Prevalence, interpretation, and management of unexpected positive cultures in revision TKA: a systematic review

Abstract

PurposeUnexpected positive intraoperative cultures (UPIC) found in revision total knee arthroplasty (TKA) are difficult to interpret. Management goes along with risks for both over‐ and undertreating a potential periprosthetic joint infection (PJI). The objective of this systematic review was to determine the prevalence of UPIC in revision TKA surgery, evaluate the diagnostic workup process and the postoperative treatment, and assess outcome regarding re‐revision rates. MethodsEvidence was gathered from Medline (PubMed) and Embase published from January 2000 until April 2021. Nine studies with data of UPIC in revision TKA and outcome after at least 2 years of follow‐up were identified. ResultsThe calculated prevalence of UPIC in aseptic knee revision surgery was 8.32%. However, the diagnostical approach differs as well as the used criteria to confirm PJI in presumed aseptic revision surgery. The work‐up generally consists of a serum C‐reactive protein and Erythrocyte Sedimentation Rate, joint fluid aspiration for culture and white blood cell count and formula, and radiographic imaging. Collection of intraoperative cultures is widely used, but inconsistent in sample amount and incubation time. Once a single UPIC is found, surgeons tend to treat it in different ways. Regarding re‐revision rates, the weighted arithmetic mean in the included studies was 18.45% in the unsuspected PJI group compared to 2.94% in the aseptic group. There also seems to be a trend towards higher re‐revision rates when a higher number of intraoperative cultures are positive. ConclusionThe interpretation of UPIC in revision TKA is of utmost importance since the decision whether to treat a UPIC as an unsuspected PJI has a major impact on implant survival and re‐revision rate. Different criteria are used to differentiate between unsuspected PJI and contamination in true aseptic failure, and the heterogeneity amongst the included papers impedes to state a clear recommendation, integrating not only quantitative findings, but also qualitative data such as virulence of the identified microorganism. Level of evidenceSystematic review, III.

Etiology of Total Knee Arthroplasty Revisions: A Two-Decade Institutional Perspective

“…The criteria used to establish PJI as the main cause in patients undergoing rTKA are also relevant in defining the infection rates in this population of patients. A recent study showed that more than 8% of patients undergoing aseptic rTKA had positive intraoperative cultures [ 50 ]. This finding shows that the ratio of infection in implant failures may be higher than considered in many studies and, at the same time, represents a challenge for the orthopedic surgeon in the management of these cases, as the decision to treat these patients or not may influence the rates of revision and implant survival [ 50 ].…”

“…A recent study showed that more than 8% of patients undergoing aseptic rTKA had positive intraoperative cultures [ 50 ]. This finding shows that the ratio of infection in implant failures may be higher than considered in many studies and, at the same time, represents a challenge for the orthopedic surgeon in the management of these cases, as the decision to treat these patients or not may influence the rates of revision and implant survival [ 50 ]. Moreover, new and advanced alternative methods for diagnosing infection can help correctly classify the reason for revision as PJI and not aseptic loosening; therefore, a shift in the results of recent studies subsequently reporting higher rates of PJI may be expected [ 51 ].…”

Alpha-defensin as a diagnostic tool in revision total knee arthroplasties with unexpected positive intraoperative cultures and unexpected culture negative intraoperative cultures

“…Moreover, there is no clear consensus on how to handle UPICs and UNICs [16, 22, 23, 28]. Over‐ as well as undertreatment of patients with UPICs and UNICs may affect morbidity, mortality, implant survival and subsequent re‐revision rates [16, 28].…”

“…These unexpected negative intraoperative cultures (UNIC) in clear infections can occur between 5 and 41% of the cases [3, 14]. In contrast, in 8.3–12.0% of presumed aseptic revisions, unexpected positive intraoperative culture/s (UPIC) can occur [10, 16, 26]. There is conflicting evidence on the clinical relevance of UPICs, which are often low‐virulent microorganisms [13, 26].…”

“…There is conflicting evidence on the clinical relevance of UPICs, which are often low‐virulent microorganisms [13, 26]. Moreover, there is no clear consensus on how to handle UPICs and UNICs [16, 22, 23, 28]. Over‐ as well as undertreatment of patients with UPICs and UNICs may affect morbidity, mortality, implant survival and subsequent re‐revision rates [16, 28].…”