Effects of Restressing on the Mechanical Properties of Stress-Shielded Patellar Tendons in Rabbits

1996 ◽  
Vol 118 (2) ◽  
pp. 216-220 ◽  
Author(s):  
Noritaka Yamamoto ◽  
Kozaburo Hayashi ◽  
Hiroyuki Kuriyama ◽  
Kazunori Ohno ◽  
Kazunori Yasuda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Patellar Tendon ◽  
Stress Shielding ◽  
Tangent Modulus ◽  
Tissue Change

We studied the effects of restressing on the mechanical properties and morphology of stress-shielded rabbit patellar tendons. After completely unloading the patellar tendon for 1 to 3 weeks, tension was again applied to the tendon for the subsequent 3 to 12 weeks. Although the stress shielding markedly decreased the tangent modulus and tensile strength of the tendon, restressing significantly increased them. However, the mechanical properties of the tendon were not completely recovered even after a prolonged period of restressing. The microstructure of the tendon was also restored by although the recovery was incomplete. These results indicate that the mechanical properties and morphology of tendinous tissue change in response to mechanical demands.

Effects of Static Stress on the Mechanical Properties of Cultured Collagen Fascicles From the Rabbit Patellar Tendon

2001 ◽  
Vol 124 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Ei Yamamoto ◽  
Wataru Iwanaga ◽  
Hiroshi Miyazaki ◽  
Kozaburo Hayashi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Applied Stress ◽  
Patellar Tendon ◽  
Control Level ◽  
Peak Stress ◽  
Static Stress ◽  
Tangent Modulus

In-vitro tissue culture experiments were performed to study the effects of static stress on the mechanical properties of collagen fascicles obtained from the rabbit patellar tendon. After collagen fascicles having the diameter of approximately 300 μm were cultured for 1 and 2 wk under static stress between 0 and 3 MPa, their mechanical properties and crimp morphology were determined using a micro-tensile tester and a light microscope, respectively. The tensile strength and tangent modulus of the fascicles were significantly decreased by culture under no load compared to control fascicles. A statistically significant correlation, which was described by a quadratic curve, was observed between applied stress and tensile strength. The maximum tensile strength (16.7 MPa) was obtained at the applied stress of 1.2 MPa; the strength was within a range of control values. There was a similar correlation between applied stress and tangent modulus, and the modulus was maintained at control level under 1.3 MPa stress. The stress of 1.2 to 1.3 MPa is equivalent to approximately 50 percent of the peak stress developed in the intact rabbit patellar tendon by running. Strain at failure of cultured collagen fascicles was negatively correlated with applied stress, and that at 1.2 to 1.3 MPa stress was almost the same as the control value. Crimp morphology in the fascicles cultured under about 1.2 MPa stress was similar to that in control fascicles. These results indicate that cultured collagen fascicles change the mechanical properties and structure in response to static tensile stress. In addition, their mechanical properties and structure are maintained at control level if the static stress of 50 percent of in-vivo peak stress is applied.

Effects of Cyclic Stress on the Mechanical Properties of Cultured Collagen Fascicles from the Rabbit Patellar Tendon

2003 ◽  
Vol 125 (6) ◽  
pp. 893-901 ◽  
Author(s):  
Ei Yamamoto ◽  
Susumu Tokura ◽  
Kozaburo Hayashi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Patellar Tendon ◽  
Control Level ◽  
Quadratic Function ◽  
Peak Stress ◽  
Cyclic Stress ◽  
Original Strength

Effects of cyclic stress on the mechanical properties of collagen fascicles were studied by in vitro tissue culture experiments. Collagen fascicles (approximately 300 μm in diameter) obtained from the rabbit patellar tendon were applied cyclic load at 4 Hz for one hour per day during culture period for one or two weeks, and then their mechanical properties were determined using a micro-tensile tester. There was a statistically significant correlation between tensile strength and applied peak stress in the range of 0 to 5 MPa, and the relation was expressed by a quadratic function. The maximum strength (19.4 MPa) was obtained at the applied peak stress of 1.8 MPa. The tensile strength of fascicles were within a range of control values, if they were cultured under peak stresses between 1.1 and 2.6 MPa. Similar results were also observed in the tangent modulus, which was maintained at control level under applied peak stresses between 0.9 and 2.8 MPa. The stress of 0.9 to 1.1 MPa is equivalent to approximately 40% of the in vivo peak stress which is developed in the intact rabbit patellar tendon by running, whereas that of 2.6 to 2.8 MPa corresponds to approximately 120% of the in vivo peak stress. Therefore, the fascicles cultured under applied peak stresses of lower than 40% and higher than 120% of the in vivo peak stress do not keep the original strength and modulus. These results indicate that the mechanical properties of cultured collagen fascicles strongly depend upon the magnitude of the stress applied during culture, which are similar to our previous results observed in stress-shielded and overstressed patellar tendons in vivo.

