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Author

  • Kilian Wegmann (19)
  • Manfred Staat (18)
  • Michael Hackl (12)
  • Stephanie Lucina Kahmann (8)
  • Tim Leschinger (8)
  • Lars P. Müller (7)
  • Lars-Peter Müller (5)
  • Lars Peter Müller (4)
  • Martin Scaal (3)
  • Stefan Birgel (3)
  • Wolfram F. Neiss (3)
  • Eduard Buess (2)
  • Julia Nacov (2)
  • Katharina Mayer (2)
  • Nicolai Heinze (2)
  • Sandra Kammerlohr (2)
  • Valentin Rausch (2)
  • Andreas Harbrecht (1)
  • Cansu Aydin (1)
  • Carolin Meyer (1)
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  • 2022 (1)
  • 2021 (2)
  • 2020 (2)
  • 2019 (3)
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  • 2017 (4)
  • 2016 (5)

Document Type

  • Article (15)
  • Conference Proceeding (3)
  • Other (1)

Keywords

  • Biomechanical simulation (1)
  • Fracture configuration (1)
  • Fracture simulation (1)
  • Proximal humerus fracture (1)
  • Rotator cuff (1)

Institute

  • IfB - Institut für Bioengineering (19)
  • Fachbereich Medizintechnik und Technomathematik (18)

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Influence of rotator cuff preload on fracture configuration in proximal humerus fractures: a proof of concept for fracture simulation (2022)
Maximilian Lenz ; Stephanie Lucina Kahmann ; Mehdi Behbahani ; Lenhard Pennig ; Michael Hackl ; Tim Leschinger ; Lars Peter Müller ; Kilian Wegmann
Introduction In regard of surgical training, the reproducible simulation of life-like proximal humerus fractures in human cadaveric specimens is desirable. The aim of the present study was to develop a technique that allows simulation of realistic proximal humerus fractures and to analyse the influence of rotator cuff preload on the generated lesions in regards of fracture configuration. Materials and methods Ten cadaveric specimens (6 left, 4 right) were fractured using a custom-made drop-test bench, in two groups. Five specimens were fractured without rotator cuff preload, while the other five were fractured with the tendons of the rotator cuff preloaded with 2 kg each. The humeral shaft and the shortened scapula were potted. The humerus was positioned at 90° of abduction and 10° of internal rotation to simulate a fall on the elevated arm. In two specimens of each group, the emergence of the fractures was documented with high-speed video imaging. Pre-fracture radiographs were taken to evaluate the deltoid-tuberosity index as a measure of bone density. Post-fracture X-rays and CT scans were performed to define the exact fracture configurations. Neer’s classification was used to analyse the fractures. Results In all ten cadaveric specimens life-like proximal humerus fractures were achieved. Two III-part and three IV-part fractures resulted in each group. The preloading of the rotator cuff muscles had no further influence on the fracture configuration. High-speed videos of the fracture simulation revealed identical fracture mechanisms for both groups. We observed a two-step fracture mechanism, with initial impaction of the head segment against the glenoid followed by fracturing of the head and the tuberosities and then with further impaction of the shaft against the acromion, which lead to separation of the tuberosities. Conclusion A high energetic axial impulse can reliably induce realistic proximal humerus fractures in cadaveric specimens. The preload of the rotator cuff muscles had no influence on initial fracture configuration. Therefore, fracture simulation in the proximal humerus is less elaborate. Using the presented technique, pre-fractured specimens are available for real-life surgical education.
Kyphoplasty of Osteoporotic Fractured Vertebrae: A Finite Element Analysis about Two Types of Cement (2019)
Carolin Meyer ; Kerstin van Gaalen ; Tim Leschinger ; Max J. Scheyerer ; Wolfram F. Neiss ; Manfred Staat ; Lars P. Müller ; Kilian Wegmann
A "comma sign"-directed subscapularis repair in anterosuperior rotator cuff tears yields biomechanical advantages in a cadaveric model (2021)
Michael Hackl ; Eduard Buess ; Sandra Kammerlohr ; Julia Nacov ; Manfred Staat ; Tim Leschinger ; Lars P. Müller ; Kilian Wegmann
Intratendinous Strain Variations of the Supraspinatus Tendon Depending on Repair Technique: A Biomechanical Analysis Regarding the Cause of Medial Cuff Failure (2021)
Michael Hackl ; Julia Nacov ; Sandra Kammerlohr ; Manfred Staat ; Eduard Buess ; Tim Leschinger ; Lars P. Müller ; Kilian Wegmann
Osteosynthesis of Phalangeal Fractures: Biomechanical Comparison of Kirschner Wires, Plates, and Compression Screws (2020)
Valentin Rausch ; Andreas Harbrecht ; Stephanie Lucina Kahmann ; Thomas Fenten ; Nebojsa Jovanovic ; Michael Hackl ; Lars P. Müller ; Manfred Staat ; Kilian Wegmann
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.
Radial shortening osteotomy reduces radiocapitellar contact pressures while preserving valgus stability of the elbow (2017)
Michael Hackl ; Kilian Wegmann ; Stephanie Lucina Kahmann ; Nicolai Heinze ; Manfred Staat ; Wolfram F. Neiss ; Martin Scaal ; Lars P. Müller
A musculoskeletal shoulder simulation of moment arms and joint reaction forces after medialization of the supraspinatus footprint in rotator cuff repair (2019)
Tim Leschinger ; Stefan Birgel ; Michael Hackl ; Manfred Staat ; Lars Peter Müller ; Kilian Wegmann
Double plate osteosynthesis of proximal ulna fractures: biomechanical and clinical results (2016)
Kilian Wegmann ; Michael Hackl ; Manfred Staat ; Katharina Mayer ; Lars-Peter Müller
While plate fixation of proximal ulna fractures might lead to superior clinical results compared to tension band wiring, regular plates represent an established risk factor for wound complications. The olecranon double plates (Medartis, Basel, CH) might decrease complications related to the osteosynthesis because of their low profile and better anatomical fit. This study aimed to evaluate the biomechanical performance and clinical results of the olecranon double plates.
Irreparable rotator cuff tears: a biomechanical comparison of superior capsuloligamentous complex reconstruction techniques and an interposition graft technique (2019)
Tim Leschinger ; Katharina Besch ; Cansu Aydin ; Manfred Staat ; Martin Scaal ; Lars Peter Müller ; Kilian Wegmann
Pressure distribution to the distal biceps tendon at the radial tuberosity: a biomechanical study (2020)
Valentin Rausch ; Stephanie Lucina Kahmann ; Christoph Baltschun ; Manfred Staat ; Lars P. Müller ; Kilian Wegmann
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.
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