Prosthetic joint infections
Prosthetic joint infections (PJIs) are infections that occur when an artificial joint, commonly a hip or knee, becomes contaminated by infectious microorganisms like bacteria or fungi. These infections can arise in about 0.5 to 3 percent of joint replacement surgeries and may develop shortly after surgery or much later. The primary causes of PJIs include local infections, which occur during surgery or from post-surgical wounds, and hematogenous infections, where organisms spread via the bloodstream from other body sites.
Individuals with certain risk factors, such as prior joint infections, obesity, diabetes, and advanced age, may have a higher likelihood of developing PJIs. Symptoms typically include joint pain, swelling, redness, fever, and in some cases, drainage from the surgical site. Diagnosing PJIs can be complex, often requiring lab tests and imaging studies, with definitive diagnosis achieved through microbiological examination of affected tissues.
Treatment typically involves a combination of intravenous antibiotics and surgical intervention to remove infected tissue. Early diagnosis and treatment are crucial for preserving joint function. While prevention of PJIs is not guaranteed, utilizing sterile techniques during surgery and administering prophylactic antibiotics can significantly reduce infection risk.
Prosthetic joint infections
ANATOMY OR SYSTEM AFFECTED: Blood, bones, joints, musculoskeletal system, tissue
ALSO KNOWN AS: Artificial joint infection, infectious arthritis of prosthetic joint, septic arthritis of prosthetic joint, periprosthetic joint infection
Definition
Prosthetic joint infections are illnesses caused by the contamination of an artificial (prosthetic) joint by an infectious microorganism such as a bacterium or fungus. According to statistics published by the National Library of Medicine in 2023, prosthetic joint infections occur in roughly 1 percent to 2 percent of individuals who receive joint replacement surgery. Infections can occur early in the course of recovery from joint replacement surgery (within the first two months) or much later.
Causes
Joint replacement is a surgical procedure designed to alleviate pain and to improve mobility in a person with damaged joints. A surgical team replaces a hip, knee, or shoulder with a prosthetic joint.
Prosthetic joint infections are caused by the growth of bacteria or fungi around a surgically implanted artificial joint. Most often, the infectious organisms reach the artificial joint during joint replacement surgery or from an infected wound after the surgery. These are called local infections and are most often caused by organisms such as coagulase-negative staphylococci, gram-negative bacilli, and Staphylococcus aureus. In other cases, the infectious organisms are present elsewhere in the body and travel through the bloodstream to affect the artificial joint. For example, the Escherichia coli bacterium that causes urinary tract infection can travel through the blood to infect a replaced hip joint. These types of infections are called hematogenous infections, and they involve a variety of organisms, including S. aureus, gram-negative rods, and anaerobes.
Risk Factors
An increased chance of becoming affected by a prosthetic joint infection can be related to a number of factors, including personal health behaviors, medical history, surgical conditions during joint replacement, and the healing process following surgery. Personal risk factors include a prior infection in the same joint, earlier joint replacement or revision surgery in the same joint, the use of tobacco products, rheumatoid arthritis, obesity, cancer, diabetes, poor nutrition, psoriasis, advanced age, and a weakened immune system. Surgical conditions that increase the risk of prosthetic joint infection include replacement of two joints at the same time and operations lasting more than two and one-half hours. After surgery, the risk for a prosthetic joint infection is increased with complications and other health issues, such as difficulties with wound healing, heart arrhythmia (such as atrial fibrillation), heart attack, and infection.
Symptoms
The most commonly reported symptom of a prosthetic joint infection is joint pain. The pain may be of sudden onset or of more gradual onset. Other general symptoms include fever, chills, joint swelling, redness, elevated white blood cell counts, and drainage from the surgical wound.
Symptoms can vary depending on the timing of the infection, that is, whether infection comes immediately after joint replacement surgery or later. Infections that develop soon after surgery most frequently include symptoms of pain, redness, and swelling at the joint, and drainage from the wound. Later-onset infections may have a more gradual onset of pain, without other signs of infection, such as fever or wound drainage.
