Refine
Year of publication
Document Type
- Article (132) (remove)
Keywords
- Einspielen <Werkstoff> (7)
- FEM (4)
- Finite-Elemente-Methode (4)
- shakedown analysis (3)
- Einspielanalyse (2)
- Shakedown analysis (2)
- Traglastanalyse (2)
- damage (2)
- limit analysis (2)
- shakedown (2)
- Alternating plasticity (1)
- Analytischer Zulaessigkeitsnachweis (1)
- Anastomotic leakage (1)
- Arthosetherapie (1)
- Aufschlagversuch (1)
- Autolysis (1)
- Axialbelastung (1)
- Axially cracked pipe (1)
- Basis Reduktion (1)
- Basis reduction (1)
- Bicharakteristikenverfahren (1)
- Biocomposites (1)
- Cardiac myocytes (1)
- Cardiac tissue (1)
- CellDrum (1)
- Computational biomechanics (1)
- Constitutive model (1)
- Convex optimization (1)
- Damage mechanics theory (1)
- Decomposition (1)
- Deformation (1)
- Design-by-analysis (1)
- Discontinuous fractures (1)
- Distorsion des oberen Sprunggelenks (1)
- Druckbeanspruchung (1)
- Druckbehälter (1)
- Druckbelastung (1)
- Druckgeräte (1)
- Drug simulation (1)
- ES-FEM (1)
- Einspiel-Analyse (1)
- Einspiel-Kriterium (1)
- Einspielen (1)
- Elastizität (1)
- Electromechanical modeling (1)
- End-to-end colorectal anastomosis (1)
- FS-FEM (1)
- Fehlerstellen (1)
- Finite element analysis (1)
- Finite element modelling (1)
- Fließgrenze (1)
- Freeze–thaw process (1)
- Frequency adaption (1)
- Fußball (1)
- Global and local collapse (1)
- Gonarthrose (1)
- Grenzwertberechnung (1)
- Heart tissue culture (1)
- Hodgkin–Huxley models (1)
- Homogenization (1)
- Induced pluripotent stem cells (1)
- Inotropic compounds (1)
- Ion channels (1)
- Kniegelenkarthrose (1)
- Knochen (1)
- Knochenbildung (1)
- Knochenchirugie (1)
- Knochendichte (1)
- Limit analysis (1)
- Liver (1)
- MBST (1)
- Materialermüdung (1)
- Natural fibres (1)
- Non-parallel fissures (1)
- Pharmacology (1)
- Plastizität (1)
- Polymer-matrix composites (1)
- Pressure loaded crack-face (1)
- Progressive plastic deformation (1)
- Ratchetting (1)
- Rohr (1)
- Rohrbruch (1)
- S-FEM (1)
- Schienbeinschoner (1)
- Schwammknochen (1)
- Shakedown (1)
- Shakedown criterion (1)
- Spleen (1)
- Sprunggelenkorthesen (1)
- Stahl (1)
- Stress concentrations (1)
- Strukturanalyse (1)
- Surgical staplers (1)
- Temperaturabhängigkeit (1)
- Traglast (1)
- Uniaxial compression test (1)
- Variable height stapler design (1)
- Wolff's Law (1)
- Wolffsches Gesetz (1)
- Zug-Druck Belastung (1)
- alternierend Verformbarkeit (1)
- anaesthetic complications (1)
- anisotropy (1)
- ankle braces (1)
- ankle sprain (1)
- arthrosis therapy (1)
- biaxial tensile experiment (1)
- bicharacteristics (1)
- bone density (1)
- bone structure (1)
- burst pressure (1)
- burst tests (1)
- cancellous bone (1)
- chance constrained programming (1)
- constitutive modeling (1)
- dental trauma (1)
- difficult airway (1)
- direct method (1)
- distorted element (1)
- double-lumen tube intubation (1)
- elastic solids (1)
- fatigue analyses (1)
- fibulare Bandruptur (1)
- flaw (1)
- fortschreitende plastische Deformation (1)
- gonarthrosis (1)
- hiPS cardiomyocytes (1)
- hyperelastic (1)
- konvexe Optimierung (1)
- limit load (1)
- load limit (1)
- non-simplex S-FEM elements (1)
- pipes (1)
- ratchetting (1)
- reliability analysis (1)
- reliability of structures (1)
- rupture of the fibular ligament (1)
- shakedown analyses (1)
- smooth muscle contraction (1)
- stochastic programming (1)
- strain energy function (1)
- tension–torsion loading (1)
- thermal ratcheting (1)
- vessels (1)
- videolaryngoscopy (1)
- virgin passive (1)
- viscoelasticity (1)
- yield stress (1)
Institute
Surgical reconstruction of the interosseous membrane (IOM) could restore longitudinal forearm stability to avoid persisting disability due to capituloradial and ulnocarpal impingement in Essex Lopresti lesions. This biomechanical study aimed to assess longitudinal forearm stability of intact specimens, after sectioning of the IOM and after reconstruction with a TightRope construct using either a single or double bundle technique.
