A Single Positive Tissue Culture Increases the Risk of Rerevision of Clinically Aseptic THA: A National Register Study

Unsuspected Positive Intra-Operative Cultures in Aseptic Revision Hip Arthroplasty: Prevalence, Management, and Infection-Free Survivorship

BACKGROUND

This study aimed to describe the management and outcomes of aseptic revision total hip arthroplasty (arTHA) with unsuspected intraoperative positive cultures (UPCs) compared to those with sterile cultures.

METHODS

A single tertiary center's institutional database was retrospectively reviewed for arTHA from January 2013 to October 2023. Preoperative Musculoskeletal Infection Society scores were assigned to patients based on available infectious workup, and those who met the criteria for periprosthetic joint infection (PJI), received antibiotic spacers, or had less than 1-year follow-up were excluded. Patients were grouped and compared according to intraoperative culture results as follows: sterile cultures, one unexpected positive culture with a new organism, one UPC with the same organism as prior PJI, ≥ two UPCs with different organisms, and ≥ 2 UPCs with the same organism.

RESULTS

There was a total of 604 arTHAs included in this study, of which 0.8% [5 of 604] had ≥ two UPCs with different organisms, 1.5% [9 of 604] had ≥ two UPCs with the same organism, 9.8% [59 of 604] had one UPC with a new organism, 0.2% [one of 604] had one UPC with an organism from prior PJI, and 87.7% [530 of 604] of patients had sterile cultures. When comparing 5-year infection-free survival between patients who had one UPC with a new organism and sterile cultures, there was no difference (P = 0.40); however, patients who had ≥ two UPCs with different organisms (P < 0.001), patients who had ≥ two UPCs with the same organism (P = 0.001), and patients who had one UPC of an organism from prior PJI (P < 0.001) had statistically worse infection-free survival compared to patients with sterile cultures.

CONCLUSIONS

Infection-free survival at five years was similar between patients who had one UPC with a new organism and those who had sterile cultures; however, ≥ two UPCs and a history of PJI are both significant risk factors for rerevision for infection after arTHA.

Postoperative antibiotic treatment does not lower re-revision rate in presumed aseptic hip and knee revision arthroplasties with unexpected positive intraoperative cultures - a matched cohort study

Aims: It remains unclear if postoperative antibiotic (AB) treatment is advantageous in presumed aseptic revision arthroplasties of the hip (rTHA) and knee (rTKA) with unexpected positive intraoperative cultures (UPIC). The aim of this study is to evaluate if there is a difference in the re-revision rate in patients with UPIC when treated with postoperative AB or when postoperative AB is withheld. Methods: In this retrospective matched cohort study we compared the re-revision rates in rTHA and rTKA with (AB group: 45 rTHA, 25 rTKA) and without (non-AB group: 45 rTHA, 25 rTKA) AB treatment in patients with UPIC. Baseline covariates for matching were the microorganism (likely or not likely to be a contaminant), patient demographics, joint, revision type, surgical site infection score, American Society of Anesthesiologists classification, serum C-reactive protein (CRP). Results: After a median follow-up of 4.1 (inter-quartile range, IQR: 2.9-5.5) years after rTHA and rTKA, the re-revision rate between the AB group and the non-AB group was 14.3 % versus 15.7 % (P=0.81). In the AB group, 4.3 % (3/70) of patients underwent revision due to septic complications compared to 5.7 % (4/70) in the non-AB group (P=0.69). None of the patients were diagnosed with a confirmed periprosthetic joint infection (PJI) according to the PJI diagnostic criteria of European Bone and Joint Infection Society (EBJIS). In 22/70 (31.4 %) of the patients in the AB group and in 15/70 (21.4 %) of the patients in the non-AB group, a diagnosis of "infection likely" was made according to the EBJIS criteria (P=0.18). All UPICs with low virulent microorganisms were considered to be contamination (coagulase-negative Staphylococci; Corynebacterium; anaerobic Gram-positive bacilli and cocci, e.g., Finegoldia magna, Cutibacterium acnes). Conclusion: Postoperative AB treatment did not result in a decreased re-revision rate in patients with UPIC in presumed aseptic rTHA and rTKA. Patients diagnosed with pathogens classified as a likely contaminant can be safely ignored.

Prognostic Implications of Unexpected Positive Intraoperative Cultures in Two-Stage Knee Arthroplasty Reimplantations: A Minimum Five-Year Retrospective Analysis

BACKGROUND

The clinical challenge of unexpected positive intraoperative cultures (UPICs) persists in 2-stage resection arthroplasty for managing periprosthetic joint infections (PJIs) following total knee arthroplasty.(TKA). This study aimed to investigate the incidence of UPICs during the definitive reimplantation phase of 2-stage resection arthroplasty of the knee and to assess both the infection-free and revision-free survivorship of the implanted prosthesis.

METHODS

This retrospective study included 450 2-stage resection arthroplasties of primary knee prostheses performed between January 2012 and April 2017. Patients were excluded if they: (1) underwent three or more staged resections, (2) had ambiguous clinical documentation or deviated from the 2-stage protocol, or (3) underwent revision arthroplasty prior to the PJI. Additionally, patients presumed aseptic before the second-stage reimplantation were excluded if they lacked joint aspiration or met the 2011 Musculoskeletal Infection Society criteria for PJI before implantation.

RESULTS

After exclusions, 300 patients were analyzed. Among them, 14% had UPIC during the second-stage reimplantation. The follow-up time was 2,316 (range, 1,888 to 3,737) days and 2,531 (range, 1,947 to 3,349) days for UPIC and negative intraoperative culture (NIC) groups, respectively. Rerevision due to subsequent PJI occurred in 26.2% of UPIC patients and 15.1% of NIC patients. The 2-year infection-free survival rates for the NIC, one UPIC, and ≥ two UPIC cohorts were 99.5, 98.2, and 94.3%, respectively, while the 5-year survival rates were 92.1, 91.1, and 54.3%, respectively. The unfavorable survivorship was significantly different in multiple UPIC cases (P < 0.001). Multiple UPICs with pathogens consistent with the first-stage findings were strongly associated with the risk of reinfection (P < 0.001).

