PERIPROSTHETIC JOINT INFECTIONS (PJIs)
While infections after knee arthroplasty occur at low rates, roughly 1/100, periprosthetic joint infections (PJIs) pose serious complications to patients . For example, Bozic et al. found that infection was the causal factor of 25.2% of total knee arthroplasty revisions . Additionally, PJI may necessitate a course of antibiotics . Medications and surgical procedures needed to treat PJIs are a burden to patients and for healthcare systems . Understanding causes, symptoms, and preventative measures can equip patients with skills to navigate PJIs.
PJI can occur for different reasons. An infection could arise when contaminants are introduced directly or adjacent to an opening in the skin . Contaminants could also travel through the blood from a previous location . Another cause for PJI could be previous infection . When a foreign object, such as a prosthetic joint, is present, fewer bacteria are needed to cause infection . The presence of a prosthesis creates a location where bacteria can adhere and form a biofilm. Biofilms are communities of bacteria that allow the infection to evade the body’s immune system .
Certain factors put patients at a higher risk of developing PJI . These risk factors include existing skin infections, deep tissue infections, uncontrolled diabetes , and blood transfusions . Additionally, morbid obesity , smoking , and alcohol consumption  increase a patient’s risk of PJI. Furthermore, immunosuppressive therapies increase the likelihood of PJI , . While some of these risk factors are not modifiable, others, such as obesity or uncontrolled diabetes, can be addressed.
Symptoms of an infected surgical site vary based on length of time since the surgery. Infections that begin within 3 months of surgery may cause pain, swelling, wound drainage, and redness around the wound . Infections that begin between 3 and 12 months after surgery typically present with persistent joint pain and about 50% of patients have a fever . Infections that arise after 12 months are usually caused by contaminant spread via the blood from another part of the body  and will cause sudden onset symptoms at the joint . Any of these symptoms should be discussed with a physician to determine appropriate diagnosis and treatment.
Various steps can be taken before an operation and during an operation to reduce the likelihood of PJI . The use of chlorohexidine gluconate as a preoperative antiseptic has been shown to reduce the risk of PJI , . Current guidelines recommend that antibiotics are administered at least an hour before surgery and discontinued within 24 hours . Hair removal should be done immediately before surgery with clippers (rather than a razor) because hair removal with a razor causes microlesions and allows more growth of endogenous microorganisms that could potentially contaminate the surgical site . These measures taken by the healthcare team and by the patient will help decrease the risk of PJI.
Treatment options for PJI include debridement and two-stage exchange arthroplasty . Debridement is a procedure where infected tissue is surgically removed and irrigated before the wound is closed. The highest success rates are seen when debridement is performed in healthy patients within 30 days of infection onset caused by low virulence organisms , . However, the most common treatment for PJI is two-stage exchange arthroplasty . The first step of two-stage exchange arthroplasty involves implant removal, debridement, and placement of an antibiotic spacer . During the second step, the antibiotic spacer is removed and a new prothesis is placed after the joint is cleaned . The first and second steps typically occur six weeks apart to allow for adequate time for the infection to be treated .
These treatment options for PJI are invasive and a burden to patients and healthcare systems and therefore measures should be taken to reduce the likelihood of PJIs. Talk to your physician if you are experiencing any new symptoms after surgery. Your healthcare team will come up with a diagnosis and treatment plan that is right for you.
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