The Superficial Digital Flexor Tendon (SDFT) in horses is a critical component of the equine musculoskeletal system, primarily responsible for supporting the limb during locomotion. It is located on the back of the leg and extends from the muscle belly in the upper limb to its attachment on the pastern bone in the lower limb. The SDFT is prone to injury due to its high load-bearing function, particularly in performance horses. Injuries to this tendon can result from overuse, sudden trauma, or degenerative changes, leading to conditions such as tendinitis. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, function, injury mechanisms, and rehabilitation strategies for the Superficial Digital Flexor Tendon in horses.
Murata D, Misumi K, Fujiki M.We hypothesized that semi-quantitative determinations of changeable blood flows in granulation and scar tissues during tendon healing could be helpful for differentiation between the acute phase rich in blood vessels and the remodeling phase with fewer vessels. Ten Thoroughbreds with injured superficial digital flexor tendon (SDFT) in a forelimb were used for evaluation of blood flows in the injured tendons of racehorses using color Doppler (CD) ultrasonography. Using longitudinal CD images, features of maximum color activities were defined. These were rhythmically blinking, tiny to small sign...
Patterson-Kane JC, Becker DL, Rich T.The equine superficial digital flexor tendon (SDFT) is a frequently injured structure that is functionally and clinically equivalent to the human Achilles tendon (AT). Both act as critical energy-storage systems during high-speed locomotion and can accumulate exercise- and age-related microdamage that predisposes to rupture during normal activity. Significant advances in understanding of the biology and pathology of exercise-induced tendon injury have occurred through comparative studies of equine digital tendons with varying functions and injury susceptibilities. Due to the limitations of in-...
Thorpe CT, Udeze CP, Birch HL, Clegg PD, Screen HR.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 tested in vitro have 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 ...
Kalisiak O.Flexor tendonitis and suspensory desmitis are among most prevalent musculoskeletal injuries observed in racehorses. The aim of this study was to determine which horse and race-related parameters can help to diminish the possibility of injury or--when injury has occurred--to evaluate the potential for the horse to continue a successful career after convalescence. Special attention was given to the comparison of Arabian and Thoroughbred racehorses. 187 horses with ultrasonographically visible lesions were included in the study. Following parameters were analyzed: structure (Superficial Digital F...
Docking SI, Daffy J, van Schie HT, Cook JL.Investigations into the response of the superficial digital flexor tendon (SDFT) of the Thoroughbred horse to mechanical stimuli have been limited to in vitro cell culture studies focused primarily on gene expression of critical matrix proteins. It is uncertain how well in vitro outcomes translate to the tendon of the horse during exercise. The current study examined changes in tendon structure in response to maximal exercise using ultrasound tissue characterisation (UTC) to scan the SDFT prior to and after competitive racing. UTC uses contiguous transverse ultrasound images to assess the dyna...
Reardon RJ, Boden LA, Mellor DJ, Love S, Newton JR, Stirk AJ, Parkin TD.Superficial digital flexor (SDF) tendinopathy is a common injury in Thoroughbred horses racing over hurdles. Identification of risk factors may allow the introduction of measures to minimise the incidence of this injury. Objective: To identify risk factors for SDF tendinopathy in Thoroughbred horses in hurdle races in the UK. Methods: Potential risk factors for SDF tendinopathy were studied between 1 January 2001 and 31 December 2009 using a retrospective cohort study design with 1031 case starts and 168,637 control starts. Potential risk factors were screened using univariable logistic regres...
Dakin SG, Werling D, Hibbert A, Abayasekara DR, Young NJ, Smith RK, Dudhia J.Macrophages (Mφ) orchestrate inflammatory and reparatory processes in injured connective tissues but their role during different phases of tendon healing is not known. We investigated the contribution of different Mφ subsets in an equine model of naturally occurring tendon injury. Post mortem tissues were harvested from normal (uninjured), sub-acute (3-6 weeks post injury) and chronically injured (>3 months post injury) superficial digital flexor tendons. To determine if inflammation was present in injured tendons, Mφ sub-populations were quantified based on surface antigen expression of...
