Diagnostic accuracy of MRI with metal artifact reduction for the detection of periprosthetic joint infection and aseptic loosening of total hip arthroplasty

Diagnosing periprosthetic hip joint infection with new-generation 0.55T MRI

PURPOSE

To assess the accuracy of 0.55 T MRI in diagnosing periprosthetic joint infection (PJI) in patients with symptomatic total hip arthroplasty (THA).

MATERIAL AND METHODS

0.55 T MRI of patients with THA PJI (Group A) and noninfected THA (Group B), including aseptic loosening (Group C, subgroup of B) performed between May 2021 and July 2023 were analysed retrospectively. Two musculoskeletal fellowship-trained radiologists independently identified MRI bone and soft tissue changes including: marrow oedema, periosteal reaction, osteolysis, joint effusion, capsule oedema and thickening, fluid collections, muscle oedema, bursitis, inguinal adenopathy, and muscle tears. The diagnostic performance of MRI discriminators of PJI was evaluated using Fisher's exact test (p < 0.05) and interrater reliability was determined. 61 MRI scans from 60 THA patients (34 female, median age 68, range 41-93 years) in Group A (n = 9; female 4; median age 69, range 56-82 years), B (n = 51; 30; 67.5, 41-93 years), and C (10; 6; 67; 41-82 years) were included.

RESULTS

Capsule oedema (sensitivity 89 %, specificity 92 %,), intramuscular oedema (89 %, 82 %) and joint effusion (89 %, 73 %) were the best performing discriminators for PJI diagnosis (p ≤ 0.001), when viewed individually and had combined 70 % sensitivity and 100 % specificity for PJI diagnosis in parallel testing. For the differentiation between PJI and aseptic loosening, intramuscular oedema (89 %, 80 %) and capsule oedema (89 %, 80 %) were significant discriminators (p ≤ 0.001) with combined 64 % sensitivity and 96 % specificity for PJI.

CONCLUSIONS

New generation 0.55 T MRI may aid in the detection of PJI in symptomatic patients. Oedema of the joint capsule, adjacent muscles as well as joint effusion were indicative of the presence of PJI.

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.

MRI of total hip arthroplasty: technical aspects and imaging findings

Total hip arthroplasty (THA) is the best surgical approach for treating advanced hip degeneration, providing pain relief, and improved function in most cases. In the past, MR imaging quality has been highly compromised by in-plane distortions, inadequate fat saturation, and other artifacts due to metal components of THA. Technological advancements have made pathologic conditions, which were previously hidden by periprosthetic artifacts, outstanding features due to the optimization of several sequences. To date, several short and long-term complications involving bony and soft-tissue structures may be detected through magnetic resonance imaging (MRI). The use of MRI with adapted sequences and protocols may drastically reduce artifacts thereby providing essential pre-operative elements for planning revision surgery of failed THA. This review has the purpose of conveying new insights to musculoskeletal radiologists about the techniques to suppress metal-related artifacts and the hallmark MRI findings of painful THA. CRITICAL RELEVANCE STATEMENT: Advancements in metal-suppression have given radiologists the opportunity to play an emerging role in THA management. This article provides technical and imaging insights into challenges that can be encountered in cases of THA, which may present complications and characteristic imaging findings. KEY POINTS: Imaging total hip arthroplasty requires adapted MRI protocol and awareness of the common complications. We have reported the available metal-suppression sequences for evaluating total hip arthroplasty. Many structures and conditions should be considered when dealing with painful aseptic or septic arthroplasty.

Imaging in osteoarticular infection in adults

BACKGROUND

Osteoarticular infections are uncommon and required a multimodal approach for diagnosis. Imaging forms an important component of this multimodal approach.

OBJECTIVES

In this narrative review, we describe the different imaging modalities, features of osteoarticular infections present on these imaging approaches and recommendations for which imaging modality should be considered in different types of osteoarticular infections.

SOURCES

This narrative review was based on literature review from PubMed and was limited to bacterial infections in adult patients.

CONTENT

Imaging modalities include modalities that provide information on the anatomy or radionuclide imaging that provides information about the metabolic activity of the area of interest. Anatomical imaging includes plain radiographs (X-ray), computed tomography, and magnetic resonance imaging. Radionuclide approaches include three-phase bone scintigraphy, gallium scans, white blood cell scintigraphy, and 18F-fluorodeoxy-glucose positron emission tomography. The optimal radiological modality for diagnosis is influenced by multiple factors, including infection location, presence of metalware, timing of infection from any preceding surgery or fracture, antibiotic use, and patient comorbidities. Local availability of scanning modality, tracer supply, technical expertise, and patient access also influences choice.