Effect of stress shielding on the mechanical properties of healing tissue in the patellar tendon after removal of its central third

2002 ◽  
Vol 2002.13 (0) ◽  
pp. 21-22
Author(s):  
Takafumi HIRO ◽  
Yoshiaki KITAMURA ◽  
Harukazu TOHYAMA ◽  
Kazunori YASUDA ◽  
Kozaburo HAYASHI
Keyword(s):  
Mechanical Properties ◽  
Patellar Tendon ◽  
Stress Shielding ◽  
Healing Tissue

EFFECTS OF CULTURE PERIODS AND LOADING ON BIOMECHANICAL PROPERTIES OF SHEEP COLLAGEN FASCICLES

2014 ◽  
Vol 14 (06) ◽  
pp. 1440010
Author(s):  
AHMET C. CILINGIR
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Soft Tissues ◽  
Culture Media ◽  
Experimental Studies ◽  
Biomechanical Properties ◽  
Collagen Fibrils ◽  
Tangent Modulus ◽  
Control Group ◽  
Stress Strain

Soft tissues (e.g., tendon, skin, cartilage) change their dimensions and properties in response to applied mechanical stress/strain, which is called remodeling. Experimental studies using tissue cultures were performed to understand the biomechanical properties of collagen fascicles under mechanical loads. Collagen fascicles were dissected from sheep Achilles tendons and loaded under 1, 2, and 3 kg for 2, 4, and 6 days under culture. The mechanical properties of collagen fascicles after being loaded into the culture media were determined using tensile tester, and resultant stress–strain curves, tangent modulus, tensile strength, and strain at failure values were compared with those in a non-loaded and non-cultured control group of fascicles. The tangent modulus and tensile strength of the collagen fascicles increased with the increasing remodeling load after two days of culture. However, these values gradually decreased with the increasing culture period compared with the control group. According to the results obtained in this study, the mechanical properties of collagen fascicles were improved by loading at two days of culture, most likely due to the remodeling of collagen fibers. However, after a period of remodeling, local strains on the collagen fibrils increased, and finally, the collagen fibrils broke down, decreasing the mechanical properties of the tissue.

Effects of the Frequency and Duration of Cyclic Stress on the Mechanical Properties of Cultured Collagen Fascicles From the Rabbit Patellar Tendon

2005 ◽  
Vol 127 (7) ◽  
pp. 1168-1175 ◽  
Author(s):  
Ei Yamamoto ◽  
Daisuke Kogawa ◽  
Susumu Tokura ◽  
Kozaburo Hayashi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Patellar Tendon ◽  
Load Condition ◽  
Peak Stress ◽  
Cyclic Stress ◽  
Control Group ◽  
Significant Difference

The effects of frequency or duration of cyclic stress on the mechanical properties of collagen fascicles were studied by means of in vitro tissue culture experiments. Collagen fascicles of approximately 300μm in diameter were obtained from rabbit patellar tendons. During culture, cyclic stress having the peak stress of approximately 2MPa was applied to the fascicles at 1Hz for 1hour∕day (1Hz-1h group), at 1Hz for 4hours∕day (1Hz-4h group), or at 4Hz for 1hour∕day (4Hz-1h group). The frequency of 4Hz and the duration of 1hour∕day are considered to be similar to those of the in vivo stress applied to fascicles in the intact rabbit patellar tendon. After culture for 1 or 2weeks, the mechanical properties of the fascicles were determined using a micro-tensile tester, and were compared to the properties of non-cultured, fresh fascicles (control group) and the fascicles cultured under no load condition (non-loaded group). The tangent modulus and tensile strength of fascicles in the 4Hz-1h group were similar to those in the control group; however, the fascicles of the 1Hz-1h and 1Hz-4h groups had significantly lower values than those of the control group. There was no significant difference in the tensile strength between the 1Hz-1h and non-loaded groups, although the strength in the 1Hz-4h group was significantly higher than that of the non-loaded group. It was concluded that the frequency and duration of cyclic stress significantly affect the mechanical properties of cultured collagen fascicles. If we apply cyclic stress having the frequency and duration which are experienced in vivo, the biomechanical properties are maintained at control, normal level. Lower frequencies or less cycles of applied force induce adverse effects.

Development of Changeable Young's Modulus with Good Mechanical Properties in β-Type Ti-Cr-O Alloys

2013 ◽  
Vol 575-576 ◽  
pp. 453-460
Author(s):  
Hui Hong Liu ◽  
Mitsuo Niinomi ◽  
Masaaki Nakai ◽  
Junko Hieda ◽  
Ken Cho
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Potential Candidate ◽  
Spinal Fixation ◽  
High Tensile Strength ◽  
Cold Rolled

A novel β-type titanium alloy with a changeable Youngs modulus, that is, with a low Young's modulus to prevent the stress-shielding effect for patients and a high Young's modulus to suppress springback for surgeons, should be developed in order to satisfy the conflicting requirements of both the patients and surgeons in spinal fixation operations. In this study, the oxygen content in ternary Ti-11Cr-O alloys was optimized in order to achieve a large changeable Young's modulus with good mechanical properties for spinal fixation applications. The increase in Youngs moduli of all the examined alloys by cold rolling is attributed to the deformation-induced ω-phase transformation which is suppressed by oxygen. Among the examined alloys, the Ti-11Cr-0.2O alloy exhibits the largest changeable Youngs modulus and a high tensile strength with an acceptable plasticity under both solution-treated (ST) and cold-rolled (CR) conditions. Therefore, the Ti-11Cr-0.2O alloy, which shows a good balance among a changeable Youngs modulus, high tensile strength and good plasticity, is considered a potential candidate for spinal fixation applications.

