[Revision arthroplasty : Histopathological diagnostics in periprosthetic joint infections]. / Revisionsendoprothetik : Infektionsdiagnostik und Histopathologie.

BACKGROUND: Histopathological differences in synovia and synovial-like interface membrane (SLIM) patterns can be used to differentiate periprosthetic particle-induced reactions, bacterial infections (bacterial synovitis and osteomyelitis), mechanical-induced tissue alterations, adverse reactions to implant material, and arthrofibrosis (SLIM consensus classification). AIM: Because of differences in treatment the diagnosis of a bacterial implant infection is very important. Histopathological tests and scoring systems are important diagnostic tools in identifying deep implant infections in patients with unclear clinical history as well as radiographic and laboratory studies. RESULTS: Modern enzyme PCR-based methods, histochemical- and immune-histopathological techniques (CD3,CD15, CD68) are useful in identifying specific and nonspecific infections, as well as differentiating postsurgical changes from recurrent infections in patients with a spacer. In all histopathological scoring systems for bacterial infection, quantifying the number of neutrophil granulocytes in a defined number of high power fields is crucial. DISCUSSION: Neutrophil granulocytes can be detected through histochemical methods and more specifically by immune-histopathological techniques and by various quantification systems (histopathological scores) leading to the diagnosis of bacterial peri-implant infection. One important function of histopathology, apart from diagnosing infection, is to rule out other mechanisms of implant failure, such as tumor infiltrations, particle-induced reactions, and adverse reactions to implant materials.

[CD15 focus score for diagnostics of periprosthetic joint infections : Neutrophilic granulocytes quantification mode and the development of morphometric software (CD15 quantifier)]. / CD15-Fokus-Score zur Diagnostik der periprothetischen Gelenkinfektion : Neutrophile-Granulozyten-Quantifizierungs-Modus und Entwicklung einer morphometrischen Software ("CD15-Quantifier").

BACKGROUND: The aim of this project was to devise a quantification method for neutrophils within a single focal point through the development of a CD15 focus score which enables bacterial infections in synovial-like interface membranes (SLIM) to be diagnosed. METHODS: In this study a histopathological classification of 91 SLIM removed during revision surgery from the hips (n = 59) and knees (n = 32) was performed. Neutrophils were identified immunohistochemically by means of a CD15-specific monoclonal antibody. The quantitative evaluation of CD15-positive neutrophils (CD15Ne) used the principle of maximum focal infiltration (focus) together with an assessment of a single focal point (0.3 mm(2)). This immunohistochemical approach made it possible to develop the CD15 quantifier software, which automatically quantifies CD15Ne. RESULTS: The SLIM cases with positive microbiological findings (n = 47) had significantly (p < 0.001, Mann-Whitney U-test) more CD15Ne/focal point than cases with negative microbiological findings (n = 44). A count of 50 CD15Ne/focal point was identified as the optimum threshold when diagnosing periprosthetic joint infections (PJI) using the CD15 focus score. If the microbiological findings are used as a gold standard, the diagnostic sensitivity is 0.83, and the specificity is 0.864 with a positive predictive value (PPV) of 0.87, a negative predictive value (NPV) of 0.83, an accuracy of 0.846 and an area under the curve (AUC) of 0.878. The evaluation of findings for the preparations using the CD15 quantifier software (n = 31) deviated by an average of 12 cells from the histopathological evaluation findings (CD15 focus score). Above a cell count of 62, the CD15-quantifier needs on average 32 s less than the pathologist. CONCLUSION: The immunohistochemical CD15 focus score has a high diagnostic value and allowed the development of the CD15 quantifier software. This provides an automated procedure, which shortens the mentally tiring and time-consuming process of microscopic cell counting and thus makes a contribution towards the standardization of tools for diagnosing PJI.

Training in vascular trauma surgery for non-vascular surgeons: Vascular trauma surgery skills course.

