Selecting a high-dose antibiotic-laden cement knee spacer

Prosthetic joint infection [PJI] after total knee arthroplasty (TKA) remains a common and challenging problem for joint replacement surgeons and patients. Once the diagnosis of PJI has been made, patient goals and characteristics as well as the infection timeline dictate treatment. Most commonly, this involves a two-stage procedure with the removal of all implants, debridement, and placement of a static or dynamic antibiotic spacer. Static spacers are commonly indicated for older, less healthy patients that would benefit from soft tissue rest after initial debridement. Mobile spacers are typically used in younger, healthier patients to improve quality of life and reduce soft-tissue contractures during antibiotic spacer treatment. Spacers are highly customizable with regard to antibiotic choice, cement variety, and spacer design, each with reported advantages, drawbacks, and indications that will be covered in this article. While no spacer is superior to any other, the modern arthroplasty surgeon must be familiar with the available modalities to optimize treatment for each patient. Here we propose a treatment algorithm to assist surgeons in deciding on treatment for PJI after TKA.

Diagnostic performances and therapeutic impact of the Unyvero Implant and Tissue Infection multiplex PCR in periprosthetic joint infections

Aim: We evaluated the diagnostic performances of Unyvero Implant and Tissue Infection multiplex PCR (mPCR) (Curetis) and the clinical impact of this PCR on therapeutic decisions. Materials & methods: A mPCR was performed on 33 joint fluids in addition to standard culture. A group of experts analyzed a posteriori the impact of the mPCR in the patient management. Results: The rate of concordance with culture was 74% (20/27). The sensitivity of the PCR was 59% and the specificity 90%. Clinicians would have started an appropriate treatment sooner for six patients (from 2 to 22 days earlier). Conclusion: The PCR would improve the management of 22% of the patients. For other patients, mPCR results have to be completed with the culture.

It can be unnecessary to combine common synovial fluid analysis and alpha-defensin tests for periprosthetic joint infection diagnosis

BACKGROUND

Periprosthetic joint infection is a serious complication after total joint arthroplasty. Despite that alpha-defensin was used as diagnostic test in the 2018 ICM (international consensus meeting) criteria, its position in the PJI diagnostic pipeline was controversial. Therefore, we performed a retrospective pilot study to identify whether synovial fluid alpha-defensin test was necessary when corresponding synovial fluid analysis (WBC count, PMN% and LE tests) was performed.

METHODS

Between May 2015 and October 2018, a total of 90 suspected PJI patients who underwent revisions after TJA were included in this study. Based on the 2018 ICM criteria, the interobserver agreements between preoperative diagnostic results and postoperative diagnostic results and the interobserver reliability between preoperative diagnostic results and postoperative diagnostic results with or without synovial fluid alpha-defensin tests were calculated. After that, the ROC analysis, and the direct cost-effectiveness of adding alpha-defensin was performed.

RESULTS

There were 48,16 and 26 patients in the PJI group, inconclusive group and non-PJI group, respectively. Adding the alpha-defensin tests into 2018 ICM criteria can't change the preoperative diagnostic results, postoperative diagnostic results, and the concordance between preoperative and postoperative diagnostic results. Moreover, the Risk-benefit Ratio is over 90 per changed decision and the direct cost-effectiveness of alpha-defensin was more than $8370($93*90) per case.

CONCLUSIONS

Alpha-defensin assay exhibit high sensitivity and specificity for PJI detection as a standalone test based on the 2018 ICM criteria. However, the additional order of Alpha-defensin can't offer additional evidence for PJI diagnosis when corresponding synovial fluid analysis was performed (synovial fluid WBC count, PMN% and LE strip tests).

EVIDENCE LEVEL

Level II, Diagnostic study.

Rapid Diagnostics of Joint Infections Using IS-Pro

Diagnosis of bone and joint infections (BJI) relies on microbiological culture which has a long turnaround time and is challenging for certain bacterial species. Rapid molecular methods may alleviate these obstacles. Here, we investigate the diagnostic performance of IS-pro, a broad-scope molecular technique that can detect and identify most bacteria to the species level. IS-pro additionally informs on the amount of human DNA present in a sample, as a measure of leukocyte levels. This test can be performed in 4 h with standard laboratory equipment. Residual material of 591 synovial fluid samples derived from native and prosthetic joints from patients suspected of joint infections that were sent for routine diagnostics was collected and subjected to the IS-pro test. Bacterial species identification as well as bacterial load and human DNA load outcomes of IS-pro were compared to those of culture. At sample level, percent positive agreement (PPA) between IS-pro and culture was 90.6% (95% CI 85.7- to 94%) and negative percent agreement (NPA) was 87.7% (95% CI 84.1 to 90.6%). At species level PPA was 80% (95% CI 74.3 to 84.7%). IS-pro yielded 83 extra bacterial detections over culture for which we found supporting evidence for true positivity in 40% of the extra detections. Missed detections by IS-pro were mostly related to common skin species in low abundance. Bacterial and human DNA signals measured by IS-pro were comparable to bacterial loads and leukocyte counts reported by routine diagnostics. We conclude that IS-pro showed an excellent performance for fast diagnostics of bacterial BJI.

The role of sonication in the diagnosis of periprosthetic joint infection in total shoulder arthroplasty

An increased sensitivity of sonication compared to periprosthetic tissue cultures in the diagnosis of periprosthetic joint infection (PJI) of hip and knee arthroplasty has been reported. The goal of this study was to determine if there is also an added value of implant sonication in the diagnosis of PJI in total shoulder arthroplasty (TSA). A retrospective analysis of patients who underwent removal of their TSA combined with sonication of the implant for suspicion of PJI between April 2009 and August 2017 was performed. The diagnosis of PJI was based on the major criteria described by Parvizi. We calculated sensitivity, specificity, predictive values, likelihood ratios and diagnostic accuracy for sonication cultures in comparison with periprosthetic tissue cultures. Data from 41 patients were analysed. Standard synovial fluid cultures combined with intraoperative periprosthetic tissue cultures had a sensitivity of 95%, specificity of 95% and total accuracy of 95%. Sonication cultures had a sensitivity of 91%, specificity of 68% and total accuracy of 80%. Six patients had negative standard cultures but positive sonication cultures. In patients with only one positive standard culture, the pathogen of the sonication culture corresponded to the pathogen of the positive soft tissue culture. We found a possible added value of sonication of TSA in the diagnosis of PJI in conjunction with standard intraoperative cultures. In some patients with suspicion of low-grade TSA infection, sonication could identify a possible causal microorganism despite negative standard cultures.

Conservative Management First Strategy in Aortic Vascular Graft and Endograft Infections

OBJECTIVE

The aim of this study was to describe and present the outcomes of a specific treatment protocol for aortic vascular graft and endograft infections (VGEIs) without explantation of the infected graft.

METHODS

This was a retrospective, observational single centre cohort study carried out between 2012 and 2022 at a tertiary hospital. An aortic VGEI was defined according to the Management of Aortic Graft Infection Collaboration (MAGIC) criteria. Fitness for graft excision was assessed by a multidisciplinary team and included an evaluation of the patient's general condition, septic status, and anatomical complexity. Antimicrobial treatments were individualised. The primary outcome was survival at the last available follow up; secondary outcomes were antimicrobial treatment duration, infection eradication, treatment failure despite antimicrobial treatment, and the development of aortic fistulation.

RESULTS

Fifty patients were included in the study, of whom 42 (84%) had had previous endovascular repair. The median patient age was 72 years (range 51 - 82 years) and median duration of treatment with antimicrobials was 18 months (range 1 - 164 months). Kaplan-Meier analysis estimated the 30 day survival to be 98% (95% confidence interval [CI] 96 - 100), the one year survival rate to be 88% (95% CI 83.4 - 92.6), and the three year survival rate to be 79% (95% CI 72.7 - 84.7). Twenty-four (48%) patients were able to discontinue antibiotic treatment after a median of 16 months (range 4 - 81 months). When categorised according to infected graft location, deaths occurred in four (40%) patients with thoracic, two (40%) with paravisceral, seven (30%) with infrarenal VGEIs, and in one (25%) patient with an aorto-iliac VGEI; no (0%) patient with a thoraco-abdominal VGEI died.

CONCLUSION

Identifying the microbiological aetiology in patients with aortic VGEI enables individualised, specific antibiotic treatment, which may be useful in patients with a VGEI excluded from surgery. This single centre retrospective analysis of patients with VGEIs without fistula selected for conservative treatment suggests that conservative management of aortic VGEIs with targeted antibiotic therapy without graft excision is potentially effective, and that antimicrobial treatment will not necessarily be needed indefinitely.

