Background:. Until recently, there has been no consensus of the best approach to dIfferentiating aseptic from septic loosening in joint replacement patients. The recent AAOS Clinical Practice Guideline Summary that was published in 2010, tasks orthopedic surgeons with the strong recommendation of obtaining ESR and CRP for all patients needing hip and knee arthroplasty revision surgery and aspirating the joint based upon these results. The purpose of this study is to determine from our patients whether this guideline has been helpful and cost effective in determining periprosthetic joint infections. Methods:. We retrospectively reviewed charts of 50 consecutive patients who underwent revision total hip or knee arthroplasty. Each patient received an ESR and CRP level prior to operation and patients with known periprosthetic joint infections were excluded from the study. As guidelines recommend, aspiration with cultures and cell count were obtained on all knees with either elevated ESR or CRP and all hips with both ESR and CRP elevated. We then determined how many patients needing revision arthroplasty of the hip or knee benefited from ESR, CRP, and aspiration by finding subclinical periprosthetic infection and changing the intraoperative treatment. Hospital charge data was used to report cost of this protocol. Results. Sixty-four percent (32/50) patients had elevated ESR and/or CRP. Eighteen patients (12 hips; 7 knees) required joint aspirations per the guidelines. None of the aspirations were positive for bacterial growth. The total hospital charges for aspiration and cultures in this patient population were $81, 712.44. No sub clinical infection was identified. Conclusion:. Although guidelines may more readily diagnose every case of subclinical joint infection, we must continue to evaluate the cost of this type protocol in a busy revision practice

Background. Osteomyelitis can be difficult to diagnose. Unlike septic arthritis no defined diagnostic criteria exist as a guide. Inflammatory markers are frequently utilized at initial presentation, (in addition to white cell count). Methods. All radiologically confirmed cases of long bone osteomyelitis without septic arthritis, joint effusion or abscess, in paediatric patients, presenting to one hospital over an eighteen-month period were included. These patients were compared with all culture positive septic arthrides presenting to the same hospital within the same time period. Inflammatory markers taken on the day of admission were studied. Results. Thirty-seven patients with long bone osteomyelitis and thirteen with culture positive septic arthritis were identified. The two groups were comparable with regards to age and gender. At presentation 65% of the osteomyelitis patients had an ESR less than 40mm/hour, 48% below 20mm/hour and 19% within the normal range. 23% of the septic arthritis patients had an ESR below 40mm/hour, and none had an ESR below 20mm/hour or in the normal range. The CRP was in the normal range in 46% of the osteomyelitis patients and none of the septic arthritis patients. The average ESR and CRP in the osteomyelitis patients were 47mm/hour and 35mg/L respectively, while in the septic arthritis group these were 72mm/hour, (P< 0.021), and 107mg/L, (P< 0.028). Conclusions. The initial rise in inflammatory markers due to long bone osteomyelitis is significantly less than that in septic arthritis. A proportion of patients presenting with osteomyelitis have normal inflammatory markers at presentation. A high index of suspicion is required in diagnosing osteomyelitis, and inflammatory markers, while a useful adjunct to monitoring treatment, may offer false reassurance regarding the initial diagnosis

Aim. The diagnosis of periprosthetic joint infection (PJI) remains a clinical dilemma, since presentations of PJI usually greatly overlap with aseptic failure (AF). The aim of this study is to evaluate the values of plasma fibrinogen, individually or in combination with CRP, ESR and WBC, for distinguishing PJI from AF. Method. We retrospectively enrolled 357 cases who underwent revision hip or knee arthroplasties in the Third Affiliated Hospital of Southern Medical University, Sun Yat-sen Memorial Hospital and the First Affiliated Hospital of Sun Yat-sen University from January 2013 to December 2021, including 197 AF, 116 PJI and 44 reimplantation. The diagnostic capacity of preoperative fibrinogen, CRP, ESR and WBC as well as their combinations for differentiating PJI from AF were assessed by ROC curves. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated according to the optimal cutoff value based on the Youden index. All biomarkers were further investigated for their potential ability to predict optimal timing of reimplantation as well as their diagnostic capacity in the subgroups of the knee and hip PJI. Furthermore, the correlations among fibrinogen, CRP and ESR in the patients with PJI and AF were analyzed to further evaluate the potential capacity of fibrinogen in the diagnosis of PJI. Results. The levels of fibrinogen, CRP, ESR and WBC were significantly higher in PJI group than in AF group. ROC analyses showed that the AUCs of fibrinogen, CRP, ESR and WBC were 0.879, 0.903, 0.879 and 0.685, respectively. The optimal threshold of fibrinogen is 4.04 g/L (74.1% sensitivity, 85.6% specificity, 76.1% PPV, 85.0% NPV and 81.8% accuracy). Combining fibrinogen with CRP and/or ESR (AUC: 0.903∼0.914) yielded almost equivalent diagnostic efficiency compared with the combination of CRP and ESR (AUC: 0.910). Besides, fibrinogen yielded AUCs of 0.869 (cutoff: 3.44 g/L) and 0.887 (cutoff: 4.12 g/L) in the hip and knee subgroups, with higher specificity and PPV of 93.1% and 96.1% in the knee PJI. Intriguingly, as for the cases with CRP < 10mg/L and ESR ≧ 30 mm/h, the specificity and NPV of fibrinogen for diagnosing PJI were 92.2% and 83.9%. Conclusions. Plasma fibrinogen is considered as a potential first-line screening marker for PJI detection and timing of reimplantation. As for the patients with an increased ESR but normal CRP, a low fibrinogen level (below 4.04 g/L) is more likely to rule out PJI

