@article{MunawarZhouPrommersbergeretal.2023, author = {Munawar, Umair and Zhou, Xiang and Prommersberger, Sabrina and Nerreter, Silvia and Vogt, Cornelia and Steinhardt, Maximilian J. and Truger, Marietta and Mersi, Julia and Teufel, Eva and Han, Seungbin and Haertle, Larissa and Banholzer, Nicole and Eiring, Patrick and Danhof, Sophia and Navarro-Aguadero, Miguel Angel and Fernandez-Martin, Adrian and Ortiz-Ruiz, Alejandra and Barrio, Santiago and Gallardo, Miguel and Valeri, Antonio and Castellano, Eva and Raab, Peter and Rudert, Maximilian and Haferlach, Claudia and Sauer, Markus and Hudecek, Michael and Martinez-Lopez, J. and Waldschmidt, Johannes and Einsele, Hermann and Rasche, Leo and Kort{\"u}m, K. Martin}, title = {Impaired FADD/BID signaling mediates cross-resistance to immunotherapy in Multiple Myeloma}, series = {Communications Biology}, volume = {6}, journal = {Communications Biology}, doi = {10.1038/s42003-023-05683-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357609}, year = {2023}, abstract = {The treatment landscape in multiple myeloma (MM) is shifting from genotoxic drugs to immunotherapies. Monoclonal antibodies, immunoconjugates, T-cell engaging antibodies and CART cells have been incorporated into routine treatment algorithms, resulting in improved response rates. Nevertheless, patients continue to relapse and the underlying mechanisms of resistance remain poorly understood. While Impaired death receptor signaling has been reported to mediate resistance to CART in acute lymphoblastic leukemia, this mechanism yet remains to be elucidated in context of novel immunotherapies for MM. Here, we describe impaired death receptor signaling as a novel mechanism of resistance to T-cell mediated immunotherapies in MM. This resistance seems exclusive to novel immunotherapies while sensitivity to conventional anti-tumor therapies being preserved in vitro. As a proof of concept, we present a confirmatory clinical case indicating that the FADD/BID axis is required for meaningful responses to novel immunotherapies thus we report impaired death receptor signaling as a novel resistance mechanism to T-cell mediated immunotherapy in MM.}, language = {en} } @article{PereiraLipphausErginetal.2021, author = {Pereira, Ana Rita and Lipphaus, Andreas and Ergin, Mert and Salehi, Sahar and Gehweiler, Dominic and Rudert, Maximilian and Hansmann, Jan and Herrmann, Marietta}, title = {Modeling of the Human Bone Environment: Mechanical Stimuli Guide Mesenchymal Stem Cell-Extracellular Matrix Interactions}, series = {Materials}, volume = {14}, journal = {Materials}, number = {16}, issn = {1996-1944}, doi = {10.3390/ma14164431}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-245012}, year = {2021}, abstract = {In bone tissue engineering, the design of in vitro models able to recreate both the chemical composition, the structural architecture, and the overall mechanical environment of the native tissue is still often neglected. In this study, we apply a bioreactor system where human bone-marrow hMSCs are seeded in human femoral head-derived decellularized bone scaffolds and subjected to dynamic culture, i.e., shear stress induced by continuous cell culture medium perfusion at 1.7 mL/min flow rate and compressive stress by 10\% uniaxial load at 1 Hz for 1 h per day. In silico modeling revealed that continuous medium flow generates a mean shear stress of 8.5 mPa sensed by hMSCs seeded on 3D bone scaffolds. Experimentally, both dynamic conditions improved cell repopulation within the scaffold and boosted ECM production compared with static controls. Early response of hMSCs to mechanical stimuli comprises evident cell shape changes and stronger integrin-mediated adhesion to the matrix. Stress-induced Col6 and SPP1 gene expression suggests an early hMSC commitment towards osteogenic lineage independent of Runx2 signaling. This study provides a foundation for exploring the early effects of external mechanical stimuli on hMSC behavior in a biologically meaningful in vitro environment, opening new opportunities to study bone development, remodeling, and pathologies.}, language = {en} } @article{RakNedopilSayreetal.2022, author = {Rak, Dominik and Nedopil, Alexander J. and Sayre, Eric C. and Masri, Bassam A. and Rudert, Maximilian}, title = {Postoperative inpatient rehabilitation does not increase knee function after primary total knee arthroplasty}, series = {Journal of Personalized Medicine}, volume = {12}, journal = {Journal of Personalized Medicine}, number = {11}, issn = {2075-4426}, doi = {10.3390/jpm12111934}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-297322}, year = {2022}, abstract = {Inpatient rehabilitation (IR) is a common postoperative protocol after total knee replacement (TKA). Because IR is expensive and should therefore be justified, this study determined the difference in knee function one year after TKA in patients treated with IR or outpatient rehabilitation, fast-track rehabilitation (FTR) in particular, which also entails a reduced hospital length of stay. A total of 205 patients were included in this multi-center prospective cohort study. Of the patients, 104 had primary TKA at a German university hospital and received IR, while 101 had primary TKA at a Canadian university hospital and received FTR. Patients receiving IR or FTR were matched by pre-operative demographics and knee function. Oxford Knee Score (OKS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), and EuroQol visual analogue scale (EQ-VAS) determined knee function one year after surgery. Patients receiving IR had a 2.8-point lower improvement in OKS (p = 0.001), a 6.7-point lower improvement in WOMAC (p = 0.063), and a 12.3-point higher improvement in EQ-VAS (p = 0.281) than patients receiving FTR. IR does not provide long-term benefits to patient recovery after primary uncomplicated TKA under the current rehabilitation regime.}, language = {en} } @article{SeilerEbertRudertetal.2022, author = {Seiler, Jonas and Ebert, Regina and Rudert, Maximilian and Herrmann, Marietta and Leich, Ellen and Weißenberger, Manuela and Horas, Konstantin}, title = {Bone metastases of diverse primary origin frequently express the VDR (vitamin D receptor) and CYP24A1}, series = {Journal of Clinical Medicine}, volume = {11}, journal = {Journal of Clinical Medicine}, number = {21}, issn = {2077-0383}, doi = {10.3390/jcm11216537}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-297377}, year = {2022}, abstract = {Active vitamin D (1,25(OH)2D3) is known to exert direct anti-cancer actions on various malignant tissues through binding to the vitamin D receptor (VDR). These effects have been demonstrated in breast, prostate, renal and thyroid cancers, which all have a high propensity to metastasise to bone. In addition, there is evidence that vitamin D catabolism via 24-hydroxylase (CYP24A1) is altered in tumour cells, thus, reducing local active vitamin D levels in cancer cells. The aim of this study was to assess VDR and CYP24A1 expression in various types of bone metastases by using immunohistochemistry. Overall, a high total VDR protein expression was detected in 59\% of cases (39/66). There was a non-significant trend of high-grade tumours towards the low nuclear VDR expression (p = 0.07). Notably, patients with further distant metastases had a reduced nuclear VDR expression (p = 0.03). Furthermore, a high CYP24A1 expression was detected in 59\% (39/66) of bone metastases. There was a significant positive correlation between nuclear VDR and CYP24A1 expression (p = 0.001). Collectively, the VDR and CYP24A1 were widely expressed in a multitude of bone metastases, pointing to a potential role of vitamin D signalling in cancer progression. This is of high clinical relevance, as vitamin D deficiency is frequent in patients with bone metastases.}, language = {en} } @article{KronerWeiglChuRudertetal.2023, author = {Kroner-Weigl, Niklas and Chu, Jin and Rudert, Maximilian and Alt, Volker and Shukunami, Chisa and Docheva, Denitsa}, title = {Dexamethasone is not sufficient to facilitate tenogenic differentiation of dermal fibroblasts in a 3D organoid model}, series = {Biomedicines}, volume = {11}, journal = {Biomedicines}, number = {3}, issn = {2227-9059}, doi = {10.3390/biomedicines11030772}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-311234}, year = {2023}, abstract = {Self-assembling three-dimensional organoids that do not rely on an exogenous scaffold but maintain their native cell-to-cell and cell-to-matrix interactions represent a promising model in the field of tendon tissue engineering. We have identified dermal fibroblasts (DFs) as a potential cell type for generating functional tendon-like tissue. The glucocorticoid dexamethasone (DEX) has been shown to regulate cell proliferation and facilitate differentiation towards other mesenchymal lineages. Therefore, we hypothesized that the administration of DEX could reduce excessive DF proliferation and thus, facilitate the tenogenic differentiation of DFs using a previously established 3D organoid model combined with dose-dependent application of DEX. Interestingly, the results demonstrated that DEX, in all tested concentrations, was not sufficient to notably induce the tenogenic differentiation of human DFs and DEX-treated organoids did not have clear advantages over untreated control organoids. Moreover, high concentrations of DEX exerted a negative impact on the organoid phenotype. Nevertheless, the expression profile of tendon-related genes of untreated and 10 nM DEX-treated DF organoids was largely comparable to organoids formed by tendon-derived cells, which is encouraging for further investigations on utilizing DFs for tendon tissue engineering.