IMPLICATIONS

A collaborative approach with imaging, pathology and clinical input in a multidisciplinary setting is paramount for the diagnosis of osteoarticular infections. Increasing research and improvements in technology will further improve the utility and accuracy of imaging approaches for imaging in osteoarticular infections.

Performance of classical serum inflammatory markers in healed and unhealed treated patients with joint and prosthetic joint infections

BACKGROUND

Serum markers, such as erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and D-dimer, are currently used by clinicians and orthopedic surgeons in diagnosing and managing joint infections (JI), although conflicting results exist on their performance. The aim of this study was to evaluate their performance in assessing healing or unhealing of patients with JI or with prosthetic joint infection (PJI).

METHODS

ESR, CRP and D-dimer serum levels were evaluated before, during and after antibiotic treatment in 61 patients (65.1 ± 12.6 years): 49 affected by PJI and 12 by JI, between 2020 and 2022. These patients had undergone orthopedic surgery and were treated with antibiotics.

RESULTS

ESR, CRP and D-dimer were significantly lower after treatment than before (p value: 0.001, 0.001 and 0.003, respectively) in healed and unhealed patients. A moderate correlation was found between the three inflammatory markers.

CONCLUSIONS

Using a cut off value of 25 mm/h for ESR, 0.5 mg/L for CRP, and 700 ng/ml for D-dimer, it might be possible to discriminate healed from unhealed patients (PPV and NPV: ESR 65.5% and 68.8%, CRP 71.9% and 79.3%, D-dimer 76.9% and 81.8%). The combined use of these three inflammatory markers might be useful in the management of joint infections.

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.

ACR Appropriateness Criteria® Imaging After Total Hip Arthroplasty

This article reviews evidence for performing various imaging studies in patients with total hip prostheses. Routine follow-up is generally performed with radiography. Radiographs are also usually the initial imaging modality for patients with symptoms related to the prosthesis. Following acute injury with pain, noncontrast CT may add information to radiographic examination regarding the presence and location of a fracture, component stability, and bone stock. Image-guided joint aspiration, noncontrast MRI, and white blood cell scan and sulfur colloid scan of the hip, are usually appropriate studies for patients suspected of having periprosthetic infection. For evaluation of component loosening, wear, and/or osteolysis, noncontrast CT or MRI are usually appropriate studies. Noncontrast MRI is usually appropriate for identifying adverse reaction to metal debris related to metal-on-metal articulations. For assessing patients after hip arthroplasty, who have trochanteric pain and nondiagnostic radiographs, ultrasound, or MRI are usually appropriate studies. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

The role of advanced metal artifact reduction MRI in the diagnosis of periprosthetic joint infection

Identification and diagnosis of periprosthetic joint infection (PJI) are challenging, requiring a multi-disciplinary approach involving clinical evaluation, laboratory tests, and imaging studies. MRI is advantageous to alternative imaging techniques due to superior soft tissue contrast and absence of ionizing radiation. However, the presence of metallic implants can cause signal loss and artifacts. Metal artifact suppression (MARS) MRI techniques have been developed that mitigate metal artifacts and improve periprosthetic soft tissue visualization. This paper provides a review of the various MARS MRI techniques, their clinical applicability and accuracy in PJI diagnosis and evaluation, and current challenges and future perspectives.

Diagnostic value of magnetic resonance imaging for patients with periprosthetic joint infection: a systematic review

PURPOSE

The purpose of this study was to provide a critical systematic review of the role of magnetic resonance imaging (MRI) as a noninvasive method to assess periprosthetic joint infections (PJIs).

METHODS

The electronic databases PubMed and EMBASE were searched, since their inception up to March 27, 2022. The included studies evaluated the reproducibility and accuracy of MRI features to diagnose PJIs. The article quality assessment was conducted by the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) and Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2).

RESULTS

Among 1909 studies identified in the initial search, 8 studies were eligible for final systematic review. The included studies evaluated the reproducibility and accuracy of MRI features to diagnose PJIs. Seven of 8 studies showed good to excellent reliability, but only one article among them in which accuracy was evaluated had a low risk of bias. The intraclass correlation coefficient (ICC) and Cohen coefficient (κ) varied between 0.44 and 1.00. The accuracy varied between 63.9% and 94.4%. Potential MRI features, such as lamellated hyperintense synovitis, edema, fluid collection, or lymphadenopathy, might be valuable for diagnosing PJIs.

