Periprosthetic joint infection (PJI) is a devastating complication in revision total hip arthroplasty (THA). As preoperative diagnosis can be difficult, some patients who undergo planned aseptic revision surgery might have positive intraoperative cultures and later be classified as infected. In this retrospective study we analyzed the influence of intraoperative positive cultures and possible underlying risk factors in patients undergoing planned aseptic THA revision. We retrospectively analyzed 276 cases of aseptic THA revision surgery between 2010 and 2017 who had a minimum follow-up period of 24 months. All patients underwent preoperative serum and synovial diagnostics according to the Center of Disease Control (CDC) (2010) or Musculoskeletal Infection Society (MSIS) Criteria (2011–2017) for PJI and were classified as aseptic prior to surgery. In all cases intraoperative tissue samples were taken and reviewed. Primary endpoint was defined as any complication leading to revision surgery. Secondary endpoint was explantation due to PJI or death. Revision free survival (RFS) and infection free survival (IFS) for intraoperative negative and positive cultures was calculated via Kaplan Meyer Method. Patients’ medical history was analyzed for possible risk factors for positive cultures.Aim
Method
Periprosthetic fungal infections are rare and account for 1–2% of all periprosthetic joint infections (PJI). This study aims at presenting treatment details, clinical and microbiological results in a large single centre cohort. We retrospectively identified 29 patients (9 total knee replacements (TKA) and 20 total hip replacements (THA) treated for a fungal infection between 2007 and 2019. Microbiological findings, patient demographics and complications were analysed. Statistical analysis was performed using descriptive statistics; non-parametric analysis were performed using the Mann-Whitney U-Test. Infection-free survival was determined using Kaplan-Meier analysis and differences in survival were analysed using the log-rank test. The p value was set at p<0.05 with 95% confidence intervals (95% CI) provided.Aims
Methods
We present the greatest study of patients with proximal fibula resection. Moreover we describe a new classification system for tumour resection of the proximal fibula independent of the tumour dignity. In 57 patients the functional and clinical outcome was evaluated. The follow up ranged between 6 months and 22.2 years (median 7.2 years). Indicationfor surgery was in 10 cases benign tumours and in 47 cases malignant tumours. In 32 patients a resection of the peroneal with resulting peroneal palsy was necessary.Aim
Method
Early and late infections are the most uneventfull complications after tumor resection and implantation of a maegaendoprosthesis. Therefore, silver-coating was introduced by our department years ago with successful reduction in infection rates. After promising results in animal and Phase exclusion of side effects in our Phase I trial, we would like to share our knowledge about latest research, especially the actual results of the Phase II study. We included the results off all implanted silver-coated Megaendoprosthesis since introduction in our department. Implantation had to be more than 12 months ago to guarantee a acceptable minimum follow up for calculation of the infection rate. Actually our infection rate lies at 3,1% (N=131) in the prevention group (no previous infection in medical history) and at 19% (N=36) in our “Highest-Risk” and previous infection group. Still no side-effects could be noticed. In one case we examined retrieved samples of three silver-coated Megaendoprosthesis. Macroscopically a leopard shaped figures could be noticed on the silver-coated surface in shiny and dark areas after being implanted in an infected region. Electron microscopy pictures show still intact surface and remaining silver with dark staining. Biofilm formation coulod not be noticed, though some few dead single bacteria could be found without any signs of proliferation or matrix production after adhesion. Signs of biofilm couldn’t be seen anywhere. Despite the discoloration silver is still intact in these areas without any loss of antibacterial properties. Blisterings or even flaking off the silver coating cannot be noticed. The thickness of the silver was not thinned in a significant way leading to a breakdown after a few years. Up to these days we have no experience in covering the whole prosthesis including the stem in human beings. Concerning osteointegration of silver-coated stems, our animal trial could not prove their effectiveness in comparison to titanium. Pull-out tests showed high significant discrepancies in osteointegration between titanium and silver coated stems in a dog model after a period of 12 months after implantation. Summarizing we recommend silver as a safe adjuvant therapy in patients undergoing endoprosthetic reconstruction after tumor resection. Intramedullary use of silver can be done only in experimental cases and needs further changes in the technical design of the coating.