Oomen AM, Oosterlinck M, Pille F, Sonneveld DC, Gasthuys F, Back W.The objective of this study was to use a pressure plate to quantify the toe-heel load redistribution in the forelimbs of sound warmblood horses with normal shoes and shoes with a wide toe and narrow branches, used empirically in the treatment of superficial digital flexor tendon or suspensory ligament injuries. In a crossover-design study, six horses, randomly shod with normal shoes and shoes with a wide toe, were led over a dynamically calibrated pressure plate to record data from both forelimbs. There were no significant differences between both shoes in the toe-heel index of stance time, pe...
Caniglia CJ, Schramme MC, Smith RK.Collagen fibril size is decreased in repair tissue following tendon injury compared to normal tendon matrix in horses. Mesenchymal stem cells have been suggested to promote regeneration of tendon matrix rather than fibrotic repair following injury, although this concept remains unproven. Objective: To explore the hypothesis that implantation of autologous mesenchymal stem cells derived from bone marrow into a surgically created central core defect in the superficial digital flexor tendon (SDFT) of horses would induce the formation of a matrix with greater ultrastructural similarities to tendon...
Lovati AB, Corradetti B, Lange Consiglio A, Recordati C, Bonacina E, Bizzaro D, Cremonesi F.Mesenchymal stem cells have been recently investigated for their potential use in regenerative medicine. Population of adult stem cells were recently identified in human and lab animal tendons, but no detailed investigations have been made in the equine species. The aim of our study is to identify a progenitor cell population from tendon tissue (TSPCs) in the horse superficial digital flexor tendon that are able to be highly clonogenic, to grow fast and to differentiate in different induced cell lineages as well as bone marrow derived progenitor cells (BM-MSCs). The hypothesis that TSPCs posse...
David F, Cadby J, Bosch G, Brama P, van Weeren R, van Schie H.Larger superficial digital flexor tendon (SDFT) injuries have a poorer prognosis than smaller lesions. During the inflammatory phase enlargement of the initial lesion is frequently noted, with biomechanical loading being recently proposed to play an important role. Objective: To evaluate the effect of lower limb cast immobilisation on tendon lesion propagation in an equine model of surgically induced SDFT injury. Methods: Core lesions were surgically induced in both front SDFTs of 6 young mature horses. At the end of surgery, one leg was randomly placed in a lower limb cast and the other leg (...
Watanabe T, Imamura Y, Suzuki D, Hosaka Y, Ueda H, Hiramatsu K, Takehana K.The equine superficial digital flexor tendon (SDFT) has a graded distribution of collagen fibril diameters, with predominantly small-diameter fibrils in the region of the myotendinous junction (MTJ), a gradual increase in large-diameter fibrils toward the osteotendinous junction (OTJ), and a mixture of small- and large-diameter fibrils in the middle metacarpal (MM) region. In this study, we investigated the ultrastructure of the SDFT, to correlate the spatial relationship of the collagen fibrils with the graded distribution. The surface-to-surface distances of pairs of fibrils were found to be...
Vergari C, Ravary-Plumioën B, Evrard D, Laugier P, Mitton D, Pourcelot P, Crevier-Denoix N.Axial 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 w...
Everett E, Barrett JG, Morelli J, DeVita R.To compare in vitro biomechanical properties of a novel suture pattern to a current standard for primary repair of equine superficial digital flexor tendon (SDFT) laceration. Methods: In vitro randomized, paired design. Methods: Cadaveric equine forelimb SDFT (n = 24). Methods: The 3-loop pulley (3LP) and 6-strand Savage (SSS) suture patterns were applied to transected equine SDFT. Ultimate failure load, stiffness, mode of failure, and load required to form a 3-mm gap were obtained using a materials testing system and synchronized high-speed video analysis. Statistical comparisons were made us...
Kihara R, Kasashima Y, Arai K, Miyamoto Y.Injury initiates a repair process characterized by influx of fibroblasts and the rapid formation of fibrous scar tissue and subsequent tissue contraction. The response to injury and behavior of the different tendon fibroblast populations, however, has been poorly characterized. We hypothesized that the fibroblasts recovered from tendon with acute injury would exhibit different cell properties relating to adhesion, migration and tensegrity. To test this hypothesis we evaluated the ability of fibroblasts recovered from normal and injured equine superficial digital flexor tendons (SDFTs). The inj...