}, language = {en} } @article{HeinzEidmannJakuscheitetal.2023, author = {Heinz, Tizian and Eidmann, Annette and Jakuscheit, Axel and Laux, Tino and Rudert, Maximilian and Stratos, Ioannis}, title = {Demographics and trends for inbound medical tourism in Germany for orthopedic patients before and during the COVID-19 pandemic}, series = {International Journal of Environmental Research and Public Health}, volume = {20}, journal = {International Journal of Environmental Research and Public Health}, number = {2}, issn = {1660-4601}, doi = {10.3390/ijerph20021209}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304955}, year = {2023}, abstract = {Medical tourism is a rapidly growing sector of economic growth and diversification. However, data on the demographics and characteristics of the traveling patients are sparse. In this study, we analyzed the common demographic properties and characteristics of the inbound medical tourists seeking orthopedic medical care in Germany for the years 2010 to 2019 compared to a domestic group. At the same time, we examined how the COVID-19 pandemic outbreak of 2020 changed the field of medical tourism in Germany. Calculations were performed using administrative hospital data provided by the Federal Statistical Department of Germany. Data were analyzed from the years 2010 to 2020. A total of six elective orthopedic surgery codes (bone biopsy, knee arthroplasty, foot surgery, osteotomy, hardware removal, and arthrodesis) were identified as key service indicators for medical tourism and further analyzed. Factors including residence, sex, year, and type of elective surgery were modeled using linear regression analysis. Age and sex distributions were compared between patients living inside Germany (DE) or outside Germany (non-DE). Between 2010 and 2020, 6,261,801 orthopedic procedures were coded for the DE group and 27,420 key procedures were identified for the non-DE group. Medical tourists were predominantly male and significantly younger than the domestic population. The linear regression analysis of the OPS codes over the past years showed a significantly different slope between the DE and non-DE groups only for the OPS code "hardware removal". With the COVID-19 pandemic, an overall decline in performed orthopedic procedures was observed for the non-DE and the DE group. A significant reduction below the 95\% prediction bands for the year 2020 could be shown for hardware removal and foot surgery (for DE), and for hardware removal, knee arthroplasty, foot surgery, and osteotomy (for non-DE). This study is the first to quantify inbound medical tourism in elective orthopedic surgery in Germany. The COVID-19 pandemic negatively affected many — but not all — areas of orthopedic surgery. It has to be seen how this negative trend will develop in the future.}, language = {en} } @article{HeinzEidmannAndersonetal.2023, author = {Heinz, Tizian and Eidmann, Annette and Anderson, Philip and Weißenberger, Manuel and Jakuscheit, Axel and Rudert, Maximilian and Stratos, Ioannis}, title = {Trends in computer-assisted surgery for total knee arthroplasty in Germany: an analysis based on the operative procedure classification system between 2010 to 2021}, series = {Journal of Clinical Medicine}, volume = {12}, journal = {Journal of Clinical Medicine}, number = {2}, issn = {2077-0383}, doi = {10.3390/jcm12020549}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304879}, year = {2023}, abstract = {Alignment strategies for primary total knee arthroplasty (TKA) have changed significantly over time with a shift towards a more individualized alignment goal. At the same time, computer-assisted surgery (CAS) has gained interest for intraoperative control and accuracy in implant positioning and limb alignment. Despite the often discussed benefits and drawbacks of robotics and navigation for TKA, the routine use of these new devices on a day-to-day basis remains obscure. Therefore, nationwide hospital billing data based on the Operation Procedure Classification System (OPS) were retrieved from the Federal Statistical Office of Germany for the period from 2010 to 2021. OPS codes for primary total knee arthroplasty (OPS code: 5-822*) were further analyzed regarding the usage of computer navigation (additional OPS code: 5-988) or robotic devices (additional OPS code: 5-987). Gender and age at the time of surgery were also assessed. The results show a total of 2,226,559 primary TKAs were implanted between 2010 and 2021, of which 2,044,914 were performed conventionally (91.84\% of all TKAs). A total of 170,276 TKAs were performed using navigation technique (7.65\% of all TKAs) and another 11,369 TKAs were performed using robotics (0.51\% of all TKAs). For the period from 2018 to 2021, a substantial increase in robot-assisted TKA (R-TKA) was observed, with an average increase rate of 84.74\% per year, while the number of navigated TKAs declined (-3.67\% per year). Computer-assisted surgery, and particularly robotics for TKA, are seeing growing popularity and stepwise translation into routine clinical use in Germany, with a steep increase rate of more than 80\% per year since 2018. Nevertheless, the majority of TKAs are still performed using manual instrumentation, rendering conventional TKA the currently unchanged gold standard.}, language = {en} } @article{EidmannKamawalLuedemannetal.2023, author = {Eidmann, Annette and Kamawal, Yama and Luedemann, Martin and Raab, Peter and Rudert, Maximilian and Stratos, Ioannis}, title = {Demographics and etiology for lower extremity amputations — experiences of an university orthopaedic center in Germany}, series = {Medicina}, volume = {59}, journal = {Medicina}, number = {2}, issn = {1648-9144}, doi = {10.3390/medicina59020200}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304856}, year = {2023}, abstract = {Background and Objectives: Currently, the worldwide incidence of major amputations in the general population is decreasing whereas the incidence of minor amputations is increasing. The purpose of our study was to analyze whether this trend is reflected among orthopaedic patients treated with lower extremity amputation in our orthopaedic university institution. Materials and Methods: We conducted a single-center retrospective study and included patients referred to our orthopaedic department for lower extremity amputation (LEA) between January 2007 and December 2019. Acquired data were the year of amputation, age, sex, level of amputation and cause of amputation. T test and Chi² test were performed to compare age and amputation rates between males and females; significance was defined as p < 0.05. Linear regression and multivariate logistic regression models were used to test time trends and to calculate probabilities for LEA. Results: A total of 114 amputations of the lower extremity were performed, of which 60.5\% were major amputations. The number of major amputations increased over time with a rate of 0.6 amputation/year. Men were significantly more often affected by LEA than women. Age of LEA for men was significantly below the age of LEA for women (men: 54.8 ± 2.8 years, women: 64.9 ± 3.2 years, p = 0.021). Main causes leading to LEA were tumors (28.9\%) and implant-associated complications (25.4\%). Implant-associated complications and age raised the probability for major amputation, whereas malformation, angiopathies and infections were more likely to cause a minor amputation. Conclusions: Among patients in our orthopaedic institution, etiology of amputations of the lower extremity is multifactorial and differs from other surgical specialties. The number of major amputations has increased continuously over the past years. Age and sex, as well as diagnosis, influence the type and level of amputation.