Aims. It can be extremely challenging to determine whether to perform reimplantation in patients who have contradictory serum inflammatory markers and frozen section results. We investigated whether patients with a positive frozen section at reimplantation were at a higher risk of reinfection despite normal ESR and CRP. Methods. We retrospectively reviewed 163 consecutive patients with periprosthetic joint infections (PJIs) who had normal ESR and CRP results pre-reimplantation in our hospital from 2014 to 2018. Of these patients, 26 had positive frozen sections at reimplantation. The minimum follow-up time was two years unless reinfection occurred within this period. Univariable and multivariable logistic regression analyses were performed to identify the association between positive frozen sections and treatment failure. Results. Treatment failure occurred in eight (30.77%) of the 26 PJI patients with positive frozen sections at reimplantation, compared with 13 (9.49%) of 137 patients with negative results. In the multivariate analysis, positive frozen section increased the risk of failure (odds ratio 4.70; 95% confidence interval (CI) 1.64 to 13.45). The mean number of months to reinfection was lower in the positive frozen section group than in the control group (p = 0.041). While there were nine (34.62%) patients with positive frozen section and 25 (18.25%) patients with negative frozen section who had prolonged antibiotic use (p = 0.042), the mean duration of antibiotic use was comparable in two groups. Synovial white blood cell count (p = 0.137) and polymorphonuclear leucocyte percentage (p = 0.454) were not associated with treatment failure in logistic regression model. Conclusion. Positive frozen section at reimplantation was independently associated with subsequent failure and earlier reinfection, despite normal ESR and CRP levels pre-reimplantation. Surgeons should be aware of the risk of treatment failure in patients with positive frozen sections and carefully consider benefits of reimplantation. Cite this article: Bone Joint J 2021;103-B(5):916–922

Aims. Leucocyte esterase (LE) has been shown to be an accurate marker of prosthetic joint infection (PJI), and has been proposed as an alternative to frozen section (FS) histology for intraoperative diagnosis. In this study, the intraoperative assessment of LE was compared with FS histology for the diagnosis of prosthetic hip infection. Patients and Methods. A total of 119 patients undergoing revision total hip arthroplasty (THA) between June 2015 and December 2017 were included in the study. There were 56 men and 63 women with a mean age of 66.2 years (27 to 88). Synovial fluid was collected before arthrotomy for the assessment of LE using enzymatic colourimetric strips. Between five and six samples were stained with haematoxylin and eosin for FS histology, and considered suggestive of infection when at least five polymorphonuclear leucocytes were found in five high-power fields. Results. The sensitivity and specificity of the LE assay were 100% and 93.8%, respectively; the positive (PPV) and the negative (NPV) predictive values were 79.3% and 100%, respectively. The mean time between the collection of the sample and the result being known was 20.1 minutes (. sd. 4.4). The sensitivity and specificity of FS histology were 78.3% and 96.9%, respectively; the PPV and the NPV were 85.7% and 94.9%, respectively. The mean time between the collection of the sample and the result being known was 27.2 minutes (. sd. 6.9). Conclusion. The sensitivity of LE assay was higher, with similar specificity and diagnostic accuracy, compared with FS histology. The faster turnaround time, its ease of use, and low costs make LE assay a valuable alternative to FS histology. We now use it routinely for the intraoperative diagnosis of PJI. Cite this article: Bone Joint J 2019;101-B:372–377

Frozen section is a recognised technique to assist in the diagnosis of infection and there are standards for reporting. Our aim of this review was to assess the value of frozen section in the diagnosis of infection, as well as other variables. We performed a retrospective review of all frozen sections for suspected infection in 2016. Patient demographics, histological and microbiological investigations, laboratory and bedside tests were recorded and analysed using statistical software. 46 patients had 55 frozen sections; the majority were for lower limb arthroplasty. No sections were reported as polymorphonuclear neutrophils per high-power field. Three sections showed signs of infection and one without evidence had positive cultures. One uncertain section did not grow organisms. 10 patients had two-stage procedures, four of these were intended to be determined by frozen section but only two had evidence of infection on analysis. Evidence of infection on frozen section does correlate with microbiological growth but does not relate to intention to stage procedures in half of patients. The effect of new tests such as Synovasure is highlighted by this review. Frozen section analysis is reported subjectively but is a good predictor of infection. Clinical assessment is accurate in diagnosing infection. Histological, microbiological and additional investigations should be considered in relation to their cost-effectiveness