Mechanical Properties of the Rabbit Patellar Tendon

1992 ◽  
Vol 114 (3) ◽  
pp. 332-337 ◽  
Author(s):  
N. Yamamoto ◽  
K. Hayashi ◽  
H. Kuriyama ◽  
K. Ohno ◽  
K. Yasuda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Structural Properties ◽  
Patellar Tendon ◽  
Tensile Tests ◽  
The Other ◽  
Central Portion ◽  
Mechanical And Structural Properties ◽  
Lateral Portion

The mechanical and structural properties of the patellar tendon fascicle-bone units of rabbit knees were determined by tensile tests, particularly focusing on their local differences. There were no significant differences in the strains measured by a video dimension analyzer among the proximal, middle, and distal regions of the central portion of tendon. The mechanical properties of the medial portion agreed well with those of the central portion. However, significant differences were observed in the tensile strength between the lateral and the other two portions: the tensile strength of the lateral portion was about 16 percent larger than those in the other portions.

Effects of complete stress-shielding on the mechanical properties and histology of in situ frozen patellar tendon

1993 ◽  
Vol 11 (4) ◽  
pp. 592-602 ◽  
Author(s):  
Kazunori Ohno ◽  
Kazunori Yasuda ◽  
Noritaka Yamamoto ◽  
Kiyoshi Kaneda ◽  
Kozaburo Hayashi
Keyword(s):  
Mechanical Properties ◽  
Patellar Tendon ◽  
Stress Shielding

Effects of stress shielding and subsequent restressing on mechanical properties of regenerated and residual tissues in rabbit patellar tendon after resection of its central one-third

2009 ◽  
Vol 42 (11) ◽  
pp. 1592-1597 ◽  
Author(s):  
Eijiro Maeda ◽  
Hiroyuki Asanuma ◽  
Hitoshi Noguchi ◽  
Harukazu Tohyama ◽  
Kazunori Yasuda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Patellar Tendon ◽  
Stress Shielding ◽  
Effects Of Stress

Characterizing the Maternal Adaptations of Pregnancy and Recovery Following Vaginal Delivery in the Rodent Model

2010 ◽  
Author(s):  
Andrew Feola ◽  
Marianna Alperin ◽  
Pamela Moalli ◽  
Steven Abramowitch
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Vaginal Delivery ◽  
Ultimate Strain ◽  
Rodent Model ◽  
Female Rats ◽  
Tangent Modulus ◽  
Birth Injury ◽  
Vaginal Tissue ◽  
Significant Difference

Pelvic organ prolapse and urinary incontinence are common conditions in women that significantly diminish quality of life. Vaginal delivery and maternal birth injury are the number one risk factors for the development of pelvic floor disorders. The goal of this study was to characterize maternal adaptations throughout pregnancy and recovery after vaginal delivery in terms of the passive quasi-static mechanical properties of the vagina using a rodent model. Virgin (n = 8), mid-pregnant (n = 7, day 15–16), late-pregnant (n = 7, day 20–21), immediate postpartum (n = 8, <2 hours post delivery), and 4 week postpartum (n = 6) Long-Evans female rats were utilized in this study. The mechanical properties (tangent modulus, tensile strength, ultimate strain, and strain energy density) were quantified by testing longitudinal sections of vaginal tissue to failure. The tangent modulus of virgin animals (25.1±5.1 MPa) was significantly higher compared to mid-pregnant (11.7±7.7 MPa, p = 0.003), late-pregnant (7.9±4.0 MPa, p<0.001), and immediate postpartum (8.5±4.7 MPa, p = 0.001) animals. A similar trend was also observed in the tensile strength, whereas the ultimate strain increased throughout pregnancy until the time of vaginal delivery. Recovery was observed four weeks postpartum as no significant difference was found from virgin animals for any of the parameters. This study has shown a significant decrease in the tangent modulus and tensile strength along with an increase in the ultimate strain of longitudinal sections of vaginal tissue throughout pregnancy. These maternal adaptations are likely to increase the overall distensibility of the vagina and allow for vagina delivery with minimal injury. This process appears to be effective in the rodent model as the properties recovered to virgin levels by 4 weeks. In the future, we hope to alter these adaptations or exceed them in order to study the risk and impact of birth injury in this model.

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