Witte TH, Yeager AE, Nixon AJ.OBJECTIVE-To evaluate outcome after intralesional injection of insulin-like growth factor-I (IGF-I) for treatment of superficial digital flexor (SDF) tendonitis in Thoroughbred racehorses. DESIGN-Retrospective case series. ANIMALS-40 Thoroughbred racehorses. PROCEDURES-Medical records of racehorses with SDF tendonitis treated within 13 weeks after injury by intralesional injection of IGF-I (25 or 50 μg every other day for 4 or 5 treatments) were reviewed. Outcome was determined via analysis of race records, owner follow-up, and examination. RESULTS-Mean age of the horses was 3.1 years (range,...
Watts AE, Nixon AJ, Yeager AE, Mohammed HO.A consistent and clinically relevant model for the induction of core lesions confined to the mid-metacarpal superficial digital flexor tendon (SDFT) has not been previously reported. Injection of bacterial collagenase is commonly used but often results in large, irregular and inconsistent lesions that disrupt the superficial tendon layers and epitenon. Objective: To develop and evaluate a new injection technique for collagenase induction of SDFT injury. Methods: Collagenase gel was injected into a physical columnar defect created by longitudinally placing a curved 16 gauge 8.89 cm needle in ...
Whitlock D, Garcia TC, Vallance SA, Stover SM.The specific biomechanical circumstances that induce excessive superficial digital flexor tendon (SDFT) strain in horses are unknown. Objective: Carpal joint hyperextension during axial limb loading during the middle of stance disproportionately enhances SDFT strains compared to suspensory ligament (SL) strains. Methods: Superficial digital flexor tendon and SL strains were measured in 7 cadaver limbs during in vitro loading that maintained carpal extension or allowed carpal hyperextension by constraining, or allowing rotation of, the radius during loading conditions that simulated the middle ...
Wright IM, Minshall GJ.Injuries of the calcaneal insertions of the superficial digital flexor tendon and their relationship to displacement of the tendon from the calcaneus have not previously been reported. Objective: To describe findings made on clinical cases with disruption of the calcaneal insertions of the superficial digital flexor tendon (SDFT) including observations on their role in horses with unstable subluxation of the tendon. To describe novel surgical techniques and the results of treatment. Objective: Disruption of the calcaneal insertions of the SDFT is associated with lameness and distension of the ...
Smith RL, Murphy DJ, Day RE, Lester GD.To test single cycle to failure tensile strength characteristics of 6 suture material-pattern combinations in equine superficial digital flexor (SDF) tenorrhaphy, specifically to compare a 10-strand modification of the Savage core suture technique with the 3-loop pulley technique. Methods: Ex vivo mechanical experiment comparing 3 different suture patterns with 2 different materials. Methods: Forelimb and hindlimb SDF tendons (n=48) harvested from adult Thoroughbred and Standardbred horses of mixed age and gender. Methods: Six suture material-pattern combinations were evaluated: (1) 10-strand ...
Arensburg L, Wilderjans H, Simon O, Dewulf J, Boussauw B.Longitudinal tears (LTs) of the digital flexor tendons are an important cause of chronic tenosynovitis of the digital flexor tendon sheath (DFTS). The origin of those marginal tears is not yet fully understood. The long-term outcome after medical and surgical treatment is guarded. Objective: To determine the prevalence of LTs of the digital flexor tendons in a large population of horses undergoing diagnostic tenoscopy of the DFTS and to assess the outcome of surgical treatment and the factors influencing the outcome. Methods: Medical records of 130 horses with chronic tenosynovitis of the DFTS...
Karlin WM, Stewart AA, Durgam SS, Naughton JF, O'Dell-Anderson KJ, Stewart MC.To evaluate tendon injuries in horses over a 16-week period by use of ultrasonography and low-field magnetic resonance imaging (MRI). Methods: Tendons of 8 young adult horses. Methods: The percentage of experimentally induced tendon injury was evaluated in cross section at the maximal area of injury by use of ultrasonography and MRI at 3, 4, 6, 8, and 16 weeks after collagenase injection. The MRI signal intensities and histologic characteristics of each tendon were determined at the same time points. Results: At 4 weeks after collagenase injection, the area of maximal injury assessed on cross ...
Noble P, Lejeune JP, Caudron I, Lejeune P, Collin B, Denoix JM, Serteyn D.Whereas the effect of heel configuration on the tension of the suspensory apparatus is well documented in the literature, there are few reports of joint contact force components in the equine distal forelimb. Objective: To improve understanding of the effect of heel configuration on equine digit joint loading, a sensitivity analysis was performed to compare the effect of a raised heel on joint contact force components in the coffin and fetlock joints during the stance phase of the trot. Methods: Four Warmblood horses were used. An inverse dynamic analysis was carried out using kinematic and ki...
