Summary about Disease
Infectious arthritis of a prosthetic joint (PJI) is a serious complication following joint replacement surgery. It occurs when microorganisms, such as bacteria, form a biofilm on the implanted device, leading to inflammation and infection within the joint. This can cause pain, swelling, stiffness, and decreased function, potentially requiring further surgery to resolve.
Symptoms
Symptoms can vary in onset and severity, but common signs include:
Increased pain in the affected joint
Swelling, warmth, and redness around the joint
Stiffness and difficulty moving the joint
Fever or chills (may be absent, especially in chronic infections)
Drainage from the surgical wound or joint area
Causes
PJI is caused by microorganisms that infect the prosthetic joint. The most common causes are bacteria, including:
Staphylococcus aureus
Staphylococcus epidermidis
Streptococci
Enterococci
Less commonly, gram-negative bacteria, fungi, or mycobacteria These microorganisms can be introduced during surgery, from a distant site in the body through the bloodstream, or through direct contamination of the wound after surgery.
Medicine Used
Treatment typically involves a combination of:
Antibiotics: Prolonged courses of intravenous and oral antibiotics are usually necessary. The specific antibiotic(s) used depend on the identified organism and its antibiotic sensitivities. Examples include vancomycin, daptomycin, cefazolin, and rifampin (often used in combination with other antibiotics to combat biofilm).
Antifungals: May be prescribed in the case of fungal infection.
Is Communicable
PJI itself is not directly communicable from person to person. The infection is contained within the joint itself. However, the bacteria or fungi that cause the infection can be communicable through other means, such as direct contact or airborne transmission.
Precautions
Precautions generally focus on preventing the spread of infection within the hospital or healthcare setting. These include:
Hand hygiene: Frequent handwashing with soap and water or using alcohol-based hand sanitizers.
Sterile technique: Strict adherence to sterile technique during surgery and wound care.
Wound care: Keeping the surgical wound clean and dry, and following instructions for proper wound care.
Antibiotic prophylaxis: Administering antibiotics before surgery to prevent infection.
Isolation (if necessary): Patients with certain types of infections (e.g., MRSA) may require isolation to prevent spread to other patients.
How long does an outbreak last?
The duration of an outbreak (meaning an individual's episode of PJI) varies significantly depending on several factors:
Severity of the infection: Acute infections caught early may be resolved more quickly.
Type of microorganism: Some organisms are more difficult to eradicate.
Treatment approach: Whether the prosthesis is retained, or a one- or two-stage revision is performed influences the length of treatment.
Patient's overall health: Underlying health conditions can affect the response to treatment. Treatment can range from several weeks of antibiotics alone (if the infection is caught very early) to months of antibiotics, surgery, and rehabilitation.
How is it diagnosed?
Diagnosis usually involves a combination of:
Physical examination: Assessing the joint for pain, swelling, warmth, redness, and range of motion.
Blood tests: Elevated white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) can indicate infection.
Joint aspiration: A sample of fluid is drawn from the joint and sent to the lab for cell count, Gram stain, and culture to identify the infecting organism.
Imaging studies: X-rays, bone scans, CT scans, or MRI may be used to assess for loosening of the prosthesis or signs of infection.
Synovial fluid analysis: Tests on the joint fluid to measure alpha-defensin levels or leukocyte esterase.
Timeline of Symptoms
The timeline of symptoms can be:
Early onset: Symptoms appear within weeks to months of surgery, often due to highly virulent organisms.
Delayed onset: Symptoms appear months to years after surgery, often due to less virulent organisms or a low-grade infection.
Acute hematogenous: Symptoms appear suddenly in a previously well-functioning joint, often due to a distant infection spreading to the joint through the bloodstream. The symptoms themselves are listed in section 2, it is the timing that varies.
Important Considerations
PJI can be a devastating complication with significant morbidity and potential for multiple surgeries.
Early diagnosis and treatment are crucial to improve outcomes.
Prevention is paramount, emphasizing strict adherence to sterile technique during surgery and meticulous wound care.
Treatment often requires a multidisciplinary approach involving infectious disease specialists, orthopedic surgeons, and rehabilitation therapists.
Even with appropriate treatment, PJI can be difficult to eradicate, and patients may require long-term antibiotic suppression or further surgery.