CONCLUSIONS

An UPIC was identified in 14% of second-stage reimplantations. Patients who had multiple UPICs demonstrated truncated survivorship and suboptimal outcomes relative to the NIC and single UPIC cohorts, especially with pathogen consistency to the first-stage surgery.

LEVEL OF EVIDENCE

III.

Prevalence and Impact of Unexpected Positive Intraoperative Cultures in Total Hip or Knee Revision Surgery

BACKGROUND

Our aim was to evaluate the prevalence and impact of unexpected positive intraoperative cultures (UPICs) on the outcome of presumed aseptic total knee and hip revision surgery.

METHODS

Data regarding patients who underwent elective total hip or knee revision surgery from January 2003 to July 2017 due to preoperatively presumed aseptic reasons was retrospectively reviewed. Partial revisions and patients who had follow-ups below 60 months were excluded from the study. In all surgeries, at least 3 intraoperative samples were taken for microbial culture. Failure was defined as the need for rerevision due to any cause at 5 years and/or the need for antibiotic suppressive therapy. Overall, 123 total hip and 431 total knee revisions were eligible for the study. All cases had at least a 5 years follow-up.

RESULTS

There were 420 cases (75.8%) that had all cultures negative, 108 (19.5%) had a single UPIC, and 26 (4.7%) had either ≥2 UPICs for the same microorganism or 1 UPIC for a virulent microorganism. This latter group was not associated with a significantly higher failure rate (2 of 26, 7.7%) compared to those in the aseptic group (54 of 528, 10.2%). Revisions performed within the first 24 months after primary implantation had a higher 5-years rerevision rate (19.3 versus 8.4%, P = .01), mainly attributable to aseptic causes.

CONCLUSIONS

Total hip and knee revisions with UPICs were not significantly associated with a higher rerevision risk at 5 years. Those revisions performed within the first 24 months after primary arthroplasty had a higher rate of any-cause failure.

Identification of preoperative predictive markers of periprosthetic joint infection in presumed aseptic revisions of total hip arthroplasty: a retrospective observational study

INTRODUCTION

Periprosthetic joint infections (PJIs) occur at a rate of 1-2% in primary arthroplasties and 4% in revisions, posing a significant healthcare challenge. PJI diagnosis is hindered by absence of a universally accepted diagnostic standard. The primary outcome was to develop a predictive model to identify patients at risk of developing unforeseen PJI subsequent to presumed aseptic revision of total hip arthroplasty (THA). The secondary aim was to determine the reintervention-free survival rate among aseptic patients and those presenting unexpected positive cultures.

METHODS

This study included all ascertained septic and presumed aseptic patients without mechanical causes of THA failure and with sufficient clinical and laboratory data. Patients with incomplete anamnestic data, mechanical loosening related causes, rheumatologic conditions, or immunosuppression were excluded. Univariable and multivariable logistic regression analyses identified preoperative predictive markers for unexpected hip PJI.

RESULTS

283 inpatients from a high volume referral center were recruited from 2016 to 2019. The predictive preoperative parameters related with hip PJI were: presence of comorbidities (OR: 0.28; 95% CI 0.10-0.78), erythrocyte sedimentation rate (OR: 1.02; 95% CI 1.00-1.03), leukocyte count (OR: 1.18; 95% CI 1.02-1.36) and prothrombin time (OR: 1.42; 95% CI 1.02-1.98). Gender, age, body mass index (BMI) and previous surgery were not significantly related with unexpected PJI. Overall, the Kaplan-Meier analysis estimated a reoperation-free survival rate at 36 months of 96% (CI 95%) for the aseptic and 98% (CI 95%) for the unexpected group; however, the relation between the two survival curves was not significant (p = 0.086).

CONCLUSIONS

Erythrocyte sedimentation rate, leukocyte count, and increased prothrombin time were risk factors for PJI, whereas comorbidities were associated with a lower risk. Further research is needed to understand this association fully. Larger datasets are recommended to explore the complex interplay between risk factors and PJI development.

Unexpected Positive Cultures in Presumed Aseptic Revision Total Hip Arthroplasty

Background:

Occult infection may be the underlying cause for a number of presumed aseptic revision total hip arthroplasty (THA) because certain periprosthetic joint infections (PJIs) can remain asymptomatic for years and present with component loosening and weight-bearing pain in the absence of any clinical signs and symptoms of infection. There is no consensus in the literature regarding the interpretation, treatment, and clinical outcomes of unexpected positive cultures (UPCs) during aseptic revision THA.

Methods:

Four main databases were searched between January 2000 and January 2023. By pooling the UPC rates from the included studies, an overall UPC rate was calculated. We examined variables reported in more than 2 articles for possible associations with UPC.

Results:

Twenty-two articles were included. UPC prevalence in presumed aseptic revision THA (7,449 cases) was 15.06% (95% confidence interval [CI]: 11.05-20.19). In regards to unexpected culture positivity and culture method or medium, conventional cultures reported a 17.2% incidence, implant sonication 19.6%, and polymerase chain reaction 12.6%. Coagulase-negative staphylococci and Cutibacterium acnes were the most common pathogens (prevalence [95% CI]: 54.4% [44.9%-63.6%] and 9.1% [5.1%-15.8%]). Polymicrobial cultures were observed in 11.6% [7.318.0%] of UPCs. UPC cases were found to include more males than culture-negative THA patients (odds ratio [OR] [95% CI]: 1.36 [1.02-1.83]). Age, body mass index, American Society of Anesthesiology, loosening, previous revision, diabetes mellitus, and rheumatoid arthritis did not show a significant association with UPC incidence (p > 0.05). The all-cause revision and PJI rate were significantly higher in those having an UPC (OR [95% CI]: 1.40 [1.09-1.80], p = 0.009 and OR [95% CI]: 1.97 [1.22-3.18], p = 0.005).

