Stress Shielding

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Kozaburo Hayashi - One of the best experts on this subject based on the ideXlab platform.

  • Stress Shielding of patellar tendon effect on small diameter collagen fibrils in a rabbit model
    Journal of Orthopaedic Science, 2003
    Co-Authors: Tokifumi Majima, Kazunori Yasuda, Takamasa Tsuchida, Kunio Tanaka, Kiyoshi Miyakawa, Akio Minami, Kozaburo Hayashi
    Abstract:

    The purpose of this study was to assess the effects of Stress Shielding on the microstructure and ultrastructure of the patellar tendon using 40 mature female Japanese white rabbits. The patellar tendon was completely released from Stress by drawing the patella toward the tibial tubercle with a stainless steel wire installed between them. Microstructurally, Stress Shielding for 3 and 6 weeks increased the number of cells approximately fivefold, to that of the control tendon. Collagen bundles were less well oriented in the Stress-shielded tendon than in the control. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm increased in the Stress-shielded tendon. The median collagen fibril diameter in 6-week Stress-shielded tendon was significantly smaller (P ≪ 0.05) than in the control tendon (58.8% of control). The ratio of the total area of collagen fibrils to the whole visualized area in the Stress-shielded patellar tendon was significantly smaller at 3 and 6 weeks than that in the control. This study demonstrated that complete Stress Shielding significantly affects the microstructure and ultrastructure of the patellar tendon

  • effects of Stress Shielding on the transverse mechanical properties of rabbit patellar tendons
    Journal of Biomechanical Engineering-transactions of The Asme, 2000
    Co-Authors: Ei Yamamoto, Kozaburo Hayashi, N Yamamoto
    Abstract:

    : With the aim of studying mechanisms of the remodeling of tendons and ligaments, the effects of Stress Shielding on the rabbit patellar tendon were studied by performing tensile and Stress relaxation tests in the transverse direction. The tangent modulus, tensile strength, and strain at failure of non-treated, control patellar tendons in the transverse direction were 1272 kPa, 370 kPa, and 40.5 percent, respectively, whereas those of the tendons Stress-shielded for 1 week were 299 kPa, 108 kPa, and 40.4 percent, respectively. Stress Shielding markedly decreased tangent modulus and tensile strength in the transverse direction, and the decreases were larger than those in the longitudinal direction, which were determined in our previous study. For example, tensile strength in the transverse and longitudinal direction decreased to 29 and 50 percent of each control value, respectively, after 1 week Stress Shielding. In addition, the Stress relaxation in the transverse direction of Stress-shielded patellar tendons was much larger than that of nontreated, control ones. In contrast to longitudinal tensile tests for the behavior of collagen, transverse tests reflect the contributions of ground substances such as proteoglycans and mechanical interactions between collagen fibers. Ground substances provide lubrication and spacing between fibers, and also confer viscoelastic properties. Therefore, the results obtained from the present study suggest that ground substance matrix, and interfiber and fiber-matrix interactions have important roles in the remodeling response of tendons to Stress.

  • effects of growth on the response of the rabbit patellar tendon to Stress Shielding a biomechanical study
    Clinical Biomechanics, 2000
    Co-Authors: Hiromichi Fujie, N Yamamoto, Takeshi Murakami, Kozaburo Hayashi
    Abstract:

    Abstract Objective. To know the effect of Stress deprivation on the dimensions and mechanical properties of the patellar tendon during growth. Design. The dimensions and tensile properties of Stress-shielded patellar tendons were studied in growing rabbits and compared to those in mature animals. Background. Although the effects of Stress deprivation on the remodeling of ligaments and tendons have been studied in various animal models, the effect of growth on the remodeling has not been studied well. Method. A Stress Shielding technique was applied to 1-, 2-, and 3-month-old Japanese white rabbits to completely remove Stress in the patellar tendons for 4, 7, and 14 days. Changes in the dimensions and mechanical properties as well as fibroblast density of the tendon were determined. Results. The tensile strength and tangent modulus of the patellar tendons were markedly decreased by Stress Shielding, while the cross-sectional area was significantly increased, with the largest changes in 1-month-old rabbits. Fibroblast density also increased; however, the degree of increase was highest in 3-month-old rabbits. Conclusion. The changes in the dimensions and mechanical properties of the patellar tendons induced by Stress Shielding were greater in younger animals. Relevance The biomechanical response of tendons and ligaments to Stress deprivation induced by, for example, limb immobilization is greater and occurs earlier in younger subjects, which is important for the surgical treatment and rehabilitation protocol of joint diseases in young subjects.

