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Axial speed of sound for the monitoring of injured equine tendons: a preliminary study.

PublishedJournal ArticleResearch Support, Non-U.S. Gov'tEquine superficial digital flexor tendons (SDFT) are often injured, and they represent an excellent model for human sport tendinopathies. While lesions can be precisely diagnosed by clinical evaluation and ultrasonography, a prognosis is often difficult to establish; the knowledge of the injured tendon's mechanical properties would help in anticipating the outcome. The objectives of the present study were to compare the axial speed of sound (SOS) measured in vivo in normal and injured tendons and to investigate their relationship with the tendons' mechanical parameters, in order to assess the potential of quantitative axial ultrasound to monitor the healing of the injured tendons. SOS was measured in vivo in the right fore SDFTs of 12 horses during walk, before and 3.5 months after the surgical induction of a bilateral core lesion. The 12 horses were then euthanized, their SDFTs isolated and tested in tension to measure their elastic modulus and maximal load (and corresponding stress). SOS significantly decreased from 2179.4 ± 31.4 m/s in normal tendons to 2065.8 ± 67.1 m/s 3.5 months after the surgical induction, and the tendons' elastic modulus (0.90 ± 0.17 GPa) was found lower than what has been reported in normal tendons. While SOS was not correlated to tendon maximal load and corresponding stress, the SOS normalized on its value in normal tendons was correlated to the tendons' elastic modulus. These preliminary results confirm the potential of axial SOS in helping the functional assessment of injured tendon.Direction Générale de l’Enseignement et de la Recherche (French Ministry of Agriculture)Région Basse-NormandieInstitut National de la Recherche AgronomiqueAgence Nationale de la Recherch

Comparing subjective and objective evaluation of show jumping competition and warm-up arena surfaces

The development of safety and quality standards for equestrian surfaces needs to be based on objective, repeatable measurements which allow comparisons between surfaces. These measurements should incorporate the assessment of surface performance by riders. This study provides data from objective and subjective assessment of functional properties of high-level show jumping competition and warm-up arenas. Twenty-five arenas in nine international show jumping events were evaluated by mechanical insitu testing with a surface tester, rider assessments using visual analogue scales (198 riders provided 749 arena evaluations), descriptions of arena constructions and by laboratory tests of surface material. Mixed models were used to present subjective evaluation of rider perception of the functional properties for each arena while controlling for rider and event. The association between objective and subjective assessments were also explored creating mixed models, controlling for rider and event. Mechanical measurements of impact firmness, and to a lesser extent cushioning and grip, had a significant positive association with the riders’ perception. Responsiveness as assessed by the Orono biomechanical surface tester (OBST) was negatively associated with the riders’ perceptions, which suggests riders and the OBST had different concepts of this functional property and that further developments of the OBST might be necessary. Objectively measured uniformity showed no useful association with riders’ perception. Even though arena assessments were made by top level riders, a substantial inter-rider variation was demonstrated

First application of an axial speed of sound measurement technique in the monitoring of tendon healing

PublishedJournal ArticleN/AInstitut National de la Recherche AgronomiqueRe´gion Basse NormandieDirection Ge´ne´rale de l’Enseignement et de la Recherch

True stress and Poisson's ratio of tendons during loading.

PublishedJournal ArticleResearch Support, Non-U.S. Gov'tExcessive axial tension is very likely involved in the aetiology of tendon lesions, and the most appropriate indicator of tendon stress state is the true stress, the ratio of instantaneous load to instantaneous cross-sectional area (CSA). Difficulties to measure tendon CSA during tension often led to approximate true stress by assuming that CSA is constant during loading (i.e. by the engineering stress) or that tendon is incompressible, implying a Poisson's ratio of 0.5, although these hypotheses have never been tested. The objective of this study was to measure tendon CSA variation during quasi-static tensile loading, in order to assess the true stress to which the tendon is subjected and its Poisson's ratio. Eight equine superficial digital flexor tendons (SDFT, about 30cm long) were tested in tension until failure while the CSA of each tendon was measured in its metacarpal part by means of a linear laser scanner. Axial elongation and load were synchronously recorded during the test. CSA was found to linearly decrease with strain, with a mean decrease at failure of -10.7±2.8% (mean±standard deviation). True stress at failure was 7.1-13.6% higher than engineering stress, while stress estimation under the hypothesis of incompressibility differed from true stress of -6.6 to 2.3%. Average Poisson's ratio was 0.55±0.12 and did not significantly vary with load. From these results on equine SDFT it was demonstrated that tendon in axial quasi-static tension can be considered, at first approximation, as an incompressible material.Direction Générale de l’Enseignement et de la Recherche (French Ministry of Agriculture)Région Basse-NormandieInstitut National de la Recherche Agronomiqu

Axial speed of sound is related to tendon's nonlinear elasticity.

