Contribution of routine joint aspiration to the diagnosis of infection before hip revision surgery

When to lavage in the absence of a sonographically visible joint effusion in painful total knee arthroplasty: a retrospective longitudinal study

OBJECTIVE

To determine if knee arthroplasty without sonographically visible effusion needs to undergo lavage to rule out infection.

METHODS

Patients were accrued by a retrospective search of a longitudinally maintained radiology database looking for patients referred for ultrasound guided aspiration of suspected TKA infection. Clinical presentations, laboratory tests, intraoperative findings, and follow-up were reviewed.

RESULTS

Four hundred sixty-nine patients were included (mean age of 67 years (range, 36-91)) including 251 females. Four hundred three patients had effusions, of which 57 were infected based on ultrasound-guided and surgical aspirates. Sixty-four patients lacked effusions, of which 47 underwent lavage at the clinicians' request, with 6/47 infected. Nineteen patients without effusion were not lavaged at the clinicians' request due to low suspicion, and none were infected. Patients with positive lavage cultures all had clinical risk factors. Infection rates were significantly higher in patients with joint effusion and clinical suspicion for infection compared to absent joint effusion and absent clinical suspicion. A significantly higher proportion of patients with hyperemia or moderate-severe synovial thickening on ultrasound were symptomatic and had joint effusion and positive joint cultures. Aspiration of native fluid had 85% sensitivity and 100% specificity while lavage had a sensitivity of 57% and specificity of 100%. Negative predictive value for native aspirates was 94% compared to 86% for lavage.

CONCLUSION

A TKA with low clinical suspicion of infection does not need to undergo lavage in the absence of a sonographically visible effusion.

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.

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.

Antibiotic Prophylaxis in One-Stage Revision of Septic Total Knee Arthroplasty: A Scoping Review

BACKGROUND

Total knee replacement (TKA) is becoming a routine procedure in orthopedic surgery. One of the possible complications of this surgery is periprosthetic joint infection (PJI). The purpose of this study is to identify, through a literature review, which antibiotic is used as prophylaxis for septic one-stage revision TKA and what is the rationale for its use.

METHODS

We searched: MEDLINE, Embase, PsycINFO on Ovid, the Cochrane Library, and the Google Scholar Database. The searches were limited by date (January 2005 to September 2022) and to the English language. All types of original research were considered, including prospective or retrospective longitudinal studies, cross-sectional studies, and randomized trials. The specific search terms were ((antibiotic [MeSH]) AND (prophylaxis)) and (TKA OR TKR OR "Arthroplasty, Replacement, Knee" [MeSH] OR ((knee) adj2 (replace* OR arthroplasty* OR prosthe*))).

RESULTS

Despite our research efforts, we found no article capable of answering the question of which antibiotic to use as surgical prophylaxis for a septic revision one-stage TKA.

CONCLUSIONS

Although the research results are inconclusive, we would recommend using the same antibiotic prophylaxis as for primary joint replacement, i.e., cefazolin, as it was recommended for its low side effect rate and relative effectiveness.

Likelihood of hip infection with image-guided hip aspiration dry tap: a 10-year retrospective study

OBJECTIVE

To determine the rate of infection in patients with suspected hip septic arthritis who underwent image-guided aspiration (IHA) resulting in dry-tap, diagnostic value of subsequent lavage and re-aspiration, and if pre-aspiration MRI can help prevent a dry tap.

MATERIALS AND METHODS

Retrospective review between 2010 to 2020 identified native hip (NH) and total hip arthroplasty (THA) patients who had a dry-tap following aspiration for suspected infection or periprosthetic joint infection (PJI). Serology tests, lavage/re-aspiration volumes, and aspirate cell-count/culture were assessed. On pre-aspiration MRI, presence/grade of joint effusion (JE), pseudocapsule dehiscence (PD), extraarticular fluid and sinus-tract were recorded.

RESULTS

Out of 215 included dry-taps, 185 (86.0%) were non-infected and 30 (13.9%) infected. In subgroup analysis, 64/71(90.1%) NH and 121/144(84.0%) THA dry-taps were non-infected. Pre-aspiration MRI of THA group with dry-tap showed significant findings; PD with extraarticular fluid (8/12, 66.7%) and sinus tract (7/12, 58.3%) were higher in the infected compared to non-infected group (5/42, 11.9% and 0/42, 0.0%) (both p < 0.001). Among THA group, polymorphonuclear-leukocytes > 80% was present in 8/9 (88.9%) of infected versus 4/28 (14.3%) non-infected group (p < 0.001). Multivariable regression showed PD (p = 0.005) and JE (p = 0.042) being significant independent predictors of PJI, similarly the elevated CRP (p = 0.044) and JE (p = 0.017).

