@article{WagenbrennerHeinzHorasetal.2020, author = {Wagenbrenner, Mike and Heinz, Tizian and Horas, Konstantin and Jakuscheit, Axel and Arnholdt, Joerg and Mayer-Wagner, Susanne and Rudert, Maximilian and Holzapfel, Boris M. and Weißenberger, Manuel}, title = {Impact of Tranexamic Acid on Chondrocytes and Osteogenically Differentiated Human Mesenchymal Stromal Cells (hMSCs) In Vitro}, series = {Journal of Clinical Medicine}, volume = {9}, journal = {Journal of Clinical Medicine}, number = {12}, issn = {2077-0383}, doi = {10.3390/jcm9123880}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-219410}, year = {2020}, abstract = {The topical application of tranexamic acid (TXA) helps to prevent post-operative blood loss in total joint replacements. Despite these findings, the effects on articular and periarticular tissues remain unclear. Therefore, this in vitro study examined the effects of varying exposure times and concentrations of TXA on proliferation rates, gene expression and differentiation capacity of chondrocytes and human mesenchymal stromal cells (hMSCs), which underwent osteogenic differentiation. Chondrocytes and hMSCs were isolated and multiplied in monolayer cell cultures. Osteogenic differentiation of hMSCs was induced for 21 days using a differentiation medium containing specific growth factors. Cell proliferation was analyzed using ATP assays. Effects of TXA on cell morphology were examined via light microscopy and histological staining, while expression levels of tissue-specific genes were measured using semiquantitative RT-PCR. After treatment with 50 mg/mL of TXA, a decrease in cell proliferation rates was observed. Furthermore, treatment with concentrations of 20 mg/mL of TXA for at least 48 h led to a visible detachment of chondrocytes. TXA treatment with 50 mg/mL for at least 24 h led to a decrease in the expression of specific marker genes in chondrocytes and osteogenically differentiated hMSCs. No significant effects were observed for concentrations beyond 20 mg/mL of TXA combined with exposure times of less than 24 h. This might therefore represent a safe limit for topical application in vivo. Further research regarding in vivo conditions and effects on hMSC functionality are necessary to fully determine the effects of TXA on articular and periarticular tissues.}, language = {en} } @article{WeissenbergerWagenbrennerSchoteetal.2022, author = {Weißenberger, Manuel and Wagenbrenner, Mike and Schote, Fritz and Horas, Konstantin and Sch{\"a}fer, Thomas and Rudert, Maximilian and Barthel, Thomas and Heinz, Tizian and Reppenhagen, Stephan}, title = {The 3-triangle method preserves the posterior tibial slope during high tibial valgus osteotomy: first preliminary data using a mathematical model}, series = {Journal of Experimental Orthopaedics}, volume = {9}, journal = {Journal of Experimental Orthopaedics}, issn = {2197-1153}, doi = {10.1186/s40634-022-00466-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300806}, year = {2022}, abstract = {Purpose Despite much improved preoperative planning techniques accurate intraoperative assessment of the high tibial valgus osteotomy (HTO) remains challenging and often results in coronal over- and under-corrections as well as unintended changes of the posterior tibial slope. Noyes et al. reported a novel method for accurate intraoperative coronal and sagittal alignment correction based on a three-dimensional mathematical model. This is the first study examining preliminary data via the proposed Noyes approach for accurate intraoperative coronal and sagittal alignment correction during HTO. Methods From 2016 to 2020 a total of 24 patients (27 knees) underwent HTO applying the proposed Noyes method (Noyes-Group). Radiographic data was analyzed retrospectively and matched to patients that underwent HTO using the conventional method, i.e., gradual medial opening using a bone spreader under fluoroscopic control (Conventional-Group). All operative procedures were performed by an experienced surgeon at a single orthopaedic university center. Results From the preoperative to the postoperative visit no statistically significant changes of the posterior tibial slope were noted in the Noyes-Group compared to a significant increase in the Conventional-Group (p = 0.01). Regarding the axial alignment no significant differences between both groups were observed pre- and postoperatively. The number of over- and under-corrections did not differ significantly between both groups. Linear regression analysis showed a significant correlation of the postoperative medial proximal tibial angle (MPTA) with the position of the weightbearing line on the tibial plateau. Conclusion The 3-triangle method by Noyes seems to be a promising approach for preservation of the posterior tibial slope during HTO.