PublishedJournal ArticleResearch Support, Non-U.S. Gov'tAxial speed of sound (SOS) measurements have been successfully applied to noninvasively evaluate tendon load, while preliminary studies showed that this technique also has a potential clinical interest in the follow up of tendon injuries. The ultrasound propagation theory predicts that the SOS is determined by the effective stiffness, mass density and Poisson's ratio of the propagating medium. Tendon stiffness characterizes the tissue's mechanical quality, but it is often measured in quasi-static condition and for entire tendon segments, so it might not be the same as the effective stiffness which determines the SOS. The objectives of the present study were to investigate the relationship between axial SOS and tendon's nonlinear elasticity, measured in standard laboratory conditions, and to evaluate if tendon's mass density and cross-sectional area (CSA) affect the SOS level. Axial SOS was measured during in vitro cycling of 9 equine superficial digital tendons. Each tendon's stiffness was characterized with a tangent modulus (the continuous derivative of the true stress/true strain curve) and an elastic modulus (the slope of this curve's linear region). Tendon's SOS was found to linearly vary with the square root of the tangent modulus during loading; tendon's SOS level was found correlated to the elastic modulus's square root and inversely correlated to the tendon's CSA, but it was not affected by tendon's mass density. These results confirm that tendon's tangent and elastic moduli, measured in laboratory conditions, are related to axial SOS and they represent one of its primary determinants.Direction Générale de l’Enseignement et de la Recherche (French Ministry of Agriculture)Région Basse-NormandieInstitut National de la Recherche Agronomiqu

Science in brief: Highlights from the biomechanics and physiotherapy abstracts at the International Conference on Equine Exercise Physiology.

Although human observations of equine locomotion are as old as our relationship with the horse, today's scientists still have much to learn about horse–human interactions. Two approaches are commonly used to study equine biomechanics and both were evident in abstracts presented at the International Conference on Equine Exercise Physiology (ICEEP) 2014. One approach is to use simplified methods of measurement and analysis that provide simple but meaningful objective information that can ultimately be used by the clinician or practitioner. Alternatively, more complex equipment and techniques may be used that directly measure or infer loading on the equine musculoskeletal system to provide detailed structural and functional information. Whichever methods are used, it is important that they are reliable and robust and that the errors and limitations of the measurement system are fully recognised when interpreting data. In his keynote speech, Professor René van Weeren proposed that the biomechanical techniques available to scientists today provide a gateway to a better understanding of the horse–rider interaction that must ultimately improve equine welfare while maintaining peak performance. The abstracts presented in this Editorial therefore cover key topics that are relevant to welfare and performance, lameness and asymmetry, locomotion and sports performance, a focus on the axial system, and the foot

Mark Philp’s notes on the form of knowledge In social work revisited

In social work literature some papers might matter more than others. We assume this might be the case with ‘Notes on the form of knowledge in Social Work’, written by Mark Philp. Even though it was written in 1979, this paper recurrently keeps appearing on and off through writings and footnotes of many scholars in social work and beyond. In brief, Philp might have been pioneering discours analysis on social work literature and practices and suggests there is an underlying constitution of everything that is said and done in social work. This constitution he argues, creates knowledge in social work but also limits social worker to this very knowledge. His analysis draws on Marxist, Foucauldian theories and is utterly ‘historical’ as social work knowledge “is created by historically located shifts in discursive relations“ (Philp, 1979: 103). However, there might be more continuity, as he positions social work historically as mediator between objectified individuals and subjectivity. A stance, which we assume, might still be acknowledged in social work today. In this respect we wondered how scholars in social work today would read and comprehend this seminal paper. What aspects of Philps’ hypothesis, analysis and arguments would they find relevant for social work analysis today and why? In what way might his ‘notes’ enable us to challenge social works knowledge base and positioning? Our analysis is based on two distinct research methods. Firstly, we read through some of his references in order to get more familiar with his thoughts, sources and time. Secondly, we held two discussion panels: one in Antwerp (B) and one held in Ghent (B). Participants, 16 in sum, were selected based on their contribution to social work practice, social work education or research. They have scholarly backgrounds in social work, philosophy, criminology, history, pedagogy and psychology. In our presentation and drawing on Philps' analysis and the comments of Belgian scholars, we will focus on the question if social work should preferably should be seen as a mediator. Or is this positioning no longer relevant or tenable in social work today as society since 1979 has changed dramatically

An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses

Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speedmatched trotting trials and in the second, five horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s � 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P D :001) from being more caudally located in hind-first dissociation (mean locationD0.41�0.04) through synchronous (0.36 � 0.02) to a more cranial location in fore-first dissociation (0.32 � 0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (RD:594; P 0:05) or speed (RD:223; P D:023). Discussion. The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP. During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts. As speed increased, only forelimb vertical peak force increased