Surgical technique and preliminary results of a moulded, mobile spacer for the treatment of periprosthetic joint infection of the knee

OBJECTIVE

Mobile knee spacers can be utilized in the first stage of a two-stage exchange in periprosthetic joint infection or septic arthritis of the knee to prevent soft tissue contraction, enable local antibiotic elution, and improve patient mobility. Commercially made moulds enable the surgeon to prepare a reproducible spacer design and match the preparation of the arthroplasty, which will be carried out in a second step.

INDICATIONS

Periprosthetic joint infection of the knee and severe cases of septic arthritis of the knee with advanced destruction/infiltration of the cartilage.

CONTRAINDICATIONS

Antibiotic resistance of the microbiological pathogen to available antibiotic agents, incompliant patient, large osseous defect preventing proper fixation, known allergy to polymethylmethacrylate (PMMA) or antibiotic, severe soft tissue damage with high ligament instability, especially deterioration of extensor mechanism and insufficient patella/quadricep tendon.

SURGICAL TECHNIQUE

After thorough debridement and removal of all foreign material, cutting blocks are used to shape femur and tibia to the implant design required. Using a silicone mould, PMMA with suitable antibiotics is moulded into the shape of the future implant. After polymerization, the implants are fixed onto the bone with additional PMMA without pressurize for the sake of easy removal.

POSTOPERATIVE MANAGEMENT

Partial weight bearing with no restriction of flexion/extension while spacer is in place; second stage reimplantation as soon as infection is controlled.

RESULTS

In all, 22 cases were treated, mostly with a PMMA spacer containing gentamicin and vancomycin. Pathogens were detected in 13 of 22 cases (59%). We observed two complications (9%). Twenty of 22 patients (86%) were reimplanted with a new arthroplasty; 16 of the 20 patients remained revision-free and infection-free at the last follow-up (average time to follow-up 13 months, range 1-46 months). Average range of motion in flexion and extension at follow-up was 98°.

A prospective study to identify preoperative serum parameters for spinal implant infection detected by sonication fluid culture

PURPOSE

Low-virulent microorganisms identified on pedicle screws by sonication fluid culture (SFC) are an important cause of implant loosening. While sonication of explanted material improves the detection rate, the risk of contamination exists and no standardized diagnostic criteria for chronic low-grade spinal implant-related infection (CLGSII) are stablished. Besides, the role of serum C-reactive protein (CRP) and procalcitonin (PCT) in CLGSII has not been adequately investigated.

METHODS

Blood samples were collected prior to implant removal. To increase sensitivity, the explanted screws were sonicated and processed separately. Patients exhibiting at least one positive SFC were classified in the infection group (loose criteria). To increase specificity, the strict criteria only considered multiple positive SFC (≥ 3 implants and/or ≥ 50% of explanted devices) as meaningful for CLGSII. Factors which might promote implant infection were also recorded.

RESULTS

Thirty-six patients and 200 screws were included. Among them, 18 (50%) patients had any positive SFCs (loose criteria), whereas 11 (31%) patients fulfilled the strict criteria for CLGSII. Higher serum protein level was the most accurate marker for the preoperative detection of CLGSSI, exhibiting an area under the curve of 0.702 (loose criteria) and 0.819 (strict criteria) for the diagnosis of CLGSII. CRP only exhibited a modest accuracy, whereas PCT was not a reliable biomarker. Patient history (spinal trauma, ICU hospitalization and/or previous wound-related complications) increased the likelihood of CLGSII.

CONCLUSION

Markers of systemic inflammation (serum protein level) and patient history should be employed to stratify preoperative risk of CLGSII and decide the best treatment strategy.

The synovial fluid calprotectin lateral flow test for the diagnosis of chronic prosthetic joint infection in failed primary and revision total hip and knee arthroplasty

PURPOSE

The diagnostic criteria of prosthetic joint infection (PJI) recommended by the most commonly used diagnostic algorithms can be obscured or distorted by other inflammatory processes or aseptic pathology. Furthermore, the most reliable diagnostic criteria are garnered during revision surgery. A robust, reliable addition to the preoperative diagnostic cascade is warranted. Calprotectin has been shown to be an excellent diagnostic marker for PJI. In this study, we aimed to evaluate a lateral flow test (LFT) in the challenging patient cohort of a national referral centre for revision arthroplasty.

METHODS

Beginning in March 2019, we prospectively included patients scheduled for arthroplasty exchange of a total hip (THA) or knee arthroplasty (TKA). Synovial fluid samples were collected intra-operatively. We used the International Consensus Meeting of 2018 (ICM) score as the gold standard. We then compared the pre-operative ICM score with the LFT result to calculate its diagnostic accuracy as a standalone pre-operative marker and in combination with the ICM score as part of an expanded diagnostic workup.

RESULTS

A total of 137 patients with a mean age of 67 (± 13) years with 53 THA and 84 TKA were included. Ninety-nine patients (72.8%) were not infected, 34 (25.0) were infected, and four (2.9%) had an inconclusive final score and could not be classified after surgery. The calprotectin LFT had a sensitivity (95% confidence interval) of 0.94 (0.80-0.99) and a specificity of 0.87 (0.79-0.93). The area under the receiver operating characteristic curve (AUC) for the calprotectin LFT was 0.94 (0.89-0.99). In nine cases with an inconclusive pre-operative ICM score, the calprotectin LFT would have led to the correct diagnosis of PJI.

CONCLUSIONS

The synovial fluid calprotectin LFT shows excellent diagnostic metrics both as a rule-in and a rule-out test, even in a challenging patient cohort with cases of severe osteolysis, wear disease, numerous preceding surgeries, and poor soft tissue conditions, which can impair the common diagnostic criteria. As it is available pre-operatively, this test might prove to be a very useful addition to the diagnostic algorithm.

The Choice of Antibiotic Prophylaxis Influences the Infection Reoperation Rate in Primary Shoulder Arthroplasty: Analysis From the Swedish Shoulder Arthroplasty Register

BACKGROUND

Periprosthetic joint infection is a serious complication and a major reason for revision surgery after primary shoulder arthroplasty. The prophylactic antibiotics for primary shoulder arthroplasty that have predominantly been used in Sweden are cloxacillin and clindamycin. To address Cutibacteriumacnes , benzylpenicillin has recently increasingly been added to cloxacillin, but it is unclear which antibiotic prophylaxis regimen is the most effective to prevent periprosthetic joint infection.

QUESTIONS/PURPOSES

After controlling for baseline differences among patients such as age, gender, previous surgery, cement fixation, and arthroplasty type, was the risk of reoperation for infection higher in patients who received cloxacillin than in those who received clindamycin or the combination of benzylpenicillin and cloxacillin?

METHODS

Data from the Swedish Shoulder Arthroplasty Register were used for this study. The inclusion criterion was registered antibiotic prophylaxis in primary arthroplasty. Between January 1, 1999, and December 31, 2019, 22,470 primary shoulder arthroplasties, including total shoulder, hemiarthroplasty, and reverse shoulder arthroplasties, were entered into the Swedish Shoulder Arthroplasty Register. Reporting of antibiotic prophylaxis to the register was introduced on January 1, 2013. Since then, the completeness of information on the type of antibiotic prophylaxis in the reports has been 85.3%. Consequently, 10,706 arthroplasties were eligible and fulfilled the inclusion criterion of reported antibiotic prophylaxis. A further 129 were excluded because of unusual prophylaxis regimens, leaving 10,577 shoulder arthroplasties for analysis. The Swedish Shoulder Arthroplasty Register gathers information from all 60 hospitals performing shoulder arthroplasty in Sweden, and through a comparison with the National Patient Register, it has been estimated that more than 90% of all primary shoulder arthroplasties and shoulder reoperations are reported to the register. The age of the study population ranged between 16 and 98 years; the mean age at the primary surgery was 70 ± 10 years for the entire cohort, with a mean age of 67 ± 10 years and 72 ± 9 years for men and women, respectively. The mean observation period was 989 ± 669 days. From 2013 to 2019, there was a clear change in prophylaxis; in particular, the use of the combination of benzylpenicillin and cloxacillin increased dramatically and the use of cloxacillin alone decreased. Clindamycin prophylaxis increased moderately. The primary study endpoint was reported reoperation for infection. In the register, this is defined as repeat procedures of any kind, including biopsy, lavage of the joint, or revision, defined as secondary surgery in which a component was exchanged, removed, or added. To compare the reoperation rate in relation to the different antibiotics used, which changed over time, we controlled for age, gender, previous surgery, cement fixation, and arthroplasty type using a Cox proportional hazards model.