CONCLUSION

Majority of patients suspected of hip joint infection with dry-tap were non-infected. Synovial PMN% following lavage maintains high sensitivity for detection of PJI. In patients with THA, PD and subsequent extraarticular collection can be associated with dry-tap therefore, pre-aspiration MRI can help determine their presence and plan the aspiration.

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.

Diagnostic value of fluoroscopy-guided hip aspiration for periprosthetic joint infection

PURPOSE

To assess the value of preoperative joint aspiration in detecting periprosthetic joint infection (PJI) in patients undergoing revision hip arthroplasty and to compare these with the clinical findings, serum markers, and intraoperative findings.

MATERIALS AND METHODS

Fluoroscopically guided hip aspirations in patients with pain after hip arthroplasty were retrospectively reviewed from January 2014 to December 2018. All hips underwent subsequent revision hip arthroplasty. Antibiotics were discontinued at least 2 weeks before the aspiration. The 2018 Musculoskeletal Infection Society (MSIS) criteria served as a standard of reference for PJI. Clinical, serum, synovial, and intraoperative parameters were recorded in all patients. Correlations between all parameters with PJI diagnosis were analyzed using linear and logistic regression models with ROC analysis.

RESULTS

In 202 hips that included 91 septic hips, hip aspiration (AUC = 0.78) and intraoperative (0.80) parameters performed better than serum-based tests (0.64) and clinical parameters (0.68) in detecting PJI. Using MSIS criteria as a standard of reference, hip aspiration had a sensitivity of 64.0% and an accuracy of 78.5% for cultures and a sensitivity of 74.2% and an accuracy of 82.1% for synovial polymorphonuclear neutrophils% (PMN%). Results substantially improved sensitivity after excluding patients that were treated with antibiotics, particularly culture results.

CONCLUSIONS

Preoperative hip aspiration showed good diagnostic performance in diagnosing PJI compared with MSIS criteria as a standard of reference. But a negative result from aspirate could not rule out PJI. Based on our findings, hip aspiration is an essential test for treatment planning in patients with pain after hip arthroplasty.

Utility of lavage in addition to native fluid collection during fluoroscopically guided joint aspiration in infection diagnosis

Image-guided prosthetic joint aspirations have been criticized in the literature as having poor sensitivity and specificity. Native fluid is typically analyzed for the presence of infection. Joint lavage during fluoroscopically guided aspiration of prosthetic joints is not routinely performed, and the lavage aspirate is not typically analyzed unless native fluid could not be aspirated for culture. This study aims to determine if concordance of culture results from native fluid and an additional joint lavage sample improves sensitivity and specificity in the diagnosis of prosthetic joint infection by fluoroscopically guided joint aspiration. A retrospective review of the fluoroscopically guided joint aspirations at our institution between December 2007 and December 2009 was performed. Data collected from the electronic medical record included culture results for both native fluid and lavage aspirate, histopathology results, final clinical diagnosis, as well as clinical/surgical management. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratio for infection were calculated for the following culture analysis scenarios: native fluid alone; lavage aspirate alone; native fluid; and lavage aspirate. Five hundred sixty-three aspirations, mostly prosthetic joints, were identified in the reviewed time period, of which 397 were sent for both native fluid and lavage aspirate analysis. Concordance between positive culture results from native fluid and joint lavage aspirate markedly increased the likelihood ratio for infection from 23.8 to 138.7 and improved specificity and PPV of fluoroscopically guided joint aspiration, with similar sensitivity and NPV to that of native fluid culture alone.

Anatomic Landmark-Guided Hip Aspiration in the Diagnosis of Periprosthetic Joint Infection

Hip aspirations used to detect a periprosthetic joint infection (PJI) are usually performed under fluoroscopy or ultrasound. The aim of this study was to evaluate the results of simply using anatomic landmarks for aspiration and detecting PJI without the use of any complicated technologies. The authors retrospectively reviewed a total of 186 consecutive hip aspirations performed between April 2015 and December 2018. All patients were suspected to have infections after total hip arthroplasty. The procedures were performed with the patients in the supine position. The authors aimed to aspirate at the neck of the prosthesis. They located the y-axis of the puncture point approximately 2 to 3 cm lateral to the pulse of the femoral artery in the region of the inguinal ligament. The x-axis was estimated by using the pubic symphysis or greater trochanter according to an anteroposterior radiograph of the hip joint. The aspiration failure rate, incidence of complications, and culture results were recorded. The overall aspiration failure rate was 3.8% (7 of 186). No obvious complications related to aspiration were observed. The saline lavage and reaspiration rate was 45.3% (81 of 179) due to "dry taps." The sensitivity, specificity, positive predictive value, and negative predictive value of the remaining 169 patients with definite diagnoses were 0.781 (95% CI, 0.678-0.860), 0.939 (95% CI, 0.857-0.977), 0.931 (95% CI, 0.841-0.975), and 0.802 (95% CI, 0.706-0.874), respectively. Anatomic landmark-guided hip aspiration was a convenient method that could provide satisfactory detection of PJI. [Orthopedics. 2021;44(1):e85-e90.].