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

Injection before total knee arthroplasty(TKA) is the one of the postoprative risk factors after TKA and Infection after TKA can result in disastrous consequences. When the duration between injection and TKA is longer than 6 months, the risk is no longer elevated. Evaluation of synovial WBC number in frozen section slide is needed to check the presence of infection in revision total knee arthroplasty. Currently many patients have a history of multiple intraarticular injection before the primary TKA. Purpose of this study is to evaluate the synovial WBC findings in primary TKA and compare between injection group and no injection group. Materials and Methods. The synovial specimen(suprapatella pouch and posterior capsule) of 68 primary total knee arthroplasty were evaluated by the pathologist and reported the number of the WBC in frozen section /5 separate high power fields(HPF) (500x).. Injection group were 37 cases and non -injection group were 31 cases. Preoperative CRP and ESR were recorded and followe-up duration was more than 2 years. Joint fluid was sent to be cultured and analysed. Results. WBC count in frozen section shoed was average 4 WBCs/HPF (range < 0∼ 25) in both specimen and the suprapatella specimen was 3 WBCs/HPW (range 0∼25) and posterior capsule specimen was 1 WBCs/HPF(range 0∼14). The WBC count of injection group was 8 (range, 0∼25) and that of no injection group was 1.2 cells (range 0∼12) (p<0.05). The WBC counts in joint fluid was average 240 cells/ml (range. 1∼300) in non injection group and 643 cells/ml(range, 50∼1000) (p<0.05). The duration from the intraarticular injection to index surgery was 9 months(range, 6 weeks∼ 7 momths). The number of injection and duration bwtween injection and operationto has no significant correlation with the WBC counts. Eight percentage of specimen showed more than 10 WBCs in injection group and these patients have been not infected after more than 24 moths after TKA. Conclusion. The WBC count of the synovium in priamry TKA with injection history for degenerative osteoarthritis is variable and we could not recommend the routine frozen section analysis in primary TKA who have a history of intraarticualr injection

The most appropriate protocol for the biopsy of musculoskeletal tumours is controversial, with some authors advocating CT-guided core biopsy. At our hospital the initial biopsies of most musculoskeletal tumours has been by operative core biopsy with evaluation by frozen section which determines whether diagnostic tissue has been obtained and, if possible, gives the definitive diagnosis. In order to determine the accuracy and cost-effectiveness of this protocol we have undertaken a retrospective audit of biopsies of musculoskeletal tumours performed over a period of two years. A total of 104 patients had biopsies according to this regime. All gave the diagnosis apart from one minor error which did not alter the management of the patient. There was no requirement for re-biopsy. This protocol was more labour-intensive and 38% more costly than CT-guided core biopsy (AU$1804 vs AU$1308). However, the accuracy and avoidance of the anxiety associated with repeat biopsy outweighed these disadvantages

Introduction. Infection after total joint arthroplasty is a challenging problem. Clinical symptoms, Erythrocyte sedimentation rate, C-reactive protein level, and cultures of synovial fluid obtained by means of percutaneous aspiration are commonly used to rule out the possibility of persistent infection before reimplantation. However, the sensitivity and specificity of the tests are low. Some authors have suggested that frozen-section analysis should always be performed during the reimplantation in order to rule out persistent infection. Methods. Retrospective review of 126 revision hip and knee arthroplasty procedure performed from 2002 - 2007 in Derriford Hospital, Plymouth NHS truts, UK. Frozen section was performed in 86 procedures out of the 126 procedures reviewed(68.2 %). A positive frozen section with more than 10 PNLs per HPF was compared with intra operative cultures results. The preoperative CRP results were recorded as well. Results. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for frozen section were 45.5 %, 93.1%,50%, 95%, 94% respectively. Combining the intraoperative frozen section with the CRP results, the specificity was 100%. Discussion. A negative finding on intra operative analysis of frozen sections has a high predictive value with regard to ruling out the presence of infection; However, the sensitivity of the test for the detection of persistent infection is low. The data support the conclusion that the Frozen Section is reasonably specific but not a sensitive. Combining it with the preoperative CRP results led to increasing the specificity to 100% in our series