RESULTS

When adjusting for age, gender, previous surgery, cement fixation, and arthroplasty type, cloxacillin prophylaxis was associated with an increased relative risk of reoperation for infection compared with the combination of cloxacillin and benzylpenicillin (hazard ratio [HR] 2.40 [95% confidence interval (CI) 1.35 to 4.25]; p = 0.003) and compared with clindamycin alone (HR 1.78 [95% CI 1.11 to 2.85]; p = 0.02). No difference was found between the cloxacillin and benzylpenicillin combination and clindamycin (HR 0.74 [95% CI 0.42 to 1.32]; p = 0.31).

CONCLUSION

Our results indicate that prophylaxis against C. acnes may be warranted in shoulder arthroplasty. Because the absolute number of infections was low and infections could have been underreported to the register, our results should be interpreted with caution. There is no available information about the causative microorganisms. The study lays the groundwork for further investigations of antibiotic prophylaxis regimens in shoulder arthroplasty. Because large randomized controlled trials would be impractical to perform, prospective register-based randomized controlled studies might be a viable method.

LEVEL OF EVIDENCE

Level Ⅲ, therapeutic study.

What is the concordance rate of preoperative synovial fluid aspiration and intraoperative biopsy in detecting periprosthetic joint infection of the shoulder?

BACKGROUND

The accuracy of preoperative synovial fluid culture for microbe detection in shoulder periprosthetic joint infection (PJI) is poorly described. To evaluate the utility of preoperative culture data for early pathogen identification for shoulder PJI, we determined the concordance between preoperative synovial fluid culture results and intraoperative tissue culture results.

METHODS

Fifty patients who met the 2014 Musculoskeletal Infection Society criteria for shoulder PJI between January 2016 and December 2019 were retrospectively reviewed for clinical and demographic data. This cohort of patients was divided into 2 groups based on the concordance between preoperative and intraoperative culture results. The pathogens identified on preoperative and intraoperative cultures were classified as high-virulence or low-virulence. Student's t tests and Mann-Whitney U tests were used as appropriate for continuous variables, and χ² and Fisher's exact tests were used as appropriate for categorical variables.

RESULTS

Concordance between preoperative aspiration and intraoperative tissue culture was identified in 28 of 50 patients (56%). Preoperative cultures positive for Gram-positive species were more likely to be concordant than discordant (P = .015). Preoperative cultures positive for Cutibacterium acnes were more likely to be concordant with intraoperative cultures (P = .022). There were more patients with polymicrobial infection in the discordant group compared with the concordant group (P < .001). No statistically significant correlation between the preoperative serum C-reactive protein level and the intraoperative category of bacteria was reported. Staphylococcus aureus and coagulase-negative Staphylococci were associated with high specificity and negative predictive value. Preoperative cultures positive for C. acnes demonstrated sensitivity, specificity, positive predictive value, and negative predictive value lower than 0.8. Gram-negative pathogens demonstrated the highest sensitivity (1) and specificity (1), whereas polymicrobial infections exhibited the lowest sensitivity and positive predictive value.

CONCLUSION

Preoperative synovial fluid aspiration for shoulder PJI poorly predicts intraoperative culture results, with a discordance of 44%. More favorable concordance was observed for monomicrobial preoperative cultures, particularly for Gram-negative organisms and methicillin-sensitive S. aureus. The overall high rate of discordance between preoperative and intraoperative culture may prompt surgeons to base medical and surgical management on patient history and other factors and avoid relying solely on preoperative synovial fluid culture data.

Periprosthetic joint infection caused by kytococcus schroeteri: The first reported case and a review of the literature

Oftentimes, Gram-positive cocci are the cause for periprosthetic joint infections (PJI). Most of these infections include bacteria such as Staphylococcus aureus, Staphylococcus epidermidis or other coagulase-negative staphylococci. We here present the first case of a PJI caused by Kytococcus schroeteri. While being a Gram-positive coccus, it is very rarely the cause for infections in the human body. K. schroeteri is part of the micrococcus branch and often encountered as a symbiotic bacterium living on the skin. Regarding its pathogenic potential, not a lot is known since less than a few dozen human infections have been reported worldwide. Furthermore, many of the cases reported are either associated with implanted material, especially heart valves, or associated with patients whose immune response is deficient. Only 3 reports of osteoarticular infections are described so far.

Targeted Versus Shotgun Metagenomic Sequencing-based Detection of Microorganisms in Sonicate Fluid for Periprosthetic Joint Infection Diagnosis

BACKGROUND

Next-generation sequencing (NGS) is increasingly used for periprosthetic joint infection (PJI) diagnosis, but its clinical utility is poorly defined. Shotgun metagenomic sequencing (sNGS) has been reported to identify PJI pathogens undetected by culture in sonicate fluid. However, sNGS is complex and costly. Here, 16S ribosomal RNA (rRNA) gene-based targeted metagenomic sequencing (tNGS) was compared to sNGS of sonicate fluid for microbial detection and identification in patients with total hip arthroplasty (THA) and total knee arthroplasty (TKA) failure.

METHODS

A convenience sample of sonicate fluids derived from patients who had undergone THA or TKA removal, enriched with culture negative PJI cases, was tested. Samples had been previously tested by sNGS. For tNGS, samples were extracted, amplified by polymerase chain reaction targeting the V1 to V3 regions of the 16S rRNA gene, and sequenced on an Illumina MiSeq.

RESULTS

A total of 395 sonicate fluids, including 208 from subjects with PJI, were studied. Compared with sonicate fluid culture, tNGS had higher positive percent agreement (72.1 vs 52.9%, P < .001), detecting potential pathogens in 48.0% of culture-negative PJIs. There was no difference between the positive percent agreement of tNGS (72.1%) and sNGS (73.1%, P = .83).

CONCLUSIONS

16S rRNA gene-based tNGS is a potential diagnostic tool for PJI pathogen identification in sonicate fluid from failed THAs and TKAs in culture-negative cases, with similar performance characteristics to sNGS.

C-reactive protein/albumin and C-reactive protein/fibrinogen ratios for the diagnosis of periprosthetic joint infection in revision total joint arthroplasty

AIM

Testing for systemic inflammation markers is considered a simpler method for diagnosing periprosthetic joint infection (PJI). Changes in the C-reactive protein/albumin ratio (CRP/Alb ratio) and C-reactive protein/fibrinogen ratio (CRP/Fib ratio) are associated with PJI. This study aimed to evaluate the application of CRP/Alb and CRP/Fib ratios as novel inflammation-based markers for the diagnosis of PJI.

METHODS

We retrospectively evaluated 445 patients who underwent total hip and knee revision arthroplasties between January 2010 and February 2021. Of these, 129 patients were also independently evaluated for PJI with coagulation-related comorbidities. The patients were divided into two groups: the aseptic revision (268 patients) and PJI revision groups (187 patients). Subsequently, we evaluated the diagnostic value of the CRP/Alb and CRP/Fib ratios compared to other inflammation-based diagnoses using the area under the curve (AUC) values.

RESULTS

The AUC values of the CRP/Alb and CRP/Fib ratios were 0.880 and 0.872, respectively, suggesting similar diagnostic potentials for PJI. The CRP/Alb and CRP/Fib ratios were better than the erythrocyte sedimentation rate (ESR), Alb, and Fib, whose AUC values were 0.765, 0.352, and 0.730, respectively, for the diagnosis of PJI. The optimal cut-off for the CRP/Alb ratio was 0.13, with good sensitivity (85.0%) and specificity (78.4%). The optimal cut-off CRP/Fib ratio was 2.04, with good sensitivity (81.3%) and specificity (80.6%). Notably, the CRP/Alb and CRP/Fib ratios had the highest sensitivity, followed by four conventional inflammatory markers, namely, CRP, ESR, Alb, and Fib, which had sensitivities of 80.2%, 67.4%, 50.8%, and 54.0%, respectively. Similar findings were observed in patients with coagulation-related comorbidities.

CONCLUSION

Both the CRP/Alb and CRP/Fib ratios were significantly higher in patients with PJI than in those with aseptic failure and showed better sensitivity and specificity for diagnosing PJI than classical inflammatory markers.

Referral Centre Experience with Infected Abdominal Aortic Endograft Explantation

OBJECTIVE

The increasing use of endovascular aneurysm repair (EVAR) appears to be associated with the burden of vascular endograft infections. Complete stent graft explantation is recommended but leads to significant mortality. This study aimed to assess the technical challenges, complications, and mortality rate following infected endograft explantation.

