@article{HacklBuessKammerlohretal.2021,
  author    = {Hackl, Michael and Buess, Eduard and Kammerlohr, Sandra and Nacov, Julia and Staat, Manfred and Leschinger, Tim and M{\"u}ller, Lars P. and Wegmann, Kilian},
  title     = {A "comma sign"-directed subscapularis repair in anterosuperior rotator cuff tears yields biomechanical advantages in a cadaveric model},
  series = {The american journal of sports medicine},
  volume    = {49},
  journal   = {The american journal of sports medicine},
  number    = {12},
  publisher = {Sage},
  address   = {London},
  issn      = {1552-3365},
  doi       = {10.1177/03635465211031506},
  pages     = {3212 -- 3217},
  year      = {2021},
  abstract  = {Background: Additional stabilization of the "comma sign" in anterosuperior rotator cuff repair has been proposed to provide biomechanical benefits regarding stability of the repair. Purpose: This in vitro investigation aimed to investigate the influence of a comma sign-directed reconstruction technique for anterosuperior rotator cuff tears on the primary stability of the subscapularis tendon repair. Study Design: Controlled laboratory study. Methods: A total of 18 fresh-frozen cadaveric shoulders were used in this study. Anterosuperior rotator cuff tears (complete full-thickness tear of the supraspinatus and subscapularis tendons) were created, and supraspinatus repair was performed with a standard suture bridge technique. The subscapularis was repaired with either a (1) single-row or (2) comma sign technique. A high-resolution 3D camera system was used to analyze 3-mm and 5-mm gap formation at the subscapularis tendon-bone interface upon incremental cyclic loading. Moreover, the ultimate failure load of the repair was recorded. A Mann-Whitney test was used to assess significant differences between the 2 groups. Results: The comma sign repair withstood significantly more loading cycles than the single-row repair until 3-mm and 5-mm gap formation occurred (P≤ .047). The ultimate failure load did not reveal any significant differences when the 2 techniques were compared (P = .596). Conclusion: The results of this study show that additional stabilization of the comma sign enhanced the primary stability of subscapularis tendon repair in anterosuperior rotator cuff tears. Although this stabilization did not seem to influence the ultimate failure load, it effectively decreased the micromotion at the tendon-bone interface during cyclic loading. Clinical Relevance: The proposed technique for stabilization of the comma sign has shown superior biomechanical properties in comparison with a single-row repair and might thus improve tendon healing. Further clinical research will be necessary to determine its influence on the functional outcome.},
  language  = {en}
}
@article{Staat2021,
  author    = {Staat, Manfred},
  title     = {An extension strain type Mohr-Coulomb criterion},
  series = {Rock mechanics and rock engineering},
  volume    = {54},
  journal   = {Rock mechanics and rock engineering},
  number    = {12},
  publisher = {Springer Nature},
  address   = {Cham},
  issn      = {1434-453X},
  doi       = {10.1007/s00603-021-02608-7},
  pages     = {6207 -- 6233},
  year      = {2021},
  abstract  = {Extension fractures are typical for the deformation under low or no confining pressure. They can be explained by a phenomenological extension strain failure criterion. In the past, a simple empirical criterion for fracture initiation in brittle rock has been developed. In this article, it is shown that the simple extension strain criterion makes unrealistic strength predictions in biaxial compression and tension. To overcome this major limitation, a new extension strain criterion is proposed by adding a weighted principal shear component to the simple criterion. The shear weight is chosen, such that the enriched extension strain criterion represents the same failure surface as the Mohr-Coulomb (MC) criterion. Thus, the MC criterion has been derived as an extension strain criterion predicting extension failure modes, which are unexpected in the classical understanding of the failure of cohesive-frictional materials. In progressive damage of rock, the most likely fracture direction is orthogonal to the maximum extension strain leading to dilatancy. The enriched extension strain criterion is proposed as a threshold surface for crack initiation CI and crack damage CD and as a failure surface at peak stress CP. Different from compressive loading, tensile loading requires only a limited number of critical cracks to cause failure. Therefore, for tensile stresses, the failure criteria must be modified somehow, possibly by a cut-off corresponding to the CI stress. Examples show that the enriched extension strain criterion predicts much lower volumes of damaged rock mass compared to the simple extension strain criterion.},