Measurement of Serum Anti-staphylococcal Antibodies Increases Positive Predictive Value of Preoperative Aspiration for Hip Prosthetic Joint Infection

BACKGROUND

Preoperative synovial fluid culture is pivotal in the early diagnosis of prosthetic joint infection (PJI) but may yield false-positive and false-negative results. We evaluated the predictive value of synovial fluid culture results combined with the measurement of serum anti-staphylococcal antibodies (SASA).

QUESTIONS/PURPOSES

(1) For hip and knee PJI, does combining positive SASA results with preoperative synovial culture results improve the positive predictive value (PPV) of preoperative synovial fluid culture alone? (2) Does combining preoperative synovial fluid culture results with a positive cell count and differential result increase the PPV of preoperative synovial fluid culture alone? (3) What proportion of isolated organisms exhibit concordance in antibiotic susceptibility: preoperative aspiration versus intraoperative isolates?

METHODS

A prospective study was conducted at two French reference centers that manage bone and joint infections and included 481 adult patients who had a revision or resection arthroplasty between June 25, 2012 and June 23, 2014. Exclusion criteria including no serum sample available for immunoassay, the lack of microbiological documentation, and the absence of preoperative aspiration reduced the patient number to 353. Seven patients with an undetermined SASA result were excluded from the analysis. We also excluded patients with PJI involving more than one Staphylococcus species (polystaphylococcal infection) and those in whom more than one Staphylococcus species was recovered from the preoperative synovial fluid culture (polystaphylococcal synovial fluid culture). In total, 340 patients were included in the analysis (no infection, 67% [226 of 340]; staphylococcal infection, 21% [71 of 340]; other infection, 13% [43 of 340]). The preoperative synovial fluid analysis included a cell count and differential and bacterial culture. SASAs were measured using a multiplex immunoassay. The diagnosis of PJI was determined using the Infectious Diseases Society of America (IDSA) criteria [] and intraoperative tissue culture at the time of revision surgery was used as the gold standard (at least one positive intraoperative sample for a "virulent" organism (such as S. aureus) or two positive samples for a "non-virulent" (for example S. epidermidis).

RESULTS

SASA increased the PPV compared with synovial fluid culture alone (92% [95% CI 82 to 97] versus 79% [95% CI 68 to 87]; p = 0.04); when stratified by site, an increase in PPV was seen in hip infections (100% [95% CI 89 to 100] versus 77% [95% CI 63 to 88]; p = 0.01) but not in knee infections (84% [95% CI 66 to 95] versus 80% [95% CI 64 to 91]; p = 0.75). A positive cell count and differential result increased the PPV of staphylococcal synovial fluid cultures compared with synovial fluid culture alone (86% [95% CI 70 to 95] versus 79% [95% CI 68 to 87]; p = 0.36); when stratified by site, no difference in hip and knee infections was observed (86% [95% CI 67 to 96] versus 77% [95% CI 63 to 88]; p = 0.42) and 86% [95% CI 70 to 95] versus 80% [95% CI 64 to 91]; p = 0.74).

CONCLUSION

SASA measurement improves the predictive value of synovial fluid cultures of the hip for all staphylococcal organisms, including coagulase-negative staphylococci, but the PPV of SASA plus synovial fluid culture it is not superior to the PPV of synovial fluid cell count/differential plus synovial culture for the knee.

LEVEL OF EVIDENCE

Level III, diagnostic study.

The diagnostic value of routine preliminary biopsy in diagnosing late prosthetic joint infection after hip and knee arthroplasty

AIMS

Biopsy of the periprosthetic tissue is an important diagnostic tool for prosthetic joint infection (PJI) as it enables the detection of the responsible microorganism with its sensitivity to antibiotics. We aimed to investigate how often the bacteria identified in the tissue analysis differed between samples obtained from preoperative biopsy and intraoperative revision surgery in cases of late PJI; and whether there was a therapeutic consequence.