Borgia LA, Valberg SJ, Essen-Gustavsson B.Flexor tendon injury may be due to flexor muscle fatigue, contributing to fetlock joint hyperextension and tendon damage. A water treadmill provides resistance training on flexor tendon muscles, which might reduce the risk of tendon injury. Objective: To determine the effect of water treadmill training on the properties of the gluteal and superficial digital flexor (SDF) muscles and on cardiocirculatory response to a standardised exercise test. Methods: Five healthy unfit horses were trained on a water treadmill for 5 days/week for 4 weeks, starting with 5 min/day increasing to 20 min/day. Bef...
Thorpe CT, Stark RJ, Goodship AE, Birch HL.Damage to the flexor tendons, particularly the superficial digital flexor tendon (SDFT), is one of the most common musculoskeletal injuries sustained by horses competing in all disciplines. Our previous work has shown that SDFTs from different individuals show a wide variation in mechanical strengths; this is important clinically as it may relate to predisposition to injury. The high mechanical strength of tendon relies on the correct orientation of collagen molecules within fibrils and stabilisation by the formation of chemical cross-links between collagen molecules. It is not known whether t...
Addis PR, Lawson SE.The flexor tendons support the metacarpophalangeal (MCP) and distal interphalangeal (DIP) joints during stance phase and since tendon stiffness and strain changes with age, it is likely that kinematics are also age-dependent. Objective: Maximum MCP and DIP angles decrease in the young horse, plateau in the mature horse and increase towards senescence. Methods: The distal limbs of 57 walking horses age 3-212 months were filmed and digitised with an automated tracking system. Maximum MCP and DIP angles during stance phase were used to calculate strain in the superficial and deep digital flexor t...
Crevier-Denoix N, Robin D, Pourcelot P, Falala S, Holden L, Estoup P, Desquilbet L, Denoix JM, Chateau H.Although beach training is commonly used in horses, limb loading on beach sand has never been investigated. A dynamometric horseshoe (DHS) is well adapted for this purpose. Objective: To compare ground reaction force (GRF) and fetlock kinematics measured in harness trotters on 2 tracks of beach sand with different water content. Methods: Two linear sand tracks were compared: firm wet sand (FWS, 19% moisture) vs. deep wet sand (DWS, 13.5% moisture). Four French trotters (550 ± 22 kg) were used. Their right forelimb was equipped with a DHS and skin markers. Each track was tested 3 times at 7 m/...
Takahashi T, Yoshihara E, Mukai K, Ohmura H, Hiraga A.Although the main cause of injury to the superficial digital flexor tendon (SDFT) is assumed to be high intensity loading of the tendon, to date the forces exerted on the SDFT during cantering have never been measured. Objective: To measure the force exerted on the SDFT at walk, trot and canter on a treadmill. Methods: Arthroscopically implantable force probes (AIFP) were implanted in the SDFT of the left and right forelimbs of 8 Thoroughbred horses (480-565 kg). The output of the AIFP was calibrated using the SDFT force calculated by inverse dynamics and an in vitro model of the lower forelim...
Godwin EE, Young NJ, Dudhia J, Beamish IC, Smith RK.Mesenchymal stem (progenitor; stromal) cell (MSC) therapy has gained popularity for the treatment of equine tendon injuries but without reports of long-term follow-up. Objective: To evaluate the safety and reinjury rate of racehorses after intralesional MSC injection in a large study of naturally occurring superficial digital flexor tendinopathy and to compare these data with those published for other treatments. Methods: Safety was assessed clinically, ultrasonographically, scintigraphically and histologically in a cohort of treated cases: 141 client-owned treated racehorses followed-up for a...
Watts AE, Nixon AJ, Reesink HL, Cheetham J, Fubini SL, Looney AL.To investigate the efficacy and safety of a low-volume, single-catheter, continuous peripheral neural blockade (CPNB) technique to locally deliver bupivacaine to alleviate signs of severe forelimb pain resulting from experimentally induced tendonitis in horses. Methods: Randomized controlled experimental trial. Methods: 14 horses and 5 forelimbs from equine cadavers. Methods: Horses underwent collagenase-induced superficial digital flexor tendonitis in the midmetacarpal region of 1 forelimb. To deliver analgesia, a closed-tip catheter was placed from lateral to medial, approximately 12 cm dist...