METHODS

Patients who underwent abdominal aortic endograft explantation for infection at the Bordeaux University Hospital from July 2008 to December 2020 were included retrospectively in this single centre observational study. The diagnosis was established based on the MAGIC criteria. The primary endpoint was 30 day mortality. Secondary endpoints were 90 day and in hospital mortality, survival, and re-infection.

RESULTS

Thirty-four patients were included, median age 69 years (interquartile range [IQR] 65, 76), with four (12%) treated as an emergency. The median time from EVAR to explantation was 17.5 months (4.5 - 36.3). In situ reconstruction was carried out with prosthetic grafts in 24 patients (71%, including 23 antimicrobial grafts combining silver and triclosan), and biological grafts in 10 (five femoral veins, four arterial allografts, three bovine patches, one biosynthetic graft). Seventeen aorto-enteric fistulae (AEnF) were addressed with direct repair of the intestinal tract (n = 10/17; 59%) or resection and anastomosis (n = 7/17; 41%). The culture was polymicrobial in 12 patients (35%) and remained sterile in four (12%). The 30 day and in hospital mortality rates were 21% (n = 7) and 27% (n = 9). Twenty-five patients (73%) presented with early post-operative complications, requiring 16 revision procedures (47%). Over a median follow up of 16.2 months (IQR 8.3, 33.6), the mortality rate was 35% (n = 12; 11 aortic related; 32%), with two re-infections (6%), both after biological reconstruction (one for an AEnF).

CONCLUSION

Early morbidity and mortality remain high after complete infected endograft explantation, even in a high volume centre. Comparison with other treatment modalities in large multicentre cohorts might be of interest.

[Translated article] Clinical validity of the intraoperative histology in the diagnosis of prosthetic joint infection

BACKGROUND AND AIM

Different authors have demonstrated the usefulness of the histological analysis in the diagnosis of prosthetic joint infection; however, its clinical validity is still controversial. The aim of this article is to describe and analyse the clinical validity of histological analysis in the diagnosis of prosthetic infection in patients undergoing hip or knee prosthetic replacement.

MATERIAL AND METHODS

We present a retrospective study including 133 hip and knee prosthetic replacements performed in our centre between 2008 and 2020. A descriptive, bivariate statistical analysis was performed and the clinical validity of the histological analysis was determined.

OUTCOMES

The clinical validity of the intraoperative histology offered a sensitivity of 48%, a specificity of 91%, a positive predictive value of 55% and a negative predictive value of 88%.

CONCLUSIONS

The determination of the clinical validity of histological analysis shows a high specificity. This analysis is an appropriate diagnostic tool for detecting healthy patients, with no infection.

Palliative arthroscopic debridement with continuous irrigation for infected total knee arthroplasty in high mortality risk patients

PURPOSE

This study aimed to evaluate the infection control rate of palliative arthroscopic debridement, antibiotics, and implant retention (DAIR) for the high mortality risk or terminal cancer stage patients.

METHODS

From March 2018 to August 2021, 21 patients met the following inclusion criteria: old age of more than 80, diagnosed as a terminal stage of cancer, high risk of mortality and morbidity representing as Charlson comorbidity index (CCI) ≥ 5, low daily activity with disabled extremity, and re-infection after two-stage revision. Each patient underwent arthroscopic DAIR and additional continuous irrigation for 48 hours. The need for subsequent re-arthroscopic DAIR or two-stage revision was determined by the post-operative trends of C-reactive protein (CRP) levels. Infection control was defined as continuing controlled status of infection based on clinical and laboratory results by one or two times of arthroscopic DAIR within initial two months. Treatment failure was defined as more than three times arthroscopic debridement, two-stage revision surgery, or expired due to uncontrolled infection.

RESULTS

Arthroscopic DAIR controlled the infection in 19 (90.5%) of the 21 cases. The other knee underwent a total of three times of re-arthroscopic DAIR and the other one underwent two-stage revision. Although five patients expired during the follow-up period due to worsening medical problems or terminal cancer, there were no deaths from uncontrolled infection, sepsis, or surgery-related complications.

CONCLUSIONS

Arthroscopic debridement with continuous irrigation for the infection TKA with high mortality risk or terminal cancer patients showed a 90.5% infection control rate. For high-risk patients, arthroscopic debridement with continuous irrigation can be an alternative treatment to improve the quality of life during survival.

Optimization and standardization of mNGS-based procedures for the diagnosis of Mycoplasma periprosthetic joint infection: A novel diagnostic strategy for rare bacterial periprosthetic joint infection

Introduction

The diagnosis of Mycoplasma periprosthetic joint infection (PJI) is rather difficult due to its rarity and difficult in isolation, there are not standardized diagnostic procedure for Mycoplasma PJI presently. This study aimed to reported a metagenomic next-generation sequencing (mNGS)-based diagnostic strategy for Mycoplasma PJI.

Methods

In the present study, we have reported the largest number of Mycoplasma PJI that were precisely diagnosed by mNGS and verified by optimized microbial culture methods and (or) 16S PCR polymerase chain reaction (PCR).

Results

The positive rate of optimized microbial culture methods and 16S PCR in the detection of Mycoplasma PJI was 57.14% and 71.43%, respectively. The infections were well controlled by targeted treatment in all cases.

Conclusion

The standardized and optimized procedure based on mNGS presented in this study is useful for the diagnosis of Mycoplasma PJI, which might also be provided as a novel diagnostic strategy for rare bacterial PJI.

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.

Limited value of coagulation parameters in diagnosing periprosthetic joint infection

PURPOSE

Exploring biomarkers for easy and reliable diagnosis of periprosthetic joint infection (PJI) has attracted an increasing attention. Coagulation parameters have been found to be associated with infections, but their role in diagnosing PJI is not well understood. The aim of this study was to explore the diagnostic value of coagulation parameters in PJI.

METHODS

We retrospectively recruited patients who underwent revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) from January 2014 to December 2020. Patients were grouped into PJIs or non-PJIs, and PJIs were further divided into culture positive and culture negative groups. The diagnostic value of coagulation parameters including fibrin degradation product (FDP), D-dimer, platelet count (PC), and platelet count to mean platelet volume ratio (PVR) was evaluated by using receiver operating characteristic curve, in comparison with traditional biomarkers C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR).

RESULTS

A total of 186 patients including 136 THA and 50 TKA were studied. There were 105 PJI and 81 non-PJI patients. The coagulation parameters showed an inferior performance to CRP and ESR, with the area under the curve (AUC) of FDP, D-dimer, PC, PVR, CRP, and ESR being 0.805, 0.571, 0.703, 0.704, 0.882, and 0.824, respectively. The diagnostic performance of those coagulation parameters was similar in THA and TKA PJIs and was not superior to ESR or CRP in either culture-positive or culture-negative PJIs.

CONCLUSION

Coagulation parameters FDP, D-dimer, PC, and PVR are of limited value for the diagnosis of periprosthetic joint infection in both THA and TKA patients.

Synovial fluid alpha-defensin in periprosthetic knee infection workup : liquid chromatography-mass spectrometry detection of alpha-defensin in synovial fluid

AIMS

The diagnosis of periprosthetic joint infection (PJI) continues to present a significant clinical challenge. New biomarkers have been proposed to support clinical decision-making; among them, synovial fluid alpha-defensin has gained interest. Current research methodology suggests reference methods are needed to establish solid evidence for use of the test. This prospective study aims to evaluate the diagnostic accuracy of high-performance liquid chromatography coupled with the mass spectrometry (LC-MS) method to detect alpha-defensin in synovial fluid.

METHODS

Between October 2017 and September 2019, we collected synovial fluid samples from patients scheduled to undergo revision surgery for painful total knee arthroplasty (TKA). The International Consensus Meeting criteria were used to classify 33 PJIs and 92 aseptic joints. LC-MS assay was performed to measure alpha-defensin in synovial fluid of all included patients. Sensitivity, specificity, positive predictive value, negative predictive value, and the area under the receiver operating characteristic curve (AUC) were calculated to define the test diagnostic accuracy.

RESULTS

The AUC was 0.99 (95% confidence interval (CI) 0.98 to 1.00). Receiver operating characteristic (ROC) analysis showed that the optimal cut-off value of synovial fluid alpha-defensin was 1.0 μg/l. The sensitivity of alpha-defensin was 100% (95% CI 96 to 100), the specificity was 97% (95% CI 90 to 98), the positive predictive value was 89.2% (95% CI 82 to 94), and negative predictive value was 100% (95% CI 96 to 100). ROC analysis demonstrated an AUC of 0.99 (95% CI 0.98 to 1.0).