METHODS

A total of 508 patients who required revision surgery of total hip arthroplasty (THA) (n = 231) or total knee arthroplasty (TKA) (n = 277) because of component loosening underwent biopsy before revision surgery. The tissue samples collected at biopsy and during revision surgery were analyzed according to the criteria of the Musculoskeletal Infection Society (MSIS).

RESULTS

In total, 178 (113 THA, 65 TKA) were classified as infected. The biopsy procedure had a sensitivity of 93.8%, a specificity of 97.3%, a positive predictive value (PPV) of 94.9%, a negative predictive value (NPV) of 96.7%, and an accuracy of 96.1%. Of the 178 infected patients, 26 showed a difference in the detected bacteria from the biopsy and the revision surgery (14.6%). This difference required a change to antibiotic therapy in only two cases (1.1%).

CONCLUSION

Biopsy is a useful tool to diagnose PJI, but there may be a difference in the detected bacteria between the biopsy and revision surgery. However, this did not affect the choice of antibiotic therapy in most cases, rendering the clinical relevance of this phenomenon as low. Cite this article: Bone Joint J 2020;102-B(3):329-335.

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.

New diagnostic tools for prosthetic joint infection

The diagnosis of peri-prosthetic bone and joint infections relies on converging information from clinical, laboratory and imaging assessments. Clinical findings alone may suffice: a sinus tract is a major criterion that establishes the diagnosis of infection. Identifying the causative organism is crucial and requires the early collection of high-quality samples from sites in contact with the prosthetic material. The bacteriological samples may be obtained by aspiration or open surgery. Imaging techniques have undergone remarkable improvements over the last two decades. Ultrasonography can be performed early and can be used to guide a needle biopsy if appropriate. Computed tomography or magnetic resonance imaging shows the extent of bone and/or soft-tissue involvement, provided effective artefact-suppression techniques are applied. Nuclear medicine methods have an undefined place in the diagnostic strategy and their possible role must be evaluated during a multidisciplinary discussion. The array of new laboratory methods introduced in recent years includes microbiological culture techniques, molecular biology tests, antigen and antibody assays and tests for immune markers in blood and/or joint fluid. When the first-line investigations fail to provide a definitive diagnosis, a multidisciplinary discussion at a referral centre for complex osteo-articular infections makes a major contribution to defining the subsequent diagnostic strategy. This lecture focusses on the following six questions: does the clinical assessment still have diagnostic relevance? What is the diagnostic contribution of imaging studies? Must the infection be documented pre-operatively and if so, how? Which microbiological techniques should be used? Which non-microbiological investigations help to diagnosis peri-prosthetic bone and joint infections? What role do referral centres for complex bone and joint infections play in the diagnostic strategy?

Joint aspiration, including culture of reaspirated saline after a 'dry tap', is sensitive and specific for the diagnosis of hip and knee prosthetic joint infection

Aims

The aim of this study was to establish the diagnostic accuracy of culture of joint aspirate with and without saline injection-reaspiration.

Patients and Methods

This is a retrospective analysis of 580 hip and knee aspirations in patients who were deemed to have a moderate to high risk of infection, and who subsequently proceeded to revision arthroplasty over a period of 12 years. It was carried out at a large quaternary referral centre where preoperative aspiration is routine.

Results

Fluid was aspirated primarily in 313 (54%) cases and after saline injection-reaspiration of a 'dry tap' in 267 (46%) cases. Overall sensitivity and specificity of the diagnostic aspirate were 84% (78% to 89%) and 85% (81% to 88%), respectively. Sensitivity and specificity of saline injection-reaspiration after 'dry tap' were 87% (79% to 92%) and 79% (72% to 84%) compared with 81% (71% to 88%) and 90% (85% to 93%) for direct aspiration.

Conclusion

Preoperative joint aspiration and culture is a sensitive and specific test for the confirmation of diagnosis in patients at a moderate to high risk of prosthetic joint infection. Culture of saline injection-reaspiration also provides accurate diagnostic information in the event of a 'dry tap'. Both methods allow susceptibility testing of relevant organisms and are therefore able to guide perioperative antibiotic therapy. Cite this article: Bone Joint J 2018;100-B:749-54.

Fluoroscopy- vs ultrasound-guided aspiration techniques in the management of periprosthetic joint infection: which is the best?

BACKGROUND

Fluid samples obtained from an affected joint still play a central role in the diagnosis of periprosthetic joint infection (PJI). It is the only preoperative test able to discover the causative microbiological agent. In the hip, fluid aspiration can be performed through fluoroscopy, ultrasound, or, less commonly, computed tomography. However, there is still a lack of consensus on which method is preferable in terms of efficacy and costbenefit.