Conclusions:

Isolating organisms through intraoperative culture is common in patients undergoing aseptic revision THA. This diagnostic step is crucial to properly investigate and exclude the possibility of an occult PJI. It should be noted that our results are prone to limitations of the included studies; therefore, well-designed prospective research is highly suggested.

Level of Evidence:

Level III. See Instructions for Authors for a complete description of levels of evidence.

Undiagnosed Periprosthetic Infections in First-Time Aseptic Revision Hip Arthroplasties

Background: Unexpected infections diagnosed after intraoperative cultures in aseptic revision hip arthroplasties are infrequent, but the features and outcomes of culture-positive cases are still poorly understood. A single-center retrospective study was conducted to assess the following: (1) the incidence, (2) the profile of the cases, and (3) the outcomes of the revision hips performed for presumed aseptic reasons that became septic after intraoperative cultures. Methods: Instances of first-time aseptic revision hips (a retrospective cohort study) in the hospital database were reviewed. The revisions with the isolation of two phenotypically identical microorganisms in the intraoperative cultures were selected. The profile (bacteria, pre-operative markers) and the outcomes of the revisions (survival rates, complications, reasons for re-revision) were assessed. Results: Out of 424 cases of presumed aseptic revision hip arthroplasty, 19 patients (4.48%) were classified as septic. Staphylococcus epidermidis (9, 47.37%) was the most frequent microorganism. In three patients (15.8%), C-reactive protein and erythrocyte sedimentation rate values were higher, and in only one case (5.26%), C-reactive protein values and the white blood cell count were elevated. An antibiotic therapy was administered in every case. At a mean follow-up of 3.72 ± 2.18 years, three patients (15.79%) experienced complications (dislocation, pain without loosening, chronic suppressive antibiotic therapy) and two patients (10.53%) required re-revision for septic relapse (same microorganisms). The survival rate of the cohort was 89.47% (95% CI: 64.08-97.26) at 2 and 4 years. Conclusions: Missed periprosthetic infections rarely occurred in presumed aseptic revision hips. However, the outcomes are fair, and septic relapses are not uncommon.

Prevalence, risk factors, microbiological results and clinical outcome in unexpected positive intraoperative cultures in unclear and presumed aseptic hip and knee revision arthroplasties - A ten-year retrospective analysis with a minimum follow up of 2 years

Background

The aim of this study was to assess the prevalence, microbiological spectrum, risk factors, and clinical outcomes of unexpected-positive-intraoperative-cultures (UPIC) in presumed aseptic and unclear revision-total-hip-/knee-arthroplasties (rTHA and rTKA) compared to culture-negative (CN) revisions.

Methods

This study reviewed all International-consensus-meeting-2018 (ICM 2018) negative or inconclusive rTHA (n = 751) and rTKA (n = 679) performed at our institution from 2011 to 2020 with a minimum follow-up of two years. A Kaplan-Meier-analysis was performed to determine the septic and aseptic-free implant survival in cases with UPIC's and matched culture-negative cases. Patient demographics, risk factors, microbiological spectrum and clinical outcomes were evaluated.

Results

There were significantly more UPIC cases in rTHA 196/751 (26.1 %) compared to rTKA 113/679 (16.6 %); (p < 0.001). UPICs in rTKA and rTHA have a lower septic and aseptic implant-free-survival compared to CN revisions. Patients with a history of nickel allergy have a higher risk of an UPIC in rTHA and rTKA (p < 0.001). Septic re-revisions after UPIC had a significantly (H: p = 0.004; K: p = 0.030) shorter time period to the primary/previous surgery (H: 84 (IQR:41-797); K: 115 (IQR:55-446)) compared to patients with aseptic re-revisions after UPIC (H:1248 (IQR:178-3534); K: 827 (IQR:361-1183)).

Conclusion

UPICs have a higher rate of septic and aseptic failure than CN outcomes. UPICs are twice as common in rTHA compared to rTKA. Preoperative PJI workup reduces the UPIC rate. Nickel allergy is a risk factor for UPIC. Early revisions with UPICs after primary THA or TKA have a higher risk of septic failure.

The translational potential of this article

This article provides new information on revision rates for UPIC and potential risk factors for UPIC and its treatment failure.

The role of BioFire Joint Infection Panel in diagnosing periprosthetic hip and knee joint infections in patients with unclear conventional microbiological results

Aims

This study aimed to evaluate the BioFire Joint Infection (JI) Panel in cases of hip and knee periprosthetic joint infection (PJI) where conventional microbiology is unclear, and to assess its role as a complementary intraoperative diagnostic tool.

Methods

Five groups representing common microbiological scenarios in hip and knee revision arthroplasty were selected from our arthroplasty registry, prospectively maintained PJI databases, and biobank: 1) unexpected-negative cultures (UNCs), 2) unexpected-positive cultures (UPCs), 3) single-positive intraoperative cultures (SPCs), and 4) clearly septic and 5) aseptic cases. In total, 268 archived synovial fluid samples from 195 patients who underwent acute/chronic revision total hip or knee arthroplasty were included. Cases were classified according to the International Consensus Meeting 2018 criteria. JI panel evaluation of synovial fluid was performed, and the results were compared with cultures.

Results

The JI panel detected microorganisms in 7/48 (14.5%) and 15/67 (22.4%) cases related to UNCs and SPCs, respectively, but not in cases of UPCs. The correlation between JI panel detection and infection classification criteria for early/late acute and chronic PJI was 46.6%, 73%, and 40%, respectively. Overall, the JI panel identified 12.6% additional microorganisms and three new species. The JI panel pathogen identification showed a sensitivity and specificity of 41.4% (95% confidence interval (CI) 33.7 to 49.5) and 91.1% (95% CI 84.7 to 94.9), respectively. In total, 19/195 (9.7%) could have been managed differently and more accurately upon JI panel evaluation.