Aim. D-dimer is a widely available serum test that detects fibrinolytic activities that occur during infection. Prior studies have explored its utility for diagnosis of chronic periprosthetic joint infections (PJI), but not explored its prognostic value for prediction of subsequent treatment failure. The purpose of this study was to: (1) assess the ability of serum D-dimer and other standard-of-care serum biomarkers to predict failure following reimplantation, and (2) establish a new cutoff value for serum D-dimer for prognostic use prior to reimplantation. Method. This prospective study enrolled 92 patients undergoing reimplantation between April 2015 and March 2019 who had previously undergone total hip/knee resection arthroplasty with placement of an antibiotic spacer for treatment of chronic PJI. Serum D-dimer level, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels were measured preoperatively for all patients. Failure following implantation was defined per the Delphi consensus criteria. Optimal cutoffs for D-dimer, ESR, and CRP were calculated based on ROC curves and compared in their association with failure following reimplantation criteria at minimum 1-year follow-up. Results. 15/92(16.3%) patients failed reimplantation surgery at mean follow up of 2.9 years (range 1.0–4.8). Optimal thresholds for D-Dimer, ESR and CRP were determined to be 1300ng/mL, 30mm/hr, and 1mg/L, respectively. The failure rate in patient with positive D-dimer was significantly higher at 32.0% (8/25) compared to those with negative D-dimer 10.6% (7/66); p=0.024. In comparison, 17.8% (8/45) of patients with ESR above threshold failed, compared to 13.89% (5/41) below (p=0.555) and 16.0% (4/25) of patients with CRP above threshold failed, compared to 16.1% (10/62) below (p=1.000). Conclusions. Patients with elevated D-Dimer appear to be at higher risk of failure after reimplantation surgery. This serum marker may be used to generate an additional data point in patients undergoing reimplantation surgery, especially in circumstances when optimal timing of reimplantation cannot be determined based on clinical circumstances

Aim. C-reactive protein(CRP) and erythrocyte sedimentation rate(ESR) are non-specific markers with variable reported accuracy in the diagnosis of prosthetic joint infection(PJI). They are often used as a part of the initial diagnostics as they are widely available and inexpensive. Given its high false-negative rate, CRP is an insufficient screening tool for PJI especially in low virulence microorganisms. Nevertheless, many advocate ESR offers no added advantage and is useless in this setting. Our goal is to determine if the combined measurement of ESR and CRP offers increased sensitivity for the preliminary screening of PJI over isolated CRP measurement. Method. We retrospectively evaluated every single- or first-stage for presumed aseptic or known infected revision total hip/knee arthroplasty procedures between 2013–2018. Cases without preoperative CRP and ESR measurement as well those without synovial fluid for differential leukocyte count and/or no multiple cultures including sonication of removed implant obtained during surgery were excluded. Diagnostic accuracy was compared against two different PJI definitions: 2013 International Consensus Meeting and ProImplant Foundation definitions. Results. A total of 398 revision were performed during the study period. After excluding 293 cases with insufficient information, a total of 105 patients were studied. Naturally, CRP and ESR mean values were significantly higher among PJI cases compared to aseptic cases. When compared against 2013 International Consensus Meeting definition, CPR has a sensibility 86.5% (45/52) that increases to 94.2% (49/52) with the combined measurement (ESR and CRP). The sensitivity also increased when compared against the ProImplant Foundation definition (72.6% (45/62) vs 85.5% (53/62)). Conclusions. After the inciting insult, CRP raises and drops rapidly and ESR response is slower but also much more enduring. One can only hypothesize that chronic PJI runs perhaps a fluctuating inflammatory course that can sometimes be more accurately picked up by ESR and not CRP measurement. Our results seem to corroborate that ESR measurement is a valid adjunct to isolated CRP measurement in the initial screening of PJI in painful total joint arthroplasties

Abstract. Aim. To study and compare the rise of Inflammatory markers post TKR operated by Medial parapatellar approach with tourniquet (MP) and by Subvastus approach used without tourniquet. (SV). Materials and Methods. 100 patients were operated for a TKR by two experienced Arthroplasty surgeons utilising either the MP approach or the SV approach. (50 knees each). The groups were well matched as regards age, degree of deformity, obesity, pre-op knee scores and co-morbidities. The patients were managed peri-operatively in an identical manner .5 inflammatory markers viz: IL-6, AST, LDH, CRP and ESR were measured pre-operatively and at 12, 24,48 and 72 hours postoperatively. Additionally, the patients' VAS score at these intervals and Morbidity Index was determined. Results. All the 5 inflammatory markers increased post surgery in both groups. However, the rise of 4 out of the 5 inflammatory markers i(IL-6, AST, CRP, ESR) in the MP group was statistically significantly higher than in the SV group. The LDH values were similar in the two groups. The VAS scores were better in the SV group and the Morbidity Index showed a higher degree of morbidity in the MP group. Discussion. Surgical technique and approach can influence the rise of Inflammatory markers post TKR. Conclusion. The Subvastus tourniquetless approach reliably produces a lesser degree of rise in inflammatory markers post TKR than the medial parapatellar approach used with tourniquet. The subvastus approach should be utilised more to improve the immediate post-operative results following a TKR

