How Does a "Dry Tap" Impact the Accuracy of Preoperative Aspiration Results in Predicting Chronic Periprosthetic Joint Infection?

Evaluating key ultrasound findings and their correlations with hip joint aspiration and prosthetic joint infection diagnosis following total hip arthroplasty

OBJECTIVE

To evaluate the association between specific ultrasound findings with the success of hip joint aspiration and the presence of joint infection in patients with hip arthroplasty.

MATERIALS AND METHODS

138 patients who underwent ultrasound-guided aspiration were analyzed, focusing on hip joint capsular thickness, joint fluid echogenicity, synovial component visualization, and vascularity. These parameters were evaluated for their correlation with technically successful aspiration and infection status, using clinical data and the modified Musculoskeletal Infection Society (MSIS) criteria. Intra- and inter-reader reliability was also assessed for all measured parameters.

RESULTS

Capsular thickness with a cutoff of 10 mm or greater, showed strong associations with technically successful aspiration (p = 0.0001) and joint infection (p = 0.0005), with high intra- and inter-observer reliability. Fluid echogenicity, when categorized as hypoechoic and moderate/heterogeneous, also showed significant associations with technically successful aspiration (p = 0.0001) and joint infection (p = 0.0009). While visualization of the synovial component did not correlate with aspiration outcomes (p = 0.24), it demonstrated a significant association with joint infection (p = 0.0007). Vascularity showed no significant correlation with technically successful aspiration (p = 0.22) or infection (p = 0.05).

CONCLUSION

Ultrasound is valuable in measuring variables that can be associated with a technically successful aspiration and the presence of prosthetic joint infection in patients with a history of total hip arthroplasty. Capsular thickness, particularly at a 10 mm cutoff, emerged as a sensitive and quantifiable parameter that can improve pre-procedural assessment accuracy. While other findings, such as fluid echogenicity and synovial component visualization showed potential, they are best interpreted alongside other clinical and imaging data.

Preoperative Synovial Fluid Cultures, and Biopsy Cultures After Dry Tap Aspiration, Are Valuable in Diagnosing a Periprosthetic Joint Infection: A Retrospective Study

Periprosthetic joint infection (PJI) is a devastating complication after total hip arthroplasty. Synovial fluid aspiration and preoperative tissue biopsy cultures can be helpful diagnostic tools for PJI. The aim of this study is to evaluate the diagnostic value of synovial fluid aspirations in general, and preoperative biopsies after inconclusive or dry tap aspiration in patients undergoing revision hip arthroplasty in particular. Patients who underwent diagnostic aspiration and subsequent preoperative biopsy and/or revision surgery between January 2015 and January 2024 were included in the study. Synovial fluid aspirations and tissue samples obtained from biopsy and revision surgery were interpreted using the European Bone and Joint Infection Society criteria for PJI. In total, 207 patients were included with 231 synovial fluid aspirations. The sensitivity and specificity of synovial fluid aspiration cultures were 76% and 98%. In 62 cases, tissue biopsies were performed, of which 23 were after dry tap aspiration. Tissue biopsies after dry tap aspiration had a sensitivity of 44% and a specificity of 93%. Tissue biopsies after dry tap aspiration led to the confirmation of PJI in 7/23 cases. Synovial fluid aspiration yields reliable results when evaluating a patient for suspicion of PJI. Diagnosing PJI can, however, be troublesome if the synovial fluid aspiration provides a dry tap or inconclusive result. Tissue biopsy cultures after dry tap aspiration are a feasible way to confirm PJI.

Construction and evaluation of a combined diagnostic model for chronic periprosthetic joint infection based on serological tests

BACKGROUND

Early diagnosis of chronic periprosthetic joint infection (CPJI) is crucial for ensuring effective treatment and improving patient outcomes. However, many auxiliary diagnostic tests are challenging to implement on a large scale due to economic and technical constraints, making CPJI diagnosis difficult. This study aims to design and validate a combined diagnostic model based on commonly used serological tests to evaluate its diagnostic value for CPJI and develop a diagnostic nomogram.

METHODS

A retrospective study from January 2019 to February 2024 involving 170 patients undergoing knee and hip arthroplasty revision for CPJI and aseptic loosening (AL) was conducted across two medical centers. These patients were divided into the training set and validation set. Patients were categorized into CPJI and AL groups based on infection status. Serological tests conducted upon admission were collected, and single-factor and multi-factor logistic regression analyses were used to identify independent diagnostic factors for early infection. These factors were integrated to construct a nomogram model. The model's performance was evaluated using the receiver operating characteristic area under the curve (AUC), Hosmer-Lemeshow test, decision curve analysis (DCA), and calibration curve, with external validation conducted on the validation set.

