Chavaunne Thorpe - Academia.edu (original) (raw)

Papers by Chavaunne Thorpe

Research paper thumbnail of Specialisation of extracellular matrix for function in tendons and ligaments

Tendons and ligaments are similar structures in terms of their composition, organisation and mech... more Tendons and ligaments are similar structures in terms of their composition, organisation and mechanical properties. The distinction between them stems from their anatomical location; tendons form a link between muscle and bone while ligaments link bones to bones. A range of overlapping functions can be assigned to tendon and ligaments and each structure has specific mechanical properties which appear to be suited for particular in vivo function. The extracellular matrix in tendon and ligament varies in accordance with function, providing appropriate mechanical properties. The most useful framework in which to consider extracellular matrix differences therefore is that of function rather than anatomical location. In this review we discuss what is known about the relationship between functional requirements, structural properties from molecular to gross level, cellular gene expression and matrix turnover. The relevance of this information is considered by reviewing clinical aspects of tendon and ligament repair and reconstructive procedures.

Research paper thumbnail of Proteomic analysis reveals age-related changes in tendon matrix composition, with age- and injury-specific matrix fragmentation

The Journal of biological chemistry, Jan 12, 2014

Energy storing tendons, such as the human Achilles and equine superficial digital flexor tendon (... more Energy storing tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT), are highly prone to injury, the incidence of which increases with aging. The cellular and molecular mechanisms that result in increased injury in aged tendons are not well established but are thought to result in altered matrix turnover. However, little attempt has been made to fully characterize the tendon proteome nor determine how the abundance of specific tendon proteins changes with aging and/or injury. The aim of this study was, therefore, to assess the protein profile of normal SDFTs from young and old horses using label-free relative quantification to identify differentially abundant proteins and peptide fragments between age groups. The protein profile of injured SDFTs from young and old horses was also assessed. The results demonstrate distinct proteomic profiles in young and old tendon, with alterations in the levels of proteins involved in matrix organization and regul...

Research paper thumbnail of Transverse and dorso-ventral changes in thoracic dimension during equine locomotion

The Veterinary Journal, 2009

Changes in shape of the equine thorax during locomotion are not well defined, although it has bee... more Changes in shape of the equine thorax during locomotion are not well defined, although it has been shown recently that the transverse hemi-diameter changes its dimension by up to 80mm on the side of the trailing forelimb during gallop, despite minimal change in thoracic circumference. The aim of this project was to analyse transverse and dorso-ventral changes in shape of the thorax simultaneously, and to determine if leading limb, treadmill slope and speed have an effect on these shape changes. Reflective markers were placed on the horse's hemi-thorax and movement of the markers was recorded using a motion capture system while the horse trotted and cantered on a treadmill. Treadmill speed and slope, and the lead the horse cantered on were varied to determine the effects these had on transverse hemi-diameter and dorso-ventral diameter. There was a negative correlation between transverse and dorso-ventral changes in thoracic dimension, the strength of which increased with speed on the trailing limb side. On the leading side, the relationship was either weakly negative or positive. The changes in dimension of the hemi-thorax were significantly greater on the trailing side compared to the leading side. Speed had small effects on thoracic shape changes, but inclined exercise caused an increase in transverse hemi-diameter on the trailing side of the thorax. The changes in thoracic shape are unlikely to contribute substantially to ventilation and rib motion is likely to be due to protraction and retraction of the forelimbs. However, it may reflect asynchronous ventilation of lung lobes and partially explain the prevalence of exercise-induced pulmonary haemorrhage.

Research paper thumbnail of The micro-structural response of tendon fascicles to applied strain is altered with ageing