  language  = {en}
}
@article{HacklNacovKammerlohretal.2021,
  author    = {Hackl, Michael and Nacov, Julia and Kammerlohr, Sandra and Staat, Manfred and Buess, Eduard and Leschinger, Tim and M{\"u}ller, Lars P. and Wegmann, Kilian},
  title     = {Intratendinous Strain Variations of the Supraspinatus Tendon Depending on Repair Technique: A Biomechanical Analysis Regarding the Cause of Medial Cuff Failure},
  series = {The American Journal of Sports Medicine},
  volume    = {49},
  journal   = {The American Journal of Sports Medicine},
  number    = {7},
  publisher = {Sage},
  address   = {London},
  issn      = {1552-3365},
  doi       = {10.1177/03635465211006138},
  pages     = {1847 -- 1853},
  year      = {2021},
  language  = {en}
}
@incollection{DuongNguyenStaat2017,
  author    = {Duong, Minh Tuan and Nguyen, Nhu Huynh and Staat, Manfred},
  title     = {Physical response of hyperelastic models for composite materials and soft tissues},
  series = {Advances in Composite Material},
  booktitle = {Advances in Composite Material},
  publisher = {Scientific Research Publishing},
  address   = {Wuhan},
  isbn      = {978-1-61896-300-0 (Hardcover), 978-1-61896-299-7 (Paperback)},
  pages     = {316},
  year      = {2017},
  language  = {en}
}
@article{HorbachDuongStaat2017,
  author    = {Horbach, Andreas and Duong, Minh Tuan and Staat, Manfred},
  title     = {Modelling of compressible and orthotropic surgical mesh implants based on optical deformation measurement},
  series = {Journal of the mechanical behavior of biomedical materials},
  volume    = {74},
  journal   = {Journal of the mechanical behavior of biomedical materials},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1751-6161},
  doi       = {10.1016/j.jmbbm.2017.06.012},
  pages     = {400 -- 410},
  year      = {2017},
  language  = {en}
}
@article{MichaelMayerWeberetal.2017,
  author    = {Michael, Hackl and Mayer, Katharina and Weber, Mareike and Staat, Manfred and van Riet, Roger and Burkhart, Klau Josef and M{\"u}ller, Lars Peter and Wegmann, Kilian},
  title     = {Plate osteosynthesis of proximal ulna fractures : a biomechanical micromotion analysis},
  series = {The journal of hand surgery},
  volume    = {42},
  journal   = {The journal of hand surgery},
  number    = {10},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0363-5023},
  doi       = {10.1016/j.jhsa.2017.05.014},
  pages     = {834.e1 -- 834.e7},
  year      = {2017},
  language  = {en}
}
@inproceedings{AbelPerezVianaCiritsisetal.2017,
  author    = {Abel, Alexander and P{\´e}rez-Viana, Daniel and Ciritsis, Bernard and Staat, Manfred},
  title     = {Prevention of femur neck fractures through femoroplasty},
  series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  editor    = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus},
  publisher = {Universit{\"a}t Duisburg-Essen},
  address   = {Duisburg},
  organization    = {MedTech Symposium},
  isbn      = {978-3-9814801-9-1},
  doi       = {10.17185/duepublico/43984},
  pages     = {114 -- 115},
  year      = {2017},
  language  = {en}
}
@inproceedings{BirgelLeschingerWegmannetal.2017,
  author    = {Birgel, Stefan and Leschinger, Tim and Wegmann, Kilian and Staat, Manfred},
  title     = {Calculation of muscle forces and joint reaction loads in shoulder area via an OpenSim based computer calculation},
  series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  editor    = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus},
  publisher = {Universit{\"a}t Duisburg-Essen},
  address   = {Duisburg},
  organization    = {MedTech Symposium},
  isbn      = {978-3-9814801-9-1},
  doi       = {10.17185/duepublico/43984},