CONCLUSION

The present study confirms the utility of alpha-defensin in the synovial fluid in patients with painful TKA to select cases of PJI. Since LC-MS is still a time-consuming technology and is available in highly specialized laboratories, further translational research studies are needed to take this evidence into routine procedures and promote a new diagnostic approach.Cite this article: Bone Joint J 2022;104-B(9):1047-1051.

Combination of C-reactive protein and fibrinogen is useful for diagnosing periprosthetic joint infection in patients with inflammatory diseases

BACKGROUND

The screening of periprosthetic joint infection (PJI) in patients with inflammatory diseases before revision arthroplasty remains uncertain. Serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), plasma fibrinogen (FIB), monocyte/lymphocyte ratio, and neutrophil/lymphocyte ratio (NLR) can help screening PJI, but their values in patients with inflammatory diseases have not been determined.

METHODS

Patients with inflammatory diseases who underwent revision hip or knee arthroplasty at West China Hospital, Sichuan University, from January 2008 to September 2020 were divided into infected and non-infected groups based on the 2013 International Consensus Meeting criteria. Sensitivity and specificity of the tested biomarkers for diagnosing infection were determined based on receiver operating characteristic (ROC) curves, and optimal cutoffs were determined based on the Youden index. The diagnostic ability of these biomarkers was re-assessed after combining them with each other.

RESULTS

A total of 62 patients with inflammatory diseases were studied; of them 30 were infected. The area under the ROC curve was 0.813 for CRP, 0.638 for ESR, 0.795 for FIB, and 0.656 for NLR. The optimal predictive cutoff of CRP was 14.04 mg/L with a sensitivity of 86.2% and a specificity of 68.7%, while FIB had a sensitivity of 72.4% and a specificity of 81.2% with the optimal predictive cutoff of 4.04 g/L. The combinations of CRP with FIB produced a sensitivity of 86.2% and specificity of 78.1%.

CONCLUSION

CRP with a slightly higher predictive cutoff and FIB are useful for screening PJI in patients with inflammatory diseases, and the combination of CRP and FIB may further improve the diagnostic values.

TRIAL REGISTRATION

ChiCTR.org.cn, ChiCTR2000039989.

Synovial Fluid Neutrophil Gelatinase-Associated Lipocalin Can be Used to Accurately Diagnose Prosthetic Joint Infection

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL)¹ in synovial fluid (SF) may have potential diagnostic value for prosthetic joint infection (PJI). The purpose of this study was to study (1) the diagnostic performance of SF-NGAL level for diagnosing PJI and (2) the impact of prior antibiotic use on the SF-NGAL levels.

METHODS

Consecutive patients who needed hip or knee revision surgery were included prospectively from January 2017 to September 2018. The patients were divided into the PJI group and the aseptic failure (AF) group. An enzyme-linked immunosorbent assay was used to determine the SF-NGAL level.

RESULTS

Fifty of 78 included patients were diagnosed with PJI. The median SF-NGAL level was 3633 ng/ml (interquartile range (IQR), 1332-10737) in the PJI group and 26.8 ng/ml (IQR, 12.4-52.5) in the AF group (p < 0.0001). When the SF-NGAL threshold was 263 ng/ml, the AUC was 0.98, the sensitivity was 92.9%, and the specificity was 98%. The median level was 5779 ng/ml (IQR, 1425-13072) in the antibiotic group and 2590 ng/ml (IQR, 932-8970) in the nonantibiotic group (p = 0.1).

CONCLUSION

SF-NGAL level can be used as a diagnostic indicator of PJI. The use of antibiotics prior to sampling does not affect the SF-NGAL level.

For Patients With Acute PJI Treated With Debridement, Antibiotics, and Implant Retention, What Factors Are Associated With Systemic Sepsis and Recurrent or Persistent Infection in Septic Patients?

BACKGROUND

Periprosthetic joint infection (PJI) can lead to a severe systemic inflammatory response and may result in systemic sepsis. However, little is known about how often systemic sepsis may occur in patients with PJI, and whether sepsis is associated with a greater likelihood of persistent or recurrent PJI.

QUESTIONS/PURPOSES

(1) Among patients who present with acute or acute hematogenous PJI and who were treated with debridement, antibiotics, and implant retention (DAIR), what proportion have sepsis and what factors are associated with a presentation with sepsis? (2) For patients presenting with sepsis, what factors are associated with persistent or recurrent PJI?

METHODS

In all, 320 patients who underwent DAIR for the treatment of acute postoperative or acute hematogenous PJI between January 2000 and December 2019 were included in this study. Exclusion criteria were patients with other known sources of infection, such as pneumonia or urinary tract infections, which could contribute to systemic sepsis (6% [18 of 320]), patients with chronic PJI, and those with less than 6 months of follow-up (21% [66 of 320]). Our final cohort consisted of 236 patients presenting with an acute postoperative or acute hematogenous PJI who underwent an irrigation and debridement procedure. Sepsis was defined by the criteria for systemic inflammatory response syndrome (SIRS) or bacteria-positive blood culture results. Inclusion of patients with positive blood culture by organisms that caused their joint infection was important as all patients presented with fulminant acute infection of a prosthetic joint. Data, including vital signs, surgical variables, and treatment outcomes, were collected retrospectively through a chart review of an electronic medical record system. The statistical analysis comparing patients with sepsis versus patients without sepsis consisted of logistic regression to identify factors associated with sepsis. After confirming its ability to identify patients with a higher association with the development of sepsis through area under the curve models, a nomogram was generated to standardize our results from the regression, which was supported by the area under the curve model, to help readers better identify patients who are more likely to develop sepsis.

RESULTS

A total of 44% (103 of 236) of patients had infections that met the criteria for sepsis. After controlling for confounding variables, including congestive heart failure, anemia, serum C-reactive protein (CRP), and the male sex, it was revealed that serum CRP (odds ratio 1.07 [95% confidence interval 1.04 to 1.11]; p < 0.001) and male sex (OR 1.96 [95% CI 1.03 to 3.81]; p = 0.04) were associated with the development of systemic sepsis. For patients presenting with sepsis, persistent or recurrent PJI were associated with an increased CRP level (OR 1.06 [95% CI 1.02 to 1.11]; p = 0.01) and number of prior surgical procedures on the joint (OR 2.30 [95% CI 1.21 to 4.89]; p = 0.02).

CONCLUSION

Overall, our findings support that patients with systematic sepsis may benefit from two-stage revision rather than DAIR to decrease the bioburden more effectively, especially in those with methicillin-resistant Staphylococcus aureus and polymicrobial infections. High serum CRP levels and a history of prior surgical procedures on the involved joint should trigger prompt, aggressive surgical treatment if the patient's overall clinical status can tolerate such an intervention.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Calprotectin Lateral Flow Test: Consistent Across Criteria for Ruling Out Periprosthetic Joint Infection

BACKGROUND

There are multiple sets of criteria used to define periprosthetic joint infection. The objective of this study is to compare the diagnostic accuracy of the calprotectin lateral flow point-of-care (POC) test in total knee arthroplasty (TKA) patients to diagnose infection using 3 different sets of criteria: (1) 2013 Musculoskeletal Infection Society, (2) 2018 Intentional Consensus Meeting (ICM), and (3) the 2019 proposed European Bone and Joint Infection Society criteria as reference standards.

METHODS

From October 2018 to January 2020, 123 intraoperative synovial fluid samples were prospectively collected from revision total knee arthroplasty patients and tested using a calprotectin lateral flow POC assay. Data were reviewed and adjudicated by 2 independent reviewers blinded to calprotectin test results.

RESULTS

The 3 criteria sets had 91.8% agreement. Using 2013 Musculoskeletal Infection Society criteria, the POC test demonstrated a sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of 98.1%, 95.7%, 94.5%, 98.5%, and 0.969, respectively. Using the 2018 ICM, the POC test demonstrated a sensitivity, specificity, PPV, NPV, and AUC of 98.2%, 98.5%, 98.2%, 98.5%, and 0.984, respectively. Using the 2019 proposed European Bone and Joint Infection Society criteria, the POC test demonstrated a sensitivity, specificity, PPV, NPV, and AUC of 93.2%, 100.0%, 100.0%, 94.2%, and 0.966, respectively.

CONCLUSION

The calprotectin lateral flow POC test had excellent sensitivity and specificity across current available periprosthetic joint infection definitions, with the best performance observed when applying 2018 ICM criteria.

LEVEL OF EVIDENCE

Diagnostic I.