Conclusion

Despite its microbial limitation, JI panel demonstrated clinical usefulness by complementing the traditional methods based on multiple cultures, particularly in PJI with unclear microbiological results.

Positive Intraoperative Cultures in Cup Revisions of THA: What Happens to the Stem?

BACKGROUND

Positive intraoperative cultures (PICs) are encountered in some patients undergoing revision of the acetabular cup after a previous THA. It is unknown whether PIC of the cup indicates whether the stem is infected as well and what happens to the stem during follow-up.

QUESTIONS/PURPOSES

(1) What proportion of patients undergoing THA who undergo cup revision have PICs? (2) What is the survival of the stem during follow-up in cup revisions with PICs versus that of those with negative cultures? (3) Does antibiotic treatment of PIC of the cup prevent revision THA during follow-up?

METHODS

In this retrospective, comparative multicenter study, five surgeons at four centers performed 338 acetabular cup revisions between January 2015 and December 2017. After evaluating the data, we excluded one patient because of an incomplete dataset and 77 patients because fewer than three intraoperative cultures were obtained during surgery, leaving 260 patients for analysis. Follow-up was 2 years. Patients were stratified into three cohorts: no PIC, one PIC, and two or more PICs.

RESULTS

The proportion of patients with one or more PIC was 15% (39 of 260). A total of 8% (21 of 260) had one and 7% (18 of 260) had two or more PICs. Stem survival was lower in patients with two or more PICs, but stem revision for periprosthetic joint infection was similar between groups. Two-year survival, which was defined as freedom from revision for any cause or infection, was 97% (95% confidence interval 95% to 99%) in the group without PICs, 100% (95% CI 95% to 100%) in the group with one PIC, and 86% (95% CI 68% to 100%; p = 0.08) in the group with two or more PICs. None of the patients in the no PIC and one PIC groups were treated with antibiotics. In the two or more PICs cohort, 12 of 18 patients were treated. The stem survived in one of 12 patients treated with antibiotics versus two of six patients who were not treated with antibiotics.

CONCLUSION

When treated with antibiotics, more than two PICs isolated during cup revision surgery do not have a major impact on survival of the stem during follow-up. A larger cohort of patients with PICs during cup revision might confirm these findings.

LEVEL OF EVIDENCE

Level III, therapeutic study.

A machine learning-based model for "In-time" prediction of periprosthetic joint infection

Background

Previous criteria had limited value in early diagnosis of periprosthetic joint infection (PJI). Here, we constructed a novel machine learning (ML)-derived, "in-time" diagnostic system for PJI and proved its validity.

Methods

We filtered "in-time" diagnostic indicators reported in the literature based on our continuous retrospective cohort of PJI and aseptic prosthetic loosening patients. With the indicators, we developed a two-level ML model with six base learners including Elastic Net, Linear Support Vector Machine, Kernel Support Vector Machine, Extra Trees, Light Gradient Boosting Machine and Multilayer Perceptron), and one meta-learner, Ensemble Learning of Weighted Voting. The prediction performance of this model was compared with those of previous diagnostic criteria (International Consensus Meeting in 2018 (ICM 2018), etc.). Another prospective cohort was used for internal validation. Based on our ML model, a user-friendly web tool was developed for swift PJI diagnosis in clinical practice.

Results

A total of 254 patients (199 for development and 55 for validation cohort) were included in this study with 38.2% of them diagnosed as PJI. We included 21 widely accessible features including imaging indicators (X-ray and CT) in the model. The sensitivity and accuracy of our ML model were significantly higher than ICM 2018 in development cohort (90.6% vs. 76.1%, P = 0.032; 94.5% vs. 86.7%, P = 0.020), which was supported by internal validation cohort (84.2% vs. 78.6%; 94.6% vs. 81.8%).

Conclusions

Our novel ML-derived PJI "in-time" diagnostic system demonstrated significantly improved diagnostic potency for surgical decision-making compared with the commonly used criteria. Moreover, our web-based tool greatly assisted surgeons in distinguishing PJI patients comprehensively.

Level of evidence

Diagnostic Level III.

Clinical and laboratory predictors for prosthetic joint infection within the first postoperative days following primary total hip and knee arthroplasty

PURPOSE

To identify clinical and laboratory predictors for low- and high-grade prosthetic joint infection (PJI) within the first postoperative days following primary total hip/knee arthroplasty (THA/TKA).

METHODS

Institutional bone and joint infection registry of a single osteoarticular infection referral centre was reviewed to identify all osteoarticular infections treated between 2011 and 2021. Among them were 152 consecutive PJI (63 acute high-grade PJI, 57 chronic high-grade PJI, and 32 low-grade PJI) who also had primary THA/TKA performed at the same institution, which were retrospectively analyzed with multivariate logistic regression and covariables.

RESULTS

For each additional day of wound discharge, persistent wound drainage (PWD) predicted PJI in the acute high-grade PJI group with odds ratio (OR) 39.4 (p = 0.000, 95%CI 1.171-1.661), in the low-grade PJI group with OR 26.0 (p = 0.045, 95%CI 1.005-1.579), but not in the chronic high-grade PJI group (OR 16.6, p = 0.142, 95%CI 0.950-1.432). The leukocyte count product of pre-surgery and POD2 >100 predicted PJI in the acute high-grade PJI group (OR 2.1, p = 0.025, 95%CI 1.003-1.039) and in the chronic high-grade PJI group (OR 2.0, p = 0.018, 95%CI 1.003-1.036). Similar trend was also seen in the low-grade PJI group, but was not statistically significant (OR 2.3, p = 0.061, 95%CI 0.999-1.048).