Background: The experience of general and trauma surgeons in vascular trauma management has decreased with sub-specialization of surgery and working hours restrictions. We introduce a vascular trauma surgery skills course established to train German military surgeons prior to their deployment to conflict areas. Methods: The intention and implementation of the vascular trauma course for non-vascular surgeons is described in detail. Results: In hands-on courses, participants learn and train basic vascular surgical techniques on more realistic extremity, neck, and abdominal models with pulsatile vessels. A fundamental and an advanced course each provide military as well as civilian surgeons from different non-vascular specialties with a surgical skill set including direct vessel sutures, patch angioplasty, anastomosis, thrombectomy, and resuscitative endovascular balloon occlusion of the aorta (REBOA) in order to render them capable of managing major vascular injuries. Conclusion: The experiences of this vascular trauma surgical skills course, initially established for military surgeons, can also be of use to all civilian general, visceral, and trauma surgeons occasionally facing traumatic or iatrogenic vascular injuries. Thus, the introduced vascular trauma course is valuable for all surgeons working in trauma centers.

CD15 focus score: Infection diagnosis and stratification into low-virulence and high-virulence microbial pathogens in periprosthetic joint infection.

INTRODUCTION: The aim of the work was to validate the CD15 focus score for the infection pathology of periprosthetic joint infection in a large group and to clarify whether a stratification into low-virulence and high-virulence microbial pathogens is possible by means of the CD15 focus score (quantification of CD15 positive granulocytes). METHODS: The histopathology of 275 synovial tissue samples taken intraoperatively during revision operations (n=127 hip, n=141 knee, n=2 shoulder, n=5 ankle) was evaluated according to the SLIM consensus classification (SLIM=synovial-like interface membrane). Neutrophilic granulocytes (NG) were quantified by the CD15 focus score on the basis of the principle of focal maximum infiltration (focus) with evaluation of one field of vision (about 0.3mm2). The quantification values were compared with the microbiological diagnoses taking into consideration the virulence groups of low-virulence and high-virulence microbial pathogens and mixed infection. RESULTS: The patients with positive microbiological findings (n=160) had significantly (p<0.001, Mann-Whitney U test) higher CD15 focus score values than patients with negative microbiological findings (n=115), the cut-off value being 39 cells per high power field (HPF). The CD15 focus score values of low-virulence microbial pathogens (n=94) were significantly lower (p<0.001, Mann-Whitney U test) than the values of high-virulence microbial pathogens (n=55), the cut-off value being 106 cells per HPF. Based on the microbiological diagnosis the sensitivity with respect to a microbial infection is 0.91, the specificity 0.92 (PPV=0.94; NPV=0.88; accuracy: 0.92; AUC=0.95). Based on the differentiation of the CD15 focus score values between low-virulence and high-virulence microbes the sensitivity is 0.70 and the specificity 0.77 (PPV=0.63; NPV=0.81; accuracy=0.74; AUC=0.74). CONCLUSION: As a result of the high sensitivity and specificity, the easy to use CD15 focus score is a diagnostically valid score for microbial periprosthetic infection. A differentiation between low-virulence and high-virulence microorganism of sufficiently high diagnostic quality is additionally possible as a result of the defined quantification of CD15 positive granulocytes (the CD15 focus score) histopathological diagnosis of microbial infections is possible, which on the one hand supports the microbiological diagnosis and on the other hand by the stratification into low-virulence and high-virulence microbial pathogens could represent an additional basis for a pathogen-specific antibiotic treatment in the event of unclear constellations of findings.

Revised histopathological consensus classification of joint implant related pathology.

This extended classification of joint implant related pathology is a practical histopathologic classification based on defined morphological criteria covering the complete spectrum of pathohistologic changes in periprosthetic tissues. These changes may occur as a consequence of endoprosthetic replacement of large joints and may lead to a reduction in the prosthesis survival rate. We describe the established consensus classification of the periprosthetic membrane, in which aseptic and septic prosthetic loosening can be subdivided into four histological types, as well as histopathological criteria for additional significant pathologies including endoprosthetic-associated arthrofibrosis, particle-induced immunological, inflammatory and toxic mechanisms (adverse reactions), and bone tissue pathologies. These characteristic tissue alterations and their relationships are summarized in the extended classification. Since particle heterogeneity in periprosthetic tissue is high and particle identification is a necessary part of diagnosis, the identification of different types of particles is described in the histopathological particle algorithm. The morphological qualities of prosthetic material particles and the demarcation between abrasion and non-abrasion endogenous particles are also summarized. This feasible classification which is based on low cost standard tissue processing and examination and on well-defined diagnostic criteria is a solid platform for the histological diagnosis of implant associated pathologies providing a stable and reproducible tool for the surgical pathologist. Since this classification is suitable for standardized histopathological diagnostics, it might also provide a useful data set for joint arthroplasty registers, particularly for registers based on so-called routine data.