Factors Associated with Surgical Field Bacterial Detection during Total Hip Arthroplasty

Total hip arthroplasty (THA) provides relief from hip pain and improves hip function. However, periprosthetic joint infection (PJI) remains an area of concern. We examined the detection rate of bacteria from surgical fields in wound closure, along with the relationship between bacterial detection rate and type of antiseptic, surgery time, and surgeon experience for 500 patients who underwent THA at our department. The mean age at surgery was 64.3 (± 27.3) years. The bacterial detection rate was 4.6%. None of the cases revealed PJI. No significant association between the detection rate and type of antiseptic used or surgery time was observed. However, for patients treated by surgeons with < 10 years of orthopedic experience, a detection rate of 7.3% was found, while a rate of 1.3% was observed for those treated by surgeons with ≥ 10 years of orthopedic experience. This finding indicated that orthopedic experience of less than 10 years was significantly associated with an increased bacterial detection rate (chi-square test, p=0.002). The detection rate was associated with surgeon experience but not with antiseptic type or surgery time. It is possible that intraoperative handling may increase the number of bacteria in surgical fields in wound closure.

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.

Human transcriptomic response to periprosthetic joint infection

Periprosthetic joint infection (PJI), a devastating complication of total joint replacement, is of incompletely understood pathogenesis and may sometimes be challenging to clinically distinguish from other causes of arthroplasty failure. We characterized human gene expression in 93 specimens derived from surfaces of resected arthroplasties, comparing transcriptomes of subjects with infection- versus non-infection-associated arthroplasty failure. Differential gene expression analysis confirmed 28 previously reported potential biomarkers of PJI, including bactericidal/permeability increasing protein (BPI), cathelicidin antimicrobial peptide (CAMP), C-C-motif chemokine ligand 3 (CCL3), 4(CCL4) and C-X-C-motif chemokine ligand 2 (CXCL2), colony stimulating factor 2 receptor beta (CSF2RB), colony stimulating factor 3 (CSF3), alpha-defensin (DEFA4), Fc fragment of IgG receptor 1B (CD64B), intercellular adhesion molecule 1 (ICAM1), interferon gamma (IFNG), interleukin 13 receptor subunit alpha 2 (IL13RA2), interleukin 17D (IL17D), interleukin 1 (IL1A, IL1B, IL1RN), interleukin 2 receptors (IL2RA, IL2RG), interleukin 5 receptor (IL5RA), interleukin 6 (IL6), interleukin 8 (IL8), lipopolysaccharide binding protein (LBP), lipocalin (LCN2), lactate dehydrogenase C (LDHC), lactotransferrin (LTF), matrix metallopeptidase 3 (MMP3), peptidase inhibitor 3 (PI3), and vascular endothelial growth factor A (VEGFA), and identified three novel molecules of potential diagnostic use for detection of PJI, namely C-C-motif chemokine ligand CCL20, coagulation factor VII (F7), and B cell receptor FCRL4. Comparative analysis of infections caused by staphylococci versus bacteria other than staphylococci and Staphylococcus aureus versus Staphylococcus epidermidis showed elevated expression of interleukin 13 (IL13), IL17D, and MMP3 in staphylococcal infections, and of IL1B, IL8, and platelet factor PF4V1 in S. aureus compared to S. epidermidis infections. Pathway analysis of over-represented genes suggested activation of host immune response and cellular maintenance and repair functions in response to invasion of infectious agents. The data presented provides new potential targets for diagnosis of PJI and for differentiation of PJI caused by different infectious agents.

What Is the Impact of Automated Synovial Cell Counting on Different Aseptic Causes and Periprosthetic Conditions Associated With Revision THA?

BACKGROUND

Studies have suggested that automated synovial cell counting may overestimate the white blood cell (WBC) count, resulting in false positive tests when evaluating patients for the possibility of periprosthetic joint infection (PJI) after THA. However, associations between WBC counts high enough to mimic PJI in patients whose arthroplasties are not infected but rather are experiencing a variety of aseptic problems-including but not limited to metallosis, polyethylene wear, and recurrent dislocation-have not, to our knowledge, been adequately addressed. In addition, there is a lack of analyses about the polymorphonuclear percentage (PMN%) when assessed by automated analyzers in this context.

QUESTIONS/PURPOSES

In the context of different indications for aseptic revision and different periprosthetic hip pathologic findings, we asked: (1) What were the synovial WBC count levels, and what proportion of values were above the 2018 International Consensus Meeting (ICM) cutoff (3000 cells/μL)? (2) What were the synovial PMN% levels, and what proportion of values were above the 2018 ICM (70%)?

METHODS

We retrospectively studied the preoperative cell count analyses of synovial fluid in patients who underwent revision THA for aseptic reasons at our tertiary referral arthroplasty center between January 2015 and December 2017. We considered all revisions performed on patients during that time potentially eligible, and after prespecified exclusions were applied (exclusions mainly included 15% [197 of 1306] sporadic missing data and 12% [155 of 1306] insufficient synovial fluid obtained in the aspirate), a total of 702 patients undergoing revision THA for aseptic reasons remained for the final analysis. As far as we know, no patients underwent re-revision for PJI at a mean follow-up of 46 ± 11 months, which tends to confirm our impression that indeed these hips did not have PJI. Cell count analyses were conducted using an automated analyzer. Clinical findings, preoperative radiographs, and surgical reports--confirmed by available histologic results--were used to establish diagnoses. We evaluated these hips considering the recommendations of the 2018 ICM (WBC count of 3000 cells/μL and PMN% of 70%) to see what proportion of them would have been characterized as likely having PJI on basis of those cutoff values. The mean WBC count for the entire cohort was 2120 ± 2395 cells/μL. The mean PMN% for the entire cohort was 36% ± 22%.

RESULTS

Compared with aseptic loosening and recurrent dislocation, polyethylene wear had the highest mean WBC count (3817 ± 3711 cells/μL; p < 0.001). Of the investigated periprosthetic conditions, wear-induced synovitis had the highest value (4464 ± 3620 cells/μL; p < 0.001). Considering the ICM threshold, polyethylene wear showed the highest proportion of WBC counts above 3000 cells/μL among the indications for aseptic revision (60% [25 of 42]; p < 0.001). Of the periprosthetic conditions, wear-induced synovitis showed the highest proportion beyond the ICM cutoff (60% [50 of 83]; p < 0.001). The mean PMN% for aseptic causes ranged between 28% and 44% without differences among them (p = 0.12). Patients with metallosis had the highest mean PMN% of the periprosthetic conditions investigated (45% ± 25%; p = 0.007). Regarding the ICM threshold, metallosis resulted in the largest proportion of patients with a PMN% above 70% (21% [10 of 47]; p = 0.003), and that for wear-induced synovitis was 6% (5 of 83; p = 0.42) and for osteolysis was 3% (1 of 33; p = 0.51). There were no differences among aseptic loosening, recurrent dislocation, and polyethylene wear in terms of the proportion above 70% among the aseptic revision causes.

CONCLUSION

Using automated cell counting, we found that WBC counts differ widely across indications for aseptic revision THA, and a high proportion of patients who underwent revision THA for aseptic reasons had WBC counts above the commonly used threshold of 3000 cells/μL. However, the PMN% was much less affected in several common indications for aseptic revision THA, making this measure more reliable for interpreting aspiration results using an automated analyzer. Based on the data distributions we observed, manual counting techniques might be considered in particular among patients with polyethylene wear, metal-on-metal bearing surfaces, or suspected metallosis. However, an elevated WBC count alone, observed using an automated analyzer in the context of polyethylene wear, should not be considered to be strongly suggestive of PJI, since that finding occurred so commonly among patients without infection.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Prior Intra-articular Corticosteroid Injection Within 3 Months May Increase the Risk of Deep Infection in Subsequent Joint Arthroplasty: A Meta-analysis

BACKGROUND

Intra-articular injections containing a corticosteroid are used frequently, and periprosthetic joint infection is a serious complication after total joint arthroplasty. There is debate regarding whether intra-articular corticosteroid injections before arthroplasty increase periprosthetic joint infection after surgery.

QUESTIONS/PURPOSES

(1) Does a previous intra-articular corticosteroid injection increase the odds of infection after subsequent hip or knee arthroplasty? (2) Does this risk vary based on how soon before the arthroplasty (such as less than 3 months before surgery) the injection is administered?