RESULTS

Multivariate logistic regression analysis showed that C-reactive protein (CRP), procalcitonin (PCT), and Platelet count/mean platelet volume ratio (PVR) were independent diagnostic factors for CPJI (p < 0.05). The AUCs for diagnosing CPJI using these individual factors were 0.806, 0.616, and 0.700 (p < 0.05), respectively, while their combined detection achieved an AUC of 0.861 (p < 0.05). The DCA clinical impact curve shows the combined model has good clinical utility when the threshold probability of infection presence is between 0.16 and 0.95. Similar results were obtained in the external validation cohort, with the combined detection having an AUC of 0.893.

CONCLUSION

The combined diagnostic model of CRP, PCT, and PVR significantly improves the The combined diagnostic model of CRP, PCT, and PVR significantly improves the diagnostic performance for CPJI compared to individual serum biomarkers. It exhibits good sensitivity, specificity, and clinical applicability, providing valuable references for CPJI diagnosis.

Imaging approach to prosthetic joint infection

The diagnosis of prosthetic joint infection (PJI) remains challenging, despite multiple available laboratory tests for both serum and synovial fluid analysis. The clinical symptoms of PJI are not always characteristic, particularly in the chronic phase, and there is often significant overlap in symptoms with non-infectious forms of arthroplasty failure. Further exacerbating this challenge is lack of a universally accepted definition for PJI, with publications from multiple professional societies citing different diagnostic criteria. While not included in many of the major societies' guidelines for diagnosis of PJI, diagnostic imaging can play an important role in the workup of suspected PJI. In this article, we will review an approach to diagnostic imaging modalities (radiography, ultrasound, CT, MRI) in the workup of suspected PJI, with special attention to the limitations and benefits of each modality. We will also discuss the role that image-guided interventions play in the workup of these patients, through ultrasound and fluoroscopically guided joint aspirations. While there is no standard imaging algorithm that can universally applied to all patients with suspected PJI, we will discuss a general approach to diagnostic imaging and image-guided intervention in this clinical scenario.

A "Dry Tap" in Prosthetic Joint Infection Workup of Total Hip Arthroplasty Is Not Reassuring

BACKGROUND

Synovial fluid analysis is important in diagnosing prosthetic joint infection (PJI). The rate of culture-positive PJI in patients who have a dry tap of a total hip arthroplasty (THA) is not well described.

METHODS

We reviewed all image-guided THA aspirations, performed from 2014 to 2021 at a single academic institution. Aspirations were categorized as successful (≥ 0.5 mL) or unsuccessful (< 0.5 mL, "dry tap"). We analyzed culture data on all repeat aspirations and revision surgeries performed within 90 days of the initial dry tap.

RESULTS

We reviewed 275 consecutive attempted THA aspirations of which 100 (36.4%) resulted in a dry tap. The dry tap cohort had a significantly higher percentage of fluoroscopic-guided aspirations (64%) and fewer ultrasound-guided aspirations (36%) compared to the successful aspiration cohort (48.9% fluoroscopic, 53.1% ultrasound, P = .0061). Of the 100 patients who have dry taps, 48 underwent revision surgery within 90 days of the initial dry tap, and 15 resulted in 2 or more positive cultures. The rate of PJI defined by MusculoSkeletal Infection Society major criteria in the dry tap cohort was 16.0%.

CONCLUSIONS

Attempted aspiration of a THA resulted in a dry tap 36.4% of the time. Of those patients who had a dry tap, 16.0% were subsequently found to have PJI based on MusculoSkeletal Infection Society major criteria. Therefore, a "dry tap" does not exclude the diagnosis of infection and should not be considered reassuring for the absence of PJI.

Pre-aspiration outpatient ultrasound can accurately predict dry taps in prosthetic hips suspected of infection; a prospective study

Introduction

Aspiration represents the most potent method for exploring the potential occurrence of Periprosthetic Joint Infection (PJI). However, dry taps are common. While aspiration under ultrasound (US) guidance in the radiology department has become increasingly popular, hip aspiration is still routinely conducted in the operating room (OR) under x-ray guidance in numerous medical centers. When conducted within the confines of the OR, a dry tap aspiration not only subjects the patient to an unnecessary invasive procedure but also constitutes a substantial strain on OR time and resources. Our objective was to assess whether an outpatient US conducted before aspiration could reliably predict the likelihood of encountering a dry hip aspiration.

Methods

In a prospective study, we enrolled 50 hips who were suspected of PJI and slated for revision total hip arthroplasty and required hip aspiration. Before the aspiration procedure, we conducted an outpatient hip ultrasound (US) to assess the presence of fluid collection. Subsequently, all patients underwent aspiration under fluoroscopy in the OR, irrespective of the ultrasound findings We then assessed the level of agreement between the ultrasound results and the outcomes of hip aspiration.

