Utility of intraoperative frozen section in the diagnosis of periprosthetic joint infection

Debridement-Reconstruction-Docking Management System Versus Ilizarov Technique for Lower-Extremity Osteomyelitis

BACKGROUND

Osteomyelitis causes marked disability and is one of the most challenging diseases for orthopaedists to treat because of the considerable rate of infection recurrence. In this study, we proposed and assessed the debridement-reconstruction-docking (DRD) system for the treatment of lower-extremity osteomyelitis. This procedure comprises 3 surgical stages and 2 preoperative assessments; namely, pre-debridement assessment, debridement, pre-reconstruction assessment, reconstruction, and docking-site management. We evaluated the use of the DRD system compared with the Ilizarov technique, which is defined as a 1-stage debridement, osteotomy, and bone transport.

METHODS

This retrospective cohort included 289 patients who underwent either DRD or the Ilizarov technique for the treatment of lower-extremity osteomyelitis at a single institution between January 2013 and February 2021 and who met the eligibility criteria. The primary outcome was the rate of infection recurrence. Secondary outcomes included the external fixator index (EFI), refracture rate, and the Paley classification for osseous and functional results. An inverse-probability-weighted regression adjustment model was utilized to estimate the effect of the DRD system and Ilizarov technique on the treatment of lower-extremity osteomyelitis.

RESULTS

A total of 131 and 158 patients underwent DRD or the Ilizarov technique, respectively. The inverse-probability-weighted regression adjustment model suggested that DRD was associated with a significant reduction in infection recurrence (risk ratio [RR], 0.26; 95% confidence interval [CI], 0.13 to 0.50; p < 0.001) and EFI (-6.9 days/cm, 95% CI; -8.3 to -5.5; p < 0.001). Patients in the DRD group had better Paley functional results than those in the Ilizarov group (ridit score, 0.55 versus 0.45; p < 0.001). There was no significant difference between the 2 groups in the rate of refracture (RR, 0.87; 95% CI, 0.42 to 1.79; p = 0.71) and Paley osseous results (ridit score, 0.51 versus 0.49; p = 0.39).

CONCLUSIONS

In this balanced retrospective cohort of patients with lower-extremity osteomyelitis, the use of the DRD system was associated with a reduced rate of infection recurrence, a lower EFI, and better Paley functional results compared with the use of the Ilizarov technique.

LEVEL OF EVIDENCE

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

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.

The Utility of Frozen Section Histology in Diagnosing Periprosthetic Joint Infection in Revision Total Joint Arthroplasty

BACKGROUND

Surgeons utilize a combination of preoperative tests and intraoperative findings to diagnose periprosthetic joint infection (PJI); however, there is currently no reliable diagnostic marker that can be used in isolation. The purpose of our study is to evaluate the utility of frozen section histology in diagnosis of PJI.

METHODS

Retrospective analysis of 614 patients undergoing revision total joint arthroplasty with frozen section histology from a single institution was performed. Discriminatory value of frozen section histology was assessed using univariate analysis and evaluation of area under the curve (AUC) of a receiver operating characteristic curve comparing frozen section histology results to the 2018 International Consensus Meeting (ICM) PJI criteria modified to exclude the histology component.

RESULTS

The sensitivity of the frozen section histology was 53.6% and the specificity was 95.2%. There was 99.2% concordance between the permanent section and frozen section results. The receiver operating characteristic curve for frozen section yielded an AUC of 0.744 (95% confidence interval 0.627-0.860) and the modified ICM score yielded an AUC of 0.912 (95% confidence interval 0.836-0.988) when compared to the full score. The addition of frozen section histology changed the decision to infected in 20% of "inconclusive" cases but less than 1% of total cases.

CONCLUSION

In comparison to the modified ICM criteria, intraoperative frozen section histology has poor sensitivity, strong specificity, and acceptable overall discrimination for diagnosing PJI. This test appears to be of particular value for patients deemed "inconclusive" for infection using the remaining ICM criteria.