CONCLUSION

The quality of the evidence regarding the role of MRI for PJIs diagnosis was low. There is preliminary evidence that MRI has a noteworthy value of distinguishing suspected periprosthetic joint infection in patients with total knee arthroplasty or total hip arthroplasty, but the definition of specific MRI features related to PJIs diagnosis lacks consensus and standardization. Large-scale studies with robust quality were required to help make better clinical decisions in the future.

Metal Artifact Reduction MRI in the Diagnosis of Periprosthetic Hip Joint Infection

A 54-year-old woman presented with progressive right hip pain after hip arthroplasty 9 years earlier. The emerging role of metal artifact reduction MRI in the noninvasive diagnosis of infectious synovitis as the surrogate marker for periprosthetic hip joint infection and differentiation from other synovitis types is discussed.

MRI-based artificial intelligence to predict infection following total hip arthroplasty failure

PURPOSE

To investigate whether artificial intelligence (AI) can differentiate septic from non-septic total hip arthroplasty (THA) failure based on preoperative MRI features.

MATERIALS AND METHODS

We included 173 patients (98 females, age: 67 ± 12 years) subjected to first-time THA revision surgery after preoperative pelvis MRI. We divided the patients into a training/validation/internal testing cohort (n = 117) and a temporally independent external-testing cohort (n = 56). MRI features were used to train, validate and test a machine learning algorithm based on support vector machine (SVM) to predict THA infection on the training-internal validation cohort with a nested fivefold validation approach. Machine learning performance was evaluated on independent data from the external-testing cohort.

RESULTS

MRI features were significantly more frequently observed in THA infection (P < 0.001), except bone destruction, periarticular soft-tissue mass, and fibrous membrane (P > 0.005). Considering all MRI features in the training/validation/internal-testing cohort, SVM classifier reached 92% sensitivity, 62% specificity, 79% PPV, 83% NPV, 82% accuracy, and 81% AUC in predicting THA infection, with bone edema, extracapsular edema, and synovitis having been the best predictors. After being tested on the external-testing cohort, the classifier showed 92% sensitivity, 79% specificity, 89% PPV, 83% NPV, 88% accuracy, and 89% AUC in predicting THA infection. SVM classifier showed 81% sensitivity, 76% specificity, 66% PPV, 88% NPV, 80% accuracy, and 74% AUC in predicting THA infection in the training/validation/internal-testing cohort based on the only presence of periprosthetic bone marrow edema on MRI, while it showed 68% sensitivity, 89% specificity, 93% PPV, 60% NPV, 75% accuracy, and 79% AUC in the external-testing cohort.

CONCLUSION

AI using SVM classifier showed promising results in predicting THA infection based on MRI features. This model might support radiologists in identifying THA infection.

Imaging in Hip Arthroplasty Management Part 2: Postoperative Diagnostic Imaging Strategy

Hip arthroplasty (HA) is a frequently used procedure with high success rates, but 7% to 27% of the patients complain of persistent postsurgical pain 1 to 4 years post-operation. HA complications depend on the post-operative delay, the type of material used, the patient’s characteristics, and the surgical approach. Radiographs are still the first imaging modality used for routine follow-up, in asymptomatic and painful cases. CT and MRI used to suffer from metallic artifacts but are nowadays central in HA complications diagnosis, both having their advantages and drawbacks. Additionally, there is no consensus on the optimal imaging workup for HA complication diagnosis, which may have an impact on patient management. After a brief reminder about the different types of prostheses, this article reviews their normal and pathologic appearance, according to each imaging modality, keeping in mind that few abnormalities might be present, not anyone requiring treatment, depending on the clinical scenario. A diagnostic imaging workup is also discussed, to aid the therapist in his imaging studies prescription and the radiologist in their practical aspects.

Metal Artefact Reduction Sequences (MARS) in Magnetic Resonance Imaging (MRI) after Total Hip Arthroplasty (THA)

Background

In the past, radiographic imaging was of minor relevance in the diagnosis of periprosthetic joint infections (PJI). Since metal artefact reduction sequences (MARS) are available, magnetic resonance imaging (MRI) has become a promising diagnostic tool for the evaluation of hip arthroplasty implants. The purpose of the present study was to evaluate the efficacy of MARS-MRI in comparison to established diagnostic tools to distinguish between aseptic failure and PJI.

