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  • 1
    Online Resource
    Online Resource
    A Higher Initial Tensioning Force of an ACL Graft Results in a Higher Graft Force After Screw Fixation Irrespective of the Screw Diameter: A Biomechanical Study
    SAGE Publications ; 2021
    In:  The American Journal of Sports Medicine Vol. 49, No. 14 ( 2021-12), p. 3825-3832
    Details
    In: The American Journal of Sports Medicine, SAGE Publications, Vol. 49, No. 14 ( 2021-12), p. 3825-3832
    Abstract: The intra-articular graft force (IAGF) in anterior cruciate ligament reconstruction decreases quickly over the first hours after surgery. Nevertheless, little is known about whether the initial extra-articular tensioning force (EATF) and screw diameter affect the graft force after fixation. Purpose: To investigate the effects of different EATFs on the IAGF of a soft tissue graft fixated via a bioabsorbable interference screw over 100 minutes after fixation and to evaluate the effects of different screw diameters within 1 mm of the tunnel width during this process. Study Design: Controlled laboratory study. Methods: In this biomechanical study, a porcine quadruple-strand soft tissue graft was inserted into the tibial anterior cruciate ligament tunnel. On the extra-articular side, 3 loads were applied during retrograde insertion of the bioabsorbable interference screw (6, 7, and 8 mm): 20 N, 80 N, and maximum manual EATF (N max ). Nine study groups consisting of 10 tibiae each were created to test the effects of different EATFs and screw sizes. The IAGF was measured up to 100 minutes after the EATF was released. Results: An EATF ≥80 N resulted in a larger IAGF for all screw sizes at 100 minutes. There were no significant associations between the IAGF at 100 minutes and different screw diameters. Inserting the tibial screw significantly increased the IAGF in all groups, with the exception of N max applied in groups with 7- or 8-mm screws. When compared with the end of screw insertion, after the release of the EATF, the IAGF dropped by 55% to 77 % at 100 minutes. Conclusion: An initial EATF ≥80 N is associated with a significantly larger IAGF at 100 minutes in this cadaveric simulation. The IAGF in soft tissue grafts decreased substantially after the retrograde placement of an interference screw. A recommendation regarding screw diameter with respect to the IAGF cannot be given. Clinical Relevance: To obtain a higher residual graft force after bioabsorbable interference screw fixation, an initial EATF ≥80 N should be applied according to this model. The significant decrease in graft force after the release of the EATF indicates that the reconstructed knee cannot be mechanically stabilized after the surgery.
    Type of Medium: Online Resource
    ISSN: 0363-5465 , 1552-3365
    URL: Article
    DOI: 10.1177/03635465211047861
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
    detail.hit.zdb_id: 2063945-4
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  • 2
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    Is initial interfragmentary compression made to last? An ovine bone in vitro study
    Elsevier BV ; 2021
    In:  Injury Vol. 52, No. 6 ( 2021-06), p. 1263-1270
    Details
    In: Injury, Elsevier BV, Vol. 52, No. 6 ( 2021-06), p. 1263-1270
    Type of Medium: Online Resource
    ISSN: 0020-1383
    URL: Article
    DOI: 10.1016/j.injury.2020.11.070
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 2011808-9
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  • 3
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    Development and systematic evaluation of decellularization protocols in different application models for diaphragmatic tissue engineering
    Elsevier BV ; 2023
    In:  Biomaterials Advances Vol. 153 ( 2023-10), p. 213493-
    Details
    In: Biomaterials Advances, Elsevier BV, Vol. 153 ( 2023-10), p. 213493-
    Type of Medium: Online Resource
    ISSN: 2772-9508
    URL: Article
    DOI: 10.1016/j.bioadv.2023.213493
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
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  • 4
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    A New System for Periprosthetic Fracture Stabilization—A Biomechanical Comparison
    MDPI AG ; 2022
    In:  Journal of Clinical Medicine Vol. 11, No. 3 ( 2022-02-08), p. 892-
    Details
    In: Journal of Clinical Medicine, MDPI AG, Vol. 11, No. 3 ( 2022-02-08), p. 892-
    Abstract: In recent years, an increase in periprosthetic femur fractures has become apparent due to the increased number of hip replacements. In the case of Vancouver type B1 fractures, locking plate systems offer safe procedures. This study compared the distal lateral femur plate (LOQTEQ®, aap Implantate AG) with a standard L.I.S.S. LCP® (DePuy Synthes) regarding their biomechanical properties in fixation of periprosthetic femur fractures after hip arthroplasty. We hypothesized that the new LOQTEQ system has superior stability and durability in comparison. Eighteen artificial left femurs were randomized in two groups (Group A: LOQTEQ®; Group B: L.I.S.S. LCP®) and tested until failure. Failure was defined as 10° varus deformity and catastrophic implant failure (loosening, breakage, progressive bending). Axial stiffness, loads of failure, cycles of failure, modes of failure were recorded. The axial stiffness in Group A with 73.4 N/mm (SD +/− 3.0) was significantly higher (p = 0.001) than in Group B (40.7 N/mm (SD +/− 2.8)). Group A resists more cycles than Group B until 10° varus deformity. Catastrophic failure mode was plate breakage in Group A and bending in Group B. In conclusion, LOQTEQ® provides higher primary stability and tends to have higher durability.