Dow SM, Leendertz JA, Silver IA, Goodship AE.In this study a method of analysing ground reaction forces was developed to help in the diagnosis of subclinical flexor tendon injury. A Kistler force plate was used to obtain records from a population of Thoroughbreds in National Hunt training over a period of two years. Characteristic features of the force patterns generated were measured and shown to have low variance, both between horses and over a period of two racing seasons in animals that were sound throughout the trial. Specific changes in the loading pattern of the limb, which correlated with injury of the superficial digital flexor ...
Bosch G, Lameris MC, van den Belt AJ, Barneveld A, van Weeren PR.Clinical tendon lesions usually enlarge during the first days to weeks after sustaining the injury due to enzymatic and biomechanical influences. Limiting this enlargement would positively influence prognosis related to lesion size. Objective: To investigate the effect of cyclic loading on the propagation of enzymatically and physically induced tendon lesions and to assess the effect of immobilisation thereon in an ex vivo model. Methods: Equine cadaver limbs with either physically or collagenase-induced SDFT lesions were placed in a pneumatic loading device. Groups consisted of unloaded limbs...
Oomen AM, Oosterlinck M, Pille F, Sonneveld DC, Gasthuys F, Back W.The objective of this study was to use a pressure plate to quantify the toe-heel load redistribution in the forelimbs of sound warmblood horses with normal shoes and shoes with a wide toe and narrow branches, used empirically in the treatment of superficial digital flexor tendon or suspensory ligament injuries. In a crossover-design study, six horses, randomly shod with normal shoes and shoes with a wide toe, were led over a dynamically calibrated pressure plate to record data from both forelimbs. There were no significant differences between both shoes in the toe-heel index of stance time, pe...
van Schie JT, Bakker EM, van Weeren PR.The objective of the in vitro experiments described in this paper was to quantify the effects of some instrumental variables on the quantitative evaluation, by means of first-order gray-level statistics, of ultrasonographic images of equine tendons. The experiments were done on three isolated equine superficial digital flexor tendons that were mounted in a frame and submerged in a waterbath. Sections with either normal tendon tissue, an acute lesion, or a chronic scar, were selected. In these sections, the following experiments were done: 1) a gradual increase of total amplifier gain output su...
Reardon RJ, Boden LA, Mellor DJ, Love S, Newton JR, Stirk AJ, Parkin TD.The objective of this study was to identify risk factors for superficial digital flexor (SDF) tendinopathy in Thoroughbred horses in steeplechase races in the United Kingdom. Potential risk factors for SDF tendinopathy were studied between 1st January 2001 and 31st December 2009 using a cohort study design with 648 injuries sustained in 102,894 starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building. In the final multivariable model, 12 statistically significant risk factors were identified. Variables that increased the odds of S...
Duesterdieck-Zellmer KF, Larson MK, Plant TK, Sundholm-Tepper A, Payton ME.OBJECTIVE To measure penetration efficiencies of low-level laser light energy through equine skin and to determine the fraction of laser energy absorbed by equine digital flexor tendons (superficial [SDFT] and deep [DDFT]). SAMPLE Samples of skin, SDFTs, and DDFTs from 1 metacarpal area of each of 19 equine cadavers. PROCEDURES A therapeutic laser with wavelength capabilities of 800 and 970 nm was used. The percentage of energy penetration for each wavelength was determined through skin before and after clipping and then shaving of hair, through shaved skin over SDFTs, and through shaved skin,...
Williams GE, Silverman BW, Wilson AM, Goodship AE.To assess the force plate as a diagnostic aid in equine locomotor abnormalities, particularly for abnormalities such as navicular disease that do not have specific diagnostic criteria. Methods: 17 Thoroughbreds without observable locomotor abnormalities (group A), 6 Thoroughbreds with superficial digital flexor tendon injury (group B), and 8 Thoroughbreds with navicular disease (group C). Methods: Using a force plate, ground reaction force patterns were recorded at the trot. Peak limb vertical force and force/time curve parameters were derived from 4 identifiable points at the beginning and en...
