Wound Management Centers & Prosthetic Joint Infections: The Unlikeliest of Allies, or a Relationship Long Overdue?

  Modern day joint-replacement surgery was first performed in the US in the 1970s. Fast forward to 2009, and approximately 1 million primary total hip arthroplasties (THAs) and total knee arthroplasties (TKAs) had been performed in this country (332,000 and 719,000 respectively), according to the 2010 National Hospital Discharge Survey. Considered a relatively low-risk surgical procedure today, artificial replacement of hip and knee joints are used to increase mobility and eliminate chronic pain caused by arthritic or severely injured joints. It is estimated that by the year 2030, these numbers will increase to almost 4 million per annum, according to the Infectious Diseases Society of America (IDSA).   Despite the low risk involved, there are a variety of reasons why these surgeries can result in unexpected complications. One major concern remains infection. With respect to primary (first time) prosthetic joint (hip or knee) replacements, there is a 1-2% risk of deep infection occurring within the joint and contaminating the arthroplasty components over the lifetime of the prosthetic. That may not seem like many, but that figure translates to 10,000-20,000 patients. Of all total hip and total knee revisions that are conducted, 15-25% are needed as a result of infection while 7% of the revisions needed for reasons other than infection will go on to become infected. With the changes thus far realized with the implementation of healthcare reform, particularly facility non-payment of certain readmissions, wound management centers have an opportunity to emerge as a potential solution for optimizing outcomes in patients presenting with possible prosthetic joint infection (PJI). Likewise, hospital systems may avoid potential financial hardships due to delayed recognition and treatment of PJIs.

PJI in the Wound Clinic

  Chances are that most wound care providers have evaluated patients presenting to the wound clinic with what could be PJI of the hip or knee. A typical patient could be a 70-year-old female just a few months removed from undergoing TKA or THA with a chief complaint of “drainage” along the incision scar line. The vast majority of the patients (men and women) treated by this author have not experienced true PJI. Rather, they had what turned out to be an obscured fistula within the scar tracking only into the subcutaneous space. More easily treated in the clinic setting, these kinds of wounds usually heal well before deeper compartments become compromised.   Alternatively, this scenario can unfold differently. For instance: Patient presents to the wound clinic and receives an unrevealing assessment of the surgical site and is referred to the surgeon who also doesn’t appreciate the fistula. Because the patient is otherwise considered to have a low probability of having PJI, no further workup is pursued and the patient is prescribed empiric oral systemic antibiotics. One problem with this scenario is that the patient may have PJI and not necessarily look much different from those without PJI — each likely will experience vague, protean symptoms such as persistent stiffness, soreness, and/or erythema that may persist longer than 1 week. Additionally, it is not at all uncommon for patients to develop PJIs, yet present to the healthcare system weeks (or even years) after the prosthesis was implanted. However, the astute clinician should carefully assess the patient for symptoms and physical findings that could place one in a higher-risk category for having a PJI. The patient’s surgeon should then immediately be notified of the situation so that a more direct and specific care plan can be initiated. If morbidity and mortality associated with any PJI or subsequent revision or staged procedure is to be minimized, establishing and delivering a patient-specific plan of care is imperative.   Within the last five years, there have been several well-written guidelines published that discuss diagnosing and treating hip and knee PJI. Although they do represent different schools of thought, they share one basic recommendation — collaboration among all involved medical and surgical specialists. As a wound-management provider, becoming familiar with the latest guidelines for diagnosing and managing PJI will not only expedite proper patient care, it will also secure your practice’s position as a proactive member of the local healthcare community.