Aim. To determine mortality and outcomes of patients diagnosed with fracture-related infections (FRIs). Method. FRI patients treated at a trauma centre between 2001 and 2020 were analysed. The primary outcome was 1-year mortality; mortality associations with FRI organism, depth of involvement, and temporality were investigated with multivariable survival analysis. Healthcare-associated and serological outcomes were reported as secondary outcomes. Results. 311 FRIs with mean age of 67.0 and median Charlson comorbidity index of 0 were analysed. Methicillin-sensitive Staphylococcus aureus (MSSA) (29.9%) was the most frequently implicated organism. The majority of FRIs were deep infections (62.7%). FRIs were diagnosed at a median of 40 (IQR 15–200) days post index surgery. The mean follow-up was 5.9 years. One-year mortality amounted to 17.7%. MSSA FRIs were associated with better survival (adj HR 0.34, 95%CI 0.15–0.76, p=0.008). There was no difference in survivorship between deep or superficial FRI (adj HR 0.86, 95%CI 0.62–1.19, p=0.353) or in relation to onset time (adj HR 1.0, 95%CI 0.99–1.00, p=0.943). Implant removal or debridement alone was performed in 61.7% and 17% respectively. Antibiotics was prescribed for 53 (IQR 23–110) days, and patients were hospitalised for 39 (IQR 19–78) days. CRP and ESR normalised in 70.3% (median 46 days) and 53.8% (median 86 days) patients respectively. Conclusions. Fracture-related infections are associated with significant mortality and morbidity regardless of depth and temporality. Non-MSSA FRIs are associated with inferior survival

Aim. Diagnosing fracture related infections (FRI) based on clinical symptoms alone can be challenging and additional diagnostic tools such as serum inflammatory markers are often utilized. The aims of this study were 1) to determine the individual diagnostic performance of three commonly used serum inflammatory markers: C-Reactive Protein (CRP), Leukocyte Count (LC) and Erythrocyte Sedimentation Rate (ESR), and 2) to determine the diagnostic performance of a combination of these markers and their value additionally to clinical predictors for FRI. Method. This cohort study included patients who presented with a suspected FRI at two level I academic trauma centers between February 1. st. 2009 and December 31. st. 2017. The parameters CRP, LC and ESR, were obtained from hospital records when FRI was suspected. The gold standard for diagnosing or ruling out FRI was defined as: positive microbiology results of surgically obtained tissue samples, or absence of FRI at a clinical follow-up of at least six months. Separate markers were analysed using hospital thresholds, to determine current diagnostic performance, and continuously, to determine maximum possible diagnostic performance. Multivariable logistic regression analyses were performed to obtain the discriminative performance (Area Under the Receiver Operating Characteristic, AUROC) of (1) the combined inflammatory markers, and (2) the value of these markers additional to clinical parameters. Results. A total of 168 patients met the inclusion criteria and were included for analysis. CRP had a 38% sensitivity, 34% specificity, 42% positive predictive value (PPV) and 78% negative predictive value (NPV). For LC this was 39%, 74%, 46% and 67% and for ESR 62%, 64%, 45% and 76% respectively. The diagnostic accuracy was 52%, 61% and 80% respectively. The AUROC was 0.64 for CRP, 0.60 for LC and 0.58 for ESR. The AUROC of the combined inflammatory markers was 0.63. Serum inflammatory markers combined with clinical parameters resulted in AUROC of 0.66 as opposed to 0.62 for clinical parameters alone. Conclusions. The added diagnostic value of CRP, LC and ESR for diagnosing FRI is limited. Clinicians should be aware of this finding in the diagnostic work-up of suspected FRI

