Infected Artificial Joints (Prosthetic Infections)
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How do joint replacements become infected?

Infections associated with total joint replacements are generally categorized as either acute or chronic. Acute infections usually develop with the first three weeks of surgery. Bacteria can enter the region during implantation or through breaches in the skin if wound healing problems and local tissue necrosis are present. Chronic infections tend to surface months or years after surgery. These infections often result from the transient presence of bacteria in the blood stream.

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Transient bacteremia can be associated with distant infections involving the urinary tract, lungs or skin. Additionally, breeches in the body's defenses that occur during invasive procedures can provide the portal of entry. In an effort to prevent these problems individuals with total joint replacements are often encouraged to take antibiotics prior to dental surgery, colonoscopy and other procedures where organisms are frequently released. In many cases no identifiable cause is present, however, immune compromise, rheumatoid arthritis, diabetes and obesity are all considered to be risk factors.

What signs and symptoms suggest an infected joint replacement?

Individuals with infected joint replacements often experience increasing joint pain and swelling. The joint may feel increasingly stiff and local redness of the skin may develop. The presence of fever is variable, however, wound drainage is a significant concern and should be evaluated.

How will my doctor diagnose this infection?

Your physcian will utilize information gathered from your physical exam, lab tests and imaging studies to investigate the possibility of infection.

After examining the region x-rays will be obtained to look for loosening of the implant and bony resorption. Laboratory tests to identify inflammation (WBC count, c-reactive protein, ESR) may be obtained. An Indium labeled white blood cell scan may be requested to provide additional information. After evaluating this information your surgeon may insert a needle into the joint to retrieve any local fluid accumulation (joint aspiration). This fluid will be sent for microbiologic evaluation to identify the infectious organism and help guild antibiotic selection.

How are infected total joint replacements treated?

Infections that are diagnosed within several weeks of surgery may be controlled with joint irrigation and suppressive antibiotics. It is difficult for the body's immune system to remove well established infections from the surface of artificial materials making chronic infections difficult to cure. Several treatment options are available and are individualized to the specific patient. A two-stage implant exchange is the most frequently utilized approach. In the initial stage the implant and cement is removed along with all infected bone, soft tissue and joint lining (synovectomy). The region is irrigated with a large volume of solution after which an antibiotic impregnated spacer is placed. The patient typically receives a 6-week course of antibiotics and the joint is aspirated prior to any further surgery to evaluate for recurrent infection. If the infection has been cleared then a new joint prosthesis can be implanted. Success rates

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