The Rule of Histology in the Diagnosis of Periprosthetic Infection: Specific Granulocyte Counting Methods and New Immunohistologic Staining Techniques may Increase the Diagnostic Value

Intraoperative frozen section analysis for detection of fracture-related infection in nonunion of the upper limb. Diagnostic accuracy study

INTRODUCTION

During revision surgery for the management of patients presenting with long-bone upper extremity nonunion, it is crucial to rule out fracture-related infection (FRI). This is especially true if there are clinical signs suggestive of FRI, or if there is a history of prior FRI, open wound fracture, or surgery. This study aimed to determine the efficacy of frozen section analysis (FSA) in providing real-time diagnosis of FRI in patients with upper-limb long-bone nonunion undergoing revision surgery.

PATIENTS AND METHODS

We included previously surgically treated patients who underwent revision surgery for chronic/late-onset nonunion of the long bones of the upper limbs over a 9-year period. We retrospectively applied the FRI criteria to identify eligible patients and recorded their clinical features and demographic characteristics. In all included patients, samples for microbiological analysis and FSA were collected simultaneously during revision surgery. Patients were categorized according to intraoperative culture results as having aseptic or infected nonunion. The sensitivity, specificity, positive and negative predictive values, and accuracy of FSA test were calculated and compared using microbiological analysis as the reference standard test. The concordance rate between FSA and definitive histopathology was also determined.

RESULTS

Sixty-two patients who were surgically treated for nonunion of the arm or forearm were included in this study. Septic nonunion was diagnosed intraoperatively in 9 patients based on FSA findings, while microbiological analysis confirmed septic nonunion in 8 patients. The sensitivity and specificity of FSA were 88 % (95 % confidence interval [CI] [47, 100]) and 96 % (95 % CI [87, 100]), respectively. Positive and negative predictive values were 78 % (95 % CI [47, 93]) and 98 % (95 % CI [89, 100]), respectively, with an overall test accuracy of 95 % (95 % CI [87, 99]). Cohen's Kappa coefficient between FSA and definitive histopathology was 0.74 (95 % CI [0.5, 1]).

CONCLUSIONS

FSA showed high sensitivity and specificity for the detection of active infection during revision surgery for nonunion of the upper limb. Owing to its high negative predictive value, it can reliably rule out active infections during revision surgery. Since the results are obtained immediately during revision surgery, this approach offers the significant advantage of enabling real-time decision-making.

Utility of histopathological examination in aseptic revision total hip arthroplasty: a preliminary analysis

INTRODUCTION

The utility of a routine histopathological examination in aseptic revision total hip arthroplasty (THA) has not been well explored. We aim to describe the approach and present the results of histopathological examination, focusing on its clinical usefulness in the setting of aseptic revision THA.

METHOD

We retrospectively reviewed 285 performed aseptic revision THA with available histopathological reports between 2015 and 2017 at a single institution. We described histopathological requests by the surgical team. Preoperative diagnoses, intraoperative findings, as well as histopathology and culture results were analysed.

RESULTS

13 painful THAs (4.5%) had preoperatively unknown diagnoses. In 10 of them, potential causes of pain were intraoperatively identified. Histopathology confirmed these findings in 8 THAs. 19 THAs (6.7%) revealed unexpected positive cultures (UPC). Histopathology was negative for infection in 18 of them. Among 16 consultants, 3 surgeons requested histopathology in 47% of the cases (130/285), usually to exclude infection (101/285; 35%). Documentation for tissue sample location was lacking in 51% (145/285), and for question asked by the surgeon in 47% (135/285).

CONCLUSIONS

Histopathology is deemed a useful confirmatory tool in the context of ruling out infection in UPCs, and in documenting intraoperative findings in painful THAs with unknown preoperative diagnoses. Importantly, the approach to requesting histopathology should be optimised. Further large-scale studies, including cost analyses, are warranted to explore the usefulness of histopathology in routine utility.