Kraus-Hansen AE, Fackelman GE, Becker C, Williams RM, Pipers FS.The vascular and microvascular anatomy of normal equine superficial digital flexor tendons was studied by dissection of vinyl-perfused specimens and by microangiography on high detail film. The presence of an extensive intratendinous vascular latticework was confirmed, and a 'nutrient artery' described closely associated with the accessory ligament of the superficial digital flexor tendon (proximal check ligament). Circumferential stripping of the paratenon from the tendon to eliminate afferent vessels was performed bilaterally in three horses and unilaterally in a fourth, followed by a treadm...
Brandão JS, Alvarenga ML, Pfeifer JPH, Dos Santos VH, Fonseca-Alves CE, Rodrigues M, Laufer-Amorim R, Castillo JAL, Alves ALG.The superficial digital flexor tendon (SDFT) is a structure frequently affected by injuries in high-performance athletic horses, and there are limited therapeutic options. Regenerative medicine has evolved significantly in treating different illnesses. However, understanding the cellular behaviour during mesenchymal stem cell (MSC) transplantation in healthy tissues is not fully known yet. To address the inflammatory response induced by allogeneic MSC transplantation, this study evaluated the local inflammatory response after the application of allogeneic adipose tissue-derived mesenchymal ste...
Karlin WM, Stewart AA, Durgam SS, Naughton JF, O'Dell-Anderson KJ, Stewart MC.To evaluate tendon injuries in horses over a 16-week period by use of ultrasonography and low-field magnetic resonance imaging (MRI). Methods: Tendons of 8 young adult horses. Methods: The percentage of experimentally induced tendon injury was evaluated in cross section at the maximal area of injury by use of ultrasonography and MRI at 3, 4, 6, 8, and 16 weeks after collagenase injection. The MRI signal intensities and histologic characteristics of each tendon were determined at the same time points. Results: At 4 weeks after collagenase injection, the area of maximal injury assessed on cross ...
Dahlgren LA, Brower-Toland BD, Nixon AJ.To clone the 5' end of type III collagen and describe its pattern of mRNA and protein expression in normal and healing tendons in horses. Methods: 14 healthy adult horses. Methods: The tensile region of collagenase-injured superficial digital flexor tendons was harvested at intervals from 1 to 24 weeks after injury. Total RNA was reverse-transcribed into cDNA for cloning and sequencing of type III collagen. Equine-specific nucleic acid probes were developed and used for northern blot analysis and in situ hybridization. Type III collagen protein and cyanogen bromide-cleaved collagen peptides we...
van Schie HT, Bakker EM.To develop a method to discriminate between structure-related echoes and echoes resulting from interference, as observed in transverse ultrasonographic images of equine superficial digital flexor (SDF) tendons. Methods: 2 normal (injury-free) SDF tendons obtained from a 3-year-old Thoroughbred and a 9-year-old Dutch Warmblood horse. Methods: Tendons were mounted in a custom-made device that permitted exact transverse and perpendicular sequential scanning with precise steps of 0.5 mm along the long axis of the tendon. Photographs of transverse tendon sections at the exact scanning locations wer...
Ehrle A, Lilge S, Clegg PD, Maddox TW.Flexor tendon injuries are a major cause of lameness in performance horses and have considerable impact on equine welfare and the wider horse industry. Ageing and repetitive strain frequently cause varying degrees of tendon micro-damage prior to the recognition of clinical tendinopathy. Whilst B-mode ultrasonography is most commonly utilised for detection and monitoring of tendon lesions at the metacarpal/metatarsal level, the emphasis of recent research has focused on the identification of subclinical tendon damage in order to prevent further tendon injury and improve outcomes. The introducti...
Cherdchutham W, Meershoek LS, van Weeren PR, Barneveld A.To determine the effects of exercise on biomechanical properties of the superficial digital flexor tendon (SDFT) in foals. Methods: 43 Dutch Warmblood foals. Methods: From 1 week until 5 months of age, 14 foals were housed in stalls and not exercised, 14 foals were housed in stalls and exercised daily, and 15 foals were maintained at pasture. Eight foals in each group were euthanatized at 5 months, and remaining foals were housed together in a stall and paddock until euthanatized at 11 months. After euthanasia, SDFT were isolated and fit in a material testing system. Mean cross-sectional area ...