The diagnosis of infection following shoulder arthroplasty is notoriously difficult. The prevalence of prosthetic shoulder infection after arthroplasty ranges from 3.9 – 15.4% and the most common infective organism is Cutibacterium acnes. Current preoperative diagnostic tests fail to provide a reliable means of diagnosis including WBC, ESR, CRP and joint aspiration. Fluoroscopic-guided percutaneous synovial biopsy (PSB) has previously been reported in the context of a pilot study and demonstrated promising results. The purpose of this study was to determine the diagnostic accuracy of percutaneous synovial biopsy compared with open culture results (gold standard). This was a multicenter prospective cohort study involving four sites and 98 patients who underwent revision shoulder arthroplasty. The cohort was 60% female with a mean age was 65 years (range 36-83 years). Enrollment occurred between June 2014 and November 2021. Pre-operative fluoroscopy-guided synovial biopsies were carried out by musculoskeletal radiologists prior to revision surgery. A minimum of five synovial capsular tissue biopsies were obtained from five separate regions in the shoulder. Revision shoulder arthroplasty was performed by fellowship-trained shoulder surgeons. Intraoperative tissue samples were taken from five regions of the joint capsule during revision surgery. Of 98 patients who underwent revision surgery, 71 patients underwent both the synovial biopsy and open biopsy at time of revision surgery. Nineteen percent had positive infection based on PSB, and 22% had confirmed culture positive infections based on intra-operative tissue sampling. The diagnostic accuracy of PSB compared with open biopsy results were as follows: sensitivity 0.37 (95%CI 0.13-0.61), specificity 0.81 (95%CI 0.7-0.91), positive predictive value 0.37 (95%CI 0.13 – 0.61), negative predictive value 0.81 (95%CI 0.70-0.91), positive likelihood ratio 1.98 and negative likelihood ratio 0.77. A patient with a positive pre-operative PSB undergoing revision surgery had an 37% probability of having true positive infection. A patient with a negative pre-operative PSB has an 81% chance of being infection-free. PSB appears to be of value mainly in ruling out the presence of peri-prosthetic infection. However, poor likelihood ratios suggest that other ancillary tests are required in the pre-operative workup of the potentially infected patient

Aim. Diagnosis of periprosthetic shoulder infections (PSI) is difficult as they are mostly caused by low-virulent bacteria and patients do not show typical infection signs, such as elevated blood markers, wound leakage, or red and swollen skin. Ultrasound-guided biopsies for culture may therefore be an alternative for mini-open biopsies as less costly and invasive method. The aim of this study was to determine the diagnostic value and reliability of ultrasound-guided biopsies for cultures alone and in combination polymerase chain reaction (PCR), and/or synovial markers for preoperative diagnosis of PSI in patients undergoing revision shoulder surgery. Method. A prospective explorative diagnostic cohort study was performed including patients undergoing revision shoulder replacement surgery. A shoulder puncture was taken preoperatively before incision to collect synovial fluid for interleukin-6 (IL-6), calprotectin, WBC, polymorphonuclear cells determination. Prior to revision surgery, six ultrasound-guided synovial tissue biopsies were collected for culture and two additional for PCR analysis. Six routine care tissue biopsies were taken during revision surgery and served as reference standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV; primary outcome measure), and accuracy were calculated for ultrasound-guided biopsies, and synovial markers, and combinations of these. Results. Fifty-five patients were included. In 24 patients, routine tissue cultures were positive for infection. Cultures from ultrasound-guided biopsies diagnosed an infection in 7 of these patients, yielding a sensitivity, specificity, PPV, NPV, and accuracy of 29.2%, 93.5%, 77.8%, 63.0%, and 65.6%, respectively. Ultrasound-guided biopsies in combination with synovial WBC increased the NPV to 76.7% and accuracy to 73.8%. When synovial WBC and calprotectin were combined with ultrasound-guided biopsies, it resulted in a better diagnostic value: sensitivity 69.2%, specificity 80.0%, PPV 69.2%, NPV 80.0%, and accuracy 75.8%. Ultrasound-guided biopsies in combination with calprotectin and ESR yielded a sensitivity of 50.0%, specificity of 93.8%, PPV of 80.0%, NPV of 78.9%, and accuracy of 79.2%. Synovial fluid was obtained in 42 patients. Sensitivities of WBC, PMN, IL-6, and calprotectin were between 25.0% and 35.7%, specificities between 89.5% and 95.0%, PPVs between 60.0% and 83.3%, NPVs between 65.4% and 69.4%, and accuracies between 64.5% and 70.6%. Conclusions. In this prospective study we showed that ultrasound-guided biopsies for cultures alone and in combination with PCR and/or synovial markers are not reliable enough to use in clinical practice for the preoperative diagnosis of low grade PSI

Aim. Traditionally, serum white blood count (WBC), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) have been utilized as markers to evaluate septic arthritis (SA). Recently, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been identified as prognostic factors for treatment failure, mortality and morbidity in various clinical settings. To date, these markers have not been utilized for evaluating outcomes after hip and knee SA. Thus, the purpose of this study was to determine the ability of admission NLR and PLR to predict treatment failure and postoperative 90-day mortality in hip and knee SA. Method. A retrospective study was performed using our institutional research patient database to identify 235 patients with native hip and knee septic arthritis from 2000–2018. Patient demographics, comorbidities and social factors (alcohol intake, smoking and intravenous drug use) were obtained, and NLR and PLR were calculated based on complete blood count values (absolute neutrophil, lymphocyte and platelet count) on admission. Treatment failure was defined as any reoperation or readmission within 90 days after surgery. Receiver operating curves were analyzed, and optimal thresholds for NLR and PLR were determined using Youden's test. Univariate and multivariate analyses were performed to determine if these ratios were independent predictors of treatment failure and 90-day mortality after surgery. These ratios were compared to serum WBC, CRP, and ESR. Results. Optimal thresholds for NLR was 9.49 (sensitivity=60%, specificity=84%) and PLR was 303 (sensitivity=54%, specificity=77%). With univariate analysis, NLR>9.49 was associated with failure (odds ratio [OR]=7.64, 95%. Confidence Interval [CI]=4.10–14.21) and 90-day mortality (OR=9.83, 95% CI=2.74–35.25). PLR>303 was associated with increased failure (OR=3.85, 95% CI=2.12–7.00). In multivariate analysis controlling for patient demographics, comorbidities and social factors, elevated NLR remained an independent predictor of failure (OR=7.04, 95% CI=3.78–13.14) and 90-day mortality (OR=5.98, 95% CI=1.60–22.32), whereas PLR remained a predictor of failure (OR=3.58, 95% CI=1.95–6.58). NLR was a better predictor of failure and 90- day mortality compared to serum WBC, CRP, and ESR. Conclusions. This study demonstrates that NLR is a good estimate of SA and performs better than serum WBC, CRP and. ESR to predict treatment failure and 90-day mortality. Elevated NLR is a reliable novel biomarker that may be utilized when evaluating SA patients, and this accessible test could be utilized in the musculoskeletal infection field