Success of staged revision reverse total shoulder arthroplasty in eradication of periprosthetic joint infection

INTRODUCTION

Management of periprosthetic joint infection (PJI) in shoulder arthroplasty remains a challenge, with no established gold standard treatment. This study presents the unique experience of a high-volume single-surgeon, single-institution approach on staged revision reverse total shoulder arthroplasty (RTSA) for infection. The authors theorize that staged revision RTSA is an effective treatment for PJI.

MATERIALS AND METHODS

Between 2013 and 2018, 38 patients underwent a staged RTSA for treatment of PJI. Patient histories were collected and classified using Cierny-Mader classification. Infection workup for all patients included radiographs, laboratory indices, and computed tomographic aspiration arthrogram. PJI was identified based on high clinical and radiographic suspicion, elevated serologic markers, and/or aspirate culture results per 2018 International Consensus Meeting Shoulder guidelines on Orthopedic Infections. All patients underwent first stage with implant removal, irrigation and débridement, and antibiotic spacer placement. Next, intravenous antibiotics were administered by infectious disease consultants for a minimum of 6 weeks. Infection workup was then repeated and, if normalized, final-stage revision commenced with antibiotic spacer removal and revision to RTSA. If indices were persistently abnormal, an additional stage of débridement and spacer placement procedure was performed. Treatment failure was defined as recurrent periprosthetic infection after final prosthesis implantation or persistently elevated indices despite adequate débridement and spacer placement.

RESULTS

Mean age of the cohort was 68 (standard deviation [SD] 8.9) years and mean follow-up was 33 (SD 14) months with 34 Cierny-Mader C hosts and 4 B hosts. Patients underwent a mean of 2 (SD 1.1) previous surgeries. The staged revision protocol was successful in 34 (89.5%) patients for management of PJI. Four patients (10.5%) were considered failures with recurrent infections at a mean of 13 months (range 2-26 months) after the final RTSA implantation and underwent repeat staged revisions. Of the 34 patients who had successful infection eradication, 31 had 2-stage treatment and 3 had to undergo 3 stages. There were no treatment-associated mortalities and 10 major complications (26%), including permanent neuropathy, instability, and periprosthetic fractures. The most common cultured microorganism was Cutibacterium acnes (18%), with no polymicrobial infections detected.

DISCUSSION

Although there are multiple treatment options for PJI management, staged revision remains an effective means of treatment. Although there were several patients who required an additional stage of treatment, and a significant complication rate, staged revision RTSA proved successful in the ultimate eradication of the PJI.

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 analyze 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 center 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.

[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.

Reliable Diagnostic Tests and Thresholds for Preoperative Diagnosis of Non-Inflammatory Arthritis Periprosthetic Joint Infection: A Meta-analysis and Systematic Review

Objective

The current diagnostic criteria for periprosthetic joint infection (PJI) are diverse and controversial, leading to delayed diagnosis. This study aimed to evaluate and unify their diagnostic accuracy and the threshold selection of serum and synovial routine tests for PJI at an early stage.

Methods

We searched the MEDLINE and Embase databases for retrospective or prospective studies which reported preoperative‐available assays (serum, synovial, or culture tests) for the diagnosis of chronic PJI among inflammatory arthritis (IA) or non‐IA populations from January 1, 2000 to June 30, 2022. Threshold effective analysis was performed on synovial polymorphonuclear neutrophils (PMN%), synovial white blood cell (WBC), serum C‐reactive protein (CRP), and erythrocyte sedimentation rate (ESR) to find the relevant cut‐offs.

Results

Two hundred and sixteen studies and information from 45,316 individuals were included in the final analysis. Synovial laboratory‐based α‐defensin and calprotectin had the best comprehensive sensitivity (0.91 [0.86–0.94], 0.95 [0.88–0.98]) and specificity (0.96 [0.94‐0.97], 0.95 [0.89–0.98]) values. According to the threshold effect analysis, the recommended cut‐offs are 70% (sensitivity 0.89 [0.85–0.92], specificity 0.90 [0.87–0.93]), 4100/μL (sensitivity 0.90 [0.87–0.93], specificity 0.97 [0.93–0.98]), 13.5 mg/L (sensitivity 0.84 [0.78–0.89], specificity 0.83 [0.73–0.89]), and 30 mm/h (sensitivity 0.79 [0.74–0.83], specificity 0.78 [0.72–0.83]) for synovial PMN%, synovial WBC, serum CRP, and ESR, respectively, and tests seem to be more reliable among non‐IA patients.