Crevier-Denoix N, Pourcelot P, Ravary B, Robin D, Falala S, Uzel S, Grison AC, Valette JP, Denoix JM, Chateau H.Although track surfaces are a risk factor of tendon injuries, their effects on tendon loading at high speed are unknown. Using a noninvasive ultrasonic technique, it is now possible to evaluate the forces in the superficial digital flexor tendon (SDFT) in exercise conditions. Objective: To compare the effects of an all-weather waxed track (W) vs. a crushed sand track (S), on the SDFT loading in the trotter horse at high speed. Methods: Two trotter horses were equipped with the ultrasonic device (1 MHz ultrasonic probe, fixed on the palmar metacarpal area of the right forelimb). For each trial,...
Meershoek LS, Lanovaz JL, Schamhardt HC, Clayton HM.To calculate forces in the flexor tendons and the influence of heel wedges in affected and contralateral (compensating) forelimbs of horses with experimentally induced unilateral tendinitis of the superficial digital flexor (SDF) tendon. Methods: 5 Warmblood horses. Procedure-Ground reaction force and kinematic data were obtained during a previous study while horses were trotting before and after induction of tendinitis in 1 forelimb SDF and after application of 6 degrees heel wedges to both forehooves. Forces in the SDF, deep digital flexor (DDF), and the suspensory ligament (SL) and strain i...
Genovese RL, Rantanen NW, Simpson BS, Simpson DM.A method to quantitate as well as to document SDFT pathology has been described. This report indicates that computer-assisted evaluation of SDFT damage can improve the accuracy of prognosis in clinical practice. It would appear that a 3.8 severity rating is a limit past which prognosis for successful racing starts to worsen rapidly.
Hosaka Y, Teraoka H, Yamamoto E, Ueda H, Takehana K.The aim of the present study was to clarify the presence and determine the role of apoptosis in the degenerative process of the superficial digital flexor tendon (SDFT) in the horse. Samples were obtained from normal and inflamed SDFTs of horses. To detect apoptosis and to identify apoptotic cells, the samples were subjected to immunohistochemical labelling and Western blot analysis. Although a large number of cells in degenerate areas showed positive reactions with caspase-3 and single stranded DNA antibodies, cells in normal tendon samples showed very weak reactions. Excessive apoptosis was ...
Cherdchutham W, Becker CK, Spek ER, Voorhout WF, van Weeren PR.To determine the effects of exercise on collagen fibril diameter distribution in the superficial digital flexor tendon (SDFT) of foals. Methods: 43 Dutch Warmblood foals. Methods: From 1 week until 5 months of age, group-1 foals (n = 14) were housed in stalls and not exercised, group-2 foals (14) were housed in stalls but were exercised, and group-3 foals (15) were maintained at pasture. Biopsy specimens were collected from the SDFT at 2 months, and 8 foals in each group were euthanatized at 5 months. Remaining foals were housed together in a loose stall and paddock until euthanatized at 11 mo...
Scharf A, Holmes SP, Thoresen M, Mumaw J, Stumpf A, Peroni J.Ultrasound-guided intralesional injection of mesenchymal stem cells (MSCs) is held as the benchmark for cell delivery in tendonitis. The primary objective of this study was to investigate the immediate cell distribution following intralesional injection of MSCs. Unilateral superficial digital flexor tendon (SDFT) lesions were created in the forelimb of six horses and injected with 10 × 10 MSCs labeled with superparamagnetic iron oxide nanoparticles (SPIOs) under ultrasound guidance. Assays were performed to confirm that there were no significant changes in cell viability, proliferation, migra...
Yin NH, Parker AW, Matousek P, Birch HL.The lack of clinical detection tools at the molecular level hinders our progression in preventing age-related tendon pathologies. Raman spectroscopy can rapidly and non-invasively detect tissue molecular compositions and has great potential for in vivo applications. In biological tissues, a highly fluorescent background masks the Raman spectral features and is usually removed during data processing, but including this background could help age differentiation since fluorescence level in tendons increases with age. Therefore, we conducted a stepwise analysis of fluorescence and Raman combined s...
Alzola R, Easter C, Riggs CM, Gardner DS, Freeman SL.Superficial digital flexor tendon (SDFT) injury is an important health and welfare concern in racehorses. It is generally diagnosed with ultrasonography, but predictive ultrasonographic features have not been reported. Objective: To determine ultrasonographic features of forelimb SDFT injury at initial presentation in Thoroughbred racehorses that could predict a successful return to racing (completing ≥5 races). Methods: Retrospective cohort study. Methods: Digitised ultrasonographic images of 469 horses with forelimb SDFT injuries from the Hong Kong Jockey Club (2003-2014) were evaluated, u...