}, 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} } @phdthesis{Heinz2022, author = {Heinz, Tizian}, title = {Das Knorpelregister DGOU zur systematischen Patientenerfassung nach knorpelchirurgischen Eingriffen des Kniegelenkes - Analyse und wissenschaftliche Aufarbeitung der ersten 100 Patienten an der Orthop{\"a}dischen Klinik K{\"o}nig-Ludwig-Haus}, doi = {10.25972/OPUS-28288}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-282882}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2022}, abstract = {Die stark limitierte intrinsische Regenerationsf{\"a}higkeit des hyalinen Gelenkknorpels stellt auch in der modernen Medizin eine große Herausforderung dar. W{\"a}hrend eine Vielzahl von knorpelchirurgischen Techniken am Kniegelenk koexistieren, bleibt die Selektion des am besten geeigneten Therapieverfahrens eine zentrale Herausforderung des orthop{\"a}dischen Chirurgen. Hierzu bieten in Zeiten evidenzbasierter Medizin medizinische Register die M{\"o}glichkeit, klinische Behandlungsdaten systematisch in einem breiten Patientenkollektiv zu erfassen, die klinische Versorgungsrealit{\"a}t ad{\"a}quat abzubilden sowie neue Behandlungsstrategien und Hypothesen zu generieren. Das Knorpelregister der DGOU bietet als webbasierte Registerform eine besonders moderne, effiziente und unb{\"u}rokratische Form der Patientennachverfolgung {\"u}ber subjektiv bewertete und validierte Funktionsscores. F{\"u}r das gesamte Registerkollektiv von 100 Patienten an der Orthop{\"a}dischen Klinik-K{\"o}nig-Ludwig Haus ergaben sich bereits sechs Monate nach dem knorpelchirurgischen Eingriff signifikant h{\"o}here Funktionsscores im IKDC und KOOS, welche sich auch im mittelfristigen Verlauf von zw{\"o}lf Monaten noch signifikant erh{\"o}ht gegen{\"u}ber ihren pr{\"a}operativen Werten zeigten. Die mediale Femurkondyle und knorpelige Patellar{\"u}ckfl{\"a}che waren im Registerkollektiv am h{\"a}ufigsten von Defekten betroffen. Meist handelte es sich hierbei um drittgradige Defekte nach ICRS degenerativer Genese. W{\"a}hrend das mechanische D{\´e}bridement bei großfl{\"a}chigem, arthrotischem Gelenkknorpelverschleiß keine suffiziente Therapieoption bietet, ist zum Nutzen und Effektivit{\"a}t des D{\´e}bridements bei fokalen, umschriebenen Gelenkknorpeldefekten bisher nur wenig bekannt. Im Registerkollektiv zeigte sich f{\"u}r das isoliert mechanische D{\´e}bridement von Gelenkknorpeldefekten eine signifikante Verbesserung der subjektiven Funktionsscores. Im Falle begleitend durchgef{\"u}hrter meniskuschirurgischer Eingriffe zeigt sich die Datenlage deutlich heterogener und bietet Anlass f{\"u}r weiteren wissenschaftlichen Diskurs.}, subject = {Hyaliner Knorpel}, language = {de} } @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{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{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{WeissenbergerHeinzRueckletal.2020, author = {Weissenberger, Manuel and Heinz, Tizian and Rueckl, Kilian and Rudert, Maximilian and Klug, Alexander and Hoffmann, Reinhard and Schmidt-Horloh{\´e}, Kay}, title = {No functional differences in anatomic reconstruction with one vs. two suture anchors after non-simultaneous bilateral distal biceps brachii tendon rupture: a case report and review of the literature}, series = {BMC Musculoskeletal Disorders}, volume = {21}, journal = {BMC Musculoskeletal Disorders}, doi = {10.1186/s12891-020-03304-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229266}, year = {2020}, abstract = {Background Surgical reattachment of the tendon is still the gold standard for ruptures of the distal biceps brachii tendon. Several fixation techniques have been described in the literature, with suture anchors being one of the most common fixation techniques. Currently, there is no data available on how many anchors are required for a safe and stable refixation. In this case report clinical data of a patient with non-simultaneous bilateral distal biceps tendon ruptures treated with a different number of suture anchors for each side (one vs. two) are demonstrated. Case presentation A 