}, language = {en} } @article{vonHertzbergBoelchWagenbrennerArnholdtetal.2021, author = {von Hertzberg-Boelch, Sebastian Philipp and Wagenbrenner, Mike and Arnholdt, J{\"o}rg and Frenzel, Stephan and Holzapfel, Boris Michael and Rudert, Maximilian}, title = {Custom Made Monoflange Acetabular Components for the Treatment of Paprosky Type III Defects}, series = {Journal of Personalized Medicine}, volume = {11}, journal = {Journal of Personalized Medicine}, number = {4}, issn = {2075-4426}, doi = {10.3390/jpm11040283}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236513}, year = {2021}, abstract = {Purpose: Patient-specific, flanged acetabular components are used for the treatment of Paprosky type III defects during revision total hip arthroplasty (THA). This monocentric retrospective cohort study analyzes the outcome of patients treated with custom made monoflanged acetabular components (CMACs) with intra- and extramedullary iliac fixation. Methods: 14 patients were included who underwent revision THA with CMACs for the treatment of Paprosky type III defects. Mechanism of THA failure was infection in 4 and aseptic loosening in 10 patients. Seven patients underwent no previous revision, the other seven patients underwent three or more previous revisions. Results: At a mean follow-up of 35.4 months (14-94), the revision rate of the implant was 28.3\%. Additionally, one perioperative dislocation and one superficial wound infection occurred. At one year postoperatively, we found a significant improvement of the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score (p = 0.015). Postoperative radiographic analysis revealed good hip joint reconstruction with a mean leg length discrepancy of 3 mm (-8-20), a mean lateralization of the horizontal hip center of rotation of 8 mm (-8-35), and a mean proximalization of the vertical hip center of rotation of 6 mm (13-26). Radiolucency lines were present in 30\%. Conclusion: CMACs can be considered an option for the treatment of acetabular bone loss in revision THA. Iliac intra- and extramedullary fixation allows soft tissue-adjusted hip joint reconstruction and improves hip function. However, failure rates are high, with periprosthetic infection being the main threat to successful outcome.}, language = {en} } @article{WagenbrennerPokerHeinzetal.2022, author = {Wagenbrenner, Mike and Poker, Konrad and Heinz, Tizian and Herrmann, Marietta and Horas, Konstantin and Ebert, Regina and Mayer-Wagner, Susanne and Holzapfel, Boris M. and Rudert, Maximilian and Steinert, Andre F. and Weißenberger, Manuel}, title = {Mesenchymal stromal cells (MSCs) isolated from various tissues of the human arthritic knee joint possess similar multipotent differentiation potential}, series = {Applied Sciences}, volume = {12}, journal = {Applied Sciences}, number = {4}, issn = {2076-3417}, doi = {10.3390/app12042239}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262334}, year = {2022}, abstract = {(1) Background: The mesenchymal stromal cells (MSCs) of different tissue origins are applied in cell-based chondrogenic regeneration. However, there is a lack of comparability determining the most suitable cell source for the tissue engineering (TE) of cartilage. The purpose of this study was to compare the in vitro chondrogenic potential of MSC-like cells from different tissue sources (bone marrow, meniscus, anterior cruciate ligament, synovial membrane, and the infrapatellar fat pad removed during total knee arthroplasty (TKA)) and define which cell source is best suited for cartilage regeneration. (2) Methods: MSC-like cells were isolated from five donors and expanded using adherent monolayer cultures. Differentiation was induced by culture media containing specific growth factors. Transforming growth factor (TGF)-ß1 was used as the growth factor for chondrogenic differentiation. Osteogenesis and adipogenesis were induced in monolayer cultures for 27 days, while pellet cell cultures were used for chondrogenesis for 21 days. Control cultures were maintained under the same conditions. After, the differentiation period samples were analyzed, using histological and immunohistochemical staining, as well as molecularbiological analysis by RT-PCR, to assess the expression of specific marker genes. (3) Results: Plastic-adherent growth and in vitro trilineage differentiation capacity of all isolated cells were proven. Flow cytometry revealed the clear co-expression of surface markers CD44, CD73, CD90, and CD105 on all isolated cells. Adipogenesis was validated through the formation of lipid droplets, while osteogenesis was proven by the formation of calcium deposits within differentiated cell cultures. The formation of proteoglycans was observed during chondrogenesis in pellet cultures, with immunohistochemical staining revealing an increased relative gene expression of collagen type II. RT-PCR proved an elevated expression of specific marker genes after successful differentiation, with no significant differences regarding different cell source of native tissue. (4) Conclusions: Irrespective of the cell source of native tissue, all MSC-like cells showed multipotent differentiation potential in vitro. The multipotent differentiation capacity did not differ significantly, and chondrogenic differentiation was proven in all pellet cultures. Therefore, cell suitability for cell-based cartilage therapies and tissue engineering is given for various tissue origins that are routinely removed during total knee arthroplasty (TKA). This study might provide essential information for the clinical tool of cell harvesting, leading to more flexibility in cell availability.}, language = {en} } @article{StreckForstervonHertzbergBoelchetal.2022, author = {Streck, Laura Elisa and Forster, Johannes and von Hertzberg-Boelch, Sebastian Philipp and Reichel, Thomas and Rudert, Maximilian and Rueckl, Kilian}, title = {The role of synovial fluid aspiration in shoulder joint infections}, series = {BMC Musculoskeletal Disorders}, volume = {23}, journal = {BMC Musculoskeletal Disorders}, doi = {10.1186/s12891-022-05285-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300795}, year = {2022}, abstract = {Background Joint aspiration with analysis of synovial fluid white blood cell count (WBC) and microbiological culture is a widely established aspect in the diagnosis of shoulder joint infections (SJI). In case of a two stage revision for SJI, joint aspiration before re-/implantation of a total shoulder arthroplasty (TSA) was used to rule out persistent infection for years but its value is under debate. Shoulder specific data on all aspects is rare. The current study aims to answer the following research questions: Does joint aspiration have an insufficient predictive value in the diagnosis of SJI in (1) initial workup and (2) before definite arthroplasty with polymethylmethacrylate (PMMA)-Spacer in place? Methods This retrospective evaluation investigates 35 patients that were treated for SJI with a two staged implantation of a TSA after debridement and implantation of an PMMA-Spacer. Joint aspirations were performed preoperatively (PA) and before re-/implantation of the prosthesis while spacer was in place (interstage aspiration, IA). Samples were taken for microbiological culture and analysis of WBC. Sensitivity and specificity were calculated with reference to intraoperative microbiological samples. Receiver Operating Characteristic (ROC), Area-Under-Curve analysis (AUC) and calculation of the Youden index were performed to find optimum cut-off for WBC. Results The sensitivity of microbiological cultures from PA was 58.3\% and the specificity was 88.9\%. The mean WBC was 27,800 leucocytes/mm3 (range 400-96,300). The maximum Youden index (0.857) was a cut-off of 2600 leucocytes/mm3 with a sensitivity of 85.7\% and a specificity of 100.0\%. The sensitivity and specificity of IA were 0.0\% and 88.5\%, respectively. Conclusions Preoperative aspiration is likely to miss Cutibacteria spp. and CoNS and cannot rule out infection for sure. However, we recommend it for its advantages of targeted antibiotic therapy in case of germ identification. Empiric antibiotic therapy should cover Cutibacteria and CoNS even if aspiration showed negative microbiological cultures. In contrast, the diagnostic value of interstage aspiration does not qualify for its routine use.}, language = {en} } @article{WeissenbergerWeissenbergerWagenbrenneretal.2020, author = {Weissenberger, Manuel and Weissenberger, Manuela H. and Wagenbrenner, Mike and Heinz, Tizian and Reboredo, Jenny and Holzapfel, Boris M. and Rudert, Maximilian and Groll, J{\"u}rgen and Evans, Christopher H. and Steinert, Andre F.}, title = {Different types of cartilage neotissue fabricated from collagen hydrogels and mesenchymal stromal cells via SOX9, TGFB1 or BMP2 gene transfer}, series = {PLoS One}, volume = {15}, journal = {PLoS One}, number = {8}, doi = {10.1371/journal.pone.0237479}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230494}, year = {2020}, abstract = {Objective As native cartilage consists of different phenotypical zones, this study aims to fabricate different types of neocartilage constructs from collagen hydrogels and human mesenchymal stromal cells (MSCs) genetically modified to express different chondrogenic factors. Design Human MSCs derived from bone-marrow of osteoarthritis (OA) hips were genetically modified using adenoviral vectors encoding sex-determining region Y-type high-mobility-group-box (SOX)9,transforming growth factor beta (TGFB) 1or bone morphogenetic protein (BMP) 2cDNA, placed in type I collagen hydrogels and maintained in serum-free chondrogenic media for three weeks. Control constructs contained unmodified MSCs or MSCs expressing GFP. The respective constructs were analyzed histologically, immunohistochemically, biochemically, and by qRT-PCR for chondrogenesis and hypertrophy. Results Chondrogenesis in MSCs was consistently and strongly induced in collagen I hydrogels by the transgenesSOX9,TGFB1andBMP2as evidenced by positive staining for proteoglycans, chondroitin-4-sulfate (CS4) and collagen (COL) type II, increased levels of glycosaminoglycan (GAG) synthesis, and expression of mRNAs associated with chondrogenesis. The control groups were entirely non-chondrogenic. The levels of hypertrophy, as judged by expression of alkaline phosphatase (ALP) and COL X on both the protein and mRNA levels revealed different stages of hypertrophy within the chondrogenic groups (BMP2>TGFB1>SOX9). Conclusions Different types of neocartilage with varying levels of hypertrophy could be generated from human MSCs in collagen hydrogels by transfer of genes encoding the chondrogenic factorsSOX9,TGFB1andBMP2. This technology may be harnessed for regeneration of specific zones of native cartilage upon damage.