  pages     = {116 -- 117},
  year      = {2017},
  language  = {en}
}
@inproceedings{JabbariBhattaraiAndingetal.2017,
  author    = {Jabbari, Medisa and Bhattarai, Aroj and Anding, Ralf and Staat, Manfred},
  title     = {Biomechanical simulation of different prosthetic meshes for repairing uterine/vaginal vault prolapse},
  series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  editor    = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus},
  publisher = {Universit{\"a}t Duisburg-Essen},
  address   = {Duisburg},
  organization    = {MedTech Symposium},
  isbn      = {978-3-9814801-9-1},
  doi       = {10.17185/duepublico/43984},
  pages     = {118 -- 119},
  year      = {2017},
  language  = {en}
}
@article{BhattaraiJabbariAndingetal.2018,
  author    = {Bhattarai, Aroj and Jabbari, Medisa and Anding, Ralf and Staat, Manfred},
  title     = {Surgical treatment of vaginal vault prolapse using different prosthetic mesh implants: a finite element analysis},
  series = {tm - Technisches Messen},
  volume    = {85},
  journal   = {tm - Technisches Messen},
  number    = {5},
  publisher = {De Gruyter},
  address   = {Berlin},
  issn      = {2196-7113},
  doi       = {10.1515/teme-2017-0115},
  pages     = {331 -- 342},
  year      = {2018},
  abstract  = {Particularly multiparous elderly women may suffer from vaginal vault prolapse after hysterectomy due to weak support from lax apical ligaments. A decreased amount of estrogen and progesterone in older age is assumed to remodel the collagen thereby reducing tissue stiffness. Sacrocolpopexy is either performed as open or laparoscopic surgery using prosthetic mesh implants to substitute lax ligaments. Y-shaped mesh models (DynaMesh, Gynemesh, and Ultrapro) are implanted in a 3D female pelvic floor finite element model in the extraperitoneal space from the vaginal cuff to the first sacral (S1) bone below promontory. Numerical simulations are conducted during Valsalva maneuver with weakened tissues modeled by reduced tissue stiffness. Tissues are modeled as incompressible, isotropic hyperelastic materials whereas the meshes are modeled either as orthotropic linear elastic or as isotropic hyperlastic materials. The positions of the vaginal cuff and the bladder base are calculated from the pubococcygeal line for female pelvic floor at rest, for prolapse and after repair using the three meshes. Due to mesh mechanics and mesh pore deformation along the loaded direction, the DynaMesh with regular rectangular mesh pores is found to provide better mechanical support to the organs than the Gynemesh and the Ultrapro with irregular hexagonal mesh pores. Insbesondere {\"a}ltere, mehrgeb{\"a}hrende Frauen leiden h{\"a}ufiger an einem Scheidenvorfall nach einer Hysterektomie aufgrund der schwachen Unterst{\"u}tzung durch laxe apikale B{\"a}nder. Es wird angenommen, dass eine verringerte Menge an {\"O}strogen und Progesteron im h{\"o}heren Alter das Kollagen umformt, wodurch die Gewebesteifigkeit reduziert wird. Die Sakrokolpopexie ist eine offene oder laparoskopische Operation, die mit prothetischen Netzimplantaten durchgef{\"u}hrt wird, um laxe B{\"a}nder zu ersetzen. Y-f{\"o}rmige Netzmodelle (DynaMesh, Gynemesh und Ultrapro) werden in einem 3D-Modell des weiblichen Beckenbodens im extraperitonealen Raum vom Vaginalstumpf bis zum Promontorium implantiert. Numerische Simulationen werden w{\"a}hrend des Valsalva-Man{\"o}vers mit geschw{\"a}chtem Gewebe durchgef{\"u}hrt, das durch eine reduzierte Gewebesteifigkeit modelliert wird. Die Gewebe werden als inkompressible, isotrop hyperelastische Materialien modelliert, w{\"a}hrend die Netze entweder als orthotrope linear elastische oder als isotrope hyperlastische Materialien modelliert werden. Die Positionen des Vaginalstumpfs, der Blase und der Harnr{\"o}hrenachse werden anhand der Pubococcygeallinie aus der Ruhelage, f{\"u}r den Prolaps und nach der Reparatur unter Verwendung der drei Netze berechnet. Aufgrund der Netzmechanik und der Netzporenverformung bietet das DynaMesh mit regelm{\"a}ßigen rechteckigen Netzporen eine bessere mechanische Unterst{\"u}tzung und eine Neupositionierung des Scheidengew{\"o}lbes, der Blase und der Urethraachse als Gynemesh und Ultrapro mit unregelm{\"a}ßigen hexagonalen Netzporen.},
  language  = {en}
}