Other than physical symptoms, further medical studies may reveal evidence of infection. This evidence includes translucent areas (periprosthetic lucencies) around the artificial joint, which can be shown through an X-ray, and blood levels that show elevated C-reactive protein, interleukin-6, erythrocyte sedimentation rate, or white blood cells.
Screening and Diagnosis
For joint pain or other physical symptoms of a joint infection, screening tests can be used to suggest the diagnosis of a prosthetic joint infection. Laboratory testing of blood may include analysis for elevated C-reactive protein, interleukin-6 levels, erythrocyte sedimentation rate, or white blood cells. These blood studies are more effective in detecting hip infections but less effective in detecting shoulder or knee infections.
Imaging studies such as X-rays can look for signs of infection, such as radiolucencies around the prosthetic joint or changes in joint positioning. Other radiology exams include serial radionuclide scans, with agents such as technetium Tc 99m phosphate; a computed tomography (CT) scan; and a magnetic resonance imaging (MRI) scan. However, CT and MRI scans have extremely limited usefulness in the evaluation of prosthetic joint infections because the material that makes up the artificial joint can affect the image quality of the scans. None of these studies can positively diagnose a prosthetic joint infection.
The definitive diagnosis of a prosthetic joint infection can be difficult, but is most often made through a microbiological examination (culture) of tissue or fluid from around the artificial joint or from the joint’s surrounding tissues. Obtaining and identifying the infectious organism from fluid or tissue found around the artificial joint often requires invasive procedures, such as joint aspiration or surgery.
Treatment and Therapy
Treatment for a prosthetic joint infection usually includes a long course of intravenous antibiotics and surgery to remove infected tissue. In many cases, the artificial joint must be removed, likely temporarily, to fight infection. The earlier the diagnosis and treatment of a joint infection are begun, the better the outcome. In an early diagnosed infection, the patient can often be given antibiotics that are tailored to treat the specific infectious agent and also a one-step surgical treatment to replace the infected tissue around the prosthesis. This is a procedure known as DAIR (debridement, antibiotics, and implant retention).
A longerduration infection may require two surgeries: removal of the infected joint (and a period of antibiotic treatment) and, once the infection is controlled, placement of a new prosthesis. In most cases, prosthetic joint infection can be treated and joint function can be preserved; however, in some cases, it is not possible to replace the prosthetic joint. In such cases, surgery to fuse the bones is recommended instead. In all cases, a team of specialists, including orthopedic surgeons, infectious disease physicians, microbiologists, and rehabilitation specialists, is needed for optimal diagnosis and treatment.
Prevention and Outcomes
The prevention of prosthetic joint infections is not guaranteed by the use of a particular procedure or device; however, the risk for infection can be decreased. Given identified risk factors, infection risk can be reduced if artificial joint replacement surgery is performed by an experienced surgical team using sterile procedures in a nonemergency setting. Also, evidence shows that administering antibiotics, such as erythromycin, before the procedure decreases the risk of infection.
Bibliography
Ayoiade, Folusakin, et al. "Periprosthetic Joint Infection." StatPearls, 14 Oct. 2023, www.ncbi.nlm.nih.gov/books/NBK448131/. Accessed 4 Feb. 2025.
Johannsson, Birgir, et al. “Treatment Approaches to Prosthetic Joint Infections: Results of an Emerging Infections Network Survey.” Diagnostic Microbiology and Infectious Disease 66 (2010): 16-23.
Lentino, Joseph R. “Prosthetic Joint Infections: Bane of Orthopedists, Challenge for Infectious DiseaseSpecialists.” Clinical Infectious Diseases 36 (2003): 1157.
Peleg, Anton Y., and David C. Hooper. “Hospital-Acquired Infections Due to Gram-Negative Bacteria.” New England Journal of Medicine 362, no. 19 (2010): 1804-1813.
Zimmerli, Werner, Andrej Trampuz, and Peter E. Ochsner. “Prosthetic-Joint Infections.” New England Journal of Medicine 351 (2004): 1645-1654. A