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Gervasi G.L.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | Vannucci J.,University of Perugia | Tiribuzi R.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | Freddolini M.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli
Technology and Health Care | Year: 2016

BACKGROUND: Biomechanical behaviour evaluation of a suture is an important information for the surgeon to choose the best technique to perform. OBJECTIVE: To assess the biomechanical behavior of the native and mechanically sutured bronchi. METHODS: Ten bronchi were harvested from slaughtered pigs and then randomly separated in two groups, a control intact group and a sutured group where specimens were cut in half and sutured, to evaluate mechanical properties during a tensile test using a loading frame machine. In addition optoelectric motion tracking system was used to evaluate suture profile motion during the test. RESULTS: Significant differences (p < 0.05) were found between the two groups for the parameters investigated. The control group showed a higher maximal stress resistance and stiffness than the suture group, while elongation at rupture was increased in the sutured group. All the sutures broke in symmetric manner, as the mean of the side difference of the sutured specimens was 0.93 ± 0.80 mm at rupture. CONCLUSIONS: Biomechanical behaviour of native and sutured bronchi was evaluated, giving highly reproducible parameters regarding mechanical properties that may help clinicians and bioengineers to rationalize the choice for a particular suture material or suture technique, increasing surgical outcomes. © 2016 - IOS Press and the authors. All rights reserved. Source


Vannucci J.,University of Perugia | Gervasi G.L.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | Freddolini M.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | Pistilli A.,University of Perugia | And 4 more authors.
Journal of Surgical Research | Year: 2016

Background Biomechanical and histological properties of stapled bronchi with and without bovine pericardial matrix plus collagen reinforcement are analyzed. Materials and methods Pneumonectomy with mechanical bronchial suture was performed in the swine model. Pigs were randomly assigned to three groups: three-row staplers without reinforcement (Traditional), with reinforcement (Buttressed) and control "wild type", non-resected normal bronchus (Normal). Intraoperative test was carried for air leaks at 20/30/40 mm Hg endobronchial pressure. After 60 d, tracheobronchial specimen was harvested, stocked, and analyzed. Tensile test was performed using INSTRON 5965 loading frame machine. Maximal strain resistance value, length of elongation at rupture parameter, and stiffness coefficient (K) were evaluated. Histological analysis was performed. Sample size calculation was assessed (four per group), and the Student t-test was used to statistically evaluate differences in biomechanical variables. Results No fistula occurred. Biomechanical analysis showed that maximal strain resistance is 41.22 ± 2.11 N (Traditional), 24.53 ± 3.47 N (Buttressed), and 30.91 ± 0.29 N (Normal); elongation at rupture is 16.01 ± 1.82 mm (Traditional), 12.89 ± 0.48 mm (Buttressed), and 9.32 ± 0.11 mm (Normal). Finally, K is 2.59 ± 0.16 N/mm (Traditional), 1.91 ± 0.33 N/mm (Buttressed), and 3.32 ± 0.01 N/mm (Normal). Stumps without reinforcement proved higher resistance and length of elongation than reinforced ones. Normal bronchial tissue shows the highest stiffness coefficient. Statistical analysis produced significant values for each biomechanical feature. Group Buttressed stumps show greater thickness and a substantial inflammatory reaction with granulation tissue along the whole scar and around areas of discontinuity within the scar, not yet healed. Conclusions Reinforcing the mechanical suture line of bronchial stump with bovine pericardial matrix plus collagen shows suboptimal biomechanical and histological characteristics compared to using the stapler alone. © 2016 Elsevier Inc. All rights reserved. Source


Criscenti G.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | Criscenti G.,University of Pisa | De Maria C.,University of Pisa | Sebastiani E.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | And 10 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2016

The medial patello-femoral ligament is considered the most important passive patellar stabilizer and its proper functionality is essential for the patello-femoral joint stability. In this work, 18 human knees were randomly divided into two groups and reconstructed through two different surgical techniques: the "Through tunnel tendon" and the "Double converging tunnel" reconstructions. Subsequently, the samples were mechanically tested to evaluate the structural properties of reconstructed femur-MPFL-Patella complex (rFMPC). Particular attention was given to maintain the anatomical orientation between the patella and the graft. Both procedures showed lower stiffness and higher ultimate strain and absorbed energy compared to the native MPFL, but the advantages of the double converging tunnel technique are related to the restoration of the native MPFL sail-shape, to a better stress distribution on the patella, to the use of a single interference screw as fixation device and to the simplicity, rapidity and cost-effectivity of the surgical procedure. The evaluation of the structural properties of rMPFL is fundamental to evaluate the adequacy of the different techniques to restore the physiological structural properties of the native MPFL. © 2016 Elsevier Ltd. Source


Criscenti G.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | Criscenti G.,University of Pisa | De Maria C.,University of Pisa | Sebastiani E.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | And 10 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2016

The medial patellofemoral ligament (MPFL) is considered the most important passive patellar stabilizer and acts 50-60% of the force of the medial soft-tissue which restrains the lateralization of the patella between 0° and 30°. In this work, 24 human knees have been tested to evaluate the material properties of MPFL and to determine the structural behavior of femur-MPFL-Patella complex (FMPC). Particular attention was given to maintain the anatomical orientation between the patella and MPFL and to the evaluation of the elongation during the mechanical tests. The ultimate stress of the isolated ligament was 16±11. MPa, the ultimate strain was 24.3±6.8%, the Young's Modulus was 116±95. MPa and the strain energy density was 2.97±1.69. MPa.The ultimate load of the whole structure, FMPC, was 145±68. N, the ultimate elongation was 9.5±2.9. mm, the linear stiffness was 42.5±10.2. N/mm and the absorbed energy was 818.8±440.7. N. mm. The evaluation of material and structural properties of MPFL is fundamental to understand its contribution as stabilizer and for the selection of repair and reconstruction methods. © 2015. Source


Criscenti G.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | Criscenti G.,University of Pisa | De Maria C.,University of Pisa | Sebastiani E.,Istituto di Ricerca Traslazionale per lApparato Locomotore Nicola Cerulli | And 10 more authors.
Journal of Biomechanics | Year: 2015

The evaluation of viscoelastic properties of human medial patello-femoral ligament is fundamental to understand its physiological function and contribution as stabilizer for the selection of the methods of repair and reconstruction and for the development of scaffolds with adequate mechanical properties. In this work, 12 human specimens were tested to evaluate the time- and history-dependent non linear viscoelastic properties of human medial patello-femoral ligament using the quasi-linear viscoelastic (QLV) theory formulated by Fung et al. (1972) and modified by Abramowitch and Woo (2004). The five constant of the QLV theory, used to describe the instantaneous elastic response and the reduced relaxation function on stress relaxation experiments, were successfully evaluated. It was found that the constant A was 1.21±0.96MPa and the dimensionless constant B was 26.03±4.16. The magnitude of viscous response, the constant C, was 0.11±0.02 and the initial and late relaxation time constants τ1 and τ2 were 6.32±1.76s and 903.47±504.73s respectively. The total stress relaxation was 32.7±4.7%. To validate our results, the obtained constants were used to evaluate peak stresses from a cyclic stress relaxation test on three different specimens. The theoretically predicted values fit the experimental ones demonstrating that the QLV theory could be used to evaluate the viscoelastic properties of the human medial patello-femoral ligament. © 2015 Elsevier Ltd. Source

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