Osteoarthritis and Cartilage, 2012

expanding chondrocytes, the chondrocytes were subcultured into 6 well culturing dishes at 4Â10 5 ... more expanding chondrocytes, the chondrocytes were subcultured into 6 well culturing dishes at 4Â10 5 cells/well. When cells grew into 80-90% confluent, the culture medium was changed for serum free medium or serum free medium with IL-1b (100pg/ml or 1ng/ml concentration). LIPUS treatment at 0, 7.5, 30, 120mW/cm 2 intensity was applied for 20 minutes. Total RNA was extracted immediately after 1 hour incubation. To elucidate the inhibitory effect of LIPUS on the articular degradation, the mRNA expression of MMP13 was analyzed by real-time PCR method. The condition of 0mW/cm 2 intensity without IL-1b was set as 1, and each of other conditions was shown as the relative amount. To compare any significant differences between control sample (LIPUS intensity 0mW/cm 2 without IL-1b or 0mW/cm 2 with IL-1b) and LIPUS-stimulated sample, the test results were statistically analyzed using the Student's t-test. The difference observed was considered to be significant when p value is lower than 0.05. Results: LIPUS stimulation inhibited the mRNA expression of MMP13 induced by IL-1b of 100pg/ml concentration in intensity-dependent manner (0mW/cm 2 : 4.67AE1.60, 7.5mW/cm 2 : 3.20AE0.24, 30mW/cm 2 : 2.06AE0.55, 120mW/cm 2 : 1.30AE0.29). However, there were no significant differences when expression of MMP13 was induced by IL-1b of 1ng/ml concentration. Conclusions: Our results indicate that LIPUS has a possibility to inhibit IL-1b induced mRNA expression of MMP13 in intensity-dependent manner on rat chondrocytes. Therefore, we may be able to use LIPUS as a daily useful modality to protect articular cartilage.

Research paper thumbnail of Specialization of tendon mechanical properties results from interfascicular differences

Journal of The Royal Society Interface, 2012

Tendons transfer force from muscle to bone. Specific tendons, including the equine superficial di... more Tendons transfer force from muscle to bone. Specific tendons, including the equine superficial digital flexor tendon (SDFT), also store and return energy. For efficient function, energy-storing tendons need to be more extensible than positional tendons such as the common digital extensor tendon (CDET), and when testedin vitrohave a lower modulus and failure stress, but a higher failure strain. It is not known how differences in matrix organization contribute to distinct mechanical properties in functionally different tendons. We investigated the properties of whole tendons, tendon fascicles and the fascicular interface in the high-strain energy-storing SDFT and low-strain positional CDET. Fascicles failed at lower stresses and strains than tendons. The SDFT was more extensible than the CDET, but SDFT fascicles failed at lower strains than CDET fascicles, resulting in large differences between tendon and fascicle failure strain in the SDFT. At physiological loads, the stiffness at th...

Research paper thumbnail of Fascicles from energy-storing tendons show an age-specific response to cyclic fatigue loading

Journal of The Royal Society Interface, 2014

Some tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT), act... more Some tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT), act as energy stores, stretching and recoiling to increase efficiency during locomotion. Our previous observations of rotation in response to applied strain in SDFT fascicles suggest a helical structure, which may provide energy-storing tendons with a greater ability to extend and recoil efficiently. Despite this specialization, energy-storing tendons are prone to age-related tendinopathy. The aim of this study was to assess the effect of cyclic fatigue loading (FL) on the microstructural strain response of SDFT fascicles from young and old horses. The data demonstrate two independent age-related mechanisms of fatigue failure; in young horses, FL caused low levels of matrix damage and decreased rotation. This suggests that loading causes alterations to the helix substructure, which may reduce their ability to recoil and recover. By contrast, fascicles from old horses, in which the helix is ...

Research paper thumbnail of Aspartic Acid Racemization and Collagen Degradation Markers Reveal an Accumulation of Damage in Tendon Collagen That Is Enhanced with Aging

