. Infections can occur soon after surgery, but can also occur days, months, weeks, years, and even decades after a joint replacement surgery.

Invasive procedures around the time of a joint replacement also increase the risk of infection. Any invasive procedures (through the skin), such as a biopsy, Moh’s surgery for skin cancer, or colonoscopy, should be done six weeks prior to your surgery date.

Dental cleaning, especially root canals, extraction, and crowns, need to be taken care of six weeks prior to surgery or six to twelve months after surgery.

Why is infection so bad in total joint replacement?

The metal and plastic parts used in joint replacements do not have an immune system. So, unlike other infections our bodies can clear with an antibiotic or on their own, infected joint replacements will remain infected without surgery. If identified early, we may be able to treat infections by a surgery to simply wash the joint out. However, bacteria create films that coat the implants and surrounding tissues that can make getting rid of them difficult, if not impossible.

The longer the infection is present, the less likely the bacteria can be removed by a simple washout surgery. In these cases, the surgery becomes more complicated, and the implants have to be removed.

How do I know if I have infection?

There are signs and symptoms that help identify an infection after joint replacement. In the days to weeks following your surgery watch for symptoms that include fevers (more than 101F), chills, excessive redness (cellulitis), opening wound edges, prolonged or excessive wound drainage, cloudy wound drainage, and foul smells. Slight redness and warmth around a recently operated on joint may be normal signs of healing. Bruising or ecchymoses are also usually a normal finding.

At the University of Utah Center for Hip and Knee Reconstruction, we use a waterproof (occlusive) dressing that is impregnated with silver ions, which has been shown to help reduce the chances of infection. You may notice some slight spotting on the dressing, but excessive drainage into that dressing should be reported to your doctor.

Long after a joint replacement has healed, if you have increases in pain, fevers, chills, swelling, redness, warmth, pain when you move the joint, or difficulty putting weight on the hip or knee, you should discuss this with your doctor.

Are there other ways that my joint can become infected?

Following joint replacement surgery, the blood flow to the joint is increased for a period of time, as the body is healing. Along with the metal and plastic parts, which have no immune system, this increased blood flow can carry bacteria from the blood stream to the replaced joint. If the bacteria reach the implants, they may stick and create an infected joint.

Bacteria can be carried by our blood stream because of severe illnesses, such as sepsis. However, more commonly, bacteria may transiently get carried through the blood, and the body clears it without any obvious illness, unless it gets carried to the replaced joint. This is why infections can occur in replaced joints even decades after the surgery.

If you get a bacterial infection in the body, it is a good idea to seek the advice of your primary care doctor. Colds, flus, or other viral infections do not require antibiotics. However, if you get a cut that looks worrisome or a redness in the legs or urinary infections or other bacterial infections in the body, your primary care doctor may need to treat these with antibiotics.

Certain medical procedures can increase the risk of pushing bacteria into the blood stream, such as dental work, abdominal surgery, or colo-rectal procedures. It is important to take antibiotics prior to these procedures. The below table (Table 1) is provided by the American Academy of Orthopaedic Surgeons (AAOS) to guide patients on which antibiotics to take for various procedures.

Note: in 2012 a clinical practice guideline was developed by the American Dental Association (ADA) and the AAOS, where they found inconclusive evidence to support the use of routine antibiotics before dental procedures. However, most experts, including those at the University of Utah Center for Hip and Knee Reconstruction still agree with and follow the prior (2009) AAOS information statement, which stated: “Given the potential adverse outcomes and cost of treating an infected joint replacement, the AAOS recommends that clinicians consider antibiotic prophylaxis for all total joint replacement patients prior to any invasive procedure that may cause bacteremia.” Additionally, while prior recommendations based on a single study done in 1986 that showed the risk was highest for the first 2 years following joint replacement, the current recommendations from our group is to continue this practice for life.

Treating Infections

How are established infections after joint replacement treated?