Review of PJI Guidelines

  In response to the CDC surveillance authority and the orthopedic community’s collective frustration regarding the lack of a standard definition for PJI, the Musculoskeletal Infection Society (MSIS) convened a 21-member workgroup in 2011 to propose the following as criteria for defining PJI:     1. A sinus tract communicating with the prostheses; or     2. A pathogen isolated by culture from 2 separate tissue or fluid samples obtained from the affected prosthetic joint; or     3. Of the following 6 criteria, 4 exist (although fewer than 4 may not be exclusive):       a. Elevated serum erythrocyte sedimentation rate (ESR) or serum C-reactive protein concentration (CRP);       b. Elevated synovial white blood cell (WBC) count;       c. Elevated synovial neutrophil percentage;       d. Presence of purulence in the affected joint;       e. Isolation of a microorganism in 1 culture of periprosthetic tissue or fluid (3-5 samples should be submitted for aerobic and anaerobic environments);       f. Greater than 5 neutrophils per high-power field in 5 high-power fields observed from histologic analysis of periprosthetic tissue at 400-times magnification.   Caveats in the MSIS definition of PJI include: Isolation of a single low-virulence pathogen in the absence of other criteria is not believed to represent a definite infection and histopathology examination of the periprosthetic tissues for the presence of WBCs by a specially trained musculoskeletal pathologist.   In 2012, IDSA published “Diagnosis and Management of Prosthetic Joint Infection: Clinical Practice Guidelines by the Infectious Diseases Society of America.”¹ The American Academy of Orthopedic Surgeons’ (AAOS) most recent guideline “The Diagnosis of Periprosthetic Joint Infections of the Hip and Knee” was published in June 2010.² Each guideline set is based on a panel consensus opinion from exhaustive reviews of published clinical and basic science research. Expert opinion was referenced in areas lacking sufficient published data. It should also be noted that the differences between these two guidelines are based on each panel’s area of expertise. The AAOS and IDSA are in general agreement that supports obtaining an initial complete blood count with differential; CRP, ESR, and plain radiograph when patients present with a possible PJI. Additionally, each group supports obtaining initial cultures after patients have been taken off antibiotics and are clinically stable for at least 2 weeks. The IDSA supports collecting aerobic and anaerobic blood cultures if fever is present; if there is acute onset of symptoms; or if the patient is living with a condition, suspected condition, concomitant infection, or pathogen (highly virulent) that would make the presence of a bloodstream infection more likely, as well as obtaining a diagnostic arthrocentesis on all patients with a suspected acute PJI. Unless the diagnosis is evident clinically, surgery is planned and antimicrobials can be safely withheld prior to surgery. Performing crystal analysis on synovial fluid aspirate if indicated clinically and sending intraoperative histopathological synovial and periprosthetic tissues for examination are also recommended by the IDSA. The AAOS supports joint aspirations of patients being evaluated for periprosthetic knee infections who have abnormal ESR and/or CRP results. However, a selective approach based on probability of having a periprosthetic infection is utilized for guiding the decision of aspiration and culture for prosthetic hip evaluation.AAOS authors (see Table) recommend repeat hip aspiration when there is a discrepancy between the probability of the periprosthetic joint infection and the initial aspiration culture.   Also, in the absence of reliable evidence, the AAOS workgroup recommends re-evaluating patients who would be considered “lower probability” and who have normal ESR and CRP values and in whom no re-operation is planned every 3 months. In patients undergoing re-operation but in whom the diagnosis of PJI has not been established or excluded, AAOS recommends use of a frozen section of peri-implant tissues as an additional means to determine whether the patient has a PJI as other reasons for implant failure should be assessed.   Finally, there is agreement from all workgroups that current research gaps still include epidemiology, diagnostics, management, and prevention of PJIs. The current system of healthcare delivery and management of care for patients undergoing evaluation and treatment of PJI, with or without surgical revisions, can be unnecessarily burdensome for all involved parties. For surgeons, these situations may require more time in the exam room trying to determine exactly what is going on in an otherwise healthy postoperative patient, or, more importantly, exposing the patient to an otherwise unnecessary surgical re-exploration of the affected joint. Hospital systems realize unnecessary risks when patients are unnecessarily readmitted, particularly if the patient undergoes any evaluation under anesthesia. However, the most important burden is endured by patients who find themselves in the crosshairs of all those tasked with managing their care. By becoming familiar with available association guidelines, surgical and medical expert recommendations, and becoming more proactive in the integration of these methods into daily practice, wound care providers can help improve outcomes and lessen morbidity and mortality for at-risk patients who are undergoing evaluation of possible THA and TKA revision and/or exploration surgeries.

Resources

1. Diagnosis and Management of Prosthetic Joint Infections: Clinical Practice Guidelines by the Infectious Diseases Society of America. 2. www.aaos.org/news/aaosnow/nov11/clinical1.asp. 3. American Academy of Orthopedic Surgeons Clinical Practice Guidelines Unit 2010. 4. Orthopedics Today. A Useful Guideline for Diagnosis of Periprosthetic Joint Infection. Harriet Jones is on staff at the University of Mississippi Medical Center and TWC editorial board member.