Journal of Biological Chemistry, 2010

Little is known about the rate at which protein turnover occurs in living tendon and whether the ... more Little is known about the rate at which protein turnover occurs in living tendon and whether the rate differs between tendons with different physiological roles. In this study, we have quantified the racemization of aspartic acid to calculate the age of the collagenous and non-collagenous components of the high strain injury-prone superficial digital flexor tendon (SDFT) and low strain rarely injured common digital extensor tendon (CDET) in a group of horses with a wide age range. In addition, the turnover of collagen was assessed indirectly by measuring the levels of collagen degradation markers (collagenase-generated neoepitope and cross-linked telopeptide of type I collagen). The fractional increase in D-Asp was similar (p ‫؍‬ 0.7) in the SDFT (5.87 ؋ 10 ؊4 /year) and CDET (5.82 ؋ 10 ؊4 /year) tissue, and D/L-Asp ratios showed a good correlation with pentosidine levels. We calculated a mean (؎S.E.) collagen half-life of 197.53 (؎18.23) years for the SDFT, which increased significantly with horse age (p ‫؍‬ 0.03) and was significantly (p < 0.001) higher than that for the CDET (34.03 (؎3.39) years). Using similar calculations, the half-life of non-collagenous protein was 2.18 (؎0.41) years in the SDFT and was significantly (p ‫؍‬ 0.04) lower than the value of 3.51 (؎0.51) years for the CDET. Collagen degradation markers were higher in the CDET and suggested an accumulation of partially degraded collagen within the matrix with aging in the SDFT. We propose that increased susceptibility to injury in older individuals results from an inability to remove partially degraded collagen from the matrix leading to reduced mechanical competence.

Research paper thumbnail of The role of the non-collagenous matrix in tendon function

International Journal of Experimental Pathology, 2013

Tendon consists of highly ordered type I collagen molecules that are grouped together to form sub... more Tendon consists of highly ordered type I collagen molecules that are grouped together to form subunits of increasing diameter. At each hierarchical level, the type I collagen is interspersed with a predominantly non-collagenous matrix (NCM) (Connect. Tissue Res., 6, 1978, 11). Whilst many studies have investigated the structure, organization and function of the collagenous matrix within tendon, relatively few have studied the non-collagenous components. However, there is a growing body of research suggesting the NCM plays an important role within tendon; adaptations to this matrix may confer the specific properties required by tendons with different functions. Furthermore, age-related alterations to non-collagenous proteins have been identified, which may affect tendon resistance to injury. This review focuses on the NCM within the tensional region of developing and mature tendon, discussing the current knowledge and identifying areas that require further study to fully understand structure-function relationships within tendon. This information will aid in the development of appropriate techniques for tendon injury prevention and treatment.

Research paper thumbnail of Mechanical properties of the equine superficial digital flexor tendon relate to specific collagen cross-link levels

Equine Veterinary Journal, 2010

The object of the study was to provide models of metacarpophalangeal (MCP) joint surface shapes a... more The object of the study was to provide models of metacarpophalangeal (MCP) joint surface shapes and assess the importance of differences between the four fingers. Preserved metacarpals (MCs) and proximal phalanges (PPs) from 25 fingers were used, with intact articular cartilage. A three dimensional contact digitiser was

Research paper thumbnail of A review of tendon injury: Why is the equine superficial digital flexor tendon most at risk?

Equine Veterinary Journal, 2010

Tendon injury is one of the most common causes of wastage in the performance horse; the majority ... more Tendon injury is one of the most common causes of wastage in the performance horse; the majority of tendon injuries occur to the superficial digital flexor tendon (SDFT) whereas few occur to the common digital extensor tendon. This review outlines the epidemiology and aetiology of equine tendon injury, reviews the different functions of the tendons in the equine forelimb and suggests possible reasons for the high rate of failure of the SDFT. An understanding of the mechanisms leading to matrix degeneration and subsequent tendon gross failure is the key to developing appropriate treatment and preventative measures.

Research paper thumbnail of Effect of fatigue loading on structure and functional behaviour of fascicles from energy-storing tendons

Acta Biomaterialia, 2014

Tendons can broadly be categorised according to their function; those that act purely to position... more Tendons can broadly be categorised according to their function; those that act purely to position the limb and those that have an additional function as energy stores. Energy-storing tendons undergo many cycles of large deformations during locomotion, and so must be able to extend and recoil efficiently, rapidly and repeatedly. Our previous work has shown rotation in response to applied strain in fascicles from energy-storing tendons, indicating the presence of helical substructures which may provide greater elasticity and recovery. In the current study, we assessed how preconditioning and fatigue loading affects the ability of fascicles from the energystoring equine superficial digital flexor tendon to extend and recoil. We hypothesised that preconditioned samples would exhibit changes in microstructural strain response, but would retain their ability to recover. We further hypothesised that fatigue loading would result in sample damage, causing further alterations in extension mechanisms and a significant reduction in sample recovery. The results broadly support these hypotheses, preconditioned samples showed some alterations in microstructural strain response, but were able to recover following the removal of load. However, fatigue loaded samples showed visual evidence of damage and exhibited further alterations in extension mechanisms, characterised by decreased rotation in response to applied strain. This was accompanied by increased hysteresis and decreased recovery. These results suggest that fatigue loading results in a compromised helix substructure, reducing the ability of energy-storing tendons to recoil. A decreased ability to recoil may lead to an impaired response to further loading, potentially increasing the likelihood of injury.