}, language = {en} } @article{BoelchRueecklStrecketal.2021, author = {Boelch, Sebastian Philipp and R{\"u}eckl, Kilian and Streck, Laura Elisa and Szewczykowski, Viktoria and Weißenberger, Manuel and Jakuscheit, Axel and Rudert, Maximilian}, title = {Diagnosis of chronic infection at total hip arthroplasty revision is a question of definition}, series = {Biomed Research International}, volume = {2021}, journal = {Biomed Research International}, doi = {10.1155/2021/8442435}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265762}, year = {2021}, abstract = {Purpose. Contradicting definitions of periprosthetic joint infection (PJI) are in use. Joint aspiration is performed before total hip arthroplasty (THA) revision. This study investigated the influence of PJI definition on PJI prevalence at THA revision. Test quality of prerevision aspiration was evaluated for the different PJI definitions. Methods. 256 THA revisions were retrospectively classified to be infected or not infected. Classification was performed according to the 4 different definitions proposed by the Musculoskeletal Infection Society (MSIS), the Infectious Diseases Society of America (IDSA), the International Consensus Meeting (ICM), and the European Bone and Joint Infection Society (EBJIS). Only chronic PJIs were included. Results. PJI prevalence at revision significantly correlated with the applied PJI definition (p=0.01, Cramer's V=0.093). PJI prevalence was 20.7\% for the MSIS, 25.4\% for the ICM, 28.1\% for the IDSA, and 32.0\% for the EBJIS definition. For synovial fluid white blood cell count, the best ROC-AUC for predicting PJI was 0.953 in combination with the MSIS definition. Conclusion. PJI definition significantly influences the rate of diagnosed PJIs at THA revision. Synovial fluid white blood cell count is a reliable means to rule out PJI. In cases with a borderline high synovial white blood cell count before THA revision as the only sign of chronic PJI, an extended diagnostic work-up should be considered.}, language = {en} } @article{StratosScarlatRudert2021, author = {Stratos, Ioannis and Scarlat, Marius M. and Rudert, Maximilian}, title = {Bibliometrics of orthopaedic articles published by authors of Germanophone countries}, series = {International Orthopaedics}, volume = {45}, journal = {International Orthopaedics}, number = {5}, doi = {10.1007/s00264-021-05052-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-266343}, pages = {1121-1124}, year = {2021}, abstract = {No abstract available.}, language = {en} } @article{StratosHellerRudert2022, author = {Stratos, Ioannis and Heller, Karl-Dieter and Rudert, Maximilian}, title = {German surgeons' technical preferences for performing total hip arthroplasties: a survey from the National Endoprosthesis Society}, series = {International Orthopaedics}, volume = {46}, journal = {International Orthopaedics}, number = {4}, doi = {10.1007/s00264-021-05188-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-266350}, pages = {733-739}, year = {2022}, abstract = {Purpose The goal of our study was to conduct an online survey that highlights patterns of practice during total hip arthroplasty (THA). Methods The survey was conducted in June and August 2020. Three hundred thirteen members of the German Society for Endoprosthesis participated in the survey. Results The anterolateral approach is by far the most popular approach used for primary total hip arthroplasty, followed by the anterior approach during minimally invasive (55\% for the anterolateral and 29\% for the anterior) and regular surgery (52\% for the anterolateral and 20\% for the anterior). Two-thirds of the orthopaedic surgeons do not use drainages during THA. Moreover, 80\% of the survey participants routinely apply tranexamic acid during surgery. Surgeons who perform minimally invasive surgery for THA use more frequently fast-track-concepts for post-operative rehabilitation. According to the interviewees, the application of fast-track-concepts leads to reduced periods of hospital stay after THA. Conclusion Our data demonstrate that patterns of practice during THA in Germany are in line with the evidence provided by current literature. This study can be seen as a stimulus to conduct similar surveys in other countries in order to promote minimally invasive surgery for THA.}, language = {en} } @article{AltmannMutWolfetal.2021, author = {Altmann, Stephan and Mut, J{\"u}rgen and Wolf, Natalia and Meißner-Weigl, Jutta and Rudert, Maximilian and Jakob, Franz and Gutmann, Marcus and L{\"u}hmann, Tessa and Seibel, J{\"u}rgen and Ebert, Regina}, title = {Metabolic glycoengineering in hMSC-TERT as a model for skeletal precursors by using modified azide/alkyne monosaccharides}, series = {International Journal of Molecular Sciences}, volume = {22}, journal = {International Journal of Molecular Sciences}, number = {6}, issn = {1422-0067}, doi = {10.3390/ijms22062820}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259247}, year = {2021}, abstract = {Metabolic glycoengineering enables a directed modification of cell surfaces by introducing target molecules to surface proteins displaying new features. Biochemical pathways involving glycans differ in dependence on the cell type; therefore, this technique should be tailored for the best results. We characterized metabolic glycoengineering in telomerase-immortalized human mesenchymal stromal cells (hMSC-TERT) as a model for primary hMSC, to investigate its applicability in TERT-modified cell lines. The metabolic incorporation of N-azidoacetylmannosamine (Ac\(_4\)ManNAz) and N-alkyneacetylmannosamine (Ac\(_4\)ManNAl) into the glycocalyx as a first step in the glycoengineering process revealed no adverse effects on cell viability or gene expression, and the in vitro multipotency (osteogenic and adipogenic differentiation potential) was maintained under these adapted culture conditions. In the second step, glycoengineered cells were modified with fluorescent dyes using Cu-mediated click chemistry. In these analyses, the two mannose derivatives showed superior incorporation efficiencies compared to glucose and galactose isomers. In time-dependent experiments, the incorporation of Ac\(_4\)ManNAz was detectable for up to six days while Ac\(_4\)ManNAl-derived metabolites were absent after two days. Taken together, these findings demonstrate the successful metabolic glycoengineering of immortalized hMSC resulting in transient cell surface modifications, and thus present a useful model to address different scientific questions regarding glycosylation processes in skeletal precursors.}, language = {en} } @article{PereiraTrivanovićStahlhutetal.2022, author = {Pereira, Ana Rita and Trivanović, Drenka and Stahlhut, Philipp and Rudert, Maximilian and Groll, J{\"u}rgen and Herrmann, Marietta}, title = {Preservation of the na{\"i}ve features of mesenchymal stromal cells in vitro: Comparison of cell- and bone-derived decellularized extracellular matrix}, series = {Journal of Tissue Engineering}, volume = {13}, journal = {Journal of Tissue Engineering}, doi = {10.1177/20417314221074453}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-268835}, pages = {1-12}, year = {2022}, abstract = {The fate and behavior of bone marrow mesenchymal stem/stromal cells (BM-MSC) is bidirectionally influenced by their microenvironment, the stem cell niche, where a magnitude of biochemical and physical cues communicate in an extremely orchestrated way. It is known that simplified 2D in vitro systems for BM-MSC culture do not represent their na{\"i}ve physiological environment. Here, we developed four different 2D cell-based decellularized matrices (dECM) and a 3D decellularized human trabecular-bone scaffold (dBone) to evaluate BM-MSC behavior. The obtained cell-derived matrices provided a reliable tool for cell shape-based analyses of typical features associated with osteogenic differentiation at high-throughput level. On the other hand, exploratory proteomics analysis identified native bone-specific proteins selectively expressed in dBone but not in dECM models. Together with its architectural complexity, the physico-chemical properties of dBone triggered the upregulation of stemness associated genes and niche-related protein expression, proving in vitro conservation of the na{\"i}ve features of BM-MSC.