Aim. Fracture related infection (FRI) remains a challenging diagnosis in orthopedic and trauma surgery. In addition to clinical signs and imaging, serum inflammatory markers are often used to estimate the probability of FRI. To what extent serum inflammatory markers can be used to rule out and diagnose FRI remains unclear. The aim of this systematic review was to assess the diagnostic value of the serum inflammatory markers C-reactive protein (CRP), leukocyte count (LC) and erythrocyte sedimentation rate (ESR) in suspected fracture related infection. Method. PubMed, Embase and Cochrane databases were searched for all articles focusing on the diagnostic value of CRP, LC and ESR in FRI. Studies on other inflammatory markers or other types of orthopedic infection, such as periprosthetic and diabetic foot infections, were excluded. For each serum inflammatory marker, all reported sensitivity and specificity combinations were extracted and graphically visualized. Average estimates were obtained using bivariate mixed effects models. This study utilized the QUADAS-2 criteria and was reported following the PRISMA statement. Results. The search resulted in 8280 articles, of which seven were eligible for inclusion. One study was excluded after quality assessment. CRP was reported in all included studies, with sensitivity ranging from 60.0 to 100.0% and specificity from 34.3 to 85.7%. Five of these studies were pooled. The average pooled sensitivity and specificity of CRP were, respectively, 77.0% (95% CI 66.5–85.0%) and 67.9% (95% CI 38.7–87.6%). LC was reported in five studies. Sensitivity ranged from 22.9 to 72.6% and specificity from 73.5 to 85.7%. The results of four of these studies were pooled, resulting in a 51.7% (95% CI 27.2–75.5%) sensitivity and 67.1% (95% CI 19.3–50.2%) specificity. ESR was reported in five studies. Sensitivity and specificity ranged from 37.1 to 100.0% and 59.0 to 85.0% respectively. Three of these studies were pooled, showing a 45.1% (95% CI 37.8–52.6%) sensitivity and 79.3% (95% CI 71.7–85.2%) specificity of ESR. Four studies analyzed the combined value of inflammatory markers, reporting an increased diagnostic accuracy. These results could not be pooled due to heterogeneity. Conclusions. The serum inflammatory markers CRP, LC and ESR are insufficiently accurate to diagnose FRI. These markers cannot rule out the presence of FRI, but they may be used as a suggestive sign in the diagnosis of FRI

Propionibacteria are organisms of low virulence, although they do cause deep periprosthetic infections. The aim of this study was to show that Propionibacteria do not always cause a significant rise in ESR and CRP. Between May 2001 and May 2004, we identified 77 patients with prosthetic joint replacements colonised with Propionibacteria, 47 males and 30 females. There were 47 hip joint replacements, 27 knee joint replacements, 2 endoprosthetic replacements of the femur and 1 shoulder joint replacement. We retrieved successfully the medical records of 66 patients in order to identify the number of patients treated for an infected prosthetic joint arthroplasty. The pre-operative values of ESR and CRP were recorded. For the purposes of this study, an ESR rate of 30mm/hr or higher and a CRP level of 10mg/lt or higher were considered to be suggestive of infection and were deemed a positive result. All of the 77 patients had both ESR and CRP measured pre-operatively. In only 16 (21%) both ESR and CRP were higher than 30mm/hr and 10mg/l respectively. In 33 patients (43%) with prosthetic joint replacements colonised with Propionibacteria, the pre-operative values of ESR and CRP were normal. 23 patients were treated for an infected prosthetic joint arthroplasty. In 7 (30%) of those patients both ESR and CRP were normal. This suggests that normal pre-operative values of ESR and CRP in suspected failed prosthetic joint replacements might not exclude infection, if the causative organism is of low virulence such as Propionibacteria