In the United States, the standard treatment of an established infection in an artificial joint is a two-stage process. We remove all of the existing implants, cleaning out the joint and surrounding soft tissues, and place a temporary artificial joint. Often this temporary joint will be placed with high-dose antibiotic to deliver antibiotics locally to the surrounding joint tissues.

Removing the existing joint is not without its own risks. Each time a joint replacement is revised and/or removed, bone is lost and tissues are further affected. Careful surgical technique by expert surgeons is often the best way to decrease the risks of these types of surgeries. After these types of surgeries, patients are often allowed to be mobile, but often have to be careful how much weight they place on the joint. They may be restricted to placing 50 percent of their weight on the extremity weeks or months afterwards.

Along with the surgery to treat the infection, systemic antibiotics are also often used. Frequently two to six weeks of intravenous (IV) antibiotics are used to target the infection. Patients have a large IV line called a PICC line placed to receive these antibiotics. Labs are checked regularly to monitor the effects of the antibiotics on the body and the body’s response to the treatment.

A few tests, such as ESR and CRP, which are markers of inflammation, are used to see if the treatments are successful. Lower numbers are good and suggest a response to the treatment. Numbers that stay elevated, or are increasing, are a concern. If these latter trends are seen, often further tests, such as an aspiration of the joint, are often performed.

In total, the treatment for an infection after joint replacement can take six months of recovery time. Antibiotics may be given for six to eight weeks via IV and possibly three to six months. Potentially, you may even take antibiotics by mouth for your lifetime. 

Are you always successful at treating the infection if it occurs?

Several factors are involved in successfully treating an infected joint replacement, such as the type of bacteria involved in the infection, the duration of the infection, and the health status of the patient. Resistant organisms (MRSA for example) are harder to treat. Patients with weakened immune systems, diabetes, and morbid obesity are at risk to get infections and may have more trouble with the treatments.

Infections that have been present for a longer period of time are typically more difficult to treat. Soft tissue complications, such as chronic wound drainage or deficiencies in soft tissues that require additional procedures, are also higher risk for failure. Success rates reported in studies range from less than 40 percent to 100 percent depending on the type of infection and treatments. On average, success rates are between 80 to 90 percent for the treatment of long-standing infections with the use of the two-staged procedure.

How do I minimize my risk of joint infection?

The best means to minimize the risk of infection after joint replacement is by being healthy. We have described above some of the risk factors. Optimize your health status by doing some of the following:

  • Obesity: Strategies to reduce weight before surgery can help minimize the risks with obesity. Diet modifications are certainly the starting point. Exercise, while often touted as the best means to reduce weight, can be very difficult, especially in patients with pain due to arthritis. Water therapy, swimming, cycling, and elliptical machines tend to offer low impact, high aerobic activities that may help. University of Utah Health also offers bariatrics services that may be able to offer additional information on weight reduction methods, including surgical options.
  • Diabetes: Diabetes can be managed by adjusting diet, exercise, and medications. HbA1c, a marker of average glycemic control over three months’ time, is a reasonable indicator of diabetic control, and numbers less than seven percent are often required prior to surgery. Glycemic control around the time of surgery is likely the greatest modifiable risk factor for infection. Poorly controlled glucoses inhibit the immune system and healing response, and increase the risk of infection dramatically. So, even if we get the HbA1c controlled well, it is just as important to maintain good control (with glucoses less than 120) when at all possible.
  • Smoking: Smoking is bad for the body’s blood flow. One cigarette, for example, has enough nicotine to constrict the tiny blood vessels that are responsible for helping the surgical site to heal for up to six hours at a time. As such, smoking cessation is mandatory around the time of surgery. At University of Utah Health, we recommend quitting no less than four weeks prior to the surgery, as quitting closer to the time of surgery leads to coughs and other respiratory issues that put the patient at risk for other complications around the time of surgery. Further, all nicotine products should be stopped around the time of surgery. Because the healing process after a joint replacement can last months and even years, we recommend stopping smoking all together, but realize that not all patients can do so, and therefore recommend not starting again until at least six weeks after surgery.
  • Malnutrition & Anemia: Patients may not know they are malnourished or anemic. Even high endurance athletes or morbidly obese patients may show evidence of malnutrition, low protein, and the like. Screening labs help identify these issues, and supplements or medical treatments may be recommended prior to the joint replacement surgery.