Conclusions

The laboratory‐based synovial α‐defensin and synovial calprotectin are the two best independent preoperative diagnostic tests for PJI. A cut off of 70% for synovial PMN% and tighter cut‐offs for synovial WBC and serum CRP could have a better diagnostic accuracy for non‐IA patients with chronic PJI.

Intraoperative frozen section histopathology for the diagnosis of periprosthetic joint infection in hip revision surgery: the influence of recent dislocation and/or periprosthetic fracture

AIMS

To evaluate the accuracy of intraoperative frozen section histopathology for diagnosing periprosthetic joint infection (PJI) during hip revision surgery, both for patients with and without recent trauma to the hip.

PATIENTS AND METHODS

The study included all revision total hip replacement procedures where intraoperative frozen section histopathology had been used for the evaluation of infection in a single institution between 2008 and 2015. Musculoskeletal Infection Society criteria were used to define infection. 210 hips were included for evaluation. Prior to revision surgery, 36 hips had a dislocation or a periprosthetic fracture (group A), and 174 did not (group B).

RESULTS

The prevalence of infection was 14.3% (5.6% in group A and 16.1% in group B). Using Feldman criteria, the sensitivity of histopathology was 50.0%, specificity 47.1%, positive predictive value 5.3% and negative predictive value 94.1% in group A. The sensitivity of frozen section histopathology was 75.0%, specificity 96.5%, positive predictive value 85% and negative predictive value 95.3% in group B.

CONCLUSIONS

Intraoperative frozen section histopathology is reliable for the diagnosis of PJI if no dislocation or periprosthetic fracture has occurred prior to hip revision surgery.

The Role of Imaging Techniques to Define a Peri-Prosthetic Hip and Knee Joint Infection: Multidisciplinary Consensus Statements

Diagnosing a peri-prosthetic joint infection (PJI) remains challenging despite the availability of a variety of clinical signs, serum and synovial markers, imaging techniques, microbiological and histological findings. Moreover, the one and only true definition of PJI does not exist, which is reflected by the existence of at least six different definitions by independent societies. These definitions are composed of major and minor criteria for defining a PJI, but most of them do not include imaging techniques. This paper highlights the pros and cons of available imaging techniques—X-ray, ultrasound, computed tomography (CT), Magnetic Resonance Imaging (MRI), bone scintigraphy, white blood cell scintigraphy (WBC), anti-granulocyte scintigraphy, and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), discusses the added value of hybrid camera systems—single photon emission tomography/computed tomography (SPECT/CT), PET/CT and PET/MRI and reports consensus answers on important clinical questions that were discussed during the Third European Congress on Inflammation/Infection Imaging in Rome, December 2019.

The W.A.I.O.T. Definition of Peri-Prosthetic Joint Infection: A Multi-center, Retrospective Validation Study