The purpose of this study was to evaluate the accuracy of the sonication fluid cultures (SFC) for the diagnosis of prosthetic joint infection and compare it with frozen section and periprosthetic tissue cultures. 108 patients underwent revision or explantation procedure for any reason. Frozen sections of intraoperative specimen were analized and multiple periprosthetic samples (at least 5) were collected and cultured. All explanted prosthesis components were subject to sonication and cultured. All cultures were incubated for 14 days. PJI was diagnosed in 52 patients (48%). Sonication achieved the highest sensivity with 95% and specificity of 98%. Frozen section showed low sensivity (44%) and specificity (80%) and periprosthetic tissue cultures showed sensivity of 75% and specificity of 98%. Sonication fluid culture is a cheap, easy, accurate and sensitive diagnostic method and helps to detect about 30% more PJI compared to frozen section and 16% more compared to periprosthetic tissue cultures. It also detect about 25% more pathogens than periprosthetic tissue cultures

Infection in arthroplasty surgery is a major complication leading long antibiotic courses and frequently requiring repeated operations to eradicate or suppress. Therefore in the situation of revision surgery on prosthesis that are possibly already infected a clear identification of possible infection is required. Previously frozen section samples have been used in Derriford Hospital in conjunction with clinical presentation and other investigations to aid in diagnosis and tailor management, however recent studies have suggested that this may not be as effective as previously thought. Kanner et al. (2008) suggested a sensitivity of 29% and positive predictive value of 40%. This retrospective audit reviewed the cases between March 2007 and May 2012, identifying 220 cases of revision surgery where infection was suspected and frozen sections analysis was performed. Results where then compared to paraffin and cultured samples if taken. A notes review was performed to demonstrate if the operative technique (single or two stage) was in line with local guidelines for the results of the frozen section. Long term survival (longest follow up of 7 years) was assessed by need for revision surgery

Leukocyte esterase (LE) has shown to be an accurate marker of prosthetic joint infections and has been proposed as an alternative to frozen section (FS) for intra-operative diagnosis. In this study, intra-operative determination of LE was compared with FS for the diagnosis of periprosthetic hip infections. One hundred and nineteen patients undergoing hip revision surgery due to prosthetic joint failure from June 2015 to December 2017 were considered. Joint fluids were collected before the arthrotomy for determination of LE which was performed by using enzymatic colorimetric strips. Four to six samples were stained with hematoxylin eosin for FS and considered suggestive for infection when at least 5 polymorphonuclear leukocytes in 5 fields at high power fields were found. Sensitivity and specificity of LE were 100% and 93.8 %, respectively. The positive predictive value was 79.3 %, while the negative predictive value was 100%. Time from collection to response was 20.1 ± 4.4 minutes. Sensitivity and specificity of FS were 83.3 % and 92.1 %, respectively. The positive and negative predictive values were 84.6 % and 97.1%. Time from sample collection response was 27.2 ± 6.9 minutes. LE showed a higher sensitivity and a slightly lower specificity and the same diagnostic accuracy of intraoperative FS. The faster turnaround time (about 20 minutes from receiving of sample by the laboratory), its ease of use and the low costs make this test a valuable alternative to frozen sections and is going to replace FS in our clinical practice

We assessed the efficacy of intraoperative frozen-section histology in detecting infection in failed arthroplasties in 106 hips and knees. We found inflammatory changes consistent with infection (an average of one or more neutrophil polymorphs or plasma cells per high-power field in several samples) in 18 cases; there was a significant growth on bacterial culture in 20 cases. Compared with the bacterial cultures, the frozen sections provided two false-negative results and three false-positive results (sensitivity, 90%; specificity, 96%; and accuracy, 95%). The positive predictive value was 88%, the negative value, 98%. These results support the inclusion of intra-operative frozen-section histology in any protocol for revision arthroplasty for loose components

