Managing periprosthetic joint infections (PJI)

November 11, 2024

While periprosthetic joint infection (PJI) affects 0.5-2% of joint replacement patients globally, its impact on a patient's health and quality of life can be catastrophic.

​​​Periprosthetic joint infection (PJI) is a severe and potentially life-threatening complication that can occur following a total hip or knee replacement surgery. While PJI is relatively rare, affecting about 0.5-2% of joint replacement patients globally, its impact on a patient's health and quality of life can be catastrophic, often requiring extensive medical intervention. 

Defining and diagnosing PJI
In diagnosing PJI, orthopedic specialists rely on criteria developed by the Musculoskeletal Infection Society (MSIS), which has been periodically revised since 2011. According to Dr Jeffrey Jaya Raj (pictured), a Consultant Orthopedic Surgeon at Sunway Medical Centre, symptoms like a sinus tract, elevated synovial white cell count (over 3,000), and high polymorphonuclear cell counts (above 80%) are significant indicators of infection. Lab tests, including erythrocyte sedimentation rate (ESR) and
C-reactive protein (CRP) levels, as well as imaging studies, help confirm the diagnosis. Dr Jeffrey presented on “Periprosthetic Joint Infection” at Sunway Medical Centre’s Orthopedic Symposium – The Art of Orthopedic Care & Management.
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Causes of PJI
PJI can arise from bacterial contamination during surgery, bacterial spread from distant infection sites, or from infected nearby tissues. Certain bacteria, such as Staphylococcus aureus and Staphylococcus epidermidis, are particularly prone to causing PJI due to their ability to form a biofilm around the implant, a protective layer that shields bacteria from antibiotics.

Key risk factors for PJI
Risk factors for PJI are divided into patient-related, surgical, and implant-specific factors. Obesity, diabetes, and weakened immune systems increase patient susceptibility, while surgical factors like prolonged operative time and poor surgical technique can also raise infection risk. Implant characteristics, including the type of material and method of fixation, further influence PJI risk.

Dr Jeffrey notes that risk factors can be classified into modifiable and non-modifiable categories. Modifiable factors, such as obesity and smoking, can be addressed before surgery, while non-modifiable risks include factors like age, genetic predispositions, and prior surgeries. Understanding and mitigating these risks pre-surgery can significantly impact a patient’s prognosis.

Clinical presentation and symptoms
Patients with PJI often experience joint pain, swelling, redness, fever, and other systemic symptoms. Joint drainage or pus discharge may also be present. Limited joint mobility, especially in flexion and extension, is another common indicator. Lab tests and imaging are used to assess inflammation levels and identify infection accurately.

The formation of biofilm is a significant challenge in treating PJI. This complex, polysaccharide-rich matrix allows bacteria to adhere to the implant surface and resist antibiotic treatment. Once biofilm forms—typically within two to fourteen days—it becomes nearly impossible to eliminate the infection without removing the implant. Dr Jeffrey emphasizes the importance of catching infections early to prevent biofilm formation.

Treatment options
Treatment for PJI generally begins with antibiotics tailored to cover both gram-positive and gram-negative bacteria. After identifying the specific pathogen through culture, a targeted antibiotic regimen can be applied. Surgical options include Debridement and Implant Retention (DAIR) if the infection is detected early, single-stage surgery to remove and immediately replace the implant, and two-stage surgery, which remains the gold standard for cases where infection is established. In two-stage surgery, the infected implant is removed, and a new one is placed after the infection has cleared, typically three months later.

Prevention strategies
Preventing PJI starts with effective preoperative, intraoperative, and postoperative protocols. Preoperative measures include thorough patient assessment and skin preparation, while intraoperative practices focus on maintaining sterile environments and reducing surgery duration. Postoperative care, such as diligent wound care and timely patient mobilization, further reduces infection risks.

Challenges in PJI management
Treating PJI presents several challenges, notably antibiotic resistance, recurrent infections, and the high financial costs associated with treatment. Dr Jeffrey underscores the need for accurate pathogen identification through culture tests to combat antibiotic resistance. Additionally, patient comorbidities and economic impacts make PJI management particularly complex and emphasize the value of preventive measures.

Studies indicate that PJI is a strong predictor of mortality, with a fourfold increase in one-year mortality rates compared to aseptic revision surgeries. Recent findings also suggest a distinct microbiome profile in osteoarthritic knees compared to non-osteoarthritic knees, with implications for infection prevention and future treatment strategies.

In conclusion, minimizing PJI risks requires a multifaceted approach involving patient screening, preoperative preparation, strict aseptic techniques, and early intervention. Techniques like DAIR and staged surgeries are essential for infection management. Future research into PJI's microbial profiles and biofilm prevention holds promise for improving patient outcomes and reducing healthcare costs.

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