Results

The US exhibited a sensitivity of 95.7% (95% CI 69.8-91.8), a specificity of 74.1% (95% CI 52.8-91.8), a positive predictive value of 75.9% (95% CI 50.9-91.3), and a negative predictive value of 95.2% (95% CI 71.3-99.8) in predicting the success of aspiration.

Discussion

Pre-aspiration outpatient US demonstrates a high degree of accuracy in predicting dry taps in these patients. We recommend its incorporation into the hip aspiration procedure in medical centers where aspiration is performed in the operating room. In the broader context, these findings reinforce the preference for US-guided aspiration within the radiology department over x-ray-guided aspiration in the operating room since about ¼ of the positive USs for hip collection will lead to a dry tap if the aspiration is performed in the OR under fluoroscopy guidance.

An overview of the current diagnostic approach to Periprosthetic Joint Infections

The diagnosis of periprosthetic joint infections (PJI) presents a formidable challenge to orthopaedic surgeons due to its complex and diverse manifestations. Accurate diagnosis is of utmost importance, as even mild pain following joint replacement surgery may indicate PJI in the absence of a definitive gold standard diagnostic test. Numerous diagnostic modalities have been suggested in the literature, and international societies have continually updated diagnostic criteria for this debilitating complication. This review article aims to comprehensively examine the latest evidence-based approaches for diagnosing PJI. Through a thorough analysis of current literature, we explore promising diagnostic strategies that have demonstrated effectiveness in identifying PJI. These strategies encompass the utilization of laboratory markers, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), alongside imaging techniques such as magnetic resonance imaging (MRI) and leukocyte scintigraphy. Additionally, we highlight the importance of synovial fluid analysis, including the potential role of alpha-defensin as a biomarker, and examine evolving international diagnostic criteria to standardize and improve diagnostic accuracy.

The Value of Preoperative Ultrasound-Determined Fluid Film and Joint Aspiration in Revision Hip Arthroplasty

BACKGROUND

Data regarding the diagnostic value of ultrasound (US)-determined fluid film and joint aspiration prior to revision total hip arthroplasty for suspected periprosthetic joint infections (PJIs) are limited. This study aimed to analyze the value of US-determined fluid film, characterized the preoperative and intraoperative microbiological spectrum and resistance patterns, and compared the concordance between preoperative synovial fluid and intraoperative culture results.

METHODS

We analyzed 366 US examinations from 324 patients prior to revision total hip arthroplasty. Selected cases were grouped into clearly infected, noninfected, and inconclusive cohorts, according to the International Consensus Meeting 2018 Criteria. For US-determined fluid film <1 mm, no aspiration was performed based on our institutional protocol. Patients were grouped into no aspiration (144 of 366; [39.3%]), dry tap (21 of 366; [5.7%]), and a successful tap (201 of 366; [54.9%]). The microbiological spectrum and antibiograms were compared between preoperative and intraoperative results.

RESULTS

The absence of US-determined fluid film showed no correlation with the presence of a hip PJI. Overall, 31.9% cases of the no-aspiration group had a PJI. In total, 13.5% discrepancies were found between successful taps and intraoperative cultures. The most prevalent microorganisms in preoperative synovial fluid were Staphylococcus epidermidis and Staphylococcus aureus (20.8%), while intraoperatively S. epidermidis (26.3%) and Cutibacterium acnes (14.5%) were leading. Additional microorganisms were identified in 32.5% of intraoperative cultures. There were no differences between resistance patterns of preoperative and intraoperative concordant microorganisms.

CONCLUSIONS

Absence of US-determined fluid film cannot rule out the presence of a hip PJI. Combined microbiological results from hip US aspirations and subsequent surgical procedures are crucial to design an effective treatment for suspected hip PJI.

Novel diagnostic markers for periprosthetic joint infection: a systematic review

Background

Identifying novel biomarkers that are both specific and sensitive to periprosthetic joint infection (PJI) has the potential to improve diagnostic accuracy and ultimately enhance patient outcomes. Therefore, the aim of this systematic review is to identify and evaluate the effectiveness of novel biomarkers for the diagnosis of PJI.

Methods

We searched the MEDLINE, EMBASE, PubMed, and Cochrane Library databases from January 1, 2018, to September 30, 2022, using the search terms "periprosthetic joint infection," "prosthetic joint infection," or "periprosthetic infection" as the diagnosis of interest and the target index, combined with the term "marker." We excluded articles that mentioned established biomarkers such as CRP, ESR, Interleukin 6, Alpha defensin, PCT (procalcitonin), and LC (leucocyte cell count). We used the MSIS, ICM, or EBJS criteria for PJI as the reference standard during quality assessment.