Peri-prosthetic joint infection (PJI) definition plays an important role in diagnostic and therapeutic decisions. However, while several criteria have been proposed by eminent institutions to define a PJI in the last decade, their clinical validation has been rarely performed. Aim of the present multicenter, international, retrospective study was to validate the World Association against Infection in Orthopedics and Trauma (WAIOT) pre/intra-operative PJI definition with post-operative confirmatory tests. A total of 210 patients, undergoing hip (n = 86) or knee (n = 124) revision surgery for any reason in six orthopedic centers in Africa, Asia, Europe and South America, were retrospectively evaluated at a two years minimum follow-up after surgery. All the available pre-, intra- and post-operative findings were collected and analyzed according to the WAIOT criteria, which include a set of tests to confirm (Rule In) or to exclude (Rule Out) a PJI. On average, patients were investigated pre/intra-operatively with 3.1 ± 1.1 rule out and 2.7 ± 0.9 rule in tests; the presence of a fistula or exposed implant was reported in 37 patients (17.6%). According to pre/intraoperative findings, 36.2% of the patients were defined as affected by high-grade PJI (n = 76; average score: 2.3 ± 0.8), 21.9% by low-grade PJI (n = 46; average score: 0.8 ± 0.8), 10.5% by biofilm-related implant malfunction (n = 22; average score: -1.6 ± 0.8), 2.9% as contamination (n = 6; average score: -3.5 ± 1.0), and 28.6% as no infection (n = 60; average score: -3.0 ± 1.4). Pre/intra-operative PJI definitions matched post-operative confirmatory tests, in 97.1% of the patients. This is, to our knowledge, one of the largest study ever conducted to validate a PJI definition The retrospective analysis in different centers was greatly facilitated by the structure of the WAIOT definition, that allows to include different tests on the basis of their sensitivity/specificity, while the comparison between pre/intra-operative and post-operative findings offered the internal validation of the scoring system. Our results authenticate the WAIOT definition as a reliable, simple tool to identify patients affected by PJI prior to joint revision surgery.

The W.A.I.O.T. Definition of High-Grade and Low-Grade Peri-Prosthetic Joint Infection

The definition of peri-prosthetic joint infection (PJI) has a strong impact on the diagnostic pathway and on treatment decisions. In the last decade, at least five different definitions of peri-prosthetic joint infection (PJI) have been proposed, each one with intrinsic limitations. In order to move a step forward, the World Association against Infection in Orthopedics and Trauma (W.A.I.O.T.) has studied a possible alternative solution, based on three parameters: 1. the relative ability of each diagnostic test or procedure to Rule OUT and/or to Rule IN a PJI; 2. the clinical presentation; 3. the distinction between pre/intra-operative findings and post-operative confirmation. According to the WAIOT definition, any positive Rule IN test (a test with a specificity > 90%) scores +1, while a negative Rule OUT test (a test with a sensitivity > 90%) scores −1. When a minimum of two Rule IN and two Rule OUT tests are performed in a given patient, the balance between positive and negative tests, interpreted in the light of the clinical presentation and of the post-operative findings, allows to identify five different conditions: High-Grade PJI (score ≥ 1), Low-Grade PJI (≥0), Biofilm-related implant malfunction, Contamination and No infection (all scoring < 0). The proposed definition leaves the physician free to choose among different tests with similar sensitivity or specificity, on the basis of medical, logistical and economic considerations, while novel tests or diagnostic procedures can be implemented in the definition at any time, provided that they meet the required sensitivity and/or specificity thresholds. Key procedures to confirm or to exclude the diagnosis of PJI remain post-operative histological and microbiological analysis; in this regard, given the biofilm-related nature of PJI, microbiological investigations should be conducted with proper sampling, closed transport systems, antibiofilm processing of tissue samples and explanted biomaterials, and prolonged cultures. The proposed WAIOT definition is the result of an international, multidisciplinary effort. Next step will be a large scale, multicenter clinical validation trial.

Can leucocyte esterase replace frozen sections in the intraoperative diagnosis of prosthetic hip infection?

AIMS

Leucocyte esterase (LE) has been shown to be an accurate marker of prosthetic joint infection (PJI), and has been proposed as an alternative to frozen section (FS) histology for intraoperative diagnosis. In this study, the intraoperative assessment of LE was compared with FS histology for the diagnosis of prosthetic hip infection.

PATIENTS AND METHODS

A total of 119 patients undergoing revision total hip arthroplasty (THA) between June 2015 and December 2017 were included in the study. There were 56 men and 63 women with a mean age of 66.2 years (27 to 88). Synovial fluid was collected before arthrotomy for the assessment of LE using enzymatic colourimetric strips. Between five and six samples were stained with haematoxylin and eosin for FS histology, and considered suggestive of infection when at least five polymorphonuclear leucocytes were found in five high-power fields.