Aim. Low-grade infections are difficult to diagnose. As the presence of a chronic infection requires extensive surgical debridement and antibiotic treatment, it is important to diagnose a SII prior to surgery, especially when the hardware is revised. We investigated whether serum inflammatory markers or nuclear imaging can accurately diagnose a chronic spinal instrumentation infection (SII) prior to surgery. Method. All patients who underwent revision spinal surgery after a scoliosis correction between 2017 and 2019 were retrospectively evaluated. The diagnostic accuracy of serum C-reactive protein (CRP) and Erythrocyte Sedimentation Rate (ESR), . 18. F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) and Technetium-99m-methylene diphosphonate (99mTc-MDP) 3-phase bone scintigraphy (TPBS) to diagnose infection were studied. Patients with an acute infection or inadequate culture sampling were excluded. SII was diagnosed if ≥ 2 of the same microorganism(s) were isolated from intra-operative tissue cultures. Results. 31 patients were included. The indication for hardware extraction was pseudoarthrosis in the majority of patients (n = 15). 22 patients (71%) were diagnosed with SII. In all infected cases, Cutibacterium acnes was isolated, including 5 cases with a polymicrobial infection. Sensitivity, specificity, PPV and NPV was: 4.5%, 100%, 100% and 30.0% for CRP >10.0 mg/L, 5.5%, 100%, 100% and 29% for ESR > 30 mm/h; 56%, 80%, 83% and 50% for FDG-PET/CT and 50%, 100%, 100% and 20% for TPBS, respectively. Conclusions. The prevalence of SII in patients undergoing revision spinal surgery is high, with Cutibacterium acnes as the main pathogen. No diagnostic tests could be identified that could accurately diagnose or exclude SII prior to surgery. Future studies should aim to find more sensitive diagnostic modalities to detect low-grade inflammation

Aim. Despite the availability of numerous tests, the diagnosis of periprosthetic infection (PJI) continues to be complex. Although several studies have suggested that coagulation-related markers, such as D-dimer and fibrinogen, may be promising tools in the diagnosis of prosthetic infections, their role is still controversial. The aim of this study is to evaluate the diagnostic accuracy of serum D-dimer and fibrinogen in patients with painful total knee replacement. Method. 83 patients with painful total knee replacement and suspected peri-prosthetic infection were included. All patients underwent pre-operative blood tests to evaluate inflammation indices (ESR and CRP) and serum D-Dimer and Fibrinogen levels. The diagnostic performance of the tests was assessed using the ICM definition as the gold standard. The diagnostic accuracy of the D-dimer and fibrinogen was measured by assessing sensitivity, specificity and by calculating the area under the ROC curve. Results. The definition of prosthetic infection based on the ICM criteria has made it possible to classify 40 peri-prosthetic infections and 43 aseptic failures. The mean value of fibrinogen, D-Dimer, VES and PCR observed in patients with prosthetic infection was significantly higher than in patients with aseptic failure [fibrinogen 468 mg / dl vs 331 mg / dl, p <0.001; D-Dimero 2177 ng/mL vs. 875 ng / mL, p <0.005], ESR 49 mm / hr vs 24 mm/h, p <0.001; PCR 25.5 mg /L vs 8.9 mg/L, p <0.001]. The optimal threshold value of the fibrinogen indicative of the presence of infection was 418 mg/dl, with a sensitivity of 72% and a specificity of 88%. The serum concentration of d-dimer greater than 945 ng / ml showed a sensitivity of 72.5% and a specificity of 76.7%. Conclusions. Although in this multicenter prospective study we found that serum D-dimer may have significantly higher statistical values in PJI than aseptic failures, its diagnostic power appears however limited when compared with other markers including plasma fibrinogen. Fibrinogen is regularly analyzed before surgery, the evaluation of this marker does not involve additional costs. The diagnostic accuracy appears to be similar to that of classic markers such as the level of PCR and VES. Plasma D-dimer may have a limited value in the diagnosis of PJI unlike plasma fibrinogen which has shown moderate sensitivity and excellent specificity. However, in our limited series of cases, both tests cannot be used alone in the diagnosis of infection but could contribute to the diagnosis if contextualized to ves and pcr

Aim. Synovial fluid investigation is the best alternative to diagnose prosthetic joint infection (PJI) before adequate microbiological/histology sampling during revision surgery. Although accurate preoperative diagnosis is certainly recommended, puncturing every patient before revision arthroplasty raises concerns about safety and feasibility issues especially in difficult to access joint (e.g., hip), that often require OR time and fluoroscopy/ultrasound guidance. Currently there is no clear guidelines regarding optimal indications to perform preoperative joint aspiration to diagnose PJI before revision surgery. The main goal of this study is to determine the accuracy of our institutional criteria using the new European Bone and Joint Infection Society (EBJIS) PJI definition. Method. We retrospectively evaluated every single- or first-stage for presumed aseptic or known infected revision total hip/knee arthroplasty procedures between 2013–2020. Preoperative clinical and laboratory features were systematically scrutinized. Cases with insufficient information for accurate final PJI diagnosis (i.e., no perioperative synovial fluid examination or no multiple cultures including sonication of removed implant) were excluded. Preoperative joint aspiration is recommended in our institution if any of the following criteria are met: 1) elevated CRP and/or ESR; 2) early failure (<2 years) or repeat failure; 3) high clinical suspicion/risk factors are present. Performance of such criteria were compared against final postoperative EBJIS definition PJI diagnosis. Results. A total of 364 revision THAs or TKAs were performed during the study period. After excluding 258 cases with insufficient information, a total of 106 patients were ultimately included. 38 (35,8 %) were classified as confirmed infections, 10 (9.4 %) as likely infected and 58 (54.7%) as infection unlikely. Of those, 37 confirmed infection cases, 9 likely infected cases and 32 infection unlikely cases did have indication for preoperative synovial fluid collection before revision surgery. Institutional criteria showed 95.8 % Sensitivity, 44.83 % Specificity, 92.9 % Negative Predictive Value (NPV) and 59 % Positive Predictive Value (PPV). Conclusions. Sensitivity and NPV of the aforementioned institutional criteria are very high even with the use of the more sensitive EBJIS PJI definition. As such they seem to be a valid alternative in selecting patients that should be punctured before revision arthroplasty. They identify the vast majority of infected patients while saving a significant number of patients from unnecessary procedures