Introduction: The most appropriate protocol for biopsying musculoskeletal tumours is controversial. Some authors advocate the use of CT-guided core biopsy. At the Royal Prince Alfred Hospital, Sydney, Australia, initial biopsies of most musculoskeletal tumours involve a surgeon-led operative core biopsy technique with frozen section evaluation. The latter is used to determine whether diagnostic tissue has been obtained and, if possible, to establish a definitive diagnosis. Aims: To determine the accuracy and cost effectiveness of a surgeon-led biopsy protocol for biopsying musculoskeletal tumours. Methods: A retrospective audit of biopsies of musculoskeletal tumours performed in the bone and soft tissue sarcoma unit at the Royal Prince Alfred Hospital over a two year period was performed. Results: One hundred and four patients had biopsies performed under the protocol. There were no non-diagnostic biopsies and one minor error resulting in no change in the patient’s management. There was no requirement to re-biopsy any of the patients. A surgeon-led operative core biopsy with frozen section evaluation was 38% more costly than a CT-guided core biopsy (AU$1804 versus AU$1308). Conclusions: Surgeon-led biopsy with intra-operative frozen section evaluation is effective and accurate and, despite being labour intensive, the reduction in the need for repeat biopsies justifies its use. Whilst the technique is approximately 38% more costly, there is no requirement for re-biopsy and anxiety associated with the need for this is allayed

Purpose: Intraoperative frozen section analysis in which the number of cells per high powered field (CPHF) are used to predict the presence or absence of infection has been found to be a very useful test in the setting of revision total joint arthroplasty. The purpose of this retrospective review was to determine the usefulness of this same test at the time of implantation of a total hip arthroplasty (THA) following the failure of hip fracture fixation. Method: A retrospective review from 1999 – 2007 of twenty-two consecutive patients who had THA performed as a result of failed hip fracture fixation. The mean age of patients was seventy-two years. The number of CPHF was correlated with the results of intraoperative cultures, and other pre-operative and post-operative parameters. The mean duration of follow-up was 14 months. Results: Two patients had a culture-proven infection (Staphylococcus aureus in one patient, and staphylococcus epidermidis and propionibacterium acnes in the other.) Both of these patients had a positive test for infection based on the frozen section having greater than ten CPHF by the pathologist. (100% agreement) Four out of the six specimens that were graded as 10 CPHF by the pathologist had negative intra-operative cultures (33% agreement). With the CPHF limit set at 10 CPHF, the sensitivity of frozen section analysis in this clinical setting was 100%, while the specificity was 19%. The positive predictive value was calculated to be 33%, and the negative predictive value was 100%. With the cutoff of 5 CPHF or greater, the sensitivity of 100% and a specificity of 52% as well as a positive predictive value of 17% and a negative predictive value of 100%. Conclusion: Although the results are preliminary, and further study is warranted, it seems that CPHF is a useful test to rule out the presence of infection when revising failed fracture fixation to Total Hip Replacement

Aims. We aimed to report the mid- to long-term rates of septic and aseptic failure after two-stage revision surgery for periprosthetic joint infection (PJI) following total hip arthroplasty (THA). Methods. We retrospectively reviewed 96 cases which met the Musculoskeletal Infection Society criteria for PJI. The mean follow-up was 90 months (SD 32). Septic failure was assessed using a Delphi-based consensus definition. Any further surgery undertaken for aseptic mechanical causes was considered as aseptic failure. The cumulative incidence with competing risk analysis was used to predict the risk of septic failure. A regression model was used to evaluate factors associated with septic failure. The cumulative incidence of aseptic failure was also analyzed. Results. There were 23 septic failures at final follow-up, with a cumulative incidence of 14% (95% confidence interval (CI) 8% to 22%) at one year, 18% (95% CI 11% to 27%) at two years, 22% (95% CI 14% to 31%) at five years, and 23% (95% CI 15% to 33%) at ten years. Having at least one positive culture (hazard ratio (HR) 2.38 (interquartile range (IQR) 1.19 to 4.74); p = 0.013), or a positive intraoperative frozen section (HR 2.55 (IQR 1.06 to 6.15); p = 0.037) was significantly associated with septic failure after reimplantation. With dislocation being the most common cause of aseptic revision (5.2%), the cumulative incidence of aseptic failure was 1% (95% CI 0% to 5%) at one year, 6% (95% CI 1% to 8%) at five years, and 8% (95%CI 3% to 17%) at ten years. Conclusion. If there is no recurrent infection in the five years following reimplantation, the chances of further infection thereafter are remote. While the results of a frozen section may be a reliable guide to the timing of reimplantation, intraoperative culture has, currently, only prognostic value. Surgeons should be aware that instability remains a potential indication for further revision surgery. Cite this article: Bone Joint J 2021;103-B(1):79–86

