Cyclic tensile tests of Shetland pony superficial digital flexor tendons (SDFTs) with an optimized cryo-clamp combined with biplanar high-speed fluoroscopy
Background: Long-term cyclic tensile testing with equine palmar/plantar tendons have not yet been performed due to problems in fixing equine tendons securely and loading them cyclically. It is well established that the biomechanical response of tendons varies during cyclic loading over time. The aim of this study was to develop a clamping device that enables repetitive cyclic tensile testing of equine superficial digital flexor tendon for at least 60 loading cycles and for 5 min.
Results: A novel cryo-clamp was developed and built. Healthy and collagenase-treated pony SDFTs were mounted in the custom-made cryo-clamp for the proximal tendon end and a special clamping device for the short pastern bone (os coronale). Simultaneously with tensile testing, we used a biplanar high-speed fluoroscopy system (FluoKin) to track tendon movement. The FluoKin system was additionally validated in precision measurements. During the cyclic tensile tests of the SDFTs, the average maximal force measured was 325 N and 953 N for a length variation of 2 and 4 % respectively. The resulting stress averaged 16 MPa and 48 MPa respectively, while the modulus of elasticity was 828 MPa and 1212 MPa respectively. Length variation of the metacarpal region was, on average, 4.87 % higher after incubation with collagenase. The precision of the FluoKin tracking was 0.0377 mm, defined as the standard deviation of pairwise intermarker distances embedded in rigid bodies. The systems accuracy was 0.0287 mm, which is the difference between the machined and mean measured distance.
Conclusion: In this study, a good performing clamping technique for equine tendons under repetitive cyclic loading conditions is described. The presented cryo-clamps were tested up to 50 min duration and up to the machine maximal capacity of 10 kN. With the possibility of repetitive loading a stabilization of the time-force-curve and changes of hysteresis and creep became obvious after a dozen cycles, which underlines the necessity of repetitive cyclical testing. Furthermore, biplanar high-speed fluoroscopy seems an appropriate and highly precise measurement tool for analysis of tendon behaviour under repetitive load in equine SDFTs.
The use of biplanar high-speed x-ray fluoroscopy to study fast, 3D movements that are inaccessible from external views has grown significantly in the past decade. Owing to the development of specialised software for calibration, distortion correction, and automated tracking of radio-opaque marker implants, this technique will soon become the standard to analyse skeletal kinematics of vertebrate animals. However, tests of important characteristics of biplanar x-ray systems, such as resolution and...
SummaryReason for performing study Biplane high-speed fluoroscopy is a new method for gait analysis of the equine distal extremity. This is the first study validating the noninvasive tracking possibilities (Autoscoping and Scientific Rotoscoping) taking equine anatomy into account. Objectives To determine the resolution with which Autoscoping and Scientific Rotoscoping depict motion of the equine phalanges in comparison to the invasive gold standard marker-based registration. Study design Compar...
ABSTRACT Lameness severely impairs cattle's locomotion, and it is among the most important threats to animal welfare, performance, and productivity in the modern dairy industry. However, insight into the pathological alterations of claw biomechanics leading to lameness and an understanding of the biomechanics behind development of claw lesions causing lameness are limited. Biplane high-speed fluoroscopic kinematography is a new approach for the analysis of skeletal motion. Biplane high-speed vid...
Last. Annette B. Ahrberg(Translational Centre for Regenerative Medicine)H-Index: 6
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Abstract Tendon disease has been treated with multipotent mesenchymal stromal cells (MSC) in the equine large animal model with promising success. The aim of this study was to gain more insight into the fate and biodistribution of MSC after local application into tendon lesions by long term cell tracking in this large animal model. Superficial digital flexor tendon lesions were induced in all limbs in 6 horses and injected with 10x10(6) Molday ION Rhodamine B(TM)-labeled MSC suspended in serum o...
ABSTRACT Marker-based XROMM requires software tools for: (1) correcting fluoroscope distortion; (2) calibrating X-ray cameras; (3) tracking radio-opaque markers; and (4) calculating rigid body motion. In this paper we describe and validate XMALab, a new open-source software package for marker-based XROMM (C++ source and compiled versions on Bitbucket). Most marker-based XROMM studies to date have used XrayProject in MATLAB. XrayProject can produce results with excellent accuracy and precision, b...
#2Graham P. Riley(UEA: University of East Anglia)H-Index: 43
Last. Hazel R.C. Screen(QMUL: Queen Mary University of London)H-Index: 36
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Tendon is composed of rope-like fascicles, bound together by interfascicular matrix (IFM). Our previous work shows that the IFM is critical for tendon function, facilitating sliding between fascicles to allow tendons to stretch. This function is particularly important in energy storing tendons, which experience extremely high strains during exercise, and therefore require the capacity for considerable inter-fascicular sliding and recoil. This capacity is not required in positional tendons. Whils...
#2Marta S C Godinho(QMUL: Queen Mary University of London)H-Index: 2
Last. Hazel R.C. Screen(QMUL: Queen Mary University of London)H-Index: 36
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While the predominant function of all tendons is to transfer force from muscle to bone and position the limbs, some tendons additionally function as energy stores, reducing the cost of locomotion. Energy storing tendons experience extremely high strains and need to be able to recoil efficiently for maximum energy storage and return. In the equine forelimb, the energy storing superficial digital flexor tendon (SDFT) has much higher failure strains than the positional common digital extensor tendo...
#2Graham P. Riley(UEA: University of East Anglia)H-Index: 43
Last. Hazel R.C. Screen(QMUL: Queen Mary University of London)H-Index: 36
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Tendons can broadly be categorized 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 pr...
#2Graham P. Riley(UEA: University of East Anglia)H-Index: 43
Last. Hazel R.C. Screen(QMUL: Queen Mary University of London)H-Index: 36
view all 5 authors...
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 th...
Last. Hazel R.C. Screen(QMUL: Queen Mary University of London)H-Index: 36
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Most overuse tendinopathies are thought to be associated with repeated microstrain below the failure threshold, analogous to the fatigue failure that affects materials placed under repetitive loading. Investigating the progression of fatigue damage within tendons is therefore of critical importance. There are obvious challenges associated with the sourcing of human tendon samples for in vitro analysis so animal models are regularly adopted. However, data indicates that fatigue life varies signif...