}, language = {en} } @article{vonHertzbergBoelchLuedemannRudertetal.2022, author = {von Hertzberg-Boelch, Sebastian Philipp and Luedemann, Martin and Rudert, Maximilian and Steinert, Andre F.}, title = {PMMA bone cement: antibiotic elution and mechanical properties in the context of clinical use}, series = {Biomedicines}, volume = {10}, journal = {Biomedicines}, number = {8}, issn = {2227-9059}, doi = {10.3390/biomedicines10081830}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-281708}, year = {2022}, abstract = {This literature review discusses the use of antibiotic loaded polymethylmethacrylate bone cements in arthroplasty. The clinically relevant differences that have to be considered when antibiotic loaded bone cements (ALBC) are used either for long-term implant fixation or as spacers for the treatment of periprosthetic joint infections are outlined. In this context, in vitro findings for antibiotic elution and material properties are summarized and transferred to clinical use.}, language = {en} } @article{HeinzWildEidmannetal.2023, author = {Heinz, Tizian and Wild, Moritz and Eidmann, Annette and Weißenberger, Manuel and Rak, Dominik and Nedopil, Alexander Johannes and Rudert, Maximilian and Stratos, Ioannis}, title = {Impact of COVID-19 on fracture incidence in germany: a comparative age and gender analysis of pre- and post-outbreak periods}, series = {Healthcare}, volume = {11}, journal = {Healthcare}, number = {15}, issn = {2227-9032}, doi = {10.3390/healthcare11152139}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-362686}, year = {2023}, abstract = {In March 2020, Germany imposed a nationwide lockdown to curb the spread of COVID-19, prompting questions about the impact on the incidence of common fractures. This study examined 15 fracture types in pre-outbreak (2010-2019) and post-outbreak (2020-2021) periods, using data categorized by age (18-64 years, 65 years) and sex (male, female). Linear regression assessed annual growth rates, and mean fracture numbers were compared across periods for significant differences. Results indicated a positive correlation between fracture incidence rates and time for various types, such as cervical, thoracic, lumbar, and pelvic spine fractures, rib fractures, femoral neck, pertrochanteric femur, femoral shaft, and ankle fractures. Frequencies of proximal humerus, distal radius, femoral neck, pertrochanteric femur, femoral shaft, and ankle fractures in 2020 and 2021 were within predicted ranges from previous years. However, rib fractures and spinal fractures (cervical, thoracic, lumbar, and pelvic spine) occurred less frequently during this time. Notably, this study found a consistent decline in most fracture types for individuals aged 18-64 after the pandemic's onset, while the fracture incidence of hip fractures, often referred to as fragility fractures, for those over 65 remained unchanged. Fibula fractures showed the most considerable decrease in both age groups. In conclusion, the COVID-19 pandemic substantially impacted fracture incidence, with lower rates among individuals under 65 and unchanged fragility fractures in the elderly population.}, language = {en} } @article{EidmannHeinzOberfeldetal.2023, author = {Eidmann, Annette and Heinz, Tizian and Oberfeld, Jan and Weißenberger, Manuel and Rudert, Maximilian and Stratos, Ioannis}, title = {Epidemiology and trends in cartilage surgery of the foot and ankle in Germany: an analysis of national healthcare billing and reporting data from 2006 to 2020}, series = {Medicina}, volume = {59}, journal = {Medicina}, number = {7}, issn = {1648-9144}, doi = {10.3390/medicina59071256}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-362835}, year = {2023}, abstract = {Background and objectives: Cartilage surgery constitutes a standard intervention in foot and ankle procedures. Currently, there is a lack of epidemiological data on its frequency, age distribution, and surgical options for cartilage surgery. This study aimed to investigate the current landscape of cartilage surgery in Germany and identify the most common procedures from an epidemiological standpoint. Materials and methods: Medical billing and reporting data from the Federal Statistical Office of Germany, encompassing the period 2006-2020, was examined, including all foot and ankle cartilage surgical procedures (summarized under OPS codes 5-812 and 5-801). The dataset incorporated information on the affected joint, patient age and sex, and surgery type. Each surgical procedure was categorized as "debridement", "regeneration" or "refixation". Linear and nonlinear regression analyses were employed, with a statistical significance threshold of 0.05. Results: From the total of 136,501 procedures conducted during the study period, the most frequently performed interventions were microfracture (58,252) and chondroplasty (56,135), and thus, debridement procedures were in the leading position. The use of acellular membranes was the most used regenerative technique (n = 11,414). At the ankle joint, interventions were mostly arthroscopic and in men, while foot cartilage surgeries were preferably performed via open surgery and mostly in women. Age distribution analysis revealed two primary peaks: the first in the 20-25-year-old group (ankle and foot) and the second in the 45-50-year-old group (ankle) and 55-60-year-old group (foot). Refixation and regenerative procedures were more frequent among younger individuals, while debriding procedures were more frequent among older individuals. Regenerative procedures, particularly in the ankle, significantly increased over time. Conclusions: Cartilage surgery of the foot and ankle was common, with two primary age groups predominantly affected. Notably, recent years have witnessed a considerable rise in cartilage regenerative procedures.}, language = {en} } @article{WagenbrennerHeinzHorasetal.2020, author = {Wagenbrenner, Mike and Heinz, Tizian and Horas, Konstantin and Jakuscheit, Axel and Arnholdt, J{\"o}rg and Hermann, Marietta and Rudert, Maximilian and Holzapfel, Boris M. and Steinert, Andre F. and Weißenberger, Manuel}, title = {The human arthritic hip joint is a source of mesenchymal stromal cells (MSCs) with extensive multipotent differentiation potential}, series = {BMC Musculoskeletal Disorders}, volume = {21}, journal = {BMC Musculoskeletal Disorders}, number = {1}, doi = {10.1186/s12891-020-03340-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229497}, year = {2020}, abstract = {Background While multiple in vitro studies examined mesenchymal stromal cells (MSCs) derived from bone marrow or hyaline cartilage, there is little to no data about the presence of MSCs in the joint capsule or the ligamentum capitis femoris (LCF) of the hip joint. Therefore, this in vitro study examined the presence and differentiation potential of MSCs isolated from the bone marrow, arthritic hyaline cartilage, the LCF and full-thickness samples of the anterior joint capsule of the hip joint. Methods MSCs were isolated and multiplied in adherent monolayer cell cultures. Osteogenesis and adipogenesis were induced in monolayer cell cultures for 21 days using a differentiation medium containing specific growth factors, while chondrogenesis in the presence of TGF-ss1 was performed using pellet-culture for 27 days. Control cultures were maintained for comparison over the same duration of time. The differentiation process was analyzed using histological and immunohistochemical stainings as well as semiquantitative RT-PCR for measuring the mean expression levels of tissue-specific genes. Results This in vitro research showed that the isolated cells from all four donor tissues grew plastic-adherent and showed similar adipogenic and osteogenic differentiation capacity as proven by the histological detection of lipid droplets or deposits of extracellular calcium and collagen type I. After 27 days of chondrogenesis proteoglycans accumulated in the differentiated MSC-pellets from all donor tissues. Immunohistochemical staining revealed vast amounts of collagen type II in all differentiated MSC-pellets, except for those from the LCF. Interestingly, all differentiated MSCs still showed a clear increase in mean expression of adipogenic, osteogenic and chondrogenic marker genes. In addition, the examination of an exemplary selected donor sample revealed that cells from all four donor tissues were clearly positive for the surface markers CD44, CD73, CD90 and CD105 by flow cytometric analysis. Conclusions This study proved the presence of MSC-like cells in all four examined donor tissues of the hip joint. No significant differences were observed during osteogenic or adipogenic differentiation depending on the source of MSCs used. Further research is necessary to fully determine the tripotent differentiation potential of cells isolated from the LCF and capsule tissue of the hip joint.