Methods

From July 2018 to September 2019, 33 patients classified as having an aseptic joint effusion were recruited into the study. The group included 22 women and 11 men with a mean age of 70.4 ± 13.7 (42–88) years. In the same period, 12 patients were classified as having a PJI. The group consisted of 9 women and 3 men with a mean age of 72.5 ± 10.6 (54–88) years. MARS-MRI was conducted using the optimized parameters at 1.5 T in a coronal and axial STIR (short-tau-inversion recovery), a non-fat-saturated T2 in coronal view and a non-fat-saturated T1 in transverse view in 45 patients with painful hip after total hip arthroplasty (THA). Normally distributed continuous data were shown as mean ± standard deviation (SD) and compared using student's t-test. Non-normally distributed continuous data were shown as mean and compared using the Mann–Whitney U test.

Results

Synovial layering and muscle edema were significant features of periprosthetic joint infection, with sensitivities of 100% and specifities of 63.0—75.0%. The combined specifity and sensitivity levels of synovial layering and muscular edema was 88.0% and 90.0%. Granulomatous synovitis was a significant feature for aseptic failure, with 90.0% sensitivity and 57.0% specifity.

Conclusion

MARS-MRI is as suitable as standard diagnostic tools to distinguish between aseptic failure and PJI in patients with THA. Further studies with larger patient numbers have to prove whether MARS-MRI could be integral part of PJI diagnostic.

Postoperative Musculoskeletal Imaging and Interventions Following Hip Preservation Surgery, Deformity Correction, and Hip Arthroplasty

Total hip arthroplasty and hip preservation surgeries have substantially increased over the past few decades. Musculoskeletal imaging and interventions are cornerstones of comprehensive postoperative care and surveillance in patients undergoing established and more recently introduced hip surgeries. Hence the radiologist's role continues to evolve and expand. A strong understanding of hip joint anatomy and biomechanics, surgical procedures, expected normal postoperative imaging appearances, and postoperative complications ensures accurate imaging interpretation, intervention, and optimal patient care. This article presents surgical principles and procedural details pertinent to postoperative imaging evaluation strategies after common hip surgeries, such as radiography, ultrasonography, computed tomography, and magnetic resonance imaging. We review and illustrate the expected postoperative imaging appearances and complications following chondrolabral repair, acetabuloplasty, osteochondroplasty, periacetabular osteotomy, realigning and derotational femoral osteotomies, and hip arthroplasty.

Use of Novel Strategies to Develop Guidelines for Management of Pyogenic Osteomyelitis in Adults: A WikiGuidelines Group Consensus Statement

IMPORTANCE

Traditional approaches to practice guidelines frequently result in dissociation between strength of recommendation and quality of evidence.

OBJECTIVE

To construct a clinical guideline for pyogenic osteomyelitis management, with a new standard of evidence to resolve the gap between strength of recommendation and quality of evidence, through the use of a novel open access approach utilizing social media tools.

EVIDENCE REVIEW

This consensus statement and systematic review study used a novel approach from the WikiGuidelines Group, an open access collaborative research project, to construct clinical guidelines for pyogenic osteomyelitis. In June 2021 and February 2022, authors recruited via social media conducted multiple PubMed literature searches, including all years and languages, regarding osteomyelitis management; criteria for article quality and inclusion were specified in the group's charter. The GRADE system for evaluating evidence was not used based on previously published concerns regarding the potential dissociation between strength of recommendation and quality of evidence. Instead, the charter required that clear recommendations be made only when reproducible, prospective, controlled studies provided hypothesis-confirming evidence. In the absence of such data, clinical reviews were drafted to discuss pros and cons of care choices. Both clear recommendations and clinical reviews were planned with the intention to be regularly updated as new data become available.

FINDINGS

Sixty-three participants with diverse expertise from 8 countries developed the group's charter and its first guideline on pyogenic osteomyelitis. These participants included both nonacademic and academic physicians and pharmacists specializing in general internal medicine or hospital medicine, infectious diseases, orthopedic surgery, pharmacology, and medical microbiology. Of the 7 questions addressed in the guideline, 2 clear recommendations were offered for the use of oral antibiotic therapy and the duration of therapy. In addition, 5 clinical reviews were authored addressing diagnosis, approaches to osteomyelitis underlying a pressure ulcer, timing for the administration of empirical therapy, specific antimicrobial options (including empirical regimens, use of antimicrobials targeting resistant pathogens, the role of bone penetration, and the use of rifampin as adjunctive therapy), and the role of biomarkers and imaging to assess responses to therapy.