    Type of Medium: Online Resource
    ISSN: 2077-0383
    URL: Article
    DOI: 10.3390/jcm11030892
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2662592-1
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  • 5
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    Há diferença na força de compressão interfragmentar entre parafusos com rosca total ou parcial? Resultados de um estudo biomecânico experimental piloto
    Georg Thieme Verlag KG ; 2023
    In:  Revista Brasileira de Ortopedia Vol. 58, No. 02 ( 2023-04), p. 231-239
    Details
    In: Revista Brasileira de Ortopedia, Georg Thieme Verlag KG, Vol. 58, No. 02 ( 2023-04), p. 231-239
    Abstract: Objective This study assessed differences between fully- and partially-threaded screws in the initial interfragmentary compression strength. Our hypothesis was that there would be an increased loss in initial compression strength with the partially-threaded screw. Methods A 45-degree oblique fracture line was created in artificial bone samples. The first group (FULL, n = 6) was fixed using a 3.5-mm fully-threaded lag screw, while the second group (PARTIAL, n = 6) used a 3.5-mm partially-threaded lag screw. Torsional stiffness for both rotational directions were evaluated. The groups were compared based on biomechanical parameters: angle-moment-stiffness, time-moment-stiffness, maximal torsional moment (failure load), and calibrated compression force based on pressure sensor measurement. Results After loss of one PARTIAL sample, no statistically significant differences in calibrated compression force measurement were observed between both groups: [median (interquartile range)] FULL: 112.6 (10.5) N versus PARTIAL: 106.9 (7.1) N, Mann-Whitney U-test: p = 0.8). In addition, after exclusion of 3 samples for mechanical testing (FULL n = 5, PARTIAL n = 4), no statistically significant differences were observed between FULL and PARTIAL constructs in angle-moment-stiffness, time-moment-stiffness, nor maximum torsional moment (failure load). Conclusion There is no apparent difference in the initial compression strength (compression force or construct stiffness or failure load) achieved using either fully- or partially-threaded screws in this biomechanical model in high-density artificial bone. Fully-threaded screws could, therefore, be more useful in diaphyseal fracture treatment. Further research on the impact in softer osteoporotic, or metaphyseal bone models, and to evaluate the clinical significance is required.