Research paper thumbnail of Helical sub-structures in energy-storing tendons provide a possible mechanism for efficient energy storage and return

Acta Biomaterialia, 2013

The predominant function of tendons is to position the limb during locomotion. Specific tendons a... more The predominant function of tendons is to position the limb during locomotion. Specific tendons also act as energy stores. Energy-storing (ES) tendons are prone to injury, the incidence of which increases with age. This is likely related to their function; ES tendons are exposed to higher strains and require a greater ability to recoil than positional tendons. The specialized properties of ES tendons are thought to be achieved through structural and compositional differences. However, little is known about structurefunction relationships in tendons. This study uses fascicles from the equine superficial digital flexor (SDFT) and common digital extensor (CDET) as examples of ES and positional tendons. We hypothesized that extension and recoil behaviour at the micro-level would differ between tendon types, and would alter with age in the injury-prone SDFT. Supporting this, the results show that extension in the CDET is dominated by fibre sliding. By contrast, greater rotation was observed in the SDFT, suggesting a helical component to fascicles in this tendon. This was accompanied by greater recovery and less hysteresis loss in SDFT samples. In samples from aged SDFTs, the amount of rotation and the ability to recover decreased, while hysteresis loss increased. These findings indicate that fascicles in the ES SDFT may have a helical structure, enabling the more efficient recoil observed. Further, the helix structure appears to alter with ageing; this coincides with a reduction in the ability of SDFT fascicles to recoil. This may affect tendon fatigue resistance and predispose aged tendons to injury.

Research paper thumbnail of Specialisation of extracellular matrix for function in tendons and ligaments

Tendons and ligaments are similar structures in terms of their composition, organisation and mech... more Tendons and ligaments are similar structures in terms of their composition, organisation and mechanical properties. The distinction between them stems from their anatomical location; tendons form a link between muscle and bone while ligaments link bones to bones. A range of overlapping functions can be assigned to tendon and ligaments and each structure has specific mechanical properties which appear to be suited for particular in vivo function. The extracellular matrix in tendon and ligament varies in accordance with function, providing appropriate mechanical properties. The most useful framework in which to consider extracellular matrix differences therefore is that of function rather than anatomical location. In this review we discuss what is known about the relationship between functional requirements, structural properties from molecular to gross level, cellular gene expression and matrix turnover. The relevance of this information is considered by reviewing clinical aspects of tendon and ligament repair and reconstructive procedures.

Research paper thumbnail of Proteomic analysis reveals age-related changes in tendon matrix composition, with age- and injury-specific matrix fragmentation

The Journal of biological chemistry, Jan 12, 2014

Energy storing tendons, such as the human Achilles and equine superficial digital flexor tendon (... more Energy storing tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT), are highly prone to injury, the incidence of which increases with aging. The cellular and molecular mechanisms that result in increased injury in aged tendons are not well established but are thought to result in altered matrix turnover. However, little attempt has been made to fully characterize the tendon proteome nor determine how the abundance of specific tendon proteins changes with aging and/or injury. The aim of this study was, therefore, to assess the protein profile of normal SDFTs from young and old horses using label-free relative quantification to identify differentially abundant proteins and peptide fragments between age groups. The protein profile of injured SDFTs from young and old horses was also assessed. The results demonstrate distinct proteomic profiles in young and old tendon, with alterations in the levels of proteins involved in matrix organization and regul...

