@article{BoelchGurokGilbertetal.2021,
  author    = {Boelch, Sebastian P. and Gurok, Anna and Gilbert, Fabian and Weißenberger, Manuel and Rudert, Maximilian and Barthel, Thomas and Reppenhagen, Stephan},
  title     = {Why compromise the patella? Five-year follow-up results of medial patellofemoral ligament reconstruction with soft tissue patellar fixation},
  series = {International Orthopaedics},
  volume    = {45},
  journal   = {International Orthopaedics},
  issn      = {0341-2695},
  doi       = {10.1007/s00264-020-04922-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-235751},
  pages     = {1493-1500},
  year      = {2021},
  abstract  = {Purpose This study investigates the redislocation rate and functional outcome at a minimum follow-up of five years after medial patellofemoral ligament (MPFL) reconstruction with soft tissue patellar fixation for patella instability. Methods Patients were retrospectively identified and knees were evaluated for trochlea dysplasia according to Dejour, for presence of patella alta and for presence of cartilage lesion at surgery. At a minimum follow-up of five years, information about an incident of redislocation was obtained. Kujala, Lysholm, and Tegner questionnaires as well as range of motion were used to measure functional outcome. Results Eighty-nine knees were included. Follow-up rate for redislocation was 79.8\% and for functional outcome 58.4\%. After a mean follow-up of 5.8 years, the redislocation rate was 5.6\%. There was significant improvement of the Kujala score (68.8 to 88.2, p = 0.000) and of the Lysholm score (71.3 to 88.4, p = 0.000). Range of motion at follow-up was 149.0° (115-165). 77.5\% of the knees had patella alta and 52.9\% trochlear dysplasia types B, C, or D. Patellar cartilage legions were present in 54.2\%. Redislocations occurred in knees with trochlear dysplasia type C in combination with patella alta. Conclusion MPFL reconstruction with soft tissue patellar fixation leads to significant improvement of knee function and low midterm redislocation rate. Patients with high-grade trochlear dysplasia should be considered for additional osseous correction.},
  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{RudertHorasHobergetal.2016,
  author    = {Rudert, Maximilian and Horas, Konstantin and Hoberg, Maik and Steinert, Andre and Holzapfel, Dominik Emanuel and H{\"u}bner, Stefan and Holzapfel, Boris Michael},
  title     = {The Wuerzburg procedure: the tensor fasciae latae perforator is a reliable anatomical landmark to clearly identify the Hueter interval when using the minimally-invasive direct anterior approach to the hip joint},
  series = {BMC Musculoskeletal Disorders},
  volume    = {17},
  journal   = {BMC Musculoskeletal Disorders},
  number    = {57},
  doi       = {10.1186/s12891-016-0908-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-146031},
  year      = {2016},
  abstract  = {Background The key for successful delivery in minimally-invasive hip replacement lies in the exact knowledge about the surgical anatomy. The minimally-invasive direct anterior approach to the hip joint makes it necessary to clearly identify the tensor fasciae latae muscle in order to enter the Hueter interval without damaging the lateral femoral cutaneous nerve. However, due to the inherently restricted overview in minimally-invasive surgery, this can be difficult even for experienced surgeons. Methods and Surgical Technique In this technical note, we demonstrate for the first time how to use the tensor fasciae latae perforator as anatomical landmark to reliably identify the tensor fasciae latae muscle in orthopaedic surgery. Such perforators are used for flaps in plastic surgery as they are constant and can be found at the lateral third of the tensor fasciae latae muscle in a direct line from the anterior superior iliac spine. Conclusion As demonstrated in this article, a simple knowledge transfer between surgical disciplines can minimize the complication rate associated with minimally-invasive hip replacement.},
  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{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{SteinertSchroederSefrinetal.2022,
  author    = {Steinert, Andre F. and Schr{\"o}der, Lennart and Sefrin, Lukas and Janßen, Bj{\"o}rn and Arnholdt, J{\"o}rg and Rudert, Maximilian},
  title     = {The impact of total knee replacement with a customized cruciate-retaining implant design on patient-reported and functional outcomes},
  series = {Journal of Personalized Medicine},
  volume    = {12},
  journal   = {Journal of Personalized Medicine},
  number    = {2},
  issn      = {2075-4426},
  doi       = {10.3390/jpm12020194},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312746},
  year      = {2022},