CONCLUSIONS

The most optimal threshold value for predicting PJI was observed only in the acute high-grade PJI group, where PWD >three days after index surgery yielded 62.9% sensitivity and 90.6% specificity, whereby the leukocyte count product of pre-surgery and POD2 >100 showed 96.9% specificity. Glucose, erythrocytes, hemoglobin, thrombocytes, and CRP showed no significant value in this regard.

Effect of single versus multiple prophylactic antibiotic doses on prosthetic joint infections following primary total hip arthroplasty in patients with osteoarthritis at public and private hospitals in Denmark: protocol for a nationwide cross-over, cluster randomised, non-inferiority trial [The Pro-Hip-Quality Trial]

INTRODUCTION

A feared complication after total hip arthroplasty (THA) is prosthetic joint infection (PJI), associated with high morbidity and mortality. Prophylactic antibiotics can reduce the risk of PJI. However, there is no consensus on the dosages and current recommendations are based on a low evidence level. The objective is to compare the effect of a single versus multiple doses of prophylactic antibiotics administered within 24 hours on PJI.

METHODS AND ANALYSIS

The study is designed as a cross-over, cluster randomised, non-inferiority trial. All clinical centres use both antibiotic practices (1 year of each intervention). All Danish orthopaedic surgery departments will be involved: Based on quality databases, 2-year cohorts of approximately 20 000 primary THAs conducted at 39 public and private hospitals, will be included.

INCLUSION CRITERIA

age ≥18 years, all indications for THA except patients operated due to acute or sequelae from proximal femoral or pelvic fractures or bone tumour or metastasis. The primary outcome is PJI within 90 days after primary THA. Secondary outcomes include (1) serious adverse events, (2) potential PJI, (3) length of hospitalisation stay, (4) cardiovascular events, (5) hospital-treated infections, (6) community-based antibiotic use, (7) opioid use and (8) use of acetaminophen and non-steroidal anti-inflammatory drugs. All outcome measures will be extracted from national databases. Analyses will be based on the intention-to-treat population. Non-inferiority will be shown if the upper limit of the two-sided 95% CI for the OR is less than 1.32 for the single dose as compared with multiple doses. The results will establish best practice on antibiotic prophylaxis dosages in the future.

ETHICS AND DISSEMINATION

This study has been approved by Committees on Health Research Ethics for The Capital Region of Denmark (21069108) and The Danish Medicines Agency (2021091723). All results will be presented in peer-reviewed medical journals and international conferences.

TRIAL REGISTRATION NUMBER

NCT05530551.

Unexpected Positive Cultures in Patients Who Have a History of Septic Revision in the Same Joint

BACKGROUND

The prevalence of unexpected positive cultures (UPC) in an aseptic revision surgery of the joint with a prior septic revision in the same joint remains unknown. The purpose of this study was to determine the prevalence of UPC in that specific group. As secondary outcomes, we explored risk factors for UPC.

METHODS

This retrospective study includes patients who had an aseptic revision total hip/knee arthroplasty procedure with a prior septic revision in the same joint. Patients who had less than 3 microbiology samples, without joint aspiration or with aseptic revision surgery performed <3 weeks after a septic revision were excluded. The UPC was defined as a single positive culture in a revision that the surgeon had classified as aseptic according to the 2018 International Consensus Meeting. After excluding 47, a total of 92 patients were analyzed, who had a mean age of 70 years (range, 38 to 87). There were 66 (71.7%) hips and 26 (28.3%) knees. The mean time between revisions was 83 months (range, 31 to 212).

RESULTS

We identified 11 (12%) UPC and in 3 cases there was a concordance of the bacteria compared to the previous septic surgery. There were no differences for UPC between hips/knees (P = .282), diabetes (P = .701), immunosuppression (P = .252), previous 1-stage or 2-stages (P = .316), causes for the aseptic revision (P = .429) and time after the septic revision (P = .773).

CONCLUSION

The prevalence of UPC in this specific group was similar to those reported in the literature for aseptic revisions. More studies are needed to better interpret the results.

The Role of Single Positive Cultures in Presumed Aseptic Total Hip and Knee Revision Surgery-A Systematic Review of the Literature

(1) Background: Prior to revision hip (THA) or knee arthroplasty (TKA), periprosthetic low-grade infection (PJI) should be ruled out. Despite advances in preoperative diagnosis, unsuspected positive cultures (UPCs) may occur in initially planned aseptic revisions. Particularly, single UPCs pose a diagnostic and therapeutic dilemma, as their impact on outcome is unclear and recommendations are heterogeneous. This review investigates the frequency of single UPCs and their impact on implant survivorship. (2) Methods: In July 2022, a comprehensive literature search was performed using PubMed and Cochrane Library search. In total, 197 articles were screened. Seven retrospective studies with a total of 5821 cases were able to be included in this review. (3) Results: Based on the cases included, UPCs were found in 794/5821 cases (14%). In 530/794 cases (67%), the majority of the UPCs were single positive. The most commonly isolated pathogens were coagulase negative Staphylococci and Cutibacterium acnes. Five of seven studies reported no influence on revision- or infection-free survival following a single positive culture. In two studies, single UPCs following THA revision were correlated with subsequent re-revision for PJI. (4) Conclusions: Single UPCs of a non-virulent pathogen following presumed aseptic TKA revision may be interpreted as contaminants. A single UPC following THA revision may be a risk factor for subsequent PJI. The role of systemic antibiotic treatment remains unclear, but it should be considered if other risk factors for PJI are present.

Do Cultures Obtained During Primary THA Predict the Likelihood of Revision?

BACKGROUND

There can be unexpectedly positive culture results during elective hip arthroplasty, but the degree to which these are associated with an increased risk of subsequent premature revision is not known.

QUESTION/PURPOSE

Are unexpectedly positive culture results obtained during elective THA associated with an increased likelihood of revision within 5 years of the procedure?