Combination Tests in the Diagnosis of Chronic Periprosthetic Joint Infection: Systematic Review and Development of a Stepwise Clinical Decision-Making Tool

BACKGROUND

Our objective was to identify combination tests used to diagnose chronic periprosthetic joint infection (PJI) and develop a stepwise decision-making tool to facilitate diagnosis.

METHODS

We conducted a systematic review of existing combinations of serum, synovial, and tissue-based tests for diagnosing chronic PJI after hip or knee replacement. This work is an extension of our systematic review of single tests, from which we chose eligible studies that also described the diagnostic performance of combination tests.

RESULTS

Thirty-seven eligible articles described the performance of 56 combination tests, of which 8 combinations had at least 2 studies informing both sensitivity and specificity. We also identified 5 types of combination tests: (1) a type-I Boolean combination, which uses Boolean logic (AND, OR) and usually increases specificity at the cost of sensitivity; (2) a type-II Boolean combination, which usually increases sensitivity at the cost of specificity; (3) a triage-conditional rule, in which the value of 1 test serves to triage the use of another test; (4) an arithmetic operation on the values of 2 tests; and (5) a model-based prediction rule based on a fitted model applied to biomarker values.

CONCLUSIONS

Clinicians can initiate their diagnostic process with a type-II Boolean combination of serum C-reactive protein (CRP) and interleukin-6 (IL-6). False negatives of the combination can be minimized when the threshold is chosen to reach 90% to 95% sensitivity for each test. Once a joint infection is suspected on the basis of serum testing, joint aspiration should be performed. If joint aspiration yields a wet tap, a leukocyte esterase (LER) strip is highly recommended for point-of-care testing, with a reading of ++ or greater indicating PJI; a reading below ++ should be followed by one of the laboratory-based synovial tests. If joint aspiration yields a dry tap, clinicians should rely on preoperative tissue culture and histological analysis for diagnosis. Combinations based on triage-conditional, arithmetic, and model-based prediction rules require further research.

LEVEL OF EVIDENCE

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

The combinations of multiple factors to improve the diagnostic sensitivity and specificity after artificial joint infection

Objective

To discuss the sensitivity and specificity of the combinations of multiple factors that work on bone infection after artificial joint, and provide evidence-based medical basis for the early diagnosis of infection after artificial joint.

Methods

A retrospective review was conducted on 35 patients diagnosed with periprosthetic joint infections (PJI) or aseptic loosening (AL) who both received revision operation from January 2011 to January 2015. Analyzing and comparing their epidemiology indexes and expounded a series of auxiliary examinations corresponding positive diagnosis ratio.

Results

Thirty-five patients were divided into two groups. One is called group PJI which includes 16 patients, and the other is called group AL which contains 19 patients. There was no statistical difference between in age (p = 0.536), gender ratio (p = 0.094), and the time of catching infection or getting loose (p = 0.055). Swelling was statistical significant (p = 0.0435 < 0.05). AUC of CRP = 0.947, ESR = 0.893, IL-6 = 0.893, PCT = 0.781, WBC = 0.839, and PMN = 0.755, respectively, CRP has a high diagnostic value to PJI, ESR, IL-6, PCT, WBC, and PMN% possess a moderate diagnostic value. There were 3 cases of PJI whose pathological paraffin section showed infectious inflammatory cells (100%). three PJI patients and one AL patient whose 99mTc-MDP examination presented 100% infection or looseness rate.

Conclusion

CRP has a high diagnostic value to PJI. Histopathology HE staining, Gram staining, and 99mTc-MDP provide a highly accurate diagnosis for PJI. Therefore, the results suggest combining the unique clinical symptoms of PJI patients with relevant laboratory indexes, histopathologic characteristics, and imageological examinations that can improve diagnostic sensitivity and specificity of PJI in its early stage.