  abstract  = {Purpose: To treat patients with tricompartimental knee osteoarthritis (OA), a customized cruciate-retaining total knee arthroplasty (CCR-TKA) system can be used, including both individualized instrumentation and implants. The objective of this monocentric cohort study was to analyze patient-reported and functional outcomes in a series of patients implanted with the second generation of this customized implant. Methods: At our arthroplasty center, we prospectively recruited a cohort of patients with tricompartmental gonarthrosis to be treated with total knee replacement (TKA) using a customized cruciate-retaining (CCR) implant design. Inclusion criteria for patients comprised the presence of intact posterior cruciate and collateral ligaments and a knee deformity that was restricted to <15° varus, valgus, or flexion contracture. Patients were assessed for their range of motion (ROM), Knee Society Score (KSS), Western Ontario and McMaster University osteoarthritis index (WOMAC), and short form (SF)-12 physical and mental scores, preoperatively, at 3 and 6 months, as well as at 1, 2, 3, and 5 years of follow-up (FU) postoperatively. Results: The average age of the patient population was 64 years (range: 40-81), the average BMI was 31 (range: 23-42), and in total, 28 female and 45 male patients were included. Implant survivorship was 97.5\% (one septic loosening) at an average follow-up of 2.5 years. The KSS knee and function scores improved significantly (p < 0.001) from, respectively, 41 and 53 at the pre-operative visit, to 92 and 86, respectively, at the 5-year post-operative time point. The SF-12 Physical and Mental scores significantly (p < 0.001) improved from the pre-operative values of 28 and 50, to 50 and 53 at the 5-year FU, respectively. Patients experienced significant improvements in their overall knee range of motion, from 106° at the preoperative visit to 122°, on average, 5 years postoperatively. The total WOMAC score significantly (p < 0.001) improved from 49.1 preoperatively to 11.4 postoperatively at 5-year FU. Conclusions: Although there was no comparison to other implants within this study, patients reported high overall satisfaction and improvement in functional outcomes within the first year from surgery, which continued over the following years. These mid-term results are excellent compared with those reported in the current literature. Comparative long-term studies with this device are needed. Level of evidence 3b (individual case-control study).},
  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{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{Rudert2022,
  author    = {Rudert, Maximilian},
  title     = {Taking the next step in personalised orthopaedic implantation},
  series = {Journal of Personalized Medicine},
  volume    = {12},
  journal   = {Journal of Personalized Medicine},
  number    = {3},
  issn      = {2075-4426},
  doi       = {10.3390/jpm12030365},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262089},
  year      = {2022},
  abstract  = {No abstract available},
  language  = {en}
}
@article{BoelchRothArnholdtetal.2018,
  author    = {Boelch, Sebastian P. and Roth, Magnus and Arnholdt, Joerg and Rudert, Maximilian and Luedemann, Martin},
  title     = {Synovial fluid aspiration should not be routinely performed during the two-stage exchange of the knee},
  series = {BioMed Research International},
  volume    = {2018},
  journal   = {BioMed Research International},
  number    = {6720712},
  doi       = {10.1155/2018/6720712},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-176800},
  year      = {2018},
  abstract  = {Purpose. Detection of infection persistence during the two-stage exchange of the knee for periprosthetic joint infection is challenging. Synovial fluid culture (SFC) and synovial white blood cell count (SWBCC) before joint reimplantation are widespread diagnostic means for this indication. The sensitivity and specificity of SFC and of SWBCC for infection persistence before planned reimplantation were evaluated. Methods. 94 two-stage exchanges of the knee with synovial fluid aspiration performed after a drug holiday of at least 14 days and before reimplantation or spacer exchange (planned reimplantation) were retrospectively analyzed. Only cases with at least 3 intraoperative samples at planned reimplantation were included. SFC and SWBCC were compared to pathogen detection (SFC\(_{(culture)}\)/SWBCC\(_{(culture)}\) and to histopathological signs of infection persistence (SFC\(_{(histo)}\)/SWBCC\(_{(histo)}\) from intraoperative samples at planned reimplantation. For SFC, the sensitivity and specificity were calculated. For SWBCC, the optimal cut-off value with its sensitivity and specificity was calculated with the Youden-Index. Results. Sensitivity and specificity of SFC\(_{(culture)}\) were 0.0\% and 98.9\%. Sensitivity and specificity of SFC\(_{(histo)}\) were 3.4\% and 100\%. The optimal cut-off value for SWBCC\(_{(culture)}\) was 4450 cells/μl with a sensitivity of 50.0\% and a specificity of 86.5\%. The optimal cut-off value for SWBCC\(_{(histo)}\) was 3250 cells/μl with a sensitivity of 35.7\% and a specificity of 92.9\%. Conclusion. The detection of infection persistence remains challenging and a consented approach is lacking. The results do not warrant the routine performance of SFC during the two-stage exchange at the knee. SWBCC can be used to confirm infection persistence at high cut-offs, but they only occur in few patients and are therefore inappropriate for the routine use.},
  language  = {en}
}