PURPOSES

We, therefore, asked whether (1) the benefits in terms of sensitivity and specificity and (2) the costs were comparable between fluoroscopy- and ultrasound-guided joint aspirations in a suspicious of hip PJI.

METHODS

Between 2013 and 2016, 52 hip aspirations were performed on 49 patients with clinical, radiological, or serological suspicion of PJI, waiting for a revision surgery. The patients were divided in two groups: fluoroscopy- (n = 26) vs ultrasound-guided hip aspiration group (n = 26). These groups were also divided in control and infected patients. The criteria of MusculoSkeletal Infection Society (MSIS) were used, as gold standard, to define PJI.

RESULTS

(1) Ultrasound-guided aspiration revealed valid sensitivity (89% vs 60%) and specificity (94% vs 81%) in comparison with fluoroscopic-guided aspiration. (2) The cost analysis was also in favor of ultrasound-guided aspiration (125.30€) than fluoroscopic-guided aspiration (343.58€).

CONCLUSIONS

We concluded that ultrasound-guided hip aspiration could represent a valid, safe, and less expensive diagnostic alternative to fluoroscopic-guided aspiration in hip PJI.

Agreement between pre-operative and intra-operative bacteriological samples in 85 chronic peri-prosthetic infections

BACKGROUND

Whether pre-operative microbiological sampling contributes to the management of chronic peri-prosthetic infection remains controversial. We assessed agreement between the results of pre-operative and intra-operative samples in patients undergoing single-stage prosthesis exchange to treat chronic peri-prosthetic infection.

HYPOTHESIS

Agreement between pre-operative and intra-operative samples exceeds 75% in patients undergoing single-stage exchange of a hip or knee prosthesis to treat chronic peri-prosthetic infection.

MATERIAL AND METHODS

This single-centre retrospective study included 85 single-stage prosthesis exchange procedures in 82 patients with chronic peri-prosthetic infection at the hip or knee. Agreement between pre-operative and intra-operative sample results was evaluated. Changes to the initial antibiotic regimen made based on the intra-operative sample results were recorded.

RESULTS

Of 149 pre-operative samples, 109 yielded positive cultures, in 75/85 cases. Of 452 intra-operative samples, 354 yielded positive cultures, in 85/85 cases. Agreement was complete in 54 (63%) cases and partial in 9 (11%) cases; there was no agreement in the remaining 22 (26%) cases. The complete agreement rate was significantly lower than 75% (P=0.01). The initial antibiotic regimen was inadequate in a single case.

DISCUSSION

Pre-operative sampling may contribute to the diagnosis of peri-prosthetic infection but is neither necessary nor sufficient to confirm the diagnosis and identify the causative agent. The spectrum of the initial antibiotic regimen cannot be safely narrowed based on the pre-operative sample results. We suggest the routine prescription of a probabilistic broad-spectrum antibiotic regimen immediately after the prosthesis exchange, even when a pathogen was identified before surgery.

LEVEL OF EVIDENCE

IV, retrospective study.

Diagnostic accuracy of arthroscopic biopsy in periprosthetic infections of the hip

Background

Diagnosis of a low-grade periprosthetic joint infection (PJI) prior to revision surgery can be challenging, despite paramount importance for further treatment. Arthroscopic biopsy of synovial and periprosthetic tissue with subsequent microbiological and histological examination can be beneficial but its specific diagnostic value has not been clearly defined.

Methods

20 consecutive patients who underwent percutaneous synovial fluid aspiration as well as arthroscopic biopsy due to suspected PJI of the hip and subsequent one- or two-stage revision surgery at our institution between January 2012 and May 2015 were enrolled. Indication was based on the criteria (1) history of PJI and increased levels of erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), (2) suspicious cell count and differential but negative bacterial culture in synovial aspirate, (3) early loosening (<less than 2 years), or (4) persisting pain without loosening but history of a PJI. At least two criteria had to be fulfilled in order to perform an arthroscopic biopsy.

Results

Best overall diagnostic value was identified for arthroscopic biopsy and a combination of bacteriological and histological analysis with a sensitivity of 87.5%, specificity of 100% and accuracy of 95%. Bacteriological assessment of synovial aspirate revealed a sensitivity of 50.0%, specificity of 91.7%, and accuracy of 75%. ESR and CRP yielded a sensitivity of 75.0% for either hematologic test and specificities of 87.5 and 66.7%, respectively.