METHODS

Using the PubMed, Embase, Cochrane Library, and Web of Science databases from inception to July 2021, we searched for comparative studies in English on patients who received intra-articular corticosteroid injections before arthroplasty and that tracked the frequency of infection after arthroplasty. We extracted data on the risk of infection after subsequent joint arthroplasty. The keywords included "corticosteroid," "steroid," "arthroplasty," "knee replacement," and "hip replacement." Eleven retrospective, comparative studies from four countries were included, of which 10 reported the specific diagnosis criteria and one did not. These articles included data on 173,465 arthroplasties in the hip or knee, as well as of 73,049 injections and 100,416 control patients. The methodologic quality of the included studies was evaluated according to the Newcastle-Ottawa Quality Assessment Scale; the articles' scores ranged from 6 to 7 (the score itself spans 0 to 9, with higher scores representing better study quality). We found no evidence of publication bias based on the Egger test, and tests of heterogeneity generally found heterogeneity, so a random-effects model was used of our meta-analyses. A meta-analysis was performed with Review Manager 5.3 software and Stata version 12.0 software.

RESULTS

Overall, there were no differences in the odds of periprosthetic joint infection between the injection group and the control group among patients who received any kind of injection (odds ratio 1.22 [95% CI 0.95 to 1.58]; p = 0.12). However, in a subgroup analysis, there was a higher OR for postoperative PJI in patients with an intra-articular corticosteroid injection in the knee or hip within 3 months (OR 1.39 [95% CI 1.04 to 1.87]; p = 0.03). There were no differences in the infection risk in patients who had injections between 3 and 6 months before arthroplasty (OR 1.19 [95% CI 0.95 to 1.48]; p = 0.13) or between 6 and 12 months before arthroplasty.

CONCLUSION

The current evidence suggests ipsilateral intra-articular corticosteroid injections within 3 months before arthroplasty were associated with an increased risk of periprosthetic joint infection during subsequent joint arthroplasty. We recommend against performing total joint arthroplasty on a patient who has received an intra-articular corticosteroid injection within 3 months. Further high-quality studies on this topic from registries, national databases, or insurance company data are still required to confirm and extend our findings.

LEVEL OF EVIDENCE

Level III, therapeutic study.

In-situ Bypass Is Associated with Superior Infection-free Survival Compared to Extra-Anatomic Bypass for the Management of Secondary Aortic Graft Infections Without Enteric Involvement

OBJECTIVE

The optimal revascularization modality following complete resection of aortic graft infection (AGI) without enteric involvement remains unclear. The purpose of this investigation is to determine the revascularization approach associated with the lowest morbidity and mortality using real-world data in patients undergoing complete excision of AGI.

METHODS

A retrospective, multi-institutional study of AGI from 2002-2014 was performed using a standardized database. Baseline demographics, comorbidities, and perioperative variables were recorded. The primary outcome was infection-free survival. Descriptive statistics, Kaplan-Meier survival analysis, and univariate and multivariable analyses were performed.

RESULTS

241 patients at 34 institutions from 7 countries presented with AGI during the study period (median age 68 years; 75% male). The initial aortic procedures that resulted in AGI were 172 surgical grafts (71%) and 66 endografts (27%) and 3 unknown (2%). 172 (71%) of the patients underwent complete excision of infected aortic graft material followed by in situ (in-line) bypass (ISB), including antibiotic-treated prosthetic graft (35%), autogenous femoral vein (NAIS) (24%), and cryopreserved allograft (41%). 69 patients (29%) underwent extra-anatomic bypass (EAB). Overall median Kaplan-Meier (KM) estimated survival was 5.8 years. Perioperative mortality was 16%. When stratified by ISB versus EAB, there was a significant difference in KM estimated infection-free survival (2910 days, IQR 391, 3771 versus 180 days, IQR 27, 3750 days; p<0.001). There were otherwise no significant differences in presentation, comorbidities, nor perioperative variables. Multivariable Cox regression showed lower infection-free survival among patients with EAB (HR 2.4, 95% CI 1.6-3.6; p<0.001), polymicrobial infection (HR 2.2, 95% CI 1.4-3.5; p=0.001), MRSA infection (HR 1.7, 95% CI 1.1-2.7; p=0.02), as well as the protective effect of omental/muscle flap coverage (HR 0.59, 95% CI 0.37-0.92; p=0.02).

CONCLUSIONS

After complete resection of AGI, perioperative mortality is 16% and median overall survival is 5.8 years. EAB is associated with nearly a two-and-half fold higher re-infection/mortality compared to ISB. Omental and/or muscle flap coverage of the repair appear protective.

Profile, presentation and outcomes of prosthetic valve endocarditis in a South African tertiary hospital: Insights from the Groote Schuur Hospital Infective Endocarditis Registry

BACKGROUND

Prosthetic valve infective endocarditis (PVE) is associated with high morbidity and mortality. The prevalence of PVE in South African retrospective studies ranges between 13% and 17%.

OBJECTIVES

To define the clinical profile and outcomes of patients with PVE, and compare them with those of native valve endocarditis (NVE) patients.

METHODS

We performed a prospective observational study of patients presenting or referred to Groote Schuur Hospital, Cape Town, with definite or possible infective endocarditis (IE) based on the 2015 European Society of Cardiology IE diagnostic criteria. Consenting adult patients who met the inclusion criteria were enrolled into the Groote Schuur Hospital Infective Endocarditis Registry, which was approved by the University of Cape Town Human Research Ethics Committee. This study is an analysis of the patients enrolled between 1 January 2017 and 31 December 2019.

RESULTS

During the study period, a total of 135 patients received a diagnosis of possible or definite IE (PVE n=18, NVE n=117). PVE therefore accounted for 13.3% of the overall IE cohort. PVE patients had a mean (standard deviation) age of 39.1 (14.6) years, and 56.6% were male. PVE occurred within 1 year of valve surgery in 50.0% of cases. Duke's modified diagnostic criteria for definite IE were met in 94.4% of the PVE cohort. Isolated aortic valve PVE was present in 33.3%, and a combination of aortic and mitral valve PVE in 66.6%. Tissue prosthetic valves were affected in 61.1% of cases. Of the PVE cases, 55.6% were healthcare associated. On transthoracic echocardiography, vegetations (61.1%), prosthetic valve regurgitation (44.4%) and abscesses (22.2%) were discovered. Staphylococcus and Streptococcus species accounted for 38.8% and 22.2% of PVE cases, respectively, and 27.8% of cases were blood culture negative. Valve surgery was performed in 38.7% of the PVE patients, and 55.6% of the patients died during the index hospitalisation. Secondary analysis indicated that the PVE patients were sicker than those with NVE, with a higher frequency of septic shock and atrioventricular block (22.2% v. 7%; p=0.02 and 27.8% v. 12%; p=0.04, respectively). In addition, in-hospital mortality was higher in PVE patients than NVE patients (55.6% v. 31.6%; p=0.04).

CONCLUSIONS

PVE was uncommon, mainly affecting tissue prosthetic valves and prosthetic valves in the aortic position. Patients with PVE were sicker than those with NVE and had high in-hospital mortality.

Metal Hypersensitivity or Missed Periprosthetic Joint Infection? A Critical Review

The World Association Against Infection in Orthopedics And Trauma (W.A.I.O.T.) Study Group on Bone And Joint Infection Definitions Metal hypersensitivity (MHS) has been investigated by several authors as a possible reason for painful total joint arthroplasty, with controversial results. Periprosthetic joint infection (PJI) is another possible source of unexplained pain and implant failure that may be difficult to diagnose if not properly investigated. We performed this critical review to assess whether the current literature on MHS includes an adequate diagnostic workup to discern metal allergy from PJI. The results of this review highlight the importance of assessing patients for PJI before making a diagnosis of MHS and emphasize that the methods currently used to exclude PJI are substantially inadequate. Therefore, well-designed clinical trials with adequate diagnostic protocols and definitions of PJI that can differentiate MHS from low-grade PJI are needed. [Orthopedics. 2022;45(2):e73-e78.].

Prosthetic hip infection due to Campylobacter jejuni

A woman in her 60s with a left hip prosthesis was presented with left hip pain and fever. She had an elevated white blood cell count and inflammatory markers. Synovial fluid Gram stain demonstrated curved Gram-negative rods identified as Campylobacter jejuni The patient initially refused surgery and after 3 months underwent one-stage exchange after which she was treated with 12 weeks of levofloxacin. Her inflammatory markers normalised and she was clinically doing well at her 6-month follow-up. C. jejuni is a rare cause of prosthetic joint infection and should be included in the differential diagnosis when a patient has risk factors even without significant preceding gastrointestinal symptoms. Per most recent Infectious Diseases Society of America guidelines, treatment after one-stage revision includes 4-6 weeks of intravenous antimicrobials followed by possible oral suppression therapy, while the European guidelines recommend 12 weeks of orally bioavailable antibiotics.

Presepsin as a diagnostic biomarker of peri-prosthetic joint infection: a review of the literature

INTRODUCTION

While presepsin has shown promise as a sepsis biomarker, it has only recently been considered in the field of orthopedic surgery. Therefore, the present review evaluates the role of presepsin in total joint arthroplasty (TJA) as well as its diagnostic and prognostic value in diagnosing PJI.