Dabbene I, Bullone M, Pagliara E, Gasparini M, Riccio B, Bertuglia A.Information on interference injuries in racehorses is lacking. Objective: To describe clinical findings and prognosis of palmar forelimb interference injuries in Standardbreds. Methods: Retrospective cohort study. Methods: Records of 74 racehorses sustaining palmar forelimb interference injuries were studied; 7 occurred during training and 67 during racing. The number of starts before injury, hind shoeing status, gait penalties and racing speeds in cases occurring during racing were compared with negative controls (67 age, sex and speed category matched horses) from the same races. The number ...
Addis PR, Lawson SE.The flexor tendons support the metacarpophalangeal (MCP) and distal interphalangeal (DIP) joints during stance phase and since tendon stiffness and strain changes with age, it is likely that kinematics are also age-dependent. Objective: Maximum MCP and DIP angles decrease in the young horse, plateau in the mature horse and increase towards senescence. Methods: The distal limbs of 57 walking horses age 3-212 months were filmed and digitised with an automated tracking system. Maximum MCP and DIP angles during stance phase were used to calculate strain in the superficial and deep digital flexor t...
Fraser BS, Bladon BM.Lacerations to the digital flexor tendon sheath (DFTS) are a common injury in the horse, but little information is available in the literature regarding prognostic indicators. Objective: To ascertain whether laceration of the DFTS carried a better prognosis if treated by tenoscopic lavage, debridement and repair within 36 h of the original injury. Methods: A retrospective analysis of 39 horses treated surgically for lacerations to the DFTS was performed over a 3 year period. The injury-to-surgery interval was recorded as <36 or >36 h. The structures damaged by the injury were also recorded, as...
Hagen J, Kojah K, Geiger M.The angulation of the equine fetlock determines the load of associated tendons and probably their predisposition for injuries. However, it is questionable how the individual toe conformation and tendon properties interact with the dorsal metacarpophalangeal joint angle (DMPJ). Data are needed for a tangible evaluation of the equine limb conformation for more specific orthopaedic treatment. The aim was to evaluate the correlation between the DMPJ, toe conformation and cross-sectional area (CSA) of both flexor tendons; the superficial digital flexor tendon (SDFT) and deep digital flexor tendon (...
Crevier N, Pourcelot P, Denoix JM, Geiger D, Bortolussi C, Ribot X, Sanaa M.To determine the local variations of mechanical properties of the equine superficial digital flexor tendon (SDFT). Methods: 10 SDFT of adult horses, selected for absence of abnormality. Methods: Needles (with a dark marker at both ends) pinned perpendicularly through each tendon to delimit 7 segments. Each tendon was tested in traction until rupture; test was filmed, using an 8-mm video camera. For each image, the coordinates of the center of mass of each marker and the corresponding force were registered. The third-degree polynomial that best fits the stress-strain curve thus obtained was cal...
Nixon AJ.An arthroscopic procedure for examination of the digital flexor tendons and tendon sheath was developed in 16 equine limbs and 12 horses. Distension of the tendon sheath and insertion of the arthroscope was accomplished through a cul-de-sac on the palmar or plantar surface of the tendon sheath 1 to 2 cm palmar or plantar to the digital neurovascular structures and between the annular ligament and proximal digital annular ligament. A single arthroscope entry point allowed examination of all regions of the tendon sheath cavity and most surfaces of the digital flexor tendons within the sheath. Di...
Oki H, Miyake T, Kasashima Y, Sasaki Y.The superficial digital flexor tendon (SDFT) injury causes considerable wastage of racing Thoroughbreds. In this study, the heritability of SDFT injury of the forelimbs was estimated in the Thoroughbred racehorses based on the Bayesian analysis with Gibbs sampling using threshold animal models. New horse patients of SDFT injury at the age of 2-5 years accommodated in the training centers in 2005 were used for the analyses. Based on clinical data of 8198 horses, heritability of SDFT was estimated to be the order of 0.17 (posterior mode) to 0.19 +/- 0.05 (posterior mean +/- posterior SD).