The infected joint arthroplasty continues to be a very challenging problem. No test has 100% diagnostic accuracy for PPI and the treating surgeon must correlate the clinical and radiographic presentation with a combination of blood tests, synovial fluid analysis, microbiological and histopathological evaluation of periprosthetic tissue and intra-operative inspection to reach a definitive diagnosis. Diagnosis should begin with a high index of suspicion for new onset of pain or symptoms in well-functioning joints. Plain radiographs may identify osteolysis or early signs of implant failure and should be promptly investigated further for PPI. Peripheral blood ESR and CRP remain the most widely used next step for the diagnosis of PPI. Both these tests are widely available, inexpensive, and have a rapid turnaround time in laboratories. The results should be interpreted with caution due to their relative lack of specificity. The sensitivity and specificity values for CRP are approximately 88 and 74%, respectively; while that of ESR is slightly lower at 75 and 70%, respectively. The combined ESR and CRP tests are 96% sensitive for ruling out PPI but the specificity of this combination is as low as 56%. Advanced imaging modalities may be used as a part of the diagnostic algorithm. However, they require expert interpretation and are limited by availability and high costs. When available they have high sensitivity and specificity but their routine use is not recommended and indications have to be individualised in the light of clinical presentation. In the presence of high clinical suspicion, the clinician should plan synovial fluid analysis. This provides a synovial fluid white cell count with differential cell count, specimen for culture and possibility of analyzing other synovial fluid markers. It is important to note that failed metal-on-metal hip arthroplasties can give a falsely elevated synovial fluid cell count when using automated cell counters. This can be overcome by manually counting cell numbers. Synovial fluid should be directly into blood culture bottles, and antibiotics should be withheld at least 2 weeks prior to aspiration, whenever possible. Cultures also help establish the organism, virulence and sensitivities that help plan subsequent treatment algorithm. Periprosthetic tissue biopsy provides valuable information in microbiological diagnosis and workup of PPI. Routine use of gram staining is not recommended due to poor sensitivity. However, frozen section may have some role especially when performed by a skilled pathologist. Tissue culture remains the gold standard for diagnosis despite false-positive and false-negative results. Whenever possible multiple samples should be obtained to aid interpretation. A threshold of 2 to 3 positive specimens yielding indistinguishable microorganisms has been recommended to improve sensitivity. Acute inflammation, evidenced by neutrophilic infiltrate on fixed or frozen tissue, is suggestive of PPI and is defined as the presence of at least 5 neutrophils per high-powered field, in at least 5 separate microscopic fields. Sonication of removed prosthetic components is used to dislodge the biofilm and the associated bacteria from the surface of the implant. The fluid surrounding the implant can be used for culture or analysis. PCR testing: Synovial fluid aspirate, periprosthetic tissue or sonicate fluid may be subject to molecular diagnosis to amplify genetic material and improve microbiological diagnosis of PPI. This technique has shown increased sensitivity in patients who had received antibiotics within 14 days before implant removal. Results have to carefully interpreted with due consideration for possibility of false positive results

Aim. To assess the effectiveness of role of frozen section in revision arthroplasty. Method. 21 patients with infected hip arthroplasties were operated in the form of one or two-staged revision hip arthroplasties. A frozen section was obtained intra-operatively and >5 PMN's/ HPF was considered as a positive indicator of infection. Fig 1 llustrating frozen section image. If the frozen section was reported negative (≤5 PMN's/HPF), the revision prosthesis was implanted after a thorough debridement and a wash. If the frozen section was reported as positive, after the debridement a non-articulating antibiotic loaded cement spacer was implanted for 8 weeks, supplemented with 3 weeks of intravenous antibiotics and 3 weeks of oral antibiotics. This was followed by an antibiotic free interval of 2 weeks. The patient was taken up for a revision surgery once the frozen section study was negative (≤5 PMN's/HPF). The patients were followed up for minimum of 1 year to a maximum of 2 years after the revision for any evidence of infection (assessed clinically and serologically, radiologically). Results. 15 patients had a positive frozen section (>5PMN's/HPF) in the first stage and were treated with prosthesis removal and cement spacer insertion for 8 weeks. In the 2nd stage, out of 15 patients, 14 underwent revision arthroplasty, while 1 patient underwent reapplication of the cement spacer. As per the follow up of ESR & CRP values, clinically and radiologically no patients had any evidence of infection. The average follow up was 17.04 months (range 12–24 months). 1 patient had persistently raised ESR (34mm/hr) which may be attributable to other causes Frozen section analysis of PMN's per high power field had 100% specificity in our patients in detecting periprosthetic joint infection. Conclusions. Intraoperative frozen section study is a reliable indicator in predicting a diagnosis of PJI with good accuracy in ruling out this diagnosis. Frozen section study should thus be considered a relevant part of the challenging diagnostic work-up for patients undergoing revision hip arthroplasty