Research paper thumbnail of Transverse and dorso-ventral changes in thoracic dimension during equine locomotion

The Veterinary Journal, 2009

Changes in shape of the equine thorax during locomotion are not well defined, although it has bee... more Changes in shape of the equine thorax during locomotion are not well defined, although it has been shown recently that the transverse hemi-diameter changes its dimension by up to 80mm on the side of the trailing forelimb during gallop, despite minimal change in thoracic circumference. The aim of this project was to analyse transverse and dorso-ventral changes in shape of the thorax simultaneously, and to determine if leading limb, treadmill slope and speed have an effect on these shape changes. Reflective markers were placed on the horse&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s hemi-thorax and movement of the markers was recorded using a motion capture system while the horse trotted and cantered on a treadmill. Treadmill speed and slope, and the lead the horse cantered on were varied to determine the effects these had on transverse hemi-diameter and dorso-ventral diameter. There was a negative correlation between transverse and dorso-ventral changes in thoracic dimension, the strength of which increased with speed on the trailing limb side. On the leading side, the relationship was either weakly negative or positive. The changes in dimension of the hemi-thorax were significantly greater on the trailing side compared to the leading side. Speed had small effects on thoracic shape changes, but inclined exercise caused an increase in transverse hemi-diameter on the trailing side of the thorax. The changes in thoracic shape are unlikely to contribute substantially to ventilation and rib motion is likely to be due to protraction and retraction of the forelimbs. However, it may reflect asynchronous ventilation of lung lobes and partially explain the prevalence of exercise-induced pulmonary haemorrhage.

Research paper thumbnail of The micro-structural response of tendon fascicles to applied strain is altered with ageing

Osteoarthritis and Cartilage, 2012

expanding chondrocytes, the chondrocytes were subcultured into 6 well culturing dishes at 4Â10 5 ... more expanding chondrocytes, the chondrocytes were subcultured into 6 well culturing dishes at 4Â10 5 cells/well. When cells grew into 80-90% confluent, the culture medium was changed for serum free medium or serum free medium with IL-1b (100pg/ml or 1ng/ml concentration). LIPUS treatment at 0, 7.5, 30, 120mW/cm 2 intensity was applied for 20 minutes. Total RNA was extracted immediately after 1 hour incubation. To elucidate the inhibitory effect of LIPUS on the articular degradation, the mRNA expression of MMP13 was analyzed by real-time PCR method. The condition of 0mW/cm 2 intensity without IL-1b was set as 1, and each of other conditions was shown as the relative amount. To compare any significant differences between control sample (LIPUS intensity 0mW/cm 2 without IL-1b or 0mW/cm 2 with IL-1b) and LIPUS-stimulated sample, the test results were statistically analyzed using the Student's t-test. The difference observed was considered to be significant when p value is lower than 0.05. Results: LIPUS stimulation inhibited the mRNA expression of MMP13 induced by IL-1b of 100pg/ml concentration in intensity-dependent manner (0mW/cm 2 : 4.67AE1.60, 7.5mW/cm 2 : 3.20AE0.24, 30mW/cm 2 : 2.06AE0.55, 120mW/cm 2 : 1.30AE0.29). However, there were no significant differences when expression of MMP13 was induced by IL-1b of 1ng/ml concentration. Conclusions: Our results indicate that LIPUS has a possibility to inhibit IL-1b induced mRNA expression of MMP13 in intensity-dependent manner on rat chondrocytes. Therefore, we may be able to use LIPUS as a daily useful modality to protect articular cartilage.

Research paper thumbnail of Specialization of tendon mechanical properties results from interfascicular differences

Journal of The Royal Society Interface, 2012

Tendons transfer force from muscle to bone. Specific tendons, including the equine superficial di... more Tendons transfer force from muscle to bone. Specific tendons, including the equine superficial digital flexor tendon (SDFT), also store and return energy. For efficient function, energy-storing tendons need to be more extensible than positional tendons such as the common digital extensor tendon (CDET), and when testedin vitrohave a lower modulus and failure stress, but a higher failure strain. It is not known how differences in matrix organization contribute to distinct mechanical properties in functionally different tendons. We investigated the properties of whole tendons, tendon fascicles and the fascicular interface in the high-strain energy-storing SDFT and low-strain positional CDET. Fascicles failed at lower stresses and strains than tendons. The SDFT was more extensible than the CDET, but SDFT fascicles failed at lower strains than CDET fascicles, resulting in large differences between tendon and fascicle failure strain in the SDFT. At physiological loads, the stiffness at th...