Plate osteosynthesis of displaced proximal phalangeal neck fractures of the hand allows early mobilization due to a stable internal fixation. Nevertheless, joint stiffness—because of soft tissue irritation—represents a common complication leading to high complication rates. Del Pinal et al. recently reported promising clinical results for a new, minimally invasive fixation technique with a cannulated headless intramedullary compression screw. Hence, the aim of this study was to compare plate fixation of proximal phalangeal neck fractures to less two less invasive techniques: Crossed k-wire fixation and intramedullary screw fixation. We hypothesized that these fixation techniques provide inferior stability when compared to plate osteosynthesis.
Pressure distribution to the distal biceps tendon at the radial tuberosity: a biomechanical study
(2020)
Purpose
Mechanical impingement at the narrow radioulnar space of the tuberosity is believed to be an etiological factor in the injury of the distal biceps tendon. The aim of the study was to compare the pressure distribution at the proximal radioulnar space between 2 fixation techniques and the intact state.
Methods
Six right arms and 6 left arms from 5 female and 6 male frozen specimens were used for this study. A pressure transducer was introduced at the height of the radial tuberosity with the intact distal biceps tendon and after 2 fixation methods: the suture-anchor and the cortical button technique. The force (N), maximum pressure (kPa) applied to the radial tuberosity, and the contact area (mm²) of the radial tuberosity with the ulna were measured and differences from the intact tendon were detected from 60° supination to 60° pronation in 15° increments with the elbow in full extension and in 45° and 90° flexion of the elbow.
Results
With the distal biceps tendon intact, the pressures during pronation were similar regardless of extension and flexion and were the highest at 60° pronation with 90° elbow flexion (23.3 ± 53.5 kPa). After repair of the tendon, the mean peak pressure, contact area, and total force showed an increase regardless of the fixation technique. Highest peak pressures were found using the cortical button technique at 45° flexion of the elbow and 60° pronation. These differences were significantly different from the intact tendon. The contact area was significantly larger in full extension and 15°, 30°, and 60° pronation using the cortical button technique.
Conclusions
Pressures on the distal biceps tendon at the radial tuberosity increase during pronation, especially after repair of the tendon.
Clinical relevance
Mechanical impingement could play a role in both the etiology of primary distal biceps tendon ruptures and the complications occurring after fixation of the tendon using certain techniques.
Postural and metabolic benefits of using a forearm support walker in older adults with impairments
(2019)
Purpose
In vivo, a loss of mesh porosity triggers scar tissue formation and restricts functionality. The purpose of this study was to evaluate the properties and configuration changes as mesh deformation and mesh shrinkage of a soft mesh implant compared with a conventional stiff mesh implant in vitro and in a porcine model.
Material and Methods
Tensile tests and digital image correlation were used to determine the textile porosity for both mesh types in vitro. A group of three pigs each were treated with magnetic resonance imaging (MRI) visible conventional stiff polyvinylidene fluoride meshes (PVDF) or with soft thermoplastic polyurethane meshes (TPU) (FEG Textiltechnik mbH, Aachen, Germany), respectively. MRI was performed with a pneumoperitoneum at a pressure of 0 and 15 mmHg, which resulted in bulging of the abdomen. The mesh-induced signal voids were semiautomatically segmented and the mesh areas were determined. With the deformations assessed in both mesh types at both pressure conditions, the porosity change of the meshes after 8 weeks of ingrowth was calculated as an indicator of preserved elastic properties. The explanted specimens were examined histologically for the maturity of the scar (collagen I/III ratio).
Results
In TPU, the in vitro porosity increased constantly, in PVDF, a loss of porosity was observed under mild stresses. In vivo, the mean mesh areas of TPU were 206.8 cm2 (± 5.7 cm2) at 0 mmHg pneumoperitoneum and 274.6 cm2 (± 5.2 cm2) at 15 mmHg; for PVDF the mean areas were 205.5 cm2 (± 8.8 cm2) and 221.5 cm2 (± 11.8 cm2), respectively. The pneumoperitoneum-induced pressure increase resulted in a calculated porosity increase of 8.4% for TPU and of 1.2% for PVDF. The mean collagen I/III ratio was 8.7 (± 0.5) for TPU and 4.7 (± 0.7) for PVDF.