  • effects of in situ freezing and Stress Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

  • Effects of in situ freezing and Stress‐Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

Kazunori Yasuda - One of the best experts on this subject based on the ideXlab platform.

  • Stress Shielding of patellar tendon effect on small diameter collagen fibrils in a rabbit model
    Journal of Orthopaedic Science, 2003
    Co-Authors: Tokifumi Majima, Kazunori Yasuda, Takamasa Tsuchida, Kunio Tanaka, Kiyoshi Miyakawa, Akio Minami, Kozaburo Hayashi
    Abstract:

    The purpose of this study was to assess the effects of Stress Shielding on the microstructure and ultrastructure of the patellar tendon using 40 mature female Japanese white rabbits. The patellar tendon was completely released from Stress by drawing the patella toward the tibial tubercle with a stainless steel wire installed between them. Microstructurally, Stress Shielding for 3 and 6 weeks increased the number of cells approximately fivefold, to that of the control tendon. Collagen bundles were less well oriented in the Stress-shielded tendon than in the control. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm increased in the Stress-shielded tendon. The median collagen fibril diameter in 6-week Stress-shielded tendon was significantly smaller (P ≪ 0.05) than in the control tendon (58.8% of control). The ratio of the total area of collagen fibrils to the whole visualized area in the Stress-shielded patellar tendon was significantly smaller at 3 and 6 weeks than that in the control. This study demonstrated that complete Stress Shielding significantly affects the microstructure and ultrastructure of the patellar tendon

  • effects of in situ freezing and Stress Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

  • Effects of in situ freezing and Stress‐Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

  • biomechanical effects of Stress Shielding of the rabbit patellar tendon depend on the degree of Stress reduction
    Journal of Orthopaedic Research, 1996
    Co-Authors: Tokifumi Majima, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Takashi Fujii, Kiyoshi Kaneda
    Abstract:

    A rabbit model was used to discover whether the effects of Stress Shielding on the mechanical properties of the patellar tendon depend on the degree of Stress reduction. Ninety mature female Japanese White rabbits were divided into three groups: completely Stress-shielded, partially Stress-shielded, and shamoperation and contralateral controls. In the experimental groups, tension applied to the patellar tendon was 0%, approximately 30%, and 100%, of the normal tension, respectively, with a polyester artificial ligament. Tensile tests were carried out on patella-patellar tendon-tibia complexes harvested 1, 2, 3, 6, or 12 weeks after surgery. The tensile strength decreased in comparison with the sham-operation group to 50.2, 13.5, 9.7, and 20.7% in the completely Stress-shielded group and to 75.2, 57.6, 59.6, 57.3, and 72.9% in the partially Stress-shielded group. The tensile strength in the completely Stress-shielded group was significantly less than that in the partially Stress-shielded group at 1, 2, 3, and 6 weeks. The cross-sectional area of the patellar tendon significantly increased to 132, 206, 237, and 136% in the completely Stress-shielded group and to 136, 170, 175, 155, and 127% in the partially Stress-shielded group, compared with the sham-operation group. The cross-sectional area of the completely Stress-shielded tendon was significantly larger than that of the partially Stress-shielded tendon at 1, 2, and 3 weeks. This study demonstrated that effects of Stress Shielding on the mechanical properties of the patellar tendon were dependent on the degree of Stress Shielding.

  • Effects of Stress Shielding on Autografts in Augmentation Procedures: Experimental Studies Using the In Situ Frozen Patellar Tendon
    Clinical Biomechanics and Related Research, 1994
    Co-Authors: Kazunori Yasuda, Kozaburo Hayashi
    Abstract:

    Stress Shielding reduces the strength of the in situ frozen patellar tendon (PT), depending on the degree of Stress Shielding, and increases the cross-sectional area, compensating for the decrease of tensile strength and keeping the maximum failure load at a normal level. However, there is some limit in the compenstion effect, depending on the extent of Stress Shielding. Mechanical response of the PT to Stress Shielding occurs independent of living cells, and therefore the remodehng is associated with noncellular components that include collagen. With regard to the ultramicrostructure of the frozen PT, complete Stress Shielding reduces the total number of collagen fibrils and the ratio of the total area of the fibrils to the whole visualized area while it increases the number of thick fibrils. With respect to effects of reStressing, if a PT that has undergone the in situ freezing treatment is completely shielded from Stress for 1 week or more, subsequent reStressing cannot produce complete recovery of tensile strength and the maximum load reduced by Stress Shielding, although it prevents the marked reduction of those parameters caused by continuous Stress Shielding. Moreover, reStressing has no effect on the tensile strength and the maximum load of the previously frozen PT if Stress is completely shielded for 6 weeks before reStressing.

