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Stress relaxation of porcine tendon under simulated biological environment: experiment and modeling

Łagan Sylwia D., Liber-Kneć Aneta

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 1

59--68

EN

Purpose: The aim of the study was to investigate the viscoelastic response in the low and high physiological strain with the use of experimental and modeling approach. Methods: Viscoelastic response in the low, transition and high physiologic strain (3, 6 and 9%) with consideration of simulated biological environment (0.9% saline solution, 37 °C) was measured in relaxation tests. Preconditioning of tendons was considered in the testing protocol and the applied range of load was obtained from tensile testing. The quasi-linear viscoelasticity theory was used to fit experimental data to obtain constants (moduli and times of relaxation), which can be used for description of the viscoelastic behavior of tendons. The exponential non-linear elastic representation of the stress response in ramp strain was also estimated. Results: Differences between stress relaxation process can be seen between tendons stretched to the physiological strain range (3%) and exceeding this range (6 and 9%). The strains of 6% and 9% showed a similar stress relaxation trend displaying relatively rapid relaxation for the first 70 seconds, whereas the lowest strain of 3% displayed relatively slow relaxation. Conclusions: Results of the model fitting showed that the quasi-linear viscoelastic model gives the best fit in the range of low physiological strain level.

2

Comparison of different suture techniques for Achilles tendon repair in rat model using collagen scaffolds

Gabler C., Gierschner S., Tischer T., Bader R.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 2

73--77

EN

Tendon injury is an increasing problem in medicine due to aging of the population and increased activity demands. Many rodent animal models are used in order to evaluate tendon reconstruction. Although tendon reruptures are a known problem, the outcomes of tendon repair in animal models are rarely discussed in the literature. The goal of the present experimental study was to compare the primary fixation stability of three suture techniques for repair of Achilles tendon defects in a rat model using a collagen scaffold. Methods: Cadaveric left hind limbs of Sprague-Dawley rats were prepared with an Achilles tendon defect of 3 mm and rejoined using a collagen scaffold. Three suture configurations (simple, simple stitch with additional framing suture, and modified Mason–Allen stitch; n = 5 each) underwent tensile testing until complete failure was observed. Results: Under a load of a mean value of 6.6 N, the failure load of simple stitches was the significantly lowest ( p < 0.01). Both, modified Mason–Allen stitches and simple stitches with additional framing suture showed a mean failure load of more than 14 N. Regardless of the suture technique, most of the samples showed failure of tendon due to suture tear-out. The suture material as well as the scaffold remained mostly intact. Conclusions: Although simple end-toend suture techniques are common in the literature, stitches with more suture strands should be preferred. Using techniques like an additional framing suture or modified Mason–Allen stitch, maximum failure load can be doubled and the risk of tendon rerupture may be decreased in vivo.

3

Wyznaczenie właściwości mechanicznych ścięgien świńskich do zastosowań ksenogenicznych

Gzik-Zroska Β., Joszko K., Rostocka J.

Aktualne Problemy Biomechaniki

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2017

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z. 14

17--22

PL

W pracy przedstawiono wyniki badań doświadczalnych przeprowadzonych na ścięgnach przednich kończyn świńskich. Badania przeprowadzono przy użyciu maszyny wytrzymałościowej MTS Insight. W ramach badań wyznaczono wartości modułu Younga, naprężeń oraz odkształceń ścięgien palców przednich jako preparatów do zastosowań ksenogenicznych.

EN

In this paper it was presented the results of experimental investigations, performed on the swine tendons samples dissected from anterior limbs. The main aim of investigations was to determine the mechanical properties of swine tendons for xenogenic applications. The tests were carried out with the use of MTS Insight static machine. It was determined the Young's modulus values and also the stress and strains of tendons that occurs during the static tensile test.

4

Patellofemoral contact pressures

Quintelier J., Lobbestael F., Verdonik P., De Baets F., Almqvist F.

Acta of Bioengineering and Biomechanics

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2008

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Vol. 10, nr 2

23-28

EN

A test rig for studying the biomechanical behaviour of post-mortem human knees is built. For loading the quadriceps tendon a special clamping device is constructed, so the forces up to 3000 N could easily be transferred to the tendon. Several post-mortem human knees used in this study are tested to collect data about the general biomechanics of knee joint during squatting. The forces in the quadriceps tendon and in the tibia are measured continuously; the flexion angle is also measured. On this modular test rig, the contact pressures of the patellofemoral joint are measured as well. Therefore a thin pressure film is used. Not only are measured the contact pressures, but the changing contact area is also visualized and measured. The forces and rotations measured in the joint and in the contact area allowed us to obtain perfectly reproducible values as well as a positive relation between contact area, contact position and working direction of the quadriceps tendon.