}, language = {en} } @article{HerrmannEngelkeEbertetal.2020, author = {Herrmann, Marietta and Engelke, Klaus and Ebert, Regina and M{\"u}ller-Deubert, Sigrid and Rudert, Maximilian and Ziouti, Fani and Jundt, Franziska and Felsenberg, Dieter and Jakob, Franz}, title = {Interactions between muscle and bone — Where physics meets biology}, series = {Biomolecules}, volume = {10}, journal = {Biomolecules}, number = {3}, issn = {2218-273X}, doi = {10.3390/biom10030432}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203399}, year = {2020}, abstract = {Muscle and bone interact via physical forces and secreted osteokines and myokines. Physical forces are generated through gravity, locomotion, exercise, and external devices. Cells sense mechanical strain via adhesion molecules and translate it into biochemical responses, modulating the basic mechanisms of cellular biology such as lineage commitment, tissue formation, and maturation. This may result in the initiation of bone formation, muscle hypertrophy, and the enhanced production of extracellular matrix constituents, adhesion molecules, and cytoskeletal elements. Bone and muscle mass, resistance to strain, and the stiffness of matrix, cells, and tissues are enhanced, influencing fracture resistance and muscle power. This propagates a dynamic and continuous reciprocity of physicochemical interaction. Secreted growth and differentiation factors are important effectors of mutual interaction. The acute effects of exercise induce the secretion of exosomes with cargo molecules that are capable of mediating the endocrine effects between muscle, bone, and the organism. Long-term changes induce adaptations of the respective tissue secretome that maintain adequate homeostatic conditions. Lessons from unloading, microgravity, and disuse teach us that gratuitous tissue is removed or reorganized while immobility and inflammation trigger muscle and bone marrow fatty infiltration and propagate degenerative diseases such as sarcopenia and osteoporosis. Ongoing research will certainly find new therapeutic targets for prevention and treatment.}, language = {en} } @article{ProdingerLazicHorasetal.2020, author = {Prodinger, Peter Michael and Lazic, Igor and Horas, Konstantin and Burgkart, Rainer and von Eisenhart-Rothe, R{\"u}diger and Weissenberger, Manuel and Rudert, Maximilian and Holzapfel, Boris Michael}, title = {Revision Arthroplasty Through the Direct Anterior Approach Using an Asymmetric Acetabular Component}, series = {Journal of Clinical Medicine}, volume = {9}, journal = {Journal of Clinical Medicine}, number = {9}, issn = {2077-0383}, doi = {10.3390/jcm9093031}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213184}, year = {2020}, abstract = {Despite increasing numbers of primary hip arthroplasties performed through the direct anterior approach (DAA), there is a lack of literature on DAA revision arthroplasty. The present study was performed in order to evaluate outcomes and revision rates after revision through the DAA using an asymmetric acetabular component with optional intra- and extramedullary fixation. In a retrospective cohort study, we analyzed prospectively collected data of 57 patients (61 hips, 43 female, 18 male) who underwent aseptic acetabular component revision through the DAA with the abovementioned implant system between January 2015 and December 2017. The mean follow-up was 40 months (12-56). Survival rates were estimated using the Kaplan-Meier method. All complications were documented and functional outcomes were assessed pre- and postoperatively. Kaplan-Meier analysis revealed an estimated five-year implant survival of 97\% (confidence interval CI 87-99\%). The estimated five-year survival with revision for any cause was 93\% (CI 83-98\%). The overall revision rate was 6.6\% (n = 4). Two patients had to undergo revision due to periprosthetic infection (3.3\%). In one patient, the acetabular component was revised due to aseptic loosening four months postoperatively. Another patient suffered from postoperative iliopsoas impingement and was treated successfully by arthroscopic iliopsoas tenotomy. Two (3.3\%) of the revised hips dislocated postoperatively. The mean Harris Hip Score improved from 35 (2-66) preoperatively to 86 (38-100) postoperatively (p < 0.001). The hip joint's anatomical center of rotation was restored at a high degree of accuracy. Our findings demonstrate that acetabular revision arthroplasty through the DAA using an asymmetric acetabular component with optional intra- and extramedullary fixation is safe and practicable, resulting in good radiographic and clinical midterm results.}, language = {en} } @article{StreckSeefriedGenestetal.2022, author = {Streck, Laura Elisa and Seefried, Lothar and Genest, Franca and Reichel, Thomas and Rudert, Maximilian and Rueckl, Kilian}, title = {Insuffizienzfraktur der Klavikula nach Implantation einer inversen Schulterendoprothese}, series = {Der Orthop{\"a}de}, volume = {51}, journal = {Der Orthop{\"a}de}, number = {3}, doi = {10.1007/s00132-021-04205-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265286}, pages = {246-250}, year = {2022}, abstract = {Wir stellen den seltenen Fall einer Insuffizienzfraktur der Klavikula nach Implantation einer inversen Schulterendoprothese (RSA) vor. Als Ursache solcher Frakturen wird eine vermehrte Zugbelastung durch den Musculus deltoideus nach RSA diskutiert. In den wenigen verf{\"u}gbaren Fallberichten zeigten die betroffenen Patienten deutliche Funktionseinschr{\"a}nkungen. Die Versorgung erfolgte im vorliegenden Fall mit Plattenosteosynthese. Trotz intraoperativ gutem Korrekturergebnis kam es im Verlauf ohne Trauma zum Osteosyntheseversagen mit weiterer Dislokation der Fraktur.}, language = {de} } @article{BoelchWeissenbergerSpohnetal.2018, author = {Boelch, Sebastian Philipp and Weissenberger, Manuel and Spohn, Frederik and Rudert, Maximilian and Luedemann, Martin}, title = {Insufficient sensitivity of joint aspiration during the two-stage exchange of the hip with spacers}, series = {Journal of Orthopedic Surgery and Research}, volume = {13}, journal = {Journal of Orthopedic Surgery and Research}, number = {7}, doi = {10.1186/s13018-017-0703-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-175576}, year = {2018}, abstract = {Background: Evaluation of infection persistence during the two-stage exchange of the hip is challenging. Joint aspiration before reconstruction is supposed to rule out infection persistence. Sensitivity and specificity of synovial fluid culture and synovial leucocyte count for detecting infection persistence during the two-stage exchange of the hip were evaluated. Methods: Ninety-two aspirations before planned joint reconstruction during the two-stage exchange with spacers of the hip were retrospectively analyzed. Results: The sensitivity and specificity of synovial fluid culture was 4.6 and 94.3\%. The sensitivity and specificity of synovial leucocyte count at a cut-off value of 2000 cells/μl was 25.0 and 96.9\%. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) values were significantly higher before prosthesis removal and reconstruction or spacer exchange (p = 0.00; p = 0.013 and p = 0.039; p = 0.002) in the infection persistence group. Receiver operating characteristic area under the curve values before prosthesis removal and reconstruction or spacer exchange for ESR were lower (0.516 and 0.635) than for CRP (0.720 and 0.671). Conclusions: Synovial fluid culture and leucocyte count cannot rule out infection persistence during the two-stage exchange of the hip.}, language = {en} } @article{ArnholdtKamawalHorasetal.2020, author = {Arnholdt, J{\"o}rg and Kamawal, Yama and Horas, Konstantin and Holzapfel, Boris M. and Gilbert, Fabian and Ripp, Axel and Rudert, Maximilian and Steinert, Andre F.}, title = {Accurate implant fit and leg alignment after cruciate-retaining patient-specific total knee arthroplasty}, series = {BMC Musculoskeletal Disorders}, volume = {21}, journal = {BMC Musculoskeletal Disorders}, doi = {10.1186/s12891-020-03707-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230012}, year = {2020}, abstract = {Background For improved outcomes in total knee arthroplasty (TKA) correct implant fitting and positioning are crucial. In order to facilitate a best possible implant fitting and positioning patient-specific systems have been developed. However, whether or not these systems allow for better implant fitting and positioning has yet to be elucidated. For this reason, the aim was to analyse the novel patient-specific cruciate retaining knee replacement system iTotal (TM) CR G2 that utilizes custom-made implants and instruments for its ability to facilitate accurate implant fitting and positioning including correction of the hip-knee-ankle angle (HKA). Methods We assessed radiographic results of 106 patients who were treated with the second generation of a patient-specific cruciate retaining knee arthroplasty using iTotal\(^{TM}\) CR G2 (ConforMIS Inc.) for tricompartmental knee osteoarthritis (OA) using custom-made implants and instruments. The implant fit and positioning as well as the correction of the mechanical axis (hip-knee-ankle angle, HKA) and restoration of the joint line were determined using pre- and postoperative radiographic analyses. Results On average, HKA was corrected from 174.4 degrees +/- 4.6 degrees preoperatively to 178.8 degrees +/- 2.2 degrees postoperatively and the coronal femoro-tibial angle was adjusted on average 4.4 degrees. The measured preoperative tibial slope was 5.3 degrees +/- 2.2 degrees (mean +/- SD) and the average postoperative tibial slope was 4.7 degrees +/- 1.1 degrees on lateral views. The joint line was well preserved with an average modified Insall-Salvati index of 1.66 +/- 0.16 pre- and 1.67 +/- 0.16 postoperatively. The overall accuracy of fit of implant components was decent with a measured medial overhang of more than 1 mm (1.33 mm +/- 0.32 mm) in 4 cases only. Further, a lateral overhang of more than 1 mm (1.8 mm +/- 0.63) (measured in the anterior-posterior radiographs) was observed in 11 cases, with none of the 106 patients showing femoral notching. Conclusion The patient-specific iTotal\(^{TM}\) CR G2 total knee replacement system facilitated a proper fitting and positioning of the implant components. Moreover, a good restoration of the leg axis towards neutral alignment was achieved as planned. Nonetheless, further clinical follow-up studies are necessary to validate our findings and to determine the long-term impact of using this patient- specific system.