Research paper thumbnail of Fascicles from energy-storing tendons show an age-specific response to cyclic fatigue loading

Journal of The Royal Society Interface, 2014

Some tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT), act... more Some tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT), act as energy stores, stretching and recoiling to increase efficiency during locomotion. Our previous observations of rotation in response to applied strain in SDFT fascicles suggest a helical structure, which may provide energy-storing tendons with a greater ability to extend and recoil efficiently. Despite this specialization, energy-storing tendons are prone to age-related tendinopathy. The aim of this study was to assess the effect of cyclic fatigue loading (FL) on the microstructural strain response of SDFT fascicles from young and old horses. The data demonstrate two independent age-related mechanisms of fatigue failure; in young horses, FL caused low levels of matrix damage and decreased rotation. This suggests that loading causes alterations to the helix substructure, which may reduce their ability to recoil and recover. By contrast, fascicles from old horses, in which the helix is ...

Research paper thumbnail of Aspartic Acid Racemization and Collagen Degradation Markers Reveal an Accumulation of Damage in Tendon Collagen That Is Enhanced with Aging

Journal of Biological Chemistry, 2010

Little is known about the rate at which protein turnover occurs in living tendon and whether the ... more Little is known about the rate at which protein turnover occurs in living tendon and whether the rate differs between tendons with different physiological roles. In this study, we have quantified the racemization of aspartic acid to calculate the age of the collagenous and non-collagenous components of the high strain injury-prone superficial digital flexor tendon (SDFT) and low strain rarely injured common digital extensor tendon (CDET) in a group of horses with a wide age range. In addition, the turnover of collagen was assessed indirectly by measuring the levels of collagen degradation markers (collagenase-generated neoepitope and cross-linked telopeptide of type I collagen). The fractional increase in D-Asp was similar (p ‫؍‬ 0.7) in the SDFT (5.87 ؋ 10 ؊4 /year) and CDET (5.82 ؋ 10 ؊4 /year) tissue, and D/L-Asp ratios showed a good correlation with pentosidine levels. We calculated a mean (؎S.E.) collagen half-life of 197.53 (؎18.23) years for the SDFT, which increased significantly with horse age (p ‫؍‬ 0.03) and was significantly (p < 0.001) higher than that for the CDET (34.03 (؎3.39) years). Using similar calculations, the half-life of non-collagenous protein was 2.18 (؎0.41) years in the SDFT and was significantly (p ‫؍‬ 0.04) lower than the value of 3.51 (؎0.51) years for the CDET. Collagen degradation markers were higher in the CDET and suggested an accumulation of partially degraded collagen within the matrix with aging in the SDFT. We propose that increased susceptibility to injury in older individuals results from an inability to remove partially degraded collagen from the matrix leading to reduced mechanical competence.

Research paper thumbnail of The role of the non-collagenous matrix in tendon function

International Journal of Experimental Pathology, 2013

Tendon consists of highly ordered type I collagen molecules that are grouped together to form sub... more Tendon consists of highly ordered type I collagen molecules that are grouped together to form subunits of increasing diameter. At each hierarchical level, the type I collagen is interspersed with a predominantly non-collagenous matrix (NCM) (Connect. Tissue Res., 6, 1978, 11). Whilst many studies have investigated the structure, organization and function of the collagenous matrix within tendon, relatively few have studied the non-collagenous components. However, there is a growing body of research suggesting the NCM plays an important role within tendon; adaptations to this matrix may confer the specific properties required by tendons with different functions. Furthermore, age-related alterations to non-collagenous proteins have been identified, which may affect tendon resistance to injury. This review focuses on the NCM within the tensional region of developing and mature tendon, discussing the current knowledge and identifying areas that require further study to fully understand structure-function relationships within tendon. This information will aid in the development of appropriate techniques for tendon injury prevention and treatment.