Megaendoprotheses are widely used in the reconstruction of large bone defects in orthopaedic tumour surgery. The major complications (up to 36%) are periprosthetic infections. Persisting periprosthetic infections lead to secondary amputation up to 37% of the cases. One underestimated reason for persisting infections are subpopulations of S. aureus called “small colony variants” (SCVs). Aim of this study was to evaluate that silver ions might prevent or cure a periprosthetic infection caused by SCVs. For testing the antimicrobial activity of silver-coated titanium we used a technique introduced by Bechert et al. Therefore an adhesion and proliferation assay was performed with clinical isolates of S. aureus SCV (A22616/3). We tested the adhesion and proliferation properties of S aureus SCV on stainless steel (steel), Cobalt-Chrome-Molybdenum-alloy (CoCrMo), Titan-Aluminium-Vanadium-alloy (TiAlVa) and silver-coated Titan-Aluminium-Vanadium-alloy (scTiAlVa). Adhesion of S. aureus SCV is significantly reduced on scTiAlVa vs. steel (p>
0001). We could also demonstrate that the proliferation rate of scTiAlVa vs. all tested materials is significant (p>
0001) lower. We concluded that silver-coating has an effective antimicrobial activity against S. aureus SCVs. Thus silver-coated megaendoprostheses are a good prophylaxis against persisting infections caused by S. aureus SCVs.
Chondrosarcoma are rare malignant tumors. About the biological characteristics of chondrosarcoma is little-known [ 32 cases were investigated clinically and histopathologically. The expression of vascular endothelial growth factor (VEGF), Endothelin-1, Endothelin-Receptor-A (ETR-A) and Endothelin-Receptor-B (ETR-B) were determined. All data were analyzed by Fisher’s exact test (p<
0,05). All tumors show an expression of either ET-1, ETR-A or ETR-B. Chondrosarcomas with grade (G) I are mostly expressing less than 10-% ET-1 in cells, Chondrosarcomas G II are expressing in most cases between 10–50% and nearly all Chondrosarcoms G III more than 50%. In addition ET-1-expression is correlating with the histological grading. The patients also show a significant high metastatic dissemination probability at the time when tumor samples present more than 10%-storing ET-1-cells. The intensity of ET-1-expression is correlating with VEGF, which is the most important angiogenetic factor in tumors. Chondrosarcomas are expressing ET-1, ETR-A and ETR-B. ET-1 seems to play a role in the angiogenesis of chondrosarcoma. Increased expression of ET-1 is accompanied with a high probability of metastatic dissemination. Endothelin receptor antagonists, which are used for example in prostate and breast cancer, can represent a potential therapy for chondrosarcoma [
Latest research concentrated on the coating of the stems, since they can still be the source of the infection if everything else is coated by silver already. Summarised so far, our experience in a rabbit model, a phase I Trial in humans and prelimnary results in Phase II Trials in humans showed no toxic side effects. Driven so far it seems to be sensible to extent the silver coating. So far, the coating is limited to all areas without joint movement or bone contact. An Animal trial was performed anylising the osteointegrative properties of an silver-coated stem versus an regular Titanium stem in 17 dogs. After 12 months of regular X-Ray Analysis a Pull-out test and a concentration analysis has been done. Results showed high significantly (p<
0.001) an osteointegration in 8 out of 8 titanium stems with an average pull-out force of 3764 Newton (Range 1755– 5967 Newton). Silver-coated stems showed no signs of Osteointegration in all 9 out of 9 femurs. The average pull-out force was 21 Newton (Range 0– 186 Newton). A cemented control could resist a pull out force of 350 Newton. Analysis of the silver concentration directly in the first millimeter of the bone-implant interface and the second millimeter showed highly elevated silver levels. The silver concentration in the bone-implant interface at Titanium stems ranged from 0.3 to 3502 parts per Billion (ng/g) compared to silver-coated stems ranging from 303 to 2.418.800 ppb parts per Billion (ng/g).
In summary, surgeons have to decide in the future how much silver they need in each individual case concerning intramedullary infection prophylaxis. The balance between loosening or infection should be based on long term expectations, taking into account that even after successful resection of a tumor an ongoning infection can lead to loosening of a limb or even life. Apart from intramedullary use, we recommend silver as a safe adjuvant therapy in all suited patients undergoing endoprosthetic reconstruction after tumor resection.