Proceedings from the 2018 International Consensus Meeting on Orthopedic Infections: evaluation of periprosthetic shoulder infection

The Second International Consensus Meeting on Orthopedic Infections was held in Philadelphia, Pennsylvania, in July 2018. More than 800 experts from all 9 subspecialties of orthopedic surgery and allied fields of infectious disease, microbiology, and epidemiology were assembled to form the International Consensus Group. The shoulder workgroup reached consensus on 27 questions related to culture techniques, inflammatory markers, and diagnostic criteria used to evaluate patients for periprosthetic shoulder infection. This document contains the group's recommendations and rationale for each question related to evaluating periprosthetic shoulder infection.

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.

Correlation of histological and microbiological findings in septic and aseptic knee implant failure

INTRODUCTION

The Musculoskeletal Infection Society (MSIS) has defined specific clinical and laboratory criteria for the diagnosis of periprosthetic joint infection (PJI). In this study we assessed the diagnostic utility of MSIS microbiological and histological criteria for PJI in 138 cases of septic and aseptic knee implant failure.

MATERIALS AND METHODS

Intra-operative samples from 60 cases of knee septic implant failure (SIF) and 78 cases of aseptic implant failure (AIF), defined on the basis of clinical, laboratory and operative findings/surgical management, were analysed microbiologically and histologically. Findings were correlated with the final clinical diagnosis and the specificity, sensitivity, accuracy, positive and negative predictive value of MSIS microbiological and histological criteria for knee PJI were assessed.

RESULTS

80% of SIF cases showed culture of the same organism from two or more samples (ie MSIS microbiological criteria for definite PJI); 8.3% grew an organism from one sample, and 11.7% showed no growth from any sample. 23.1% of AIF cases grew an organism from one sample and 76.9% showed no growth from any sample. MSIS histological criteria for PJI identified 96.7% of SIF cases. The sensitivity, specificity, accuracy and positive and negative predictive value of MSIS histological criteria for PJI were 96.7%, 100%, 98.6%, 100% and 97.5%, respectively. MSIS microbiological and histological criteria identified all AIF cases.

CONCLUSIONS

Knee PJI is more often identified by current MSIS histological than microbiological criteria. A significant proportion of SIF cases show either no growth or growth of an organism from only one sample. AIF is identified by both MSIS microbiological and histological criteria. Correlation of clinical, radiological and laboratory findings is required for the diagnosis of knee PJI.

Identifying Common Pathogens in Periprosthetic Joint Infection and Testing Drug-resistance Rate for Different Antibiotics: A Prospective, Single Center Study in Beijing

OBJECTIVE

The aim of this study is to identify the common microorganisms causing PJI as well as the drug-resistant spectrum for each microorganism, to help orthopaedic surgeons to choose appropriate antibiotics.

METHOD

One hundred and sixty patients who suffered from failure of primary or revision total hip or knee arthroplasty for different reasons were prospectively recruited. These patients underwent revision or re-revision total hip or knee arthroplasty in our institution between August 2013 to August 2016. The details of patients' medical history and comprehensive physical examination, as well as demographic data were recorded precisely. Routine blood test results, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), high sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6) levels, and synovial leukocyte counts were collected. Additionally, aspiration was conducted during surgery to avoid pollution unless when PJI was strongly suspected, in which case, joint puncture and aspiration were conducted before surgery. Intraoperatively, the implant-surrounding tissue and the prosthesis were collected under aseptic conditions. Postoperatively, the prosthesis, implant-surrounding tissue and synovium were sent to the laboratory immediately. The sonicate extraction (the prosthesis was sent for ultrasound sonication first), implant surrounding tissue and synovium were sent for microbiologic culture, and the implant-surrounding tissue was also sent for pathological examination. The isolated bacteria strains and drug-resistance rates for each pathogen for different antibiotics were presented.