Conclusions

In conclusion, our data indicate that arthroscopic biopsy is superior to ESR and CRP as well as joint aspiration and their combinations. Concurrent microbiological and histological examination of the biopsy specimens allows for identification of the causative pathogen and its susceptibility pattern in order to preoperatively plan the surgical strategy as well as the antibiotic regimen. Moreover, intraarticular mechanical failure can be detected during hip arthroscopy emphasizing its diagnostic value. Level II diagnostic study.

One-stage exchange arthroplasty for chronic periprosthetic hip infection: results of a large prospective cohort study

BACKGROUND

Exchange arthroplasty of one or two stages is required for the treatment of chronic periprosthetic joint infections. Two-stage exchange is costly and has high morbidity with limited patient mobility between procedures. One-stage exchange has been promoted by several European teams as the preferred alternative. The aim of this study was to prospectively analyze the outcome of patients with a periprosthetic hip infection treated with one-stage exchange arthroplasty.

METHODS

We performed a prospective cohort study in a French referral center for osteoarticular infections including all periprosthetic hip infections treated with one-stage exchange arthroplasty from November 2002 to March 2010. Direct exchange was performed in chronic periprosthetic hip infection with no or minor bone loss and preoperative identification of a microorganism from joint fluid aspirate. No antibiotic-loaded bone cement was used. Antibiotic therapy was administered for twelve weeks: intravenously for four to six weeks, followed by an oral regimen for six to eight weeks. Follow-up was a minimum of two years. The following events were noted: relapse, new infection, joint revision for mechanical reasons, and periprosthetic hip infection-related and unrelated deaths.

RESULTS

One hundred and fifty-seven patients with periprosthetic hip infections with a median infection duration of 258 days (interquartile range, 120 to 551 days) prior to our index surgical procedure for infection were included. Periprosthetic hip infection occurred in ninety-nine cases of primary hip arthroplasty, twenty-seven cases of revision arthroplasty, and thirty-one cases in which the periprosthetic hip infection had been treated previously. A difficult-to-treat organism was isolated in fifty-nine cases (38%). After a median follow-up of 41.6 months (interquartile range, 28.1 to 66.9 months), two relapses, six new infections, nine revisions for mechanical reasons, two related deaths, and nineteen unrelated deaths occurred.

CONCLUSIONS

One-stage exchange arthroplasty is an effective surgical procedure in patients with periprosthetic hip infection who have good bone quality. Precise identification of the microorganism(s) and prolonged administration of appropriate intravenous antibiotic therapy are key factors for successful treatment.

Preoperative aspiration culture for preoperative diagnosis of infection in total hip or knee arthroplasty

This meta-analysis evaluated preoperative aspiration culture for diagnosing prosthetic joint infection (PJI) in total hip arthroplasty (THA) and total knee arthroplasty (TKA). The pooled sensitivity and specificity were 0.72 (95% confidence interval, 0.65 to 0.78) and 0.95 (0.93 to 0.97), respectively. Subgroup analyses revealed nonsignificant worse diagnostic performance for THA than for TKA (sensitivity, 0.70 versus 0.78; specificity, 0.94 versus 0.96). Preoperative aspiration culture has moderate to high sensitivity and very high specificity for diagnosing PJI.

Usefulness of histology for predicting infection at the time of hip revision for the treatment of Vancouver B2 periprosthetic fractures

When facing a Vancouver B2 periprosthetic fracture, the most recommended treatment is the prosthesis replacement. Current tests do not provide enough reliability to identify whether the fracture has been produced on a septic or an aseptic loosened prosthesis. Our aim was to evaluate the usefulness of the histology for the diagnosis of infection in these cases. A total of 11 hip revision procedures were performed (mean age: 78.1 years, 8 women and 3 men). Sensitivity, specificity, positive predictive value and negative predictive value of the histology were 100%, 55.5%, 33.3% and 100% respectively. Of the six patients presenting with a positive histology, four of them had negative cultures (66.6% of false positives). Our results suggest that periprosthetic fractures are a cause of false-positive histology results for the diagnosis of infection during revision of a hip prosthesis for the treatment of Vancouver B2 periprosthetic fractures.

High diagnostic value of synovial biopsy in periprosthetic joint infection of the hip

BACKGROUND

The role of the synovial biopsy in the preoperative diagnosis of a periprosthetic joint infection (PJI) of the hip has not been clearly defined.

QUESTIONS/PURPOSES

We asked whether the value of a biopsy for a PJI is greater than that of aspiration and C-reactive protein (CRP).

METHODS

Before revision in 100 hip endoprostheses, we obtained CRP values, aspirated the joint, and obtained five synovial biopsy samples for bacteriologic analysis and five for histologic analysis. Microbiologic and histologic analyses of the periprosthetic tissue during revision surgery were used to verify the results of the preoperative diagnostic methods. The minimum followup was 24 months (median 32; range, 24-47 months).