CONCLUSIONS AND RELEVANCE

The WikiGuidelines approach offers a novel methodology for clinical guideline development that precludes recommendations based on low-quality data or opinion. The primary limitation is the need for more rigorous clinical investigations, enabling additional clear recommendations for clinical questions currently unresolved by high-quality data.

Basic and Advanced Metal-Artifact Reduction Techniques at Ultra-High Field 7-T Magnetic Resonance Imaging-Phantom Study Investigating Feasibility and Efficacy

OBJECTIVES

The aim of this study was to demonstrate the feasibility and efficacy of basic (increased receive bandwidth) and advanced (view-angle tilting [VAT] and slice-encoding for metal artifact correction [SEMAC]) techniques for metal-artifact reduction in ultra-high field 7-T magnetic resonance imaging (MRI).

MATERIALS AND METHODS

In this experimental study, we performed 7-T MRI of titanium alloy phantom models composed of a spinal pedicle screw (phantom 1) and an intervertebral cage (phantom 2) centered in a rectangular LEGO frame, embedded in deionized-water-gadolinium (0.1 mmol/L) solution. The following turbo spin-echo sequences were acquired: (1) nonoptimized standard sequence; (2) optimized, that is, increased receive bandwidth sequence (oBW); (3) VAT; (4) combination of oBW and VAT (oBW-VAT); and (5) SEMAC. Two fellowship-trained musculoskeletal radiologists independently evaluated images regarding peri-implant signal void and geometric distortion (a, angle measurement and b, presence of circular shape loss). Statistics included Friedman test and Cochran Q test with Bonferroni correction for multiple comparisons. P values <0.05 were considered to represent statistical significance.

RESULTS

All metal-artifact reduction techniques reduced peri-implant signal voids and diminished geometric distortions, with oBW-VAT and SEMAC being most efficient. Compared with nonoptimized sequences, oBW-VAT and SEMAC produced significantly smaller peri-implant signal voids (all P ≤ 0.008) and significantly smaller distortion angles (P ≤ 0.001). Only SEMAC could significantly reduce distortions of circular shapes in the peri-implant frame (P ≤ 0.006). Notably, increasing the number of slice-encoding steps in SEMAC sequences did not lead to a significantly better metal-artifact reduction (all P ≥ 0.257).

CONCLUSIONS

The use of basic and advanced methods for metal-artifact reduction at 7-T MRI is feasible and effective. Both a combination of increased receive bandwidth and VAT as well as SEMAC significantly reduce the peri-implant signal void and geometric distortion around metal implants.

Magnetic Resonance Imaging Around Metal at 1.5 Tesla: Techniques From Basic to Advanced and Clinical Impact

ABSTRACT

During the last decade, metal artifact reduction in magnetic resonance imaging (MRI) has been an area of intensive research and substantial improvement. The demand for an excellent diagnostic MRI scan quality of tissues around metal implants is closely linked to the steadily increasing number of joint arthroplasty (especially knee and hip arthroplasties) and spinal stabilization procedures. Its unmatched soft tissue contrast and cross-sectional nature make MRI a valuable tool in early detection of frequently encountered postoperative complications, such as periprosthetic infection, material wear-induced synovitis, osteolysis, or damage of the soft tissues. However, metal-induced artifacts remain a constant challenge. Successful artifact reduction plays an important role in the diagnostic workup of patients with painful/dysfunctional arthroplasties and helps to improve patient outcome. The artifact severity depends both on the implant and the acquisition technique. The implant's material, in particular its magnetic susceptibility and electrical conductivity, its size, geometry, and orientation in the MRI magnet are critical. On the acquisition side, the magnetic field strength, the employed imaging pulse sequence, and several acquisition parameters can be optimized. As a rule of thumb, the choice of a 1.5-T over a 3.0-T magnet, a fast spin-echo sequence over a spin-echo or gradient-echo sequence, a high receive bandwidth, a small voxel size, and short tau inversion recovery-based fat suppression can mitigate the impact of metal artifacts on diagnostic image quality. However, successful imaging of large orthopedic implants (eg, arthroplasties) often requires further optimized artifact reduction methods, such as slice encoding for metal artifact correction or multiacquisition variable-resonance image combination. With these tools, MRI at 1.5 T is now widely considered the modality of choice for the clinical evaluation of patients with metal implants.

