Infection After Joint Replacement Surgery

In this article, Dr. Lawrie discusses everything you want to know about infection after hip or knee joint replacement surgery.

Infection after a hip or knee replacement can be a devastating complication. Although it most commonly occurs in the first few weeks after surgery, a small risk of developing a late infection months or years after the procedure does exist. Modern surgical technique, antibiotic regimens, and skin preparation have significantly reduced the rate of infection over time; however, despite these best efforts, infection after joint replacement surgery is still possible. Here’s what you need to know.

What causes an infection after a joint replacement?

Microorganisms, including bacteria and less commonly fungi, may cause infections after hip and knee replacement surgery. The majority of infections are caused by organisms that normally live in our skin. These bacteria and fungi, like staphylococcus (“staph”), streptococcus (“strep”) and candida (yeast) live on our skin and typically do not cause problems. Occasionally, they may cause skin infections that usually go away with antibiotics or ointments.

However, when these organisms are able to travel deeper than the skin, through cuts or surgical incisions, they can cause more serious infections. Other bacteria or fungi from the environment may also cause infections in a similar manner from contamination during or after surgery. 

While it’s usually impossible to determine exactly when the infection started and the exact cause, most infections are believed to start at the time of surgery or in the first weeks after surgery while the incision is healing. It’s during this vulnerable time period, bacteria or fungus are able to get into the surgical site and multiply.

Late infections, or those that occur months or years after joint replacement, are far less common. These infections are usually due to bacterial spread from active infections in other parts of the body like lung infections (pneumonias), urinary tract infections, dental infections, and the gastrointestinal system. It’s important to note that viruses like influenza (the flu) and coronavirus (the common cold and COVID-19) cannot cause infections in knee or hip replacements.

What are signs and symptoms I need to worry about?

The signs and symptoms of an infected hip or knee replacement can vary widely. The most common signs and symptoms are: increase in pain, swelling, redness, and/or drainage from the surgical site, as well as fever and/or chills. It’s important to note that many of these can be seen as a normal part of the healing process, or may be due to illness unrelated to the replaced joint. That being said, talk to your surgeon to understand their specific instructions should any of these symptoms occur:

  • Increased pain – recovery after knee or hip replacement typically has ups and downs related to increases in activity level or exercise. Continued increase in pain that doesn’t improve with rest or pain medication, inability to move the affected joint without severe pain, or inability to bear weight may indicate a problem that needs the attention of your surgeon.
  • Swelling – swelling is normal after joint replacement and may wax and wane for several months. Swelling that persists, involves the entire surgical leg, worsens, or fails to respond to rest, elevation, ice and compression may indicate a problem that needs the attention of your surgeon.
  • Drainage – depending on how your incision was closed, complexity of the procedure, use of blood thinners, and your underlying healing ability, drainage from the incision may be expected. Drainage that persists beyond 7 days after surgery or increases in amount may indicate a problem that needs the attention of your surgeon.
  • Fever or chills – low-grade fevers and chills are very common in the early post-surgical period and usually aren’t caused by infection in the joint. Most commonly, they are caused by the effects of anesthesia on your lungs, your body revving up its metabolism to heal the surgical site, and urinary tract infections. Fevers over 101.1 F or those that don’t respond to fever reducing medications may indicate a problem that needs the attention of your surgeon.

R.I.C.E. After Surgery

How will my surgeon check for infection?

If your surgeon is concerned about infection in your replaced joint, the next steps typically involve lab work. Your surgeon will likely order a blood draw to test for markers of body-wide inflammation, called Erythrocyte Sedementation Rate (ESR) and C-Reactive Protein (CRP), among others. A joint aspiration (fluid pulled off of the affected joint with a needle) may also be obtained and sent for bacterial markers, measurements of the number of white blood cells in the fluid, and attempt to grow bacteria (culture).

The results of such labs and tests may come back as early as the same day but typically take up to 1 week for final results. Taking all of this information together, your surgeon will decide if he/she is concerned about infection in the joint based on well-established criteria from research on the subject.

How will my infection be treated?

The treatment of infection after total joint replacement depends on the depth of the infection, and the duration of the infection. If your surgeon believes the infection only involves the skin and tissues immediately below the skin, and does not involve the replaced joint itself, then a course of oral antibiotics may be recommended.

If your surgeon believes the infection goes deep into the joint itself, surgery may be required to treat the infection, as our immune systems cannot clean or fight organisms off of the metal, plastic, and ceramic materials used in joint replacements the same way the immune system can in our own tissues.

Depending on the organism causing the infection, how quickly the infection was caught, as well as other factors, your surgeon’s recommendation may involve one of the following surgical options:

  • Irrigation and debridement with exchange of modular components
  • Irrigation and debridement with removal of all components and placement of an antibiotic cement spacer, static or dynamic, followed by placement of a new joint replacement 3-6 months later (aka: two-stage reconstruction)
  • Irrigation and debridement with removal of the joint without placement of an antibiotic cement spacer (girdlestone)
  • Amputation

All of these procedures are typically followed by a minimum of 6 weeks of intravenous (IV) antibiotics delivered through peripherally inserted central catheter (PICC), which can be thought of as a portable IV that will allow antibiotics to be given at home or a rehab center.

How successful is the treatment of infection?

Depending on the organism causing the infection, the duration of the infection, your underlying health and other factors, the risk of persistent infection or reinfection varies widely. Talk to your surgeon about your specific situation to get a better idea of chances of success.

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