METHODS

Between March 2007 and March 2011, the hip unit at our institution performed elective primary THA in 829 patients. We systematically collected three samples in 52% (428 of 829) of the interventions. Of those, 26 patients were excluded because of sampling errors; 94% (402 of 428) had samples that were collected systematically and were eligible for the study. We only considered one hip randomly in bilateral procedures (4% [15 of 428]); patients presenting with acute (< 3 months) periprosthetic joint infection undergoing open debridement (4% [16 of 402]) and patients who died before 5 years of follow-up (2% [seven of 402]) were excluded from the study, leaving 91% (364 of 402) eligible for analysis in this retrospective study of a previous prospective trial. No patient included in the final analysis was lost to follow-up within 5 years from the index surgery. The patient group consisted of 52% (188 of 364) women, with a mean ± SD age of 64.8 ± 13.9 years.

RESULTS

Positives culture results were associated with a higher risk of revision within 5 years of the index surgery. The proportion of revision surgery was higher in the group with positive culture results than in those with negative results (10% [eight of 77] versus 2% [seven of 290]; p = 0.01). The difference was mainly attributable to a higher proportion of aseptic loosening in those with positive culture results than in those with negative results (8% [six of 74] versus 1% [four of 290]; p = 0.01). After a multivariable analysis, the only independent variable associated with 5-year revision surgery was the presence of positive results during THA (odds ratio 4.9 [95% confidence interval 1.72 to 13.99]).

CONCLUSION

Our findings suggest that bacterial contamination during THA is associated with an increased likelihood of early revision. This higher risk of revision is mainly because of presumed aseptic loosening; thus, efforts should focus on the need to rule out infection. These results not only open new questions that should be answered in new prospective and well-designed studies, but also may help to better select patients to obtain a more favorable outcome after THA.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The European Bone and Joint Infection Society definition of periprosthetic joint infection is meaningful in clinical practice: a multicentric validation study with comparison with previous definitions

BACKGROUND AND PURPOSE

A new periprosthetic joint infection (PJI) definition has recently been proposed by the European Bone and Joint Infection Society (EBJIS). The goals of this paper are to evaluate its diagnostic accuracy and compare it with previous definitions and to assess its accuracy in preoperative diagnosis.

PATIENTS AND METHODS

We retrospectively evaluated a multicenter cohort of consecutive revision total hip and knee arthroplasties. Cases with minimum required diagnostic workup were classified according to EBJIS, 2018 International Consensus Meeting (ICM 2018), Infectious Diseases Society of America (IDSA), and modified 2013 Musculoskeletal Infection Society (MSIS) definitions. 2 years' minimum follow-up was required to assess clinical outcome.

RESULTS

Of the 472 cases included, PJI was diagnosed in 195 (41%) cases using EBJIS; 188 (40%) cases using IDSA; 172 (36%) using ICM 2018; and 145 (31%) cases using MSIS. EBJIS defined fewer cases as intermediate (5% vs. 9%; p = 0.01) compared with ICM 2018. Specificity was determined by comparing risk of subsequent PJI after revision surgery. Infected cases were associated with higher risk of subsequent PJI in every definition. Cases classified as likely/confirmed infections using EBJIS among those classified as not infected in other definitions showed a significantly higher risk of subsequent PJI compared with concordant non-infected cases using MSIS (RR = 3, 95% CI 1-6), but not using ICM 2018 (RR = 2, CI 1-6) or IDSA (RR = 2, CI 1-5). EBJIS showed the highest agreement between pre-operative and definitive classification (k = 0.9, CI 0.8-0.9) and was better at ruling out PJI with an infection unlikely result (sensitivity 89% [84-93], negative predictive value 90% [85-93]).

CONCLUSION

The newly proposed EBJIS definition emerged as the most sensitive of all major definitions. Cases classified as PJI according to the EBJIS criteria and not by other definitions seem to have increased risk of subsequent PJI compared with concordant non-infected cases. EBJIS classification is accurate in ruling out infection preoperatively.

Simple and inexpensive synovial fluid biomarkers for the diagnosis of prosthetic joint infection according to the new EBJIS definition

Introduction: diagnosis of periprosthetic joint infection (PJI) is challenging, as no single test has absolute accuracy. The purpose of this study was to assess the utility of different simple synovial biomarkers in the diagnosis of PJI as defined by the European Bone and Joint Infection Society (EBJIS). Methods: we retrospectively identified all patients undergoing revision hip or knee arthroplasty from 2013 to 2019 on our prospectively maintained database. Only patients with minimum required infection diagnostic workup were included in the study. Patients with comorbidities that may influence the accuracy of synovial biomarkers were excluded. Receiver operator characteristic (ROC) curves were utilised to assess the diagnostic utility of synovial fluid white blood cell (WBC) count, polymorphonuclear leukocyte percentage (PMN %), C-reactive protein (CRP), adenosine deaminase (ADA), and alpha-2-microglobulin (A2M). Results: in total, 102 patients met the inclusion criteria. Of these, 58 were classified as infection unlikely, 8 as infection likely, and 36 as infection confirmed. Synovial WBC count (area under the curve (AUC) 0.94) demonstrated the best utility for the diagnosis of PJI, followed by PMN % (AUC 0.91), synovial CRP (AUC 0.90), ADA (AUC 0.82), and A2M (AUC 0.76). We found added value in the combined interpretation of different biomarkers. We calculated high sensitivity and negative predictive value if at least two of them are negative and high specificity and positive predictive value if at least two are elevated. Conclusion: current results show that synovial fluid investigation is a useful tool for the diagnosis of PJI, and the combined interpretation of simple and inexpensive biomarkers demonstrated improved diagnostic accuracy.

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

PURPOSE

Unexpected-positive-intraoperative-cultures (UPIC) are common in presumed aseptic revision-total-knee-arthroplasties (rTKA). However, the clinical significance is not entirely clear. In contrast, in some presumably septic rTKA, identification of an underlying pathogen was not possible, so-called unexpected-negative-intraoperative-cultures (UNIC). The purpose of this study was to evaluate the potential use of synovial alpha-defensin (AD) levels in these patients.