N Yamamoto - One of the best experts on this subject based on the ideXlab platform.

  • effects of Stress Shielding on the transverse mechanical properties of rabbit patellar tendons
    Journal of Biomechanical Engineering-transactions of The Asme, 2000
    Co-Authors: Ei Yamamoto, Kozaburo Hayashi, N Yamamoto
    Abstract:

    : With the aim of studying mechanisms of the remodeling of tendons and ligaments, the effects of Stress Shielding on the rabbit patellar tendon were studied by performing tensile and Stress relaxation tests in the transverse direction. The tangent modulus, tensile strength, and strain at failure of non-treated, control patellar tendons in the transverse direction were 1272 kPa, 370 kPa, and 40.5 percent, respectively, whereas those of the tendons Stress-shielded for 1 week were 299 kPa, 108 kPa, and 40.4 percent, respectively. Stress Shielding markedly decreased tangent modulus and tensile strength in the transverse direction, and the decreases were larger than those in the longitudinal direction, which were determined in our previous study. For example, tensile strength in the transverse and longitudinal direction decreased to 29 and 50 percent of each control value, respectively, after 1 week Stress Shielding. In addition, the Stress relaxation in the transverse direction of Stress-shielded patellar tendons was much larger than that of nontreated, control ones. In contrast to longitudinal tensile tests for the behavior of collagen, transverse tests reflect the contributions of ground substances such as proteoglycans and mechanical interactions between collagen fibers. Ground substances provide lubrication and spacing between fibers, and also confer viscoelastic properties. Therefore, the results obtained from the present study suggest that ground substance matrix, and interfiber and fiber-matrix interactions have important roles in the remodeling response of tendons to Stress.

  • effects of growth on the response of the rabbit patellar tendon to Stress Shielding a biomechanical study
    Clinical Biomechanics, 2000
    Co-Authors: Hiromichi Fujie, N Yamamoto, Takeshi Murakami, Kozaburo Hayashi
    Abstract:

    Abstract Objective. To know the effect of Stress deprivation on the dimensions and mechanical properties of the patellar tendon during growth. Design. The dimensions and tensile properties of Stress-shielded patellar tendons were studied in growing rabbits and compared to those in mature animals. Background. Although the effects of Stress deprivation on the remodeling of ligaments and tendons have been studied in various animal models, the effect of growth on the remodeling has not been studied well. Method. A Stress Shielding technique was applied to 1-, 2-, and 3-month-old Japanese white rabbits to completely remove Stress in the patellar tendons for 4, 7, and 14 days. Changes in the dimensions and mechanical properties as well as fibroblast density of the tendon were determined. Results. The tensile strength and tangent modulus of the patellar tendons were markedly decreased by Stress Shielding, while the cross-sectional area was significantly increased, with the largest changes in 1-month-old rabbits. Fibroblast density also increased; however, the degree of increase was highest in 3-month-old rabbits. Conclusion. The changes in the dimensions and mechanical properties of the patellar tendons induced by Stress Shielding were greater in younger animals. Relevance The biomechanical response of tendons and ligaments to Stress deprivation induced by, for example, limb immobilization is greater and occurs earlier in younger subjects, which is important for the surgical treatment and rehabilitation protocol of joint diseases in young subjects.