Results

We collected 19 studies that analyzed fourteen different novel biomarkers. Proteins were the most commonly analyzed biomarkers (nine studies), followed by molecules (three studies), exosomes (two studies), DNA (two studies), interleukins (one study), and lysosomes (one study). Calprotectin was a frequently analyzed and promising marker. In the scenario where the threshold was set at ≥50-mg/mL, the calprotectin point-of-care (POC) performance showed a high sensitivity of 98.1% and a specificity of 95.7%.

Conclusion

None of the analyzed biomarkers demonstrated outstanding performance compared to the established parameters used for standardized treatment based on established PJI definitions. Further studies are needed to determine the benefit and usefulness of implementing new biomarkers in diagnostic PJI settings.

Is ultrasound-guided hip aspiration more successful than fluoroscopic-guided aspiration in diagnosing prosthetic joint infection?

Introduction: aspiration of total hip arthroplasty (THA) is commonly performed to assist in the diagnosis of prosthetic joint infection (PJI). This study aimed to determine whether fluoroscopic- or ultrasound- guided hip aspiration differs in the ability to acquire synovial fluid and in the accuracy of diagnosing infection. Methods: all THA aspirations performed between 2014 and 2021 at our institution were retrospectively identified. Aspirations were classified as successful or dry. If successful, the volume of fluid obtained was recorded. The sensitivity and specificity of hip aspiration in identifying PJI were calculated with four methods: (1) culture results excluding saline lavage, (2) culture results including saline lavage, (3) 2018 Musculoskeletal Infection Society (MSIS) International Consensus Meeting (ICM) criteria, and (4) 2021 European Bone and Joint Infection Society (EBJIS) criteria. Analyses were performed using Student's t test or Wilcoxon rank sum for continuous variables and chi-squared or Fisher's exact test for categorical variables. Results: 290 aspirations were included (155 fluoroscopic-guided and 135 ultrasound-guided). Success of aspiration (> 0.5  mL) was more common in the ultrasound cohort (69 %) than fluoroscopy (53 %) (p < 0.0055 ). When successful, more volume was obtained in the ultrasound cohort (mean 13.1 mL vs. 10.0 mL; p = 0.0002 ). Ultrasound-guided aspiration was more sensitive than fluoroscopy in diagnosing PJI using culture results excluding saline lavage (85 % vs. 73 %; p = 0.03 ), culture results including saline lavage (85 % vs. 69 %; p = 0.001 ), 2018 MSIS-ICM criteria (77 % vs. 52 %; p = 0.02 ), and 2021 EBJIS criteria (87 % vs. 65 %; p = 0.02 ). Ultrasound-guided aspiration was more specific than fluoroscopy in diagnosing PJI using 2021 EBJIS criteria (100 % vs. 96 %; p = 0.001 ). Conclusions: ultrasound-guided aspiration is more frequently successful and yields more fluid than fluoroscopic-guided aspiration of THA. Ultrasound-guided aspiration is more sensitive in diagnosing PJI than fluoroscopy using culture data, 2018 MSIS-ICM criteria, and 2021 EBJIS criteria.

The concordance between preoperative synovial fluid culture and intraoperative tissue cultures in periprosthetic joint infection: a systematic review

Background: this systematic review aims to evaluate the concordance between preoperative synovial fluid culture and intraoperative tissue cultures in patients with periprosthetic joint infection (PJI) undergoing total hip (THA) or knee arthroplasty (TKA) revision surgery. Methods: this review was conducted in accordance with the preferred reporting items for a systematic review and meta-analysis of diagnostic test accuracy studies (PRISMA-DTA) statement. Cochrane, Embase, PubMed, and Web of Science databases were searched to identify studies involving patients who had THA or TKA revision surgery for PJI and for whom preoperative synovial fluid culture and intraoperative tissue cultures were performed. Studies were only included if the diagnosis of PJI was based on the EBJIS (the European Bone and Joint Infection Society) or MSIS (Musculoskeletal Infection Society) criteria. Risk of bias was assessed using an amended version of Joanna Briggs Institute's (JBI) critical appraisal checklist for case series. Results: seven studies were included in this review comprising 1677 patients. All studies had a retrospective study design and five studies explored patients undergoing revision surgery of THA or TKA. Concordance rates varied between 52 % and 79 %, but different authors defined and calculated concordance differently. Six studies were judged as having an unclear to high risk of bias and one study as having a low risk of bias. Conclusions: the included studies showed a wide range of concordance rates between preoperative synovial fluid culture and intraoperative tissue cultures and the majority of studies had a high risk of bias. Higher-quality studies are warranted to obtain a more accurate estimate of this concordance rate. We recommend continuing the use of a system such as the EBJIS definition or MSIS criteria when diagnosing PJI.