METHODS

Synovial AD levels from 143 rTKAs were evaluated retrospectively from our prospectively maintained institutional periprostetic joint infection (PJI) biobank and database. The 2018-International Consensus Meeting (ICM) criteria was used to define the study groups. Samples from UPICs with a minimum of one positive intraoperative culture (ICM 2- ≥ 6) (n = 20) and UNIC's (ICM ≥ 6) (n = 14) were compared to 34 septic culture-positive samples (ICM ≥ 6) and 75 aseptic culture-negative (ICM 0-1). Moreover, AD-lateral-flow-assay (ADLF) and an enzyme-linked-immunosorbent-assay (ELISA) in detecting the presence of AD in native and centrifuged synovial fluid specimens was performed. Concentration of AD determined by ELISA and ADLF methods, as well as microbiological, and histopathological results, serum and synovial parameters along with demographic factors were analysed.

RESULTS

AD was positive in 31/34 (91.2%) samples from the septic culture-positive group and in 14/14 (100%) samples in the UNIC group. All UPIC samples showed a negative AD result. Positive AD samples were highly associated with culture positive and histopathological results (p < 0.001). No high-virulent microorganisms (0/20) were present in the UPIC group, compared to infected-group (19/34; 55.9%). High virulent microorganisms showed a positive AD result in 89.5% (17/19) of the cases. Methicillin resistant Staphylococcus epidermis (MRSE) infections had significantly higher AD levels than with methicillin susceptible S. epidermdis (MSSE) (p = 0.003). ELISA and ADLF tests were positive with centrifuged (8/8) and native (8/8) synovial fluid.

CONCLUSION

AD showed a solid diagnostic performance in infected and non-infected revisions, and it provided an additional value in the diagnosis of UPIC and UNIC associated to rTKAs. Pathogen virulence as well as antibiotic resistance pattern may have an effect on AD levels. Centrifugation of synovial fluid had no influence on ADLF results.

Changes of the microbiological spectrum and antibiotic resistance pattern in postoperative spinal implant infections with multiple culture-positive revision surgeries

BACKGROUND CONTEXT

In severe cases of postoperative spinal implant infections (PSII) multiple revision surgeries may be needed. Little is known if changes in the microbiological spectrum and antibiotic resistance pattern occur between revision surgeries.

PURPOSE

Analysis of the microbiological spectrum and antibiotic resistance pattern in patients with multiple revision surgeries for the treatment of PSII STUDY DESIGN: Retrospective database analysis.

PATIENT SAMPLE

Between 01/2011 and 12/2018, 103 patients underwent 248 revision surgeries for the treatment of PSII. Twenty patients (19.4%) who underwent multiple revision surgeries for PSII were included in this study.

OUTCOME MEASURES

Microbiological spectrum, antibiotic resistance pattern.

METHODS

A retrospective analysis of a prospectively maintained single center spine infection database was performed with a minimum follow-up of 3 years. Overall, 20 patients (six male/14 female) underwent 82 revisions for PSII (median 3; range 2-12). There were 55 of 82 (67.1%) procedures with a positive microbiological result. Microbiological analysis was performed on tissue and implant sonication fluid. Changes in microbial spectrum and antibiotic resistance pattern between surgeries were evaluated using Chi-Square and Fisher's exact test.

RESULTS

In total, 74 microorganisms (83.3% gram-positive; 10.8% gram-negative) were identified. The most common microorganisms were Staphylococcus epidermidis (18.9%) and Cutibacterium acnes (18.9%). All S. epidermidis identified were methicillin-resistant (MRSE). Overall, there were 15 of 55 (27.3%) polymicrobial infections. The microbiological spectrum changed in 57.1% (20/35) between the revision stages over the entire PSII period. In 42.9% (15/35) the microorganism persisted between the revision surgeries stages. Overall, changes of the antibiotic resistance pattern were seen in 17.4% (8/46) of the detected microorganisms, comparing index revision and all subsequent re-revisions. Moreover, higher resistance rates were found for moxifloxacin and for ciprofloxacin at first re-revision surgery compared with index PSII revision. Resistances against vancomycin increased from 4.5% (1/23) at index PSII revision to 7.7% (2/26) at first re-revision surgery.

CONCLUSIONS

Changes of the microbiological spectrum and the resistance pattern can occur in patients with severe PSII who require multiple revision surgeries. It is important to consider these findings in the antimicrobial treatment of PSII. The microbiological analysis of intraoperative tissue samples should be performed at every revision procedure for PSII.

Unsuspected Positive Cultures in Planned Aseptic Revision Knee or Hip Arthroplasty-Risk Factors and Impact on Survivorship

BACKGROUND

Unsuspected positive cultures (UPCs) may be found at the time of planned aseptic revision surgery and have previously been associated with decreased implant survival. However, reported rates vary greatly, and potential risk factors are widely unknown. This study investigates the rate of UPCs, implant survival, as well as potential risk factors for UPCs and revision.

METHODS

This is a retrospective, single-center study on 434 cases of total hip arthroplasty (THA 277) and knee revision arthroplasty (TKA 157) performed between 2010 and 2017. Microbiology culture results, revision-free survival (RFS) and infection-free (IFS) survival, and the potential impact of UPCs as well as patient- or procedure-related risk factors were investigated at a minimum follow-up of 24 months (median 41 months).

RESULTS

A total of 37% of patients had a positive culture (160/434). 27% (119/434) had a solitary positive culture, and 9% (41/434) had ≥2 positive cultures of the same species. Most commonly, coagulase-negative staphylococci were cultured. Overall, 32% (13/41) of patients with ≥2 positive cultures underwent revision for infection compared with 6% (17/274) of patients with negative cultures. RFS and IFS were reduced if ≥2 cultures were positive. Single positive cultures had no impact on RFS or IFS. Male sex, elevated serum C-reactive protein, and obesity were independently associated with finding ≥2 UPCs in revision THA.