RESULTS

There were 59 PJI cases in the infectious group and 101 cases in the non-infectious group (PJI is diagnosed according to the diagnosing criteria from the Workgroup of the Musculoskeletal Infection Society). Of 69 strains of pathogens isolated, Gram-positive bacterium is the most common pathogenic bacteria causing PJI (60, 86.96%). Staphylococcus epidermidis and Staphylococcus aureus played an important role as well, followed by Gram-negative bacteria (8, 11.59%) and fungus (1, 1.45%). Penicillin (78.57%), erythromycin (66.67%) and clindamycin (44.74%) showed high antibiotic resistance rate. In addition, the second-generation cephalosporin, usually as the prophylactic antibiotic, resistance rate was high (20%) as well. Fortunately, no vancomycin-resistant bacteria were discovered in the current study.

CONCLUSION

This study provides some information on the most common pathogens in our institution and the selection of antibiotics in the perioperative period in northern China. Cefuroxime and clindamycin might not be appropriate for use as prophylactic antibiotics in revision total knee or hip arthroplasty. Vancomycin is ideal for empiric antibiotic use in suspected PJI cases because of the low drug-resistance rate.

Intraoperative evaluation of polymorphonuclear leukocyte during second-stage revision surgery promote overdiagnosis of persistent periprosthetic joint infection

Objective

The aim of this study was to evaluate whether intraoperative histopathological examination could predict the risk of relapse of infection in periprosthetic joint infections (PJI).

Methods

The study included 25 patients (14 women and 11 men, with a mean age of 67.0 years (range, 37–83 years)), who had two-staged revision surgery for a PJI. Following prosthetic removal in the first stage, all patient underwent an intraoperative histopathological examination during the second stage. The patients were divided into PMNs-positive group (≥five PMNs per high-powered field) or -negative group (<five PMNs). A relapse was defined as the occurrence of PJI. Median follow-up was 51 months (range, 32–80 months) following second-stage revision surgery.

Results

Intraoperative histopathological revealed that 8.0% of cases were PMNs-positive. Postoperative histopathological examination revealed that 28.0% of cases were PMNs-positive. 28.0% of cases showed discrepancy between the PMNs-positivity. Intraclass correlation coefficient indicates poor reproducibility. Infection relapse after revision surgery occurred in two cases (8.0%); both relapse cases were from the PMNs-negative group. There was no statistical relationship between the presence of PMNs in periprosthetic tissue by intraoperative or postoperative histopathological examination and relapse of infection.

Conclusions

Our findings showed that intraoperative histopathological examination could not predict the relapse of infection. Intraoperative histopathological examination promotes overdiagnosis of the requirement for re-implantation of antibiotic-impregnated cement and prolonged treatment periods.

Level of evidence

Level III, diagnostic study

Excellent Diagnostic Characteristics for Ultrafast Gene Profiling of DEFA1-IL1B-LTF in Detection of Prosthetic Joint Infections

The timely and exact diagnosis of prosthetic joint infection (PJI) is crucial for surgical decision-making. Intraoperatively, delivery of the result within an hour is required. Alpha-defensin lateral immunoassay of joint fluid (JF) is precise for the intraoperative exclusion of PJI; however, for patients with a limited amount of JF and/or in cases where the JF is bloody, this test is unhelpful. Important information is hidden in periprosthetic tissues that may much better reflect the current status of implant pathology. We therefore investigated the utility of the gene expression patterns of 12 candidate genes (TLR1, -2, -4, -6, and 10, DEFA1, LTF, IL1B, BPI, CRP, IFNG, and DEFB4A) previously associated with infection for detection of PJI in periprosthetic tissues of patients with total joint arthroplasty (TJA) (n = 76) reoperated for PJI (n = 38) or aseptic failure (n = 38), using the ultrafast quantitative reverse transcription-PCR (RT-PCR) Xxpress system (BJS Biotechnologies Ltd.). Advanced data-mining algorithms were applied for data analysis. For PJI, we detected elevated mRNA expression levels of DEFA1 (P < 0.0001), IL1B (P < 0.0001), LTF (P < 0.0001), TLR1 (P = 0.02), and BPI (P = 0.01) in comparison to those in tissues from aseptic cases. A feature selection algorithm revealed that the DEFA1-IL1B-LTF pattern was the most appropriate for detection/exclusion of PJI, achieving 94.5% sensitivity and 95.7% specificity, with likelihood ratios (LRs) for positive and negative results of 16.3 and 0.06, respectively. Taken together, the results show that DEFA1-IL1B-LTF gene expression detection by use of ultrafast qRT-PCR linked to an electronic calculator allows detection of patients with a high probability of PJI within 45 min after sampling. Further testing on a larger cohort of patients is needed.