Aims. Histology is widely used for diagnosis of persistent infection during reimplantation in two-stage revision hip and knee arthroplasty, although data on its utility remain scarce. Therefore, this study aims to assess the predictive value of permanent sections at reimplantation in relation to reinfection risk, and to compare results of permanent and frozen sections. Methods. We retrospectively collected data from 226 patients (90 hips, 136 knees) with periprosthetic joint infection who underwent two-stage revision between August 2011 and September 2021, with a minimum follow-up of one year. Histology was assessed via the SLIM classification. First, we analyzed whether patients with positive permanent sections at reimplantation had higher reinfection rates than patients with negative histology. Further, we compared permanent and frozen section results, and assessed the influence of anatomical regions (knee versus hip), low- versus high-grade infections, as well as first revision versus multiple prior revisions on the histological result at reimplantation. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), chi-squared tests, and Kaplan-Meier estimates were calculated. Results. Overall, the reinfection rate was 18%. A total of 14 out of 82 patients (17%) with positive permanent sections at reimplantation experienced reinfection, compared to 26 of 144 patients (18%) with negative results (p = 0.996). Neither permanent sections nor fresh frozen sections were significantly associated with reinfection, with a sensitivity of 0.35, specificity of 0.63, PPV of 0.17, NPV of 0.81, and accuracy of 58%. Histology was not significantly associated with reinfection or survival time for any of the analyzed sub-groups. Permanent and frozen section results were in agreement for 91% of cases. Conclusion. Permanent and fresh frozen sections at reimplantation in two-stage revision do not serve as a reliable predictor for reinfection. Cite this article: Bone Joint J 2024;106-B(4):372–379

The December 2024 Oncology Roundup. 360. looks at: Non-reversed great saphenous vein grafts for vascular reconstruction after resection of lower limb sarcoma; Detrimental effects of COVID-19 pandemic on patients with limb bone sarcoma: reference centre experience; Whole-body staging guidelines in sarcoma; Intraoperative marrow margin frozen section in limb bone sarcoma resection; Vacuum-assisted closure and paediatric oncological limb salvage; Treatment differences and long-term outcomes in adults and children with Ewing’s sarcoma; Survival, complications, and functional outcomes of uncemented distal femoral endoprosthesis with short, curved stem for patients with bone tumours

The December 2024 Spine Roundup. 360. looks at: Rostral facet joint violations in robotic- and navigation-assisted pedicle screw placement; The inhibitory effect of non-steroidal anti-inflammatory drugs and opioids on spinal fusion: an animal model;L5-S1 transforaminal lumbar interbody fusion is associated with increased revisions compared to L4-L5 TLIF at two years; Immediate versus gradual brace weaning protocols in adolescent idiopathic scoliosis: a randomized clinical trial; Effectiveness and cost-effectiveness of an individualized, progressive walking, and education intervention for the prevention of low back pain recurrence in Australia (WalkBack): a randomized controlled trial; Usefulness and limitations of intraoperative pathological diagnosis using frozen sections for spinal cord tumours; Effect of preoperative HbA1c and blood glucose level on the surgical site infection after lumbar instrumentation surgery; How good are surgeons at achieving their alignment goals?

Aim. Diagnosing low-grade periprosthetic joint infections (PJI) can be very challenging due to low-virulent microorganisms capable of forming biofilm. Clinical signs can be subtle and may be similar to those of aseptic failure. To minimize morbidity and mortality and to preserve quality of life, accurate diagnosis is essential. The aim of this study was to assess the performance of various diagnostic tests in diagnosing low-grade PJI. Methods. Patients undergoing revision surgery after total hip and knee arthroplasty were included in this retrospective cohort study. A standardized diagnostic workup was performed using the components of the 2021 European Bone and Joint Infection Society (EBJIS) definition of PJI. For statistical analyses, the respective test was excluded from the infection definition to eliminate incorporation bias. Receiver-operating-characteristic curves were used to calculate the diagnostic performance of each test, and their area-under-the-curves (AUC) were compared using the z-test. Results. 422 patients undergoing revision surgery after total hip and knee arthroplasty were included in this study. 208 cases (49.3%) were diagnosed as septic. Of those, 60 infections (28.8%) were defined as low-grade PJI (symptoms >4 weeks and caused by low-virulent microorganisms (e. g. coagulase-negative staphylococci, Cutibacterium spp., enterococci and Actinomyces)). Performances of the different test methods are listed in Table 1. Synovial fluid (SF) - WBC (white blood cell count) >3000G/L (0.902), SF - %PMN (percentage of polymorphonuclear neutrophils) > 65% (0.959), histology (0.948), and frozen section (0.925) showed the best AUCs. Conclusion. The confirmatory criteria according to the EBJIS definition showed almost ideal performances in ruling-in PJI (>99% specificity). Histology and synovial fluid cell count (SF-WBC and SF-%PMN) showed excellent accuracies for diagnosing low-grade PJI. However, a reduced immune reaction in these cases may necessitate lower cut-off values. Intraoperative frozen section may be valuable in cases with inconclusive preoperative diagnosis. For any tables or figures, please contact the authors directly