CONCLUSION

Appearance of ≥2 UPCs in aseptic revision leads to reduced RFS and IFS. Males, obese patients, and patients with elevated serum C-reactive protein planned for THA revision should be considered for extended diagnostics to rule out periprosthetic joint infection.

Outcomes of patients with unexpected diagnosis of infection at total hip or total knee arthroplasty revisions

PURPOSE

The pre-operative differential diagnosis between periprosthetic joint infections (PJIs) and aseptic failure is challenging particularly in low virulence and biofilm-related infections. This study aimed to assess the incidence and survival of patients with unexpected PJIs in a presumed aseptic revision of total hip (THA) and knee (TKA) arthroplasties.

METHODS

A retrospective analysis of a prospective cohort of patients was performed with 295 patients undergoing THA (n = 241) or TKA (n = 54) revision for presumed aseptic causes. Patients were diagnosed with unexpected PJI taking into account leukocyte count in the synovial fluid, sonicate, synovial culture, and tissue cultures of samples collected during surgery. The primary endpoint was the infection-free implant survival rate at theone year follow-up.

RESULTS

The unexpected PJIs were 60 out of 295 (20.3%), whereas 235 (79.7%) were aseptic revisions. In the unexpected PJI group, 6 (11.1%) patients underwent knee revision and 54 (22.4%) hip revision. At the one year follow-up, one patient (1.6%) in the unexpected PJI group and 3 (1.3%) in the aseptic group (p = 1.0) failed for infection. The infection-free implant survival rate at the one year follow-up was 98.3% (C.I. 95%, 94.9-99.9%) for the unexpected PJI group and 98.7% (C.I. 95%, 97.3-99.9%) (p = 0.82) for the aseptic group.

CONCLUSION

The incidence of unexpected PJIs in a presumed aseptic revision of THAs and TKAs has been previously underestimated. The infection-free implant survival rate at the one year follow-up in patients with unexpected PJIs was not significantly lower compared with patients undergoing aseptic revision.

Unexpected low-grade infections in revision hip arthroplasty for aseptic loosening : a single-institution experience of 274 hips

AIMS

The purpose of this study was to evaluate unexpected positive cultures in total hip arthroplasty (THA) revisions for presumed aseptic loosening, to assess the prevalence of low-grade infection using two definition criteria, and to analyze its impact on implant survival after revision.

METHODS

A total of 274 THA revisions performed for presumed aseptic loosening from 2012 to 2016 were reviewed. In addition to obtaining intraoperative tissue cultures from all patients, synovial and sonication fluid samples of the removed implant were obtained in 215 cases (79%) and 101 cases (37%), respectively. Histopathological analysis was performed in 250 cases (91%). Patients were classified as having low-grade infections according to institutional criteria and Musculoskeletal Infection Society (MSIS) International Consensus Meeting (ICM) 2013 criteria. Low-grade infections according to institutional criteria were treated with targeted antibiotics for six weeks postoperatively. Implant failure was defined as the need for re-revision resulting from periprosthetic joint infection (PJI) and aseptic reasons. The mean follow-up was 68 months (26 to 95).

RESULTS

Unexpected positive intraoperative samples were found in 77 revisions (28%). Low-grade infection was diagnosed in 36 cases (13%) using institutional criteria and in nine cases (3%) using MSIS ICM 2013 criteria. In all, 41 patients (15%) had single specimen growth of a low-virulent pathogen and were deemed contaminated. Coagulase-negative Staphylococcus and anaerobes were the most commonly isolated bacteria. Implant failure for PJI was higher in revisions with presumed contaminants (5/41, 12%) compared to those with low-grade infections (2/36, 6%) and those with negative samples (5/197, 3%) (p = 0.021). The rate of all-cause re-revision was similar in patients diagnosed with low-grade infections (5/36, 14%) and those with presumed contaminants (6/41, 15%) and negative samples (21/197, 11%) (p = 0.699).

CONCLUSION

Our findings suggest that the presumption of culture contamination in aseptic revision hip arthroplasty may increase the detection of PJI. In this cohort, the presence of low-grade infection did not increase the risk of re-revision. Further studies are needed to assess the relevance of single specimen growth and the benefits of specific postoperative antibiotic regimens. Cite this article: Bone Joint J 2021;103-B(6):1070-1077.

Prevalence and Impact of Positive Intraoperative Cultures in Partial Hip or Knee Revision

BACKGROUND

Our aim is to investigate the impact of unexpected positive cultures on the outcome of partial prosthetic revisions.

METHODS

Data regarding patients who underwent a partial hip or knee revision from 2003 and 2012 with the preoperative diagnosis of aseptic loosening was retrospectively reviewed. The protocol of revision included at least 3 intraoperative cultures. Failure was defined as the need for re-revision due to aseptic or septic loosening at 5 years.

RESULTS

A total of 99 hip and 46 knee partial revisions were included. All cases had at least 5 years of follow-up. Ninety-seven cases (66.9%) had all cultures negative, 35 (24.1%) a single positive culture and 13 (9.0%) ≥2 positive cultures for the same microorganism. The median time from primary arthroplasty to partial revision was significantly shorter for patients with ≥2 positive cultures (26 months) than in those with all cultures negative (48 months) or with a single positive culture (51 months). Partial revisions performed within the first 5 years of implantation had a higher 5-year re-revision rate. The presence of a single positive culture during the partial exchange was not associated with a higher re-revision rate (2 of 35, 5.7%) than in those with negative cultures (3 of 97, 3.1%). On the contrary, re-revision rate was significantly higher in cases with ≥2 positive cultures (3 of 13, 23.1%) than in those with negative cultures (P = .02).

CONCLUSION

Partial revisions performed within the first 5 years from implantation and ≥2 intraoperative positive cultures were associated with a higher re-revision risk at 5 years.