  • effects of in situ freezing and Stress Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

  • Effects of in situ freezing and Stress‐Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

  • biomechanical effects of Stress Shielding of the rabbit patellar tendon depend on the degree of Stress reduction
    Journal of Orthopaedic Research, 1996
    Co-Authors: Tokifumi Majima, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Takashi Fujii, Kiyoshi Kaneda
    Abstract:

    A rabbit model was used to discover whether the effects of Stress Shielding on the mechanical properties of the patellar tendon depend on the degree of Stress reduction. Ninety mature female Japanese White rabbits were divided into three groups: completely Stress-shielded, partially Stress-shielded, and shamoperation and contralateral controls. In the experimental groups, tension applied to the patellar tendon was 0%, approximately 30%, and 100%, of the normal tension, respectively, with a polyester artificial ligament. Tensile tests were carried out on patella-patellar tendon-tibia complexes harvested 1, 2, 3, 6, or 12 weeks after surgery. The tensile strength decreased in comparison with the sham-operation group to 50.2, 13.5, 9.7, and 20.7% in the completely Stress-shielded group and to 75.2, 57.6, 59.6, 57.3, and 72.9% in the partially Stress-shielded group. The tensile strength in the completely Stress-shielded group was significantly less than that in the partially Stress-shielded group at 1, 2, 3, and 6 weeks. The cross-sectional area of the patellar tendon significantly increased to 132, 206, 237, and 136% in the completely Stress-shielded group and to 136, 170, 175, 155, and 127% in the partially Stress-shielded group, compared with the sham-operation group. The cross-sectional area of the completely Stress-shielded tendon was significantly larger than that of the partially Stress-shielded tendon at 1, 2, and 3 weeks. This study demonstrated that effects of Stress Shielding on the mechanical properties of the patellar tendon were dependent on the degree of Stress Shielding.

Kiyoshi Kaneda - One of the best experts on this subject based on the ideXlab platform.

  • effects of in situ freezing and Stress Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

  • Effects of in situ freezing and Stress‐Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

  • biomechanical effects of Stress Shielding of the rabbit patellar tendon depend on the degree of Stress reduction
    Journal of Orthopaedic Research, 1996
    Co-Authors: Tokifumi Majima, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Takashi Fujii, Kiyoshi Kaneda
    Abstract:

    A rabbit model was used to discover whether the effects of Stress Shielding on the mechanical properties of the patellar tendon depend on the degree of Stress reduction. Ninety mature female Japanese White rabbits were divided into three groups: completely Stress-shielded, partially Stress-shielded, and shamoperation and contralateral controls. In the experimental groups, tension applied to the patellar tendon was 0%, approximately 30%, and 100%, of the normal tension, respectively, with a polyester artificial ligament. Tensile tests were carried out on patella-patellar tendon-tibia complexes harvested 1, 2, 3, 6, or 12 weeks after surgery. The tensile strength decreased in comparison with the sham-operation group to 50.2, 13.5, 9.7, and 20.7% in the completely Stress-shielded group and to 75.2, 57.6, 59.6, 57.3, and 72.9% in the partially Stress-shielded group. The tensile strength in the completely Stress-shielded group was significantly less than that in the partially Stress-shielded group at 1, 2, 3, and 6 weeks. The cross-sectional area of the patellar tendon significantly increased to 132, 206, 237, and 136% in the completely Stress-shielded group and to 136, 170, 175, 155, and 127% in the partially Stress-shielded group, compared with the sham-operation group. The cross-sectional area of the completely Stress-shielded tendon was significantly larger than that of the partially Stress-shielded tendon at 1, 2, and 3 weeks. This study demonstrated that effects of Stress Shielding on the mechanical properties of the patellar tendon were dependent on the degree of Stress Shielding.

  • effects of complete Stress Shielding on the mechanical properties and histology of in situ frozen patellar tendon
    Journal of Orthopaedic Research, 1993
    Co-Authors: K Ohno, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda
    Abstract:

    Abstract The effects of freezing and Stress-Shielding on the mechanical properties and histology of the patellar tendon (PT) were studied with the use of 28 mature Japanese white rabbits. The PT was frozen in situ by liquid nitrogen to kill the fibroblasts and then, for Stress-Shielding, a stainless-steel wire, installed between the patella and the tibial tubercle, was stretched to release all tension in the PT. After being allowed unrestricted activity in their cages for 1, 2, 3, or 6 weeks, the animals were killed, and the PTs were excised for mechanical and histological study. The cross-sectional area of the frozen and Stress-shielded PT started to increase significantly 1 week after the treatment and leveled off at 3 weeks. In contrast, the tensile strength and elastic modulus began to decrease significantly at 1 week, falling to 15% of the control values at 6 weeks. Histologically, cells were absent until 2 weeks after freezing and Stress-Shielding, although new cells appeared by 3 weeks. Splitting and fragmentation of collagen bundles were observed beginning at 2 weeks. These results indicate that complete Stress-Shielding led to substantial changes in the mechanical properties of the once-frozen PT, even in the absence of the tissue remodeling process by fibroblasts.