RESULTS

Forty-five of the 100 prostheses were identified as infected. The biopsy, with a combination of the bacteriologic and histologic examinations, showed the greatest diagnostic value of all the diagnostic procedures and led to a sensitivity of 82% (95% CI, ± 11%), specificity of 98% (95% CI, ± 4%), positive predictive value of 97% (95% CI, ± 5%), negative predictive value of 87% (95% CI, ± 8.3%), and accuracy of 91%.

CONCLUSIONS

The biopsy technique has a greater value than aspiration and CRP in the diagnosis of PJI of the hip (Masri et al. J Arthroplasty 22:72-78, 2007). In patients with a negative aspirate, but increased CRP or clinical signs of infection, we regard biopsy to be preferable to just repeating the aspiration.

LEVEL OF EVIDENCE

Level II prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

In vitro study of the antimicrobial effects of radiological contrast agents used in arthrography

Aspiration arthrography using an iodinated contrast medium is a useful tool for the investigation of septic or aseptic loosening of arthroplasties and of septic arthritis. Previously, the contrast media have been thought to cause false negative results in cultures when present in aspirated samples of synovial fluid, probably because free iodine is bactericidal, but reports have been inconclusive. We examined the influence of the older, high osmolar contrast agents and the low osmolar media used currently on the growth of ten different micro-organisms capable of causing deep infection around a prosthesis. Five media were tested, using a disc diffusion technique and a time-killing curve method in which high and low inocula of micro-organisms were incubated in undiluted media. The only bactericidal effects were found with low inocula of Escherichia coli and Pseudomonas aeruginosa in ioxithalamate, one of the older ionic media. The low and iso-osmolar iodinated contrast media used currently do not impede culture. Future study must assess other causes of false negative cultures of synovial fluid and new developments in enhancing microbial recovery from aspirated samples.

Unexplained pain after THR: what should i do?

Early causes of hip pain within the first year of total hip replacement (THR) include failure of fixation, infection, instability, other sources of pain (eg, lumbar spine), and mechanical dysfunction such as psoas tendon impingement or other soft tissue irritation. Metal-on-metal THRs may present with pain due to hypersensitivity within the first 1 to 3 years after arthroplasty. Late causes of pain include loosening, wear reactions, or mechanical dysfunction such as subluxation associated with wear of the articular couple. Late hematogenous infection is often sudden in onset, but may be subtle. Other sources of pain such as spinal stenosis or lumbar degenerative disk disease may also present as hip pain. Evaluation of the painful hip should start with a careful history: is the current pain similar or different to the preoperative symptoms? A review of the preoperative radiographs will provide clues as to the extent of the pathology, and if not obvious, may suggest other sources for the pain syndrome. Careful comparison of serial radiographs is necessary to identify loosening. Serologic tests should include a sedimentation rate and C-reactive protein; if both are elevated, aspiration of the joint under radiograph control for culture is indicated. In the absence of abnormalities in the studies described above, serial Technetium bone scans performed every 6 to 12 months may suggest loosening if progressive increases in uptake are observed about a component. Malposition of the acetabular component may be associated with psoas tendon impingement (symptomatic with active flexion of the hip) and may be confirmed by computed tomography scan or a psoas tenosynogram. Hypersensitivity of metal-on-metal THRs should be suspected in the presence of early (subtle) osteolysis, and the presence of predominantly mononuclear cells on the sterile aspirate. Perseverance and patience are encouraged in the pursuit of an accurate diagnosis, and objective analysis of the data is necessary. Do not operate without sufficient cause.

Is there a role for tissue biopsy in the diagnosis of periprosthetic infection?

BACKGROUND

Successful treatment of an infected joint arthroplasty depends on correctly identifying the responsible pathogens. The value of a preoperative biopsy remains controversial.

QUESTIONS/PURPOSES

We (1) compared the sensitivity and specificity of both tests separately and in combination, and (2) asked whether the combination of tissue biopsy and aspiration would improve our diagnostic yield in the evaluation of periprosthetic joint infections.

PATIENTS AND METHODS

We prospectively followed 120 patients with suspected infection of a total joint arthroplasty: 64 with THAs and 56 with TKAs. All patients had aspiration with culture and biopsy.

RESULTS

The sensitivity was 83% for aspiration, 79% for biopsy, and 90% for the combination of both techniques. The specificity was 100% for aspiration and biopsy and the combination. The overall accuracy was 84%, 81%, and 90%, respectively.