Conclusion
The elastic properties of TPU mesh implants result in improved tissue integration compared to conventional PVDF meshes, and they adapt more efficiently to the abdominal wall. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 827–833, 2018.
Improved collapse loads of thick-walled, crack containing pipes and vessels are suggested. Very deep cracks have a residual strength which is better modelled by a global limit load. In all burst tests, the ductility of pressure vessel steels was sufficiently high whereby the burst pressure could be predicted by limit analysis with no need to apply fracture mechanics. The relative prognosis error increases however, for long and deep defects due to uncertainties of geometry and strength data.
Der vorliegende Artikel fokussiert sich auf die weibliche Belastungsinkontinenz als Insuffizienz der Speicherfunktion der Blase, auch wenn im klinischen Alltag die Harninkontinenz der Frau häufig verschiedene Ursachen hat und insbesondere eine Belastungsinkontinenz im Alter und bei neurologischer Komorbidität nur selten isoliert vorkommt.
Das kleine Becken der Frau ist sowohl als Funktions- als auch als strukturelle Einheit zu betrachten. Dabei unterliegen bei der Frau Blase, Harnröhre, Gebärmutter und Enddarm sowie die muskulären und ligamentösen Strukturen des kleinen Beckens durch Fertilitätsphase, mögliche Schwangerschaften, Geburten und Menopausen-Phase, über das „normale Altern“ hinaus, gravierenden Veränderungen.
This article focuses on female stress incontinence in the form of pelvic floor dysfunction and urethral sphincter deficiency, although isolated stress incontinence accounts for less than half of all incontinence cases. Especially in women of old age and those with neurological comorbidities, the causes of incontinence are mostly multifactorial. Also it has to be considered that the female bladder, urethra, uterus and rectum as well as the muscular and ligamentous structures of the female pelvis minor are affected by phases of fertility, possible pregnancies, births and menopause in addition to the normal ageing process.
Purpose
The aim of this study was to compare several osteosynthesis techniques (intramedullary headless compression screws, T-plates, and Kirschner wires) for distal epiphyseal fractures of proximal phalanges in a human cadaveric model.
Methods
A total of 90 proximal phalanges from 30 specimens (index, ring, and middle fingers) were used for this study. After stripping off all soft tissue, a transverse distal epiphyseal fracture was simulated at the proximal phalanx. The 30 specimens were randomly assigned to 1 fixation technique (30 per technique), either a 3.0-mm intramedullary headless compression screw, locking plate fixation with a 2.0-mm T-plate, or 2 oblique 1.0-mm Kirschner wires. Displacement analysis (bending, distraction, and torsion) was performed using optical tracking of an applied random speckle pattern after osteosynthesis. Biomechanical testing was performed with increasing cyclic loading and with cyclic load to failure using a biaxial torsion-tension testing machine.
Results
Cannulated intramedullary compression screws showed significantly less displacement at the fracture site in torsional testing. Furthermore, screws were significantly more stable in bending testing. Kirschner wires were significantly less stable than plating or screw fixation in any cyclic load to failure test setup.
Conclusions
Intramedullary compression screws are a highly stable alternative in the treatment of transverse distal epiphyseal phalangeal fractures. Kirschner wires seem to be inferior regarding displacement properties and primary stability.
Clinical relevance
Fracture fixation of phalangeal fractures using plate osteosynthesis may have the advantage of a very rigid reduction, but disadvantages such as stiffness owing to the more invasive surgical approach and soft tissue irritation should be taken into account. Headless compression screws represent a minimally invasive choice for fixation with good biomechanical properties.
The porosity of surgical meshes makes them flexible for large elastic deformation and establishes the healing conditions of good tissue in growth. The biomechanic modeling of orthotropic and compressible materials requires new materials models and simulstaneoaus fit of deformation in the load direction as well as trannsversely to to load. This nonlinear modeling can be achieved by an optical deformation measurement. At the same time the full field deformation measurement allows the dermination of the change of porosity with deformation. Also the socalled effective porosity, which has been defined to asses the tisssue interatcion with the mesh implants, can be determined from the global deformation of the surgical meshes.