The Fate of Revision Total Knee Arthroplasty With Preoperative Abnormalities in Either Sedimentation Rate or C-Reactive Protein

BACKGROUND

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are important markers in the evaluation and treatment of painful total knee arthroplasty (TKA). Elevation of both markers usually occurs with infected TKAs while a normal ESR and CRP usually point to aseptic causes for failure. The purpose of this study is to compare (1) rate of revision, (2) infection, and (3) reason for reoperation in a group of patients undergoing revision TKA with a single abnormality in either ESR or CRP in an otherwise negative conventional infection work-up compared to patients with normal preoperative ESR and CRP.

METHODS

We retrospectively reviewed 791 consecutive revision TKAs performed at our institution between years 2004 and 2011. Following exclusion for infection, periprosthetic fracture, prior revision TKA, positive cultures, incomplete records, and patients with less than 24-month follow-up, a total of 228 aseptic revisions (89 knees with 1 abnormal serologic marker) were available for final analysis. No patients met the current established criteria for infection. All knees underwent revision TKA using antibiotic-impregnated cement. The 2 groups were compared in terms of overall survivorship, infection rate, and rate and causes of subsequent aseptic revision.

RESULTS

The average follow-up was 60 months (24-110). There were no significant differences between the 2 groups in terms of age, sex, American Society of Anesthesiologists class, and Charlson comorbidity index. A preoperative abnormality of either ESR or CRP significantly increased the risk for reoperation for all reasons (odds ratio [OR], 3.2; P = .0028), infection (OR, 4.0; P = .034), and revision for aseptic loosening (OR, 3.69; P = .044). There were no differences in reoperations for any other reason. The average time to revision in the study group was 28.3 months compared to 40.0 months in the control group (P = .213).

CONCLUSION

A single abnormality in either the ESR or CRP increased the likelihood of both infection and reoperation following revision TKA. Conventional methods and criteria for infection detection may not be sufficiently sensitive or specific in these cases. Further work-up with additional modalities may help increase the confidence of aseptic failure before revision TKA.

Intraoperative Diagnosis of Periprosthetic Joint Infection Using a Novel Alpha-Defensin Lateral Flow Assay

BACKGROUND

The present study investigates the novel Synovasure periprosthetic joint infection (PJI) lateral flow test device for detection of alpha-defensin and attempts to determine its diagnostic accuracy for the intraoperative diagnosis of PJI and compares it to frozen section.

METHODS

Forty consecutive patients, who underwent revision surgery, between September 2014 and September 2015 were included. The patients underwent 29 revision total knee arthroplasties and 11 revision total hip arthroplasties. Twelve patients had a confirmed PJI based on Musculoskeletal Infection Society criteria, and 28 patients were considered aseptic.

RESULTS

The overall accuracy to detect PJI using the lateral flow assay was 85% (95% CI 70%-93%). The device has a positive predictive value of 80% (95% CI 44%-96%) and a negative predictive value of 87% (95% CI 68%-96%) and showed a sensitivity of 67% (95% CI 35%-89%) and specificity of 93% (95% CI 75%-99%). Frozen section had a lower sensitivity (58% [95% CI 29%-84%]) but a higher specificity (96% [95% CI 80%-100%]). Receiver operator curve analysis demonstrates an area under the curve of the Synovasure PJI Lateral Flow Test Kit and frozen section of 0.80 and 0.77, respectively.