CONCLUSIONS

Our data suggest tissue biopsy alone offers no clear advantage over joint aspiration. However, the combination of both techniques provides improved sensitivity and accuracy. We recommend the use of tissue biopsy as an adjunct to joint aspiration in the diagnosis of total joint infection.

LEVEL OF EVIDENCE

Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Validity of frozen sections for analysis of periprosthetic loosening membranes

Clinical findings and blood parameters often are inconclusive in patients with periprosthetic joint infections. Among the accepted criteria for diagnosis, histologic analysis of debrided tissue can detect infection in most cases but does not allow intraoperative decision making. We evaluated the validity of intraoperative frozen sections for detection of prosthetic infections. The results from frozen and permanent sections of periprosthetic membranes of 64 consecutive patients who underwent exchange procedures after hip arthroplasty were compared using the histopathologic consensus classification of Morawietz et al. Blood parameters (erythrocyte sedimentation rate, leukocyte count, C-reactive protein) and culture results of preoperatively aspirated joint fluid and intraoperative tissue samples were correlated with the histologic results. In 50 patients (78.1%), agreement was found between the frozen and permanent sections. Two patients (3.1%) revealed a discrepancy between the two histologic methods. In 12 patients (18.8%), a diagnosis was not possible based on the frozen sections because the tissue samples were not representative enough for definite classification. For the analyzable cases (n = 52), the sensitivity of frozen-section histologic analysis was 86.6%, specificity 100%, and accuracy 96.2%. Our data support a recommendation for use of intraoperative frozen sections for diagnosis of septic versus aseptic loosening in revision hip surgery.

LEVEL OF EVIDENCE

Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Infection or allergy in the painful metal-on-metal total hip arthroplasty?

Metal-on-metal articulations are increasingly used in total hip arthroplasty. Patients can be sensitive to metal ions produced by the articulation and present with pain or early loosening. Infection must be excluded. Correct diagnosis before revision surgery is crucial to implant selection and operation planning. There is no practical guide in the literature on how to differentiate between allergy and infection in a painful total hip arthroplasty. We present the history, clinical findings and hip scores, radiology, serology, hip arthroscopy and aspirate results, labeled white cell scan, revision-hip findings, histology and clinical results of a typical patient with a hypersensitivity response to a metal-on-metal hip articulation, and how results differ from patients with an infected implant. A practical scheme to investigate patients with a possible hypersensitivity response to an implant is presented.

Propionibacterium acnes: An agent of prosthetic joint infection and colonization

BACKGROUND

Prosthetic joint infection (PJI) can present a diagnostic challenge, especially with slow-growing and poorly virulent bacteria.

OBJECTIVE

To describe the epidemiological, clinical and biological characteristics of Propionibacterium acnes PJI, their treatments and outcomes and compare 2 clinical pictures (according to the time PJI symptoms appeared after the index operation: < or = 2 years, > 2 years).

METHODS

We conducted a cohort study on P. acnes PJI. Diagnosis was based on > or = 2 positive cultures of intraoperative specimens taken during revision arthroplasties for infection or presumed aseptic loosening.

RESULTS

Fifty patients with prosthetic hip (34), knee (10) or shoulder (6) infections were included and analyzed according to their symptom-free interval: < or = 2 years for 35 and > 2 years for 15 (mean interval: 11+/-6 years). The numbers of previous prostheses (p=0.04) were higher for the shorter-interval group, which had more frequent signs of infection (p=0.004). These findings suggest infection in most of the patients whose PJI symptoms appeared: < or = 2 years after the index operation, and colonization in the majority of those whose symptoms appeared > 2 years after index surgery. Treatment combining exchange arthroplasty with prolonged intravenous antibiotics was successful for 92% of the patients.

CONCLUSION

P. acnes can cause different types of PJI: late chronic infections, colonization of loosened prostheses and, exceptionally, acute postoperative infections.

Infection of a total hip prosthesis in a dog caused by Achromobacter(Alcaligenes) xylosoxidans

A four-year-old male, neutered Labrador retriever was presented with progressive left hindlimb lameness 10 months following total hip replacement. Radiography revealed changes consistent with infection and culture of joint fluid from the left coxofemoral joint revealed Achromobacter (Alcaligenes) xylosoxidans. The prosthesis was removed. Culture of the acetabular cup confirmed Achromobacter xylosoxidans. Achromobacter xylosoxidans is an uncommon but serious cause of nosocomial epidemics in hospitals for human beings. To the authors' knowledge, this is the first report of total hip prosthetic infection with Achromobacter xylosoxidans. Little is reported about its pathogenicity in human beings and the authors failed to retrieve any reports of its clinical significance in animals.