    Type of Medium: Online Resource
    ISSN: 0102-3616 , 1982-4378
    URL: Article
    DOI: 10.1055/s-0042-1750828
    Language: Portuguese
    Publisher: Georg Thieme Verlag KG
    Publication Date: 2023
    detail.hit.zdb_id: 2411301-3
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  • 6
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    In vitro recellularization of decellularized bovine carotid arteries using human endothelial colony forming cells
    Springer Science and Business Media LLC ; 2021
    In:  Journal of Biological Engineering Vol. 15, No. 1 ( 2021-12)
    Details
    In: Journal of Biological Engineering, Springer Science and Business Media LLC, Vol. 15, No. 1 ( 2021-12)
    Abstract: Many patients suffering from peripheral arterial disease (PAD) are dependent on bypass surgery. However, in some patients no suitable replacements (i.e. autologous or prosthetic bypass grafts) are available. Advances have been made to develop autologous tissue engineered vascular grafts (TEVG) using endothelial colony forming cells (ECFC) obtained by peripheral blood draw in large animal trials. Clinical translation of this technique, however, still requires additional data for usability of isolated ECFC from high cardiovascular risk patients. Bovine carotid arteries (BCA) were decellularized using a combined SDS (sodium dodecyl sulfate) -free mechanical-osmotic-enzymatic-detergent approach to show the feasibility of xenogenous vessel decellularization. Decellularized BCA chips were seeded with human ECFC, isolated from a high cardiovascular risk patient group, suffering from diabetes, hypertension and/or chronic renal failure. ECFC were cultured alone or in coculture with rat or human mesenchymal stromal cells (rMSC/hMSC). Decellularized BCA chips were evaluated for biochemical, histological and mechanical properties. Successful isolation of ECFC and recellularization capabilities were analyzed by histology. Results Decellularized BCA showed retained extracellular matrix (ECM) composition and mechanical properties upon cell removal. Isolation of ECFC from the intended target group was successfully performed (80% isolation efficiency). Isolated cells showed a typical ECFC-phenotype. Upon recellularization, co-seeding of patient-isolated ECFC with rMSC/hMSC and further incubation was successful for 14 ( n  = 9) and 23 ( n  = 5) days. Reendothelialization (rMSC) and partial reendothelialization (hMSC) was achieved. Seeded cells were CD31 and vWF positive, however, human cells were detectable for up to 14 days in xenogenic cell-culture only. Seeding of ECFC without rMSC was not successful. Conclusion Using our refined decellularization process we generated easily obtainable TEVG with retained ECM- and mechanical quality, serving as a platform to develop small-diameter ( 〈  6 mm) TEVG. ECFC isolation from the cardiovascular risk target group is possible and sufficient. Survival of diabetic ECFC appears to be highly dependent on perivascular support by rMSC/hMSC under static conditions. ECFC survival was limited to 14 days post seeding.
    Type of Medium: Online Resource
    ISSN: 1754-1611
    URL: Article
    DOI: 10.1186/s13036-021-00266-5
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2391582-1
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  • 7
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    Elastin stabilization prevents impaired biomechanics in human pulmonary arteries and pulmonary hypertension in rats with left heart disease
    Springer Science and Business Media LLC ; 2023
    In:  Nature Communications Vol. 14, No. 1 ( 2023-07-21)
    Details
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 14, No. 1 ( 2023-07-21)
    Abstract: Pulmonary hypertension worsens outcome in left heart disease. Stiffening of the pulmonary artery may drive this pathology by increasing right ventricular dysfunction and lung vascular remodeling. Here we show increased stiffness of pulmonary arteries from patients with left heart disease that correlates with impaired pulmonary hemodynamics. Extracellular matrix remodeling in the pulmonary arterial wall, manifested by dysregulated genes implicated in elastin degradation, precedes the onset of pulmonary hypertension. The resulting degradation of elastic fibers is paralleled by an accumulation of fibrillar collagens. Pentagalloyl glucose preserves arterial elastic fibers from elastolysis, reduces inflammation and collagen accumulation, improves pulmonary artery biomechanics, and normalizes right ventricular and pulmonary hemodynamics in a rat model of pulmonary hypertension due to left heart disease. Thus, targeting extracellular matrix remodeling may present a therapeutic approach for pulmonary hypertension due to left heart disease.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    URL: Article
    DOI: 10.1038/s41467-023-39934-z
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2553671-0
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  • 8
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    Role of extracellular matrix structural components and tissue mechanics in the development of postoperative pancreatic fistula