}, language = {en} } @article{LuedemannJakuscheitEwaldetal.2021, author = {L{\"u}demann, Martin and Jakuscheit, Axel and Ewald, Andrea and Fr{\"u}hmann, Leena and H{\"o}lscher-Doht, Stefanie and Rudert, Maximilian and von Hertzberg-Boelch, Sebastian Philipp}, title = {Influence of Tranexamic Acid on Elution Characteristics and Compressive Strength of Antibiotic-Loaded PMMA-Bone Cement with Gentamicin}, series = {Materials}, volume = {14}, journal = {Materials}, number = {19}, issn = {1996-1944}, doi = {10.3390/ma14195639}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-246236}, year = {2021}, abstract = {Purpose: The topical application of tranexamic acid (TXA) into the joint space during total joint arthroplasty (TJA) with no increase of complications, has been widely reported. We investigated the influence of TXA on antibiotic release, activity of the released antibiotic against a clinical isolate of S. aureus, and compressive strength of a widely used commercially prepared gentamicin-loaded cement brand (PALACOS R + G). Method: 12 bone cement cylinders (diameter and height = 6 and 12 mm, respectively) were molded. After curing in air for at least 1 h, six of the cylinders were completely immersed in 5 mL of fetal calf serum (FCS) and the other six were completely immersed in a solution consisting of 4.9 mL of FCS and 0.1 mL (10 mg) of TXA. Gentamicin elution tests were performed over 7 d. Four hundred µL of the gentamicin eluate were taken every 24 h for the first 7 d without renewing the immersion fluid. The gentamicin concentration was determined in a clinical analyzer using a homogeny enzyme immuno-assay. The antimicrobial activity of the eluate, obtained after day 7, was tested. An agar diffusion test regime was used with Staphylococcus aureus. Bacteria were grown in a LB medium and plated on LB agar plates to get a bacterial lawn. Fifty µL of each eluate were pipetted on 12-mm diameter filter discs, which were placed in the middle of the agar gel. After 24 h of cultivation at 37 °C, the zone of inhibition (ZOI) for each specimen was measured. The compressive strength of the cements was determined per ISO 5833. Results: At each time point in the gentamicin release test, the difference in gentamicin concentration, obtained from specimens immersed in the FCS solution only and those immersed in the FCS + TXA solution was not significant (p = 0.055-0.522). The same trend was seen in each of the following parameters, after 7 d of immersion: (1) Cumulative gentamicin concentration (p < 0.297); (2) gentamicin activity against S. aureus (strongly visible); (3) ZOI size (mostly > 20 mm) (p = 0.631); and (4) compressive strength (p = 0.262). Conclusions: For the PALACOS R + G specimens, the addition of TXA to FCS does not produce significant decreases in gentamicin concentration, in the activity of the gentamicin eluate against a clinical isolate of S. aureus, the zone of inhibition of S. aureus, and in the compressive strength of the cement, after 7 d of immersion in the test solution.}, language = {en} } @article{ArnholdtGilbertBlanketal.2017, author = {Arnholdt, J{\"o}rg and Gilbert, Fabian and Blank, Marc and Papazoglou, Jannis and Rudert, Maximilian and N{\"o}th, Ulrich and Steinert, Andre F.}, title = {The Mayo conservative hip: complication analysis and management of the first 41 cases performed at a University level 1 department}, series = {BMC Muskoskeletal Disorders}, volume = {18}, journal = {BMC Muskoskeletal Disorders}, number = {250}, doi = {10.1186/s12891-017-1613-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-157812}, year = {2017}, abstract = {Background: To prevent bone loss in hip arthroplasty, several short stem systems have been developed, including the Mayo conservative hip system. While there is a plethora of data confirming inherent advantages of these systems, only little is known about potential complications, especially when surgeons start to use these systems. Methods: In this study, we present a retrospective analysis of the patients' outcome, complications and the complication management of the first 41 Mayo conservative hips performed in 37 patients. For this reason, functional scores, radiographic analyses, peri- and postoperative complications were assessed at an average follow-up of 35 months. Results: The overall HHS improved from 61.2 pre-operatively to 85.6 post-operatively. The German Extra Short Musculoskeletal Function Assessment Questionnaire (XSFMA-D) improved from 30.3 pre-operatively to 12.2 post-operatively. The most common complication was an intraoperative non-displaced fracture of the proximal femur observed in 5 cases (12.1\%). Diabetes, higher BMI and older ages were shown to be risk factors for these intra-operative periprosthetic fractures (p < 0.01). Radiographic analysis revealed a good offset reconstruction in all cases. Conclusion: In our series, a high complication rate with 12.1\% of non-displaced proximal femoral fractures was observed using the Mayo conservative hip. This may be attributed to the flat learning curve of the system or the inherent patient characteristics of the presented cohort."}, language = {en} } @article{BoelchRuecklFuchsetal.2018, author = {Boelch, Sebastian P. and Rueckl, Kilian and Fuchs, Clara and Jordan, Martin and Knauer, Markus and Steinert, Andre and Rudert, Maximilian and Luedemann, Martin}, title = {Comparison of elution characteristics and compressive strength of biantibiotic-loaded PMMA bone cement for spacers: Copal\(^®\) spacem with gentamicin and vancomycin versus Palacos\(^®\) R+G with vancomycin}, series = {BioMed Research International}, volume = {2018}, journal = {BioMed Research International}, number = {4323518}, doi = {10.1155/2018/4323518}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177435}, year = {2018}, abstract = {Purpose. Copal\(^®\) spacem is a new PMMA bone cement for fabricating spacers. This study compares elution of gentamicin, elution of vancomycin, and compressive strength of Copal\(^®\) spacem and of Palacos\(^®\) R+G at different vancomycin loadings in the powder of the cements. We hypothesized that antibiotic elution of Copal\(^®\) spacem is superior at comparable compressive strength. Methods. Compression test specimens were fabricated using Copal\(^®\) spacem manually loaded with 0.5 g gentamicin and additionally 2 g, 4 g, and 6 g of vancomycin per 40 g of cement powder (COP specimens) and using 0.5 g gentamicin premixed Palacos\(^®\) R+G manually loaded with 2 g, 4 g, and 6 g of vancomycin per 40 g of cement powder (PAL specimens). These specimens were used for determination of gentamicin and vancomycin elution (in fetal calf serum, at 22°C) and for determination of compressive strength both prior and following the elution tests. Results. Cumulative gentamicin concentrations (p < 0.005) and gentamicin concentration after 28 days (p ≤ 0.043) were significantly lower for COP specimens compared to PAL specimens. Cumulative vancomycin concentrations were significantly higher (p ≤ 0.043) for COP specimens after the second day. Vancomycin concentrations after 28 days were not significantly higher for the Copal specimens loaded with 2 g and 4 g of vancomycin. Compressive strength was not significantly different between COP specimens and PAL specimens before elution tests. Compressive strength after the elution tests was significantly lower (p = 0.005) for COP specimens loaded with 2 g of vancomycin. Conclusion. We could not demonstrate consistent superior antibiotic elution from Copal\(^®\) spacem compared to Palacos\(^®\) R+G for fabricating gentamicin and vancomycin loaded spacers. The results do not favor Copal\(^®\) spacem over Palacos\(^®\) R+G for the use as a gentamicin and vancomycin biantibiotic-loaded spacer.