  • effects of Stress Shielding on the mechanical properties of rabbit patellar tendon
    Journal of Biomechanical Engineering-transactions of The Asme, 1993
    Co-Authors: N Yamamoto, K Ohno, Kozaburo Hayashi, H Kuriyama, Kazunori Yasuda, Kiyoshi Kaneda
    Abstract:

    : Mechanical properties of the Stress-shielded patellar tendon were studied in the rabbit knee. Stress Shielding was accomplished by stretching a stainless-steel wire installed between the patella and tibial tubercle and thus, releasing the tension in the patellar tendon completely. Tensile tests were carried out on the specimens obtained from the patellar tendons which were exposed to the Stress Shielding for 1 to 6 weeks. The Stress Shielding changed the mechanical properties of the patellar tendon significantly: it decreased the tangent modulus and tensile strength to 9 percent of the control values after 3 weeks. There was a 131 percent increase in the cross-sectional area and a 15 percent decrease in the tendinous length. Remarkable changes were also observed in the structural properties: for example, the maximum load of the bone-tendon complex decreased to 20 percent of the control value after 3 weeks. Histological studies showed that the Stress Shielding increased the number of fibroblasts and decreased the longitudinally aligned collagen bundles. These results imply that if no Stress is applied to the autograft in the case of augmentative reconstruction of the knee ligament, the graft strength decreases remarkably.

Kunio Tanaka - One of the best experts on this subject based on the ideXlab platform.

  • Stress Shielding of patellar tendon effect on small diameter collagen fibrils in a rabbit model
    Journal of Orthopaedic Science, 2003
    Co-Authors: Tokifumi Majima, Kazunori Yasuda, Takamasa Tsuchida, Kunio Tanaka, Kiyoshi Miyakawa, Akio Minami, Kozaburo Hayashi
    Abstract:

    The purpose of this study was to assess the effects of Stress Shielding on the microstructure and ultrastructure of the patellar tendon using 40 mature female Japanese white rabbits. The patellar tendon was completely released from Stress by drawing the patella toward the tibial tubercle with a stainless steel wire installed between them. Microstructurally, Stress Shielding for 3 and 6 weeks increased the number of cells approximately fivefold, to that of the control tendon. Collagen bundles were less well oriented in the Stress-shielded tendon than in the control. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm increased in the Stress-shielded tendon. The median collagen fibril diameter in 6-week Stress-shielded tendon was significantly smaller (P ≪ 0.05) than in the control tendon (58.8% of control). The ratio of the total area of collagen fibrils to the whole visualized area in the Stress-shielded patellar tendon was significantly smaller at 3 and 6 weeks than that in the control. This study demonstrated that complete Stress Shielding significantly affects the microstructure and ultrastructure of the patellar tendon

  • effects of in situ freezing and Stress Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

  • Effects of in situ freezing and Stress‐Shielding on the ultrastructure of rabbit patellar tendons
    Journal of Orthopaedic Research, 1997
    Co-Authors: Takamasa Tsuchida, N Yamamoto, Kozaburo Hayashi, Kazunori Yasuda, Kiyoshi Kaneda, Kiyoshi Miyakawa, Kunio Tanaka
    Abstract:

    : The effects of in situ freezing and the combination of in situ freezing and Stress-Shielding on the microstructure and ultrastructure of the patellar tendon were studied with use of 20 mature rabbits. The patellar tendon was frozen in situ with liquid nitrogen to kill fibroblasts and then was completely released from Stress by chronically pulling a stainless-steel wire installed between the patella and the tibial tubercle. Microstructurally, the freezing treatment induced separation of collagen fiber bundles and fibroblast necrosis at 3 weeks, although the separation disappeared at 6 weeks. Ultrastructurally, small collagen fibrils with a diameter of less than 90 nm were predominant; at 6 weeks, the area occupied by collagen fibrils had decreased. In the frozen-shielded tendon, numerous large spaces were observed in the matrix at 3 weeks. This treatment increased the number of fibrils with a diameter greater than 360 nm and decreased the number of collagen fibrils per unit of area and the area occupied by collagen fibrils at 3 weeks. This study demonstrated that in situ freezing and the combination of in situ freezing and Stress-Shielding leads to a smaller volume of collagen fibrils per unit of cross section of the patellar tendon by mechanisms that remain to be defined.

Related terms

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