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Management of Chronic Periprosthetic Joint Infection


Introduction

Chronic periprosthetic joint infection (PJI) is a devastating complication of hip and knee arthroplasty that leads to a significant increase in joint loss of function, morbidity, and mortality. The traditional assumption is that chronic PJI can be defined as an infection in a prosthetic joint that occurs greater than 4 weeks from the index procedure or, according to the Centers for Disease Control and Prevention (CDC), greater than 90 days after the patient’s index procedure. However, following the recommendations from the last International Consensus Meeting (ICM) on PJI, it is better to understand a chronic PJI as a continuum that leads to the establishment of biofilm. Chronic PJI can also occur as a result of late hematogenous spread in which duration of symptoms is variable and does not necessarily have an established time frame. The key to setting the goals of treatment in chronic PJI is to rely on understanding bacterial biofilms and the pathogenic mechanisms that make them resistant to regular antibiotic treatment and allow them to invade the implant, its bone interface and surrounding tissues, and how host and bacterial factors may affect treatment success. This has led to the coupling of surgical interventions with local and systemic antibiotic therapy to mechanically or chemically disrupt the biofilm and allow antibiotic therapy to further eradicate residual infection in the joint, including the soft tissues and the bone. The surgical treatment options available with the goal of controlling infection include debridement and implant retention (DAIR), and one-stage and two-stage procedures. The choice of treatment depends on the bacterial factors, host factors, and condition of the extremity in terms of the soft-tissue coverage and bone stock. Furthermore, targeted antibiotic therapy, based on cultures and antibiogram to known organisms, significantly improves treatment success. However, despite advances in our understanding of chronic PJI, pathophysiology, and advances in surgical techniques to address chronic infection, treatment failure remains common; a recent study has reported failure rates as high as 36%. Moreover, the 5-year mortality rate after acquiring PJI is about 21.12%, which is higher than some of the most common cancers. In failed cases, resection arthroplasty, amputation, and fusion procedures must be discussed with the patient. Chronic suppression with antibiotics is necessary in some selected cases, as we will discuss further. There are two types of factors and their grading, in addition to the type of bacteria that would guide the decision-making processes and the current available treatment methods for chronic PJI, that will be described in this book chapter: systemic host grade and local extremity grade.

Systemic Host Grade

Consideration of host factors and the condition of the patient’s extremity are integral to treatment success or failure in chronic PJI and can also help guide treatment selection. Systemic host compromising factors enlisted by McPherson et al. are as follows:

  • Age ≥80 years

  • Alcoholism

  • Chronic active dermatitis or cellulitis

  • Chronic indwelling catheter

  • Chronic malnutrition (albumin ≤3 g/dL)

  • Current nicotine use (inhalational or oral)

  • Diabetes (requiring oral agents and/or insulin)

  • Hepatic insufficiency (cirrhosis)

  • Immunosuppressive drugs (methotrexate, prednisone, cyclosporine, and the like)

  • Malignancy (history or active)

  • Pulmonary insufficiency (room air arterial blood gas O 2 <60%)

  • Renal failure requiring dialysis

  • Systemic inflammatory disease (rheumatoid arthritis, systemic lupus erythematosus)

  • Systemic immunocompromise from infection or disease

Host grade can be classified as A, B, or C based on the number of risk factors a patient has for potential treatment failure ( Table 28.1 ).

TABLE 28.1
McPherson Classification of Infection, Host, and Local Extremity Grading System
Category Systemic Host Grade Local Extremity Grade
Grade/Description A—Uncompromised 1—Uncompromised
B—Compromised (1–2 compromising factors) 2—Compromised (1–2 compromising factors)
C—Significant compromise (>2 factors) or 1 of the following:

  • Absolute neutrophil count <1000

  • CD4+ T cell count <100

  • Chronic active infection other site

  • Dysplasia or neoplasm of immune system

3—Significant compromise (>2 compromising factors)

Some modifiable host factors that must be addressed prior to initiating surgical treatment for chronic PJI include uncontrolled diabetes, low host neutrophil count (<1000 absolute neutrophil count [ANC]), CD4+ T cell count <100, active intravenous drug abuse, active hepatitis C virus, poor dentition, nicotine use, malnutrition with low serum albumin and prealbumin levels, chronic active infection at another site or joint, and neoplasm or inflammatory condition under treatment that compromises the host’s immune system. There are some mental conditions such anxiety and depression, or chronic use of narcotics that should be addressed as well if possible. Failure to address these factors leads to a significant increase in treatment failure regardless of the treatment chosen.

Local Extremity Grade

The local extremity or wound factors that must be taken into consideration when deciding what type of treatment to administer include soft-tissue loss from the active infection, prior debridements or trauma, large subcutaneous abscesses, prior periarticular fracture, prior local irradiation to wound areas, and vascular insufficiency (see Table 28.1 ). Local extremity (wound) compromising factors are as follows:

  • Active infection present >3 to 4 months

  • Multiple incisions (creating skin bridges)

  • Soft-tissue loss from prior trauma

  • Subcutaneous abscess >8 cm 2

  • Synovial cutaneous fistula

  • Prior periarticular fracture or trauma about the joint (especially crush injury)

  • Prior local irradiation to wound area

  • Vascular insufficiency to extremity (absent extremity pulses, chronic venous stasis disease, significant calcific arterial disease)

By taking a systematic approach to classifying host and extremity grade, a treatment algorithm can be selected, which has been developed by the senior author (CAH, Table 28.2 ).

TABLE 28.2
Treatment Algorithm for Periprosthetic Joint Infection Proposed by the Authors Based on the McPherson Classification
Treatment Relative Indications
Antibiotic suppression alone Host C with Extremity 1
I&D/DAIR Host A or B with Extremity 1
1-stage revision Host A or B with Extremity 1
2-stage revision Any host with any extremity
Arthrodesis Host A or B with Extremity 1
Amputation/Disarticulation Any host with Extremity 3
DAIR , debridement, antibiotics and implant retention; I&D , irrigation and debridement.

Treatment Options

PJI should be suspected in any patient with either a consistently painful total joint (hip or knee) or an acute onset of pain in a once pain-free hip or knee. The Musculoskeletal Infection Society (MSIS) criteria used to diagnose PJI, which was slightly modified in 2013, has been shown to have a sensitivity and specificity of 86.9% and 99.5%, respectively. In addition to the full history, physical examination, documentation of fixation state on radiographs, and data collection for the MSIS criteria, synovial fluid aspiration biomarkers such as alpha-defensin and leukocyte esterase have been shown to be very useful and accurate in immunosuppressed patients and patients using antibiotics at the time of joint aspiration. Revised diagnostic criteria were introduced during the last ICM in 2018 that have improved sensitivity and specificity when combined with alpha-defensin and D-dimer as adjuvant biomarkers. The main base of diagnosis of PJI is joint aspiration. In cases in which synovial fluid has not been obtained or the results are inconclusive, the next step is to repeat the aspiration. , Antibiotic-resistant bacteria—i.e., methicillin-resistant Staphylococcus aureu s (MRSA)—increase the chances of failure when treating PJI, especially when DAIR is used as the main treatment. Once the host and extremity grades have been established and the type of bacteria that is causing the infection has been identified, the most appropriate type of treatment will be chosen (see Table 28.2 ).

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