Introduction. In revision surgery, detection of periprosthetic joint infection is of prime importance. Valuable preoperative and intraoperative diagnostic tests and tools are necessary. The classical standard procedures are puncture and bacteriology examination, frozen section intraoperative and powerfield micro analysis. Since autumn 2014 a new device for detection of periprosthetic joint infection is available, named Synovasure. It is a fast test for the detection of Alpha defensing, which plays a major role in the antimicrobial defence and only occurs in inflammatory processes. „The alpha-defensin test is an immunoassay that measures the concentration of the alpha-defensin peptide in human synovialfluid. A-Defensin is an antimicrobial peptide that is secreted into the synovial fluid by human cells in response to pathogenic presence” (Deirmengian C et al., CORR 2014). Summarized, the evidence of Alpha defensin indicates infection. It is produced by CD Diagnostics (Wynnewood, PA, USA) and merchandised by Zimmer (Warsaw, IL, USA). We are using Synovasure in daily routine at our department since September 2014. The aim of this conducted study is to present our first clinical experience and to report our results of the first 54 cases. Material and Methods. At our department Synovasure is standardly used in hip and knee revision surgery. Additionally an intraoperative frozen section and a standard bacteriology were performed. The explanted endprosthesis were sent to examination by sonification in order to gain culture of the sonification fluid and were further examined by Multiplex PCR. A pathologist with more than 15 years of experience conducted the frozen section. The results of Synovasure were matched with all above examinations in order to describe specifity and sensitivity of it. Results. A negative Synovasure Test during surgery and a negative PCR were observed in 3 patients, however, the bacterial culture was positive (after 14 days of breeding) as well as the Multiplex PCR. One patient had a negative frozen section and a negative culture but a positive PCR. Another patient with a high CRP level, all clinical signs of infection and a positive Synovasure Test, had 6 negative cultures. This patient suffered from a Metallosis as well, due to a broken PE inlay of the TKA, which supports the previously stated that Metallosis may interfere this new tool. Unfortunately in this patient neither a frozen section nor a PCR are available. One patient, who had explanation due to infection, underwent reimplantation. During surgery the Synovasure Test and the frozen section were negative (Synovial Fluid), but postoperatively a positive culture and a positive histological report for infection were assessed. Furthermore, a total of 5 tests showed an application error and the test did not show any control line. Conclusion. In conclusion Synovasure helps to detect perprosthetic joint infection in an easy and fast manner. It is simple to integrate into daily routine, nevertheless all standardized examinations for infection need to be conducted

Introduction. The intra-operative diagnosis of Prosthetic Joint Infection (PJI) is a dilemma requiring intra-operative sampling of suspicious tissues for frozen section, deep tissue culture and histopathology to secure a diagnosis. Alfa defensin-1 testing has been introduced as a quick and reliable test for confirming or ruling out PJI. This study aims to assess its intra-operative reliability compared to the standard tests. Methods. Twenty patients who underwent revision hip and knee arthroplasty surgery were included. Patients joint aspirate was tested intra-operatively with the Synovasure kit, which takes approximately ten minutes for a result. Our standard protocol of collecting 5 deep tissue samples for culture and one sample for histopathology was followed. Results for Alfa defensin-1 test were then compared with final culture and histopathology results in all these patients. Results. Our results show an excellent correlation with the final deep tissue cultures and histopathology outcomes. Literature reports frozen section to have low (58–73%) sensitivity but high (96%) specificity. Conclusions. Alfa defensin-1 test is easy, quick and efficient; results were available immediately intra-operatively. Cryosection is time consuming with samples shipped to the reference laboratory at times resulting in intra-operative delays. In our practice Alfa defensin-1 test certainly will replace frozen section for intra-operative testing