RESULTS

The sensitivity and specificity of the LE assay were 100% and 93.8%, respectively; the positive (PPV) and the negative (NPV) predictive values were 79.3% and 100%, respectively. The mean time between the collection of the sample and the result being known was 20.1 minutes (sd 4.4). The sensitivity and specificity of FS histology were 78.3% and 96.9%, respectively; the PPV and the NPV were 85.7% and 94.9%, respectively. The mean time between the collection of the sample and the result being known was 27.2 minutes (sd 6.9).

CONCLUSION

The sensitivity of LE assay was higher, with similar specificity and diagnostic accuracy, compared with FS histology. The faster turnaround time, its ease of use, and low costs make LE assay a valuable alternative to FS histology. We now use it routinely for the intraoperative diagnosis of PJI. Cite this article: Bone Joint J 2019;101-B:372-377.

Diagnostic Accuracy of Serum, Synovial, and Tissue Testing for Chronic Periprosthetic Joint Infection After Hip and Knee Replacements: A Systematic Review

BACKGROUND

Chronic periprosthetic joint infection (PJI) is a devastating complication that can occur following total joint replacement. Patients with chronic PJI report a substantially lower quality of life and face a higher risk of short-term mortality. Establishing a diagnosis of chronic PJI is challenging because of conflicting guidelines, numerous tests, and limited evidence. Delays in diagnosing PJI are associated with poorer outcomes and morbid revision surgery. The purpose of this systematic review was to compare the diagnostic accuracy of serum, synovial, and tissue-based tests for chronic PJI.

METHODS

This review adheres to the Cochrane Collaboration's diagnostic test accuracy methods for evidence searching and syntheses. A detailed search of MEDLINE, Embase, the Cochrane Library, and the grey literature was performed to identify studies involving the diagnosis of chronic PJI in patients with hip or knee replacement. Eligible studies were assessed for quality and bias using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Meta-analyses were performed on tests with sufficient data points. Summary estimates and hierarchical summary receiver operating characteristic (HSROC) curves were obtained using a bivariate model.

RESULTS

A total of 12,616 citations were identified, and 203 studies met the inclusion criteria. Of these 203 studies, 170 had a high risk of bias. Eighty-three unique PJI diagnostic tests were identified, and 17 underwent meta-analyses. Laboratory-based synovial alpha-defensin tests and leukocyte esterase reagent (LER) strips (2+) had the best performance, followed by white blood-cell (WBC) count, measurement of synovial C-reactive protein (CRP) level, measurement of the polymorphonuclear neutrophil percentage (PMN%), and the alpha-defensin lateral flow test kit (Youden index ranging from 0.78 to 0.94). Tissue-based tests and 3 serum tests (measurement of interleukin-6 [IL-6] level, CRP level, and erythrocyte sedimentation rate [ESR]) had a Youden index between 0.61 to 0.75 but exhibited poorer performance compared with the synovial tests mentioned above.

CONCLUSIONS

The quality of the literature pertaining to chronic PJI diagnostic tests is heterogeneous, and the studies are at a high risk for bias. We believe that greater transparency and more complete reporting in studies of diagnostic test results should be mandated by peer-reviewed journals. The available literature suggests that several synovial fluid-based tests perform well for diagnosing chronic PJI and their use is recommended in the work-up of any suspected case of chronic PJI.

LEVEL OF EVIDENCE

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

Diagnostic challenges and future perspectives in fracture-related infection

Fracture-related infection (FRI) is one of the most challenging complications in orthopaedic trauma surgery. It has severe consequences for patients and an important socio-economic impact. FRI has distinct properties and needs to be addressed interdisciplinary. Since criteria for the diagnosis of FRI are not standardized, an expert panel recently proposed a definition for FRI. In this review the current diagnostic modalities and an interdisciplinary diagnostic algorithm based on this recently published definition, are presented and future diagnostic techniques discussed. Since to date, there is no single universal diagnostic test available that gives the clinician the definitive diagnosis of FRI, it is mandatory to follow a standardized diagnostic algorithm to correctly diagnose FRI.