47-year-old factory worker suffered a rupture of the distal biceps tendon on both arms following two different occasions. The left side was fixed using a single suture anchor, while refixation on the right side was performed with two anchors. The patient was prospectively followed for one year. Functional outcome was assessed using the Andrews Carson Score (ACS), the Oxford Elbow Score (OES), and the Disabilities of Arm, Shoulder and Hand (DASH) Score after six, twelve, 24 and 48 weeks. Furthermore, an isokinetic strength measurement for flexion strength was performed after 24 and 48 weeks. After 48 weeks the patient presented with excellent functional outcome scores and no follow-up complications. During the follow-up period, no differences in the functional scores nor in the isokinetic flexion strength measurement could be detected. Furthermore, no radiological complications (like heterotopic ossifications) could be detected in the postoperative radiographs after one year. Conclusions Anatomic reattachment of the distal biceps tendon is a successful operative treatment option for distal biceps tendon ruptures. Suture anchor fixation remains one of the most common techniques, as it allows fast surgery and provides good results with respect to range of motion (ROM) and functional scoring according to the current literature. However, the number of anchors required for a stable fixation remains unclear. As indicated by our presented case, we hypothesize, that there are no significant differences between a one-point or a two-point fixation. In the presented case report, no intraindividual differences between the usage of one versus two suture anchors were evident in the short-term follow-up.}, language = {en} } @article{RakKlannHeinzetal.2023, author = {Rak, Dominik and Klann, Lukas and Heinz, Tizian and Anderson, Philip and Stratos, Ioannis and Nedopil, Alexander J. and Rudert, Maximilian}, title = {Influence of mechanical alignment on functional knee phenotypes and clinical outcomes in primary TKA: a 1-year prospective analysis}, series = {Journal of Personalized Medicine}, volume = {13}, journal = {Journal of Personalized Medicine}, number = {5}, issn = {2075-4426}, doi = {10.3390/jpm13050778}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313646}, year = {2023}, abstract = {In total knee arthroplasty (TKA), functional knee phenotypes are of interest regarding surgical alignment strategies. Functional knee phenotypes were introduced in 2019 and consist of limb, femoral, and tibial phenotypes. The hypothesis of this study was that mechanically aligned (MA) TKA changes preoperative functional phenotypes, which decreases the 1-year Forgotten Joint (FJS) and Oxford Knee Score (OKS) and increases the 1-year WOMAC. All patients included in this study had end-stage osteoarthritis and were treated with a primary MA TKA, which was supervised by four academic knee arthroplasty specialists. To determine the limb, femoral, and tibial phenotype, a long-leg radiograph (LLR) was imaged preoperatively and two to three days after TKA. FJS, OKS, and WOMAC were obtained 1 year after TKA. Patients were categorized using the change in functional limb, femoral, and tibial phenotype measured on LLR, and the scores were compared between the different categories. A complete dataset of preoperative and postoperative scores and radiographic images could be obtained for 59 patients. 42\% of these patients had a change of limb phenotype, 41\% a change of femoral phenotype, and 24\% a change of tibial phenotype of more than ±1 relative to the preoperative phenotype. Patients with more than ±1 change of limb phenotype had significantly lower median FJS (27 points) and OKS (31 points) and higher WOMAC scores (30 points) relative to the 59-, 41-, and 4-point scores of those with a 0 ± 1 change (p < 0.0001 to 0.0048). Patients with a more than ±1 change of femoral phenotype had significantly lower median FJS (28 points) and OKS (32 points) and higher WOMAC scores (24 points) relative to the 69-, 40-, and 8-point scores of those with a 0 ± 1 change (p < 0.0001). A change in tibial phenotype had no effect on the FJS, OKS, and WOMAC scores. Surgeons performing MA TKA could consider limiting coronal alignment corrections of the limb and femoral joint line to within one phenotype to reduce the risk of low patient-reported satisfaction and function at 1-year.}, 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} }