    Elsevier BV ; 2021
    In:  Journal of Biomechanics Vol. 128 ( 2021-11), p. 110714-
    Details
    In: Journal of Biomechanics, Elsevier BV, Vol. 128 ( 2021-11), p. 110714-
    Type of Medium: Online Resource
    ISSN: 0021-9290
    URL: Article
    DOI: 10.1016/j.jbiomech.2021.110714
    RVK:
    WA 15000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 1498351-5
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  • 9
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    Clinical and Technical Validation of Novel Bite Force Measuring Device for Functional Analysis after Mandibular Reconstruction
    MDPI AG ; 2023
    In:  Diagnostics Vol. 13, No. 4 ( 2023-02-05), p. 586-
    Details
    In: Diagnostics, MDPI AG, Vol. 13, No. 4 ( 2023-02-05), p. 586-
    Abstract: Bite force measuring devices that are generally suitable for edentulous patients or patients undergoing mandibular reconstruction are missing. This study assesses the validity of a new bite force measuring device (prototype of loadpad®, novel GmbH) and evaluates its feasibility in patients after segmental mandibular resection. Accuracy and reproducibility were analyzed with two different protocols using a universal testing machine (Z010 AllroundLine, Zwick/Roell, Ulm, Germany). Four groups were tested to evaluate the impact of silicone layers around the sensor: no silicone (“pure”), 2.0 mm soft silicone (“2-soft”), 7.0 mm soft silicone (“7-soft”) and 2.0 mm hard silicone (“2-hard”). Thereafter, the device was tested in 10 patients prospectively who underwent mandibular reconstruction using a fibula free flap. Average relative deviations of the measured force in relation to the applied load reached 0.77% (“7-soft”) to 5.28% (“2-hard”). Repeated measurements in “2-soft” revealed a mean relative deviation of 2.5% until an applied load of 600 N. Maximum bite force decreased postoperatively by 51.8% to a maximum mean bite force of 131.5 N. The novel device guarantees a high accuracy and degree of reproducibility. Furthermore, it offers new opportunities to quantify perioperative oral function after reconstructive surgery of the mandible also in edentulous patients.
    Type of Medium: Online Resource
    ISSN: 2075-4418
    URL: Article
    DOI: 10.3390/diagnostics13040586
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2662336-5
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  • 10
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    Significant Loss of ACL Graft Force With Tibial-Sided Soft Tissue Interference Screw Fixation Over 24 Hours: A Biomechanical Study
    SAGE Publications ; 2020
    In:  Orthopaedic Journal of Sports Medicine Vol. 8, No. 5 ( 2020-05-01), p. 232596712091643-
    Details
    In: Orthopaedic Journal of Sports Medicine, SAGE Publications, Vol. 8, No. 5 ( 2020-05-01), p. 232596712091643-
    Abstract: Tibial-sided graft fixation is thought to be critical for the success of anterior cruciate ligament (ACL) reconstruction. Nevertheless, little is known about the graft force after fixation during the first 24 hours after surgery or the influence of screw diameter and length during this time. Purpose: To investigate the force, over the course of 24 hours, in soft tissue grafts secured with a tibial interference screw and to evaluate the effect of different screw diameters (7, 8, and 9 mm) and lengths (25 and 30 mm) on the force in these grafts. Study Design: Controlled laboratory study. Methods: Quadruple-strand flexor tendon grafts were fixed with bioabsorbable interference screws in 60 porcine tibiae. Grafts were pretensioned at 80 N over 10 minutes, and screws were inserted outside-in while a preload force of 80 N was applied. Different screw lengths (25 and 30 mm) and diameters (7, 8, and 9 mm), resulting in 6 groups with 10 specimens each, were tested. After release of the preload, graft force was recorded over 24 hours. Results: A significant decrease in graft force progressed in all groups over the 24-hour period. In total, a median loss of 75 N (IQR, 68-79 N) compared with the initial loading force was observed. Compared with the loading force of 80 N, this corresponded to a median loss of 91%. No significant differences in the remaining graft force could be found among the 6 different screw length and diameter groups after 10 minutes, 100 minutes, or 24 hours. Conclusion: Graft force in soft tissue grafts secured with a tibial interference screw decreased substantially over the first 24 hours after fixation. Neither the screw diameter nor the screw length affected the decrease in graft force. This raises substantial questions regarding the remaining fixation strength in vivo. Clinical Relevance: It should not be expected that ACL reconstruction can mechanically restabilize an injured knee as would an intact ACL. Reconstructed knees should be protected from mechanical overload in the early postoperative period.
    Type of Medium: Online Resource
    ISSN: 2325-9671 , 2325-9671
    URL: Article
    DOI: 10.1177/2325967120916437
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
    detail.hit.zdb_id: 2706251-X
    SSG: 31
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