METHODS

Utilizing 4 online databases, we thoroughly searched the literature for articles evaluating the role of presepsin in TJA as well as its prognostic and diagnostic value for PJI.

RESULTS

Studies evaluating perioperative presepsin trends in primary TJA demonstrated that its natural course is similar to C-Reactive Protein (CRP). The area under (AUC) the receiver operating characteristic curves values for serum presepsin ranged from 0.86 to 0.926. These values were higher than the AUCs for CRP in each of their respective studies. However, synovial presepsin demonstrated a lower AUC (0.41). Prognostically, presepsin demonstrated potential in terms of infection monitoring following revision TJA for PJI.

CONCLUSION

Although the data remains limited, presepsin may serve as a potential biomarker to evaluate the natural inflammatory response following TJA as well as to help diagnose PJI. The present review serves to set the foundation for future study into serum presepsin in larger patient cohorts. Further study is needed to evaluate how this biomarker compares to other laboratory values traditionally used for PJI diagnosis.

Clinical features, diagnosis and treatment outcome of fungal endocarditis: A systematic review of reported cases

The landscape of fungal endocarditis (FE) has constantly been evolving in the last few decades. Despite the advancement in diagnostic methods and the introduction of newer antifungals, mortality remains high in FE. This systematic review aimed to evaluate the epidemiology, clinical features, diagnostic and therapeutic interventions in patients with FE. We also aim to examine the aforementioned factors as a determinant of mortality in FE. A literature search was performed in PubMed, Google Scholar and Scopus, and all patients ≥18 years with proven fungal endocarditis were included. A total of 220 articles (250 patients) were included in the final analysis. Candida was the commonest aetiology (49.6%), followed by Aspergillus (30%) and Scedosporium species (3.2%). The proportion of prosthetic valve endocarditis (PVE) and intravenous drug users was 35.2% and 16%, respectively. The overall mortality rate was 40%. On multivariate analysis, Aspergillus endocarditis (HR 3.7, 95% CI 1.4-9.7; p = .009) and immunocompromised state (HR 2.8, 95% CI 1.24-6.3; p = .013) were independently associated with mortality. Patients treated with surgery along antifungals had better survival (HR 0.20, 95% CI 0.09-0.42; p < .001) compared to those treated with antifungals alone. Recurrence of FE was reported in 10.4% of patients. In conclusion, FE carries significant mortality, particularly in immunodeficient and Aspergillus endocarditis. We advocate the use of surgery combined with antifungals to improve clinical outcomes.

Listeria abdominal endograft infection miming pseudoaneurysm treated with in-situ aortic reconstruction: a case report

We report the case of a 72-year old man previously treated with an aortic endograft for an abdominal aortic aneurysm. After 3 years the patient developed a sepsis. Imaging and blood exams detected an endograft infection related to Listeria monocytogenes. Patients underwent endograft removal and in-situ aortic reconstruction with a cryopreserved allograft. A continuous antibacterial therapy has been established. One-month follow-up revealed the absence of clinically relevant infection with patency of the graft and absence of biochemical inflammatory markers.

The poor accuracy of D-dimer for the diagnosis of prosthetic joint infection but its potential usefulness in early postoperative infections following revision arthroplasty for aseptic loosening

BACKGROUND

D-dimer was introduced in 2018 as an alternative biomarker for C-reactive protein (CRP) in the diagnostic of prosthetic joint infection (PJI) criteria of the Musculoskeletal Infection Society. We assessed the accuracy of plasma D-dimer for the diagnosis of early, delayed, and late PJI according to Infectious Diseases Society of America (IDSA) criteria, and whether persistently high levels of D-dimer in cases of aseptic loosening (AL) may be predictive of subsequent implant-related infection.

METHODS

A prospective study of a consecutive series of 187 revision arthroplasties was performed at a single institution. Septic (n = 39) and aseptic revisions (n = 141) were classified based on IDSA criteria. Preoperative assessment of CRP, erythrocyte sedimentation rate (ESR) and D-dimer was performed. Receiver operating curves were used to determine maximum sensitivity and specificity of the biomarkers. The natural progress of D-dimer for AL cases was followed up either until the date of implant-related infection at any time during the first year or 1 year after revision in patients without failure. Clinical outcomes for those AL cases included infection-related failure that required a new surgery or need for antibiotic suppression.

RESULTS

Preoperative D-dimer level was significantly higher in PJI cases than in AL cases (p = 0.000). The optimal threshold of D-dimer for the diagnosis of PJI was 1167 ng/mL. For overall diagnosis of PJI, C-reactive protein (CRP) achieved the highest sensitivity (84.6%), followed by erythrocyte sedimentation rate (ESR) and D-dimer (82% and 71.8%, respectively). Plasma D-dimer sensitivity was lower for all PJI types. When combinations of 2 tests were studied, the combined use of ESR and CRP achieved the best accuracy for all types of PJI (76.9%). 4.25% of AL cases had implant failure due to implant-related infection during the first year after the index revision arthroplasty, only the cases with early failure maintained high D-dimer levels.

CONCLUSIONS

Plasma D-dimer did not offer an improvement over the individual or combined diagnosis for any type of PJI according to IDSA criteria. Persistently raised levels of D-dimer after revision arthroplasty in AL cases might be used to effectively diagnose early postoperative infection.

Differential microbiological spectrum and resistance pattern in periprosthetic hip joint infections: a matched-cohort analysis comparing direct anterior versus lateral approach

BACKGROUND

In recent years, total hip arthroplasty via the direct anterior approach (DAA) has become more common. Little is known on the influence of the surgical approach on the microbiological spectrum and resistance pattern in periprosthetic hip joint infections. The aim of the present study was to evaluate the microbiological spectrum and resistance pattern in periprosthetic hip joint infections comparing the direct anterior versus lateral approach in a matched-cohort analysis at a single institution.

METHODS

Patients who underwent revision hip arthroplasty due to PJI following primary total hip arthroplasty with culture positive microbiology were analyzed. In all study patients, both the primary surgery and the revisions surgery were performed at the same institution. Only patients in whom primary surgery was performed via a direct anterior or lateral approach were included (n = 87). A matched cohort analysis was performed to compare the microbiological spectrum and resistance pattern in PJI following direct anterior (n = 36) versus lateral (n = 36) primary THA.

RESULTS

We identified both a significantly different microbiological spectrum and resistance pattern in PJI comparing direct anterior versus lateral approach THA. Cutibacterium avidum was obtained more frequently in the anterior subgroup (22.2% vs. 2.8%, p = 0.028). In the subgroup of infections with Staphylococcus aureus (n = 12), methicillin resistance was detected in 3/5 cases in the direct anterior group versus 0/7 cases in the lateral group (p = 0.045). Overall, Staphylococcus epidermidis was the most common causative microorganism in both groups (direct anterior: 36.1%; lateral: 27.8%, p = 0.448).

CONCLUSION

The present study indicates a potential influence of the localization of the skin incision in THA on the microbiological spectrum and resistance pattern in PJI. Cutibacterium avidum seemed to be a more common causative microorganism in PJI in patients who underwent direct anterior compared to lateral approach THA.

Aptamer selection against alpha-defensin human neutrophil peptide 1 on an integrated microfluidic system for diagnosis of periprosthetic joint infections

Periprosthetic joint infections (PJIs) arising from joint arthroplasty are dreadful, yet difficult to diagnose in subtle cases. Definite diagnosis requires microbiological culture to confirm the causative pathogens. However, up to 40% of culture-negative PJI needs other surrogate biomarkers such as human neutrophil peptide 1 (HNP 1) to improve diagnostic accuracy or gauge therapeutic responses. To devise a diagnostic method, systematic evolution of ligands by exponential enrichment (SELEX) (five rounds) was used to screen PJI biomarkers on a compact (20 × 20 × 35 cm), integrated microfluidic system equipped with two separate Peltier devices and one magnetic control module where an aptamer with high affinity and specificity for HNP 1, which has been used as one of the synovial fluid (SF) biomarkers for detecting PJI, was identified for the first time. Two rounds of negative selection (with immunoglobulin G & human serum album) on-chip followed by one round of unique "competitive selection" with SF extracted from PJI patients validated the specificity of the HNP 1 aptamer. The dissociation constant was measured to be 19 nM. The applicability of SF HNP 1 levels for diagnosing PJI was then verified by a new aptamer-based enzyme-linked immunosorbent assay (ELISA)-like assay. It is envisioned that this new aptamer and the associated assay could be used in future clinical applications.