Infection of a Joint Replacement

Infections of joint replacements can become a very serious problem. An infection can result in needing to remove the implanted joint. The most commonly performed joint replacements are knee replacements, hip replacements, and shoulder replacements. Much less commonly, other joints, such as elbows, wrists, and ankles, are being replaced.

Bacteria are usually well controlled by our immune system. Once an infection is detected, our immune system rapidly responds and attacks the infecting bacteria. However, implanted materials, like those found in a joint replacement, can allow infections to persist. Our immune system is unable to attack bacteria that live on these implants, and these infections can become serious problems. If an infection of an implant goes untreated, the problem can worsen, and the bacteria can gain such a foothold that they can become a systemic problem.

The reason infections are such a significant problem is that bacteria cannot be easily eliminated from a joint replacement implant. Despite excellent antibiotics and preventative treatments, patients with a joint replacement infection often will require removal of the implanted joint in order to cure the infection.

At the time of surgery, there are several measures taken to minimize the risk of infection of a total joint replacement. Some of the steps are known to lower the risk of infection, some are thought to help but whether they actually do is not known. Among the most important, known measures to lower the risk of infection after total joint replacement are:

• Antibiotics before and after surgery
  • Antibiotics are given within one hour of the start of surgery (usually once in the operating room) and continued for a short period following the procedure. Different antibiotics may be used depending on factors including the patient's individual history of infection, allergies to specific medications, and other concerns. The dose may also be adjusted depending on the patient's weight.
• Short operating time and minimal operating room traffic
  • Efficiency in the operation by your surgeon helps to lower the risk of infection by limiting the time the joint is exposed. Limiting the number of operating room personnel entering and leaving the room is thought to decrease the risk of infection.
• Use of strict sterile technique and sophisticated sterilization techniques
  • Care is taken to ensure the operating site is sterile. Any reusable instruments have been sterilized in an autoclave and not exposed to any contamination. The implants are packaged to ensure their sterility. Disposable items are sterile and discarded after use.

After the operation, the risk of developing an infection from an outside source is reduced, but there is still a risk of developing an infection from the bloodstream. Because of this, patients with a joint replacement implant should take antibiotics before invasive procedures such as dental work, colonoscopies, etc. It is known that these procedures may cause a transient risk of bacteria entering the bloodstream. Antibiotics will help control this and prevent joint infection.

When a total joint replacement becomes infected, it may loosen, become painful, and need to be removed. Unfortunately, even if the implant is washed clean during surgery, most types of infections require removal of the implant to cure the infection.

Infections have a tendency of adhering to the implant, and the implant itself is a hospitable location for infections. The way that our immune system fights infections, and the way that antibiotics are delivered to an area of infection, is both through our bodies blood supply. Artificial implants do not have a blood supply, and therefore joint replacements are a safe haven for infection. Even with aggressive antibiotic treatment and even surgical cleansing, curing an infection on a joint replacement is often impossible. Many times, the only way to cure an infection is to remove the entire implant, allow the infection to be treated, and then redo the joint replacement.

There are several risk factors for developing an infection after a total joint replacement, but most patients have no identifiable cause for developing an infection. Some of the risk factors include:

• Immune deficiencies (e.g. HIV, lymphoma), or immune suppressive treatments (e.g. chemotherapy)
• Diabetes
• Rheumatoid arthritis
• Obesity

Sometimes it is difficult to discern exactly why somebody gets an infection. Unfortunately, even with modern surgical techniques, they continue to occur. The chance of getting an infection after a joint replacement surgery is around 1-2%, slightly higher in people who have risk factors for developing infections.

Infection after joint replacement surgery is among the most feared complications of this surgical procedure. While joint replacements are often successful, they can have serious risks. If an infection occurs after joint replacement, additional surgery is almost always required, and sometimes multiple surgical procedures. In many cases, long-term antibiotics are necessary, and removal of the implants may be necessary depending on the type and timing of infection. Prompt identification and treatment are keys to successful management of a joint replacement infection.