CONCLUSION

The present study suggests that the intraoperative lateral flow test is at least equivalent to intraoperative frozen section and is a useful tool to confirm the absence of PJI. Although the clinical results are promising, they are not as good as previous studies using alpha-defensin levels measured in a laboratory.

Histological analysis of surgical samples and a proposed scoring system for infections in intervertebral discs

Back pain remains one the most prevalent types of pain and disability worldwide. Infection is estimated to be the underlying cause in approximately 0.01% of patients. Despite recent evidence demonstrating prominent infection rates, a standardised algorithm for diagnosis of disc infection is lacking. Histopathological evaluation can aid in confirming inflammatory changes and also in identifying degenerative changes. Hence, standardising practice through a clear scoring system with regards to inflammation and degeneration may have some utility in the clinical setting. To our knowledge no such systems exist specifically for intervertebral disc infection. A literature review of current methods of scoring inflammation and degeneration in spine surgery and orthopaedic surgery was performed. Based on the current evidence, a scoring system for disc inflammatory and degenerative changes was proposed. We propose four domains for consideration: (1) granulation tissue, (2) dense fibrosis, (3) chronic inflammatory cells, and (4) neutrophil count. The non-standardised nature of diagnosing infections and degeneration in the spinal surgery literature means that this scoring system is currently of particular value. Based on a literature review, our proposed method for diagnosis incorporates a combination of histopathological criteria expected to increase diagnostic sensitivity in the setting of disc infection. Overall, scoring can be applied to surgically obtained material and integrated directly into routine pathological practice.

Cut-off values of latent infection in patients with rapid migration following bipolar hip hemiarthroplasty

BACKGROUND

Although most patients achieve favorable results following bipolar hip hemiarthroplasty (BHA), some experience rapid migration of the prosthesis. We retrospectively reviewed 18 patients with BHA that necessitated revision.

METHODS

We examined soft tissues obtained from periprosthetic lesions. In total, 18 patients with pain and acetabular migration of the BHA prosthesis were included. The patients were divided into a polymorphonuclear leukocyte (PMN)-positive (≥5 PMNs per high-power field [HPF]) and PMN-negative (<5 PMNs/HPF) group.

RESULTS

Pathological findings showed that 11 patients were PMN-positive, which was indicative of infection. All patients in the PMN-positive group showed no polyethylene particles or foreign body giant cells, while all patients in the PMN-negative group showed polyethylene debris or foreign body giant cells (p < 0.001). BHA survival, C-reactive protein (CRP) levels, and the Japanese Orthopaedic Association (JOA) hip score were significantly different between the PMN-positive and PMN-negative group (p < 0.01). A BHA survival cut-off value of 3270 days was diagnostic for PMN positivity (sensitivity: 100%; specificity: 100%). The cut-off values for CRP and the JOA hip score were 0.43 mg/dl and 56 points, respectively. Four of 11 PMN-positive patients showed no clinical symptoms of infection (asymptomatic PMN-positive group). BHA survival, CRP levels, and JOA hip scores were significantly different between the asymptomatic PMN-positive and PMN-negative group (p < 0.05). A BHA survival cut-off of 3270 days was diagnostic for asymptomatic PMN positivity (sensitivity: 100%; specificity: 100%). The cut-off values for CRP and the JOA hip score were 0.43 mg/dl and 57 points, respectively.

CONCLUSION

Our findings suggest that some portion of rapid BHA prosthesis migration is caused by mild infection. Careful pathological examination should be performed to identify infection before removal of the BHA prosthesis in patients who develop migration within 9 years.