The infected joint arthroplasty continues to be a very challenging problem. No test has 100% diagnostic accuracy for PPI and the treating surgeon must correlate the clinical and radiographic presentation with a combination of blood tests, synovial fluid analysis, microbiological and histopathological evaluation of periprosthetic tissue and intra-operative inspection to reach a definitive diagnosis. Diagnosis should begin with a high index of suspicion for new onset of pain or symptoms in well-functioning joints. Plain radiographs may identify osteolysis or early signs of implant failure and should be promptly investigated further for PPI. Peripheral blood ESR and CRP remain the most widely used next step for the diagnosis of PPI. Both these tests are widely available, inexpensive, and have a rapid turnaround time in laboratories. The results should be interpreted with caution due to their relative lack of specificity. The sensitivity and specificity values for CRP are approximately 88 and 74%, respectively; while that of ESR is slightly lower at 75 and 70%, respectively. The combined ESR and CRP tests are 96% sensitive for ruling out PPI but the specificity of this combination is as low as 56%. Advanced imaging modalities may be used as a part of the diagnostic algorithm. However, they require expert interpretation and are limited by availability and high costs. When available they have high sensitivity and specificity but their routine use is not recommended and indications have to be individualised in the light of clinical presentation. In the presence of high clinical suspicion, the clinician should plan synovial fluid analysis. This provides a synovial fluid white cell count with differential cell count, specimen for culture and possibility of analyzing other synovial fluid markers. It is important to note that failed metal-on-metal hip arthroplasties can give a falsely elevated synovial fluid cell count when using automated cell counters. This can be overcome by manually counting cell numbers. Synovial fluid should be directly into blood culture bottles, and antibiotics should be withheld at least 2 weeks prior to aspiration, whenever possible. Cultures also help establish the organism, virulence and sensitivities that help plan subsequent treatment algorithm. Periprosthetic tissue biopsy provides valuable information in microbiological diagnosis and workup of PPI. Routine use of gram staining is not recommended due to poor sensitivity. However, frozen section may have some role especially when performed by a skilled pathologist. Tissue culture remains the gold standard for diagnosis despite false-positive and false-negative results. Whenever possible multiple samples should be obtained to aid interpretation. A threshold of 2 to 3 positive specimens yielding indistinguishable microorganisms has been recommended to improve sensitivity. Acute inflammation, evidenced by neutrophilic infiltrate on fixed or frozen tissue, is suggestive of PPI and is defined as the presence of at least 5 neutrophils per high-powered field, in at least 5 separate microscopic fields. Sonication of removed prosthetic components is used to dislodge the biofilm and the associated bacteria from the surface of the implant. The fluid surrounding the implant can be used for culture or analysis. PCR testing: Synovial fluid aspirate, periprosthetic tissue or sonicate fluid may be subject to molecular diagnosis to amplify genetic material and improve microbiological diagnosis of PPI. This technique has shown increased sensitivity in patients who had received antibiotics within 14 days before implant removal. Results have to carefully interpreted with due consideration for possibility of false positive results

Postoperative infection is a difficult complication affecting total hip arthroplasty. It is painful, disabling, costly and it lacks definitive treatment guidelines. Klebsiella spp. are uncommon causes of Total Hip Arthroplasty. The aim of this case report was to document an effective treatment algorithm for a multidrug resistant Klebsiella spp infection after THA. We report a case of a 56-year-old male who has performed a THA in 2007 at our institution. After 4 admissions due to posterior hip dislocations it was performed an Acetabular Revision in May 2014. The periprothesic infection was suspected by delayed wound healing with inflammatory signals and both abnormal values of Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). The patient was submitted to two hip arthrocenteses, one before and the other after antibiotic therapy (EV). The intra-articular cultures revealed a Klebsiella Pneumoniae infection only carbapenem-sensitive. We decided to performed a two-stage total hip arthroplasty revision approach. After the First Acetabular revision, ESR and CRP were augmented. X-rays and CT scans were performed, but inconclusive for infection. The patient completed longterm ertapenem therapy after the results of intra-articular cultures. We repeated arthrocentesis and the result was positive for the same bacteria. After 3 months of the Acetabular procedure we performed a Girldstone. We continued with Ertapenem and after 4 months we performed a Total Revision Arthroplasty. Final intra-articular cultures were negative for infection and ESR and CRP were both normal. After 5 months of follow-up the patient is pain-free and has good ROM. The infection risk is greater with the number of revision surgeries. Our institution has good outcomes with 2-stage procedure for multi drug infections. The best diagnosis tools were ESR and CRP, and intra-articular cultures. Two-stage revision surgery is a good choice for multi-resistent infections, and proper indications must be followed