Bacteria Screening

What is this nasal swab all about?

Many bacteria that colonize our bodies actually live in our airways and especially in our nose. One method of detecting this type of bacterial colonization is to do nasal screening. Studies have shown that patients who undergo nasal screening and decolonization can have a significantly lower risk of infection. By treating just the patients that are colonized, we can decrease the likelihood of creating resistant organisms and needlessly going through the effort and expense of decolonizing patients that are not colonized.

The most common organism that leads to infection following joint replacement is Staph Aureus, and the nasal swab-screening test looks for this bacteria. We currently screen all patients for Staph Aureus prior to joint surgery in an effort to reduce the possibility of infection.

What are Staph Aureus and MRSA?

Staph Aureus is a common type of bacteria that lives on the skin or in the nasal passages of about one in four healthy people. The apparent bacteria do not always cause problems or infections, but those affected are said to be colonized with staph. If the staph bacteria enters a person’s body through a cut, sore, catheter, or breathing tube, it may cause an infection.

MRSA (Methicillin Resistant Staphylococcus Aureus) is a bacterium from the staph family and is resistant to commonly used antibiotics. It is typically harmless to healthy people; however, carriers of MRSA are at an increased risk of the bacteria getting into their wound during surgery and possibly causing an infection. Up to one in 20 persons can carry MRSA on their skin or in their nose. MSSA (Methicillin Susceptible Staphylococcus Aureus) is readily treated by common antibiotic but also has the potential to cause infections.

What does the screening entail?

When you schedule your surgery, you will have a nasal swab done in clinic. A cotton swab will be placed in your nose to get a sample. The process is painless and only takes a few seconds. The sample will then be sent to the lab to have cultures done, with results returning to your provider in five to seven days.

What if I test positive?

Many people are carriers of MRSA/MSSA. This does not mean you are ill or a risk to other healthy people. If your culture results come back positive, we contact our patients and send additional instructions, including a decolonization process.

This process will involve the use of a special body wash (chlorhexidine or Hibalcens®) and ointment prior to surgery. You can also minimize your risk of becoming recolonized by using clean linens and clothing, and taking other hygiene precautions.

What if I test negative?

We will only contact patients with a positive result prior to surgery. If we do not contact you, continue the following hygiene routines:

  • Bathe regularly.
  • Clean your hands with soap and water or an alcohol-based hand sanitizer.
  • Avoid reusing or sharing personal items.
  • Examples: disposable razors, linens, towels, and the like.
  • Maintain clean sheets, clothing, and home.
  • Wear clean, washed clothing for the five days leading up to surgery.
  • Wash all eating utensils after each use.

In addition, you will be given an anti-bacterial (chlorhexidine or Hibalcens®) wash to use prior to surgery.

Chlorhexidine Shower Instructions:

  • Use the chlorhexidine soap for your shower the night before and the day of the surgery.
  • Use your normal shampoo on your hair.
  • Apply the chlorhexidine soap from the neck down.
  • While standing out of the stream of the shower, apply to the skin, and rub in gently.
  • Soak for five minutes, and then rinse the chlorhexidine soap off.
  • Do not use regular soap after the chlorhexidine soap, as the chlorhexidine soap bonds to the skin and with repeated use has a cumulative effect. It continues to work with anti-microbial activity after it is rinsed off.
  • Do not use the chlorhexidine soap if you have an allergy. There is a low risk for skin irritation with the use of this soap.

Read more information about Staph Aureus.