Ultrasound-Guided Periprosthetic Biopsy in Failed Total Hip Arthroplasty: A Novel Approach to Test Infection in Patients With Dry Joints

BACKGROUND

To diagnose periprosthetic joint infection (PJI) preoperatively, ultrasound-guided joint aspiration (US-JA) may not be performed when effusion is minimal or absent. We aimed to report and investigate the diagnostic performance of ultrasound-guided periprosthetic biopsy (US-PB) of synovial tissue to obtain joint samples in patients without fluid around the implants.

METHODS

One-hundred nine patients (55 men; mean age: 68 ± 13 years) with failed total hip arthroplasty (THA) who underwent revision surgery performed preoperative US-JA or US-PB to rule out PJI.

RESULTS

Sixty-nine of 109 patients had joint effusion and underwent US-JA, while the remaining 40 with dry joint required US-PB. Thirty-five of 109 patients (32.1%) had PJI, while 74/109 (67.9%) had aseptic THA failure. No immediate complications were observed in both groups. Technical success of US-PB was 100%, as the procedure was carried on as planned in all cases. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of US-JA were 52.2%, 97.8%, 92.3%, 80.3%, and 82.6%, while for US-PB, they were 41.7%, 100%, 100%, 80%, and 82.5%, respectively, with no significant difference (P = .779). Using the final diagnosis as reference standard, we observed a moderate agreement with both US-JA (k = 0.56) and US-PB (k = 0.50).

CONCLUSION

We present a novel US-guided technique to biopsy periprosthetic synovial tissue of failed THA to rule out PJI. We found similar diagnostic performance as compared with traditional US-JA. This supports future larger studies on this procedure that might be applied in patients without joint effusion.

Diagnostic algorithm in septic total knee arthroplasty failure - What is evidence-based?

Prosthetic joint infection (PJI) is among the most common differential diagnoses of total knee arthroplasty failure. It is a challenging complication, not least because of the difficulty of establishing the correct diagnosis. The fact that no single diagnostic parameter or test has been identified that can accurately rule in or out PJI has led to an evolution of similar but competing definitions of PJI on the grounds of an array of criteria. This development has had very positive effects on the scientific evaluation of various methods of PJI diagnostics and treatment because of an increased comparability. However, it can be challenging to stay abreast of the evidence these definitions are based on. Also, the definitions alone do not necessarily entail an algorithm to aid in evaluating the right criteria in a sound order to be able to use the definitions as a sensible tool. The aim of this overview is to state the most recent evidence on the diagnostic parameters included in the most established PJI definitions and to exhibit and compare the few algorithmic approaches published. Clinical symptoms of PJI are very rarely reported on in the literature, hence the evidence on their diagnostic value is poor. The only symptom that is part of the established PJI definitions is the presence of a fistula. Concerning serological markers, CRP and ESR are still the common denominator in the literature, most recently accompanied by D-Dimer as a potentially suitable marker that has been included in the most recent update of the International Consensus Meeting (ICM) criteria. Imaging plays a minor role in the diagnostic cascade because of inconsistent evidence, and no role whatsoever in the established definitions. The most important preoperative diagnostic measure is arthrocentesis and cultural and cytological analysis of the synovial fluid. The much acclaimed α-Defensin test has so far not been included in the established criteria due to inconsistent reports on its diagnostic accuracy, it is, however, in wide use and considered an optional diagnostic tool for inconclusive cases. The most diagnostic accuracy lies in the cultural and histological analysis of periprosthetic tissue biopsies, whether they are gathered in a small procedure or during arthroplasty revision. Published algorithmic approaches to PJI diagnosis are much rarer than the well-established definitions by various associations. With their PJI definition, the American Academy of Orthopedic Surgeons (AAOS) published a consensus based flowchart for PJI diagnosis. Another algorithm was proposed as part of the endeavor of the MSIS and the first consensus meeting, also based on a consensus among experts. There have been two more recent publications of flowcharts based on the current evidence, one introduced at our institution in 2013, one established in 2020 by the German Society for Arthroplasty (AE).