Research paper thumbnail of Mechanical properties of the equine superficial digital flexor tendon relate to specific collagen cross-link levels

Equine Veterinary Journal, 2010

The object of the study was to provide models of metacarpophalangeal (MCP) joint surface shapes a... more The object of the study was to provide models of metacarpophalangeal (MCP) joint surface shapes and assess the importance of differences between the four fingers. Preserved metacarpals (MCs) and proximal phalanges (PPs) from 25 fingers were used, with intact articular cartilage. A three dimensional contact digitiser was

Research paper thumbnail of A review of tendon injury: Why is the equine superficial digital flexor tendon most at risk?

Equine Veterinary Journal, 2010

Tendon injury is one of the most common causes of wastage in the performance horse; the majority ... more Tendon injury is one of the most common causes of wastage in the performance horse; the majority of tendon injuries occur to the superficial digital flexor tendon (SDFT) whereas few occur to the common digital extensor tendon. This review outlines the epidemiology and aetiology of equine tendon injury, reviews the different functions of the tendons in the equine forelimb and suggests possible reasons for the high rate of failure of the SDFT. An understanding of the mechanisms leading to matrix degeneration and subsequent tendon gross failure is the key to developing appropriate treatment and preventative measures.

Research paper thumbnail of Effect of fatigue loading on structure and functional behaviour of fascicles from energy-storing tendons

Acta Biomaterialia, 2014

Tendons can broadly be categorised according to their function; those that act purely to position... more Tendons can broadly be categorised according to their function; those that act purely to position the limb and those that have an additional function as energy stores. Energy-storing tendons undergo many cycles of large deformations during locomotion, and so must be able to extend and recoil efficiently, rapidly and repeatedly. Our previous work has shown rotation in response to applied strain in fascicles from energy-storing tendons, indicating the presence of helical substructures which may provide greater elasticity and recovery. In the current study, we assessed how preconditioning and fatigue loading affects the ability of fascicles from the energystoring equine superficial digital flexor tendon to extend and recoil. We hypothesised that preconditioned samples would exhibit changes in microstructural strain response, but would retain their ability to recover. We further hypothesised that fatigue loading would result in sample damage, causing further alterations in extension mechanisms and a significant reduction in sample recovery. The results broadly support these hypotheses, preconditioned samples showed some alterations in microstructural strain response, but were able to recover following the removal of load. However, fatigue loaded samples showed visual evidence of damage and exhibited further alterations in extension mechanisms, characterised by decreased rotation in response to applied strain. This was accompanied by increased hysteresis and decreased recovery. These results suggest that fatigue loading results in a compromised helix substructure, reducing the ability of energy-storing tendons to recoil. A decreased ability to recoil may lead to an impaired response to further loading, potentially increasing the likelihood of injury.

Research paper thumbnail of Helical sub-structures in energy-storing tendons provide a possible mechanism for efficient energy storage and return

Acta Biomaterialia, 2013

The predominant function of tendons is to position the limb during locomotion. Specific tendons a... more The predominant function of tendons is to position the limb during locomotion. Specific tendons also act as energy stores. Energy-storing (ES) tendons are prone to injury, the incidence of which increases with age. This is likely related to their function; ES tendons are exposed to higher strains and require a greater ability to recoil than positional tendons. The specialized properties of ES tendons are thought to be achieved through structural and compositional differences. However, little is known about structurefunction relationships in tendons. This study uses fascicles from the equine superficial digital flexor (SDFT) and common digital extensor (CDET) as examples of ES and positional tendons. We hypothesized that extension and recoil behaviour at the micro-level would differ between tendon types, and would alter with age in the injury-prone SDFT. Supporting this, the results show that extension in the CDET is dominated by fibre sliding. By contrast, greater rotation was observed in the SDFT, suggesting a helical component to fascicles in this tendon. This was accompanied by greater recovery and less hysteresis loss in SDFT samples. In samples from aged SDFTs, the amount of rotation and the ability to recover decreased, while hysteresis loss increased. These findings indicate that fascicles in the ES SDFT may have a helical structure, enabling the more efficient recoil observed. Further, the helix structure appears to alter with ageing; this coincides with a reduction in the ability of SDFT fascicles to recoil. This may affect tendon fatigue resistance and predispose aged tendons to injury.