}, language = {en} } @article{JakuscheitSchaeferRoedigetal.2021, author = {Jakuscheit, Axel and Schaefer, Nina and Roedig, Johannes and Luedemann, Martin and Hertzberg-Boelch, Sebastian Philipp von and Weissenberger, Manuel and Schmidt, Karsten and Holzapfel, Boris Michael and Rudert, Maximilian}, title = {Modifiable individual risks of perioperative blood transfusions and acute postoperative complications in total hip and knee arthroplasty}, series = {Journal of Personalized Medicine}, volume = {11}, journal = {Journal of Personalized Medicine}, number = {11}, issn = {2075-4426}, doi = {10.3390/jpm11111223}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-250290}, year = {2021}, abstract = {Background: The primary aim of this study was to identify modifiable patient-related predictors of blood transfusions and perioperative complications in total hip and knee arthroplasty. Individual predictor-adjusted risks can be used to define preoperative treatment thresholds. Methods: We performed this retrospective monocentric study in orthopaedic patients who underwent primary total knee or hip arthroplasty. Multivariate logistic regression models were used to assess the predictive value of patient-related characteristics. Predictor-adjusted individual risks of blood transfusions and the occurrence of any perioperative adverse event were calculated for potentially modifiable risk factors. Results: 3754 patients were included in this study. The overall blood transfusion and complication rates were 4.8\% and 6.4\%, respectively. Haemoglobin concentration (Hb, p < 0.001), low body mass index (BMI, p < 0.001) and estimated glomerular filtration rate (eGFR, p = 0.004) were the strongest potentially modifiable predictors of a blood transfusion. EGFR (p = 0.001) was the strongest potentially modifiable predictor of a complication. Predictor-adjusted risks of blood transfusions and acute postoperative complications were calculated for Hb and eGFR. Hb = 12.5 g/dL, BMI = 17.6 kg/m\(^2\), and eGFR = 54 min/mL were associated, respectively, with a 10\% risk of a blood transfusion, eGFR = 59 mL/min was associated with a 10\% risk of a complication. Conclusion: The individual risks for blood transfusions and acute postoperative complications are strongly increased in patients with a low preoperative Hb, low BMI or low eGFR. We recommend aiming at a preoperative Hb ≥ 13g/dL, an eGFR ≥ 60 mL/min and to avoid a low BMI. Future studies must show if a preoperative increase of eGFR and BMI is feasible and truly beneficial.}, language = {en} } @article{HeinzMellerLuetkensetal.2022, author = {Heinz, Tizian and Meller, Felix and Luetkens, Karsten Sebastian and Horas, Konstantin and Sch{\"a}fer, Thomas and Rudert, Maximilian and Reppenhagen, Stephan and Weißenberger, Manuel}, title = {Can the MRI based AMADEUS score accurately assess pre-surgery chondral defect severity according to the ICRS arthroscopic classification system?}, series = {Journal of Experimental Orthopaedics}, volume = {9}, journal = {Journal of Experimental Orthopaedics}, number = {1}, issn = {2197-1153}, doi = {10.1186/s40634-022-00511-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300781}, year = {2022}, abstract = {Purpose The AMADEUS (Area Measurement And DEpth and Underlying Structures) scoring and grading system has been proposed for the MRI based evaluation of untreated focal chondral defects around the knee. The clinical practicability, its correlation with arthroscopically assessed grading systems (ICRS - International Cartilage Repair Society) and thereby its clinical value in terms of decision making and guiding prognosis was yet to determine. Methods From 2008 to 2019 a total of 89 individuals were indicated for high tibial valgus osteotomy (HTO) due to tibial varus deformity and concomitant chondral defects of the medial compartment of the knee. All patients received a preoperative MRI (1.5 Tesla or 3.0 Tesla) and pre-osteotomy diagnostic arthroscopy. Chondral defects of the medial compartment were scored and graded with the MRI based AMADEUS by three independent raters and compared to arthroscopic defect grading by the ICRS system. Interrater and intrarater reliability as well as correlation analysis with the ICRS classification system were assessed. Results Intraclass correlation coefficients for the various subscores of the AMADEUS showed an overall good to excellent interrater agreement (min: 0.26, max: 0.80). Intrarater agreement turned out to be substantially inferior (min: 0.08, max: 0.53). Spearman correlation revealed an overall moderate correlative association of the AMADEUS subscores with the ICRS classification system, apart from the defect area subscore. Sensitivity of the AMADEUS to accurately identify defect severity according to the ICRS was 0.7 (0.69 for 3.0 Tesla MRI, 0.67 for 1.5 Tesla MRI). The mean AMADEUS grade was 2.60 ± 0.81 and the mean ICRS score 2.90 ± 0.63. Conclusions Overall, the AMADEUS with all its subscores shows moderate correlation with the arthroscopic chondral grading system according to ICRS. This suggests that chondral defect grading by means of the MRI based AMADEUS is well capable of influencing and guiding treatment decisions. Interrater reliability shows overall good agreement.}, language = {en} } @article{TylekSchillingSchlegelmilchetal.2019, author = {Tylek, Tina and Schilling, Tatjana and Schlegelmilch, Katrin and Ries, Maximilian and Rudert, Maximilian and Jakob, Franz and Groll, J{\"u}rgen}, title = {Platelet lysate outperforms FCS and human serum for co-culture of primary human macrophages and hMSCs}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, doi = {10.1038/s41598-019-40190-9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229174}, year = {2019}, abstract = {In vitro co-cultures of different primary human cell types are pivotal for the testing and evaluation of biomaterials under conditions that are closer to the human in vivo situation. Especially co-cultures of macrophages and mesenchymal stem cells (MSCs) are of interest, as they are both present and involved in tissue regeneration and inflammatory reactions and play crucial roles in the immediate inflammatory reactions and the onset of regenerative processes, thus reflecting the decisive early phase of biomaterial contact with the host. A co-culture system of these cell types might thus allow for the assessment of the biocompatibility of biomaterials. The establishment of such a co-culture is challenging due to the different in vitro cell culture conditions. For human macrophages, medium is usually supplemented with human serum (hS), whereas hMSC culture is mostly performed using fetal calf serum (FCS), and these conditions are disadvantageous for the respective other cell type. We demonstrate that human platelet lysate (hPL) can replace hS in macrophage cultivation and appears to be the best option for co-cultivation of human macrophages with hMSCs. In contrast to FCS and hS, hPL maintained the phenotype of both cell types, comparable to that of their respective standard culture serum, as well as the percentage of each cell population. Moreover, the expression profile and phagocytosis activity of macrophages was similar to hS.}, language = {en} } @article{HettichSchierjottRammetal.2019, author = {Hettich, Georg and Schierjott, Ronja A. and Ramm, Heiko and Graichen, Heiko and Jansson, Volkmar and Rudert, Maximilian and Traina, Francesco and Grupp, Thomas M.}, title = {Method for quantitative assessment of acetabular bone defects}, series = {Journal of Orthopaedic Research}, volume = {37}, journal = {Journal of Orthopaedic Research}, doi = {10.1002/jor.24165}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-320226}, pages = {181-189}, year = {2019}, abstract = {The objective of the study was to suggest a novel quantitative assessment of acetabular bone defects based on a statistical shape model, validate the method, and present preliminary results. Two exemplary CT-data sets with acetabular bone defects were segmented to obtain a solid model of each defect pelvis. The pathological areas around the acetabulum were excluded and a statistical shape model was fitted to the remaining healthy bone structures. The excluded areas were extrapolated such that a solid model of the native pelvis per specimen resulted (i.e., each pelvis without defect). The validity of the reconstruction was tested by a leave-one-out study. Validation results showed median reconstruction errors of 3.0 mm for center of rotation, 1.7 mm for acetabulum diameter, 2.1° for inclination, 2.5° for anteversion, and 3.3 mm3 for bone volume around the acetabulum. By applying Boolean operations on the solid models of defect and native pelvis, bone loss and bone formation in four different sectors were assessed. For both analyzed specimens, bone loss and bone formation per sector were calculated and were consistent with the visual impression. In specimen_1 bone loss was predominant in the medial wall (10.8 ml; 79\%), in specimen_2 in the posterior column (15.6 ml; 46\%). This study showed the feasibility of a quantitative assessment of acetabular bone defects using a statistical shape model-based reconstruction method. Validation results showed acceptable reconstruction accuracy, also when less healthy bone remains. The method could potentially be used for implant development, pre-clinical testing, pre-operative planning, and intra-operative navigation. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 9999:1-9, 2018.}, language = {en} }