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.
Dowling BA, Dart AJ.The in vitro and in vivo mechanical properties of the superficial digital flexor tendon have been described. To date the focus has been on single load to failure testing, however refined in vivo methods may prove useful to evaluate the effects of treatment and exercise on tendons. During maximal exercise, the adult superficial digital flexor tendon operates close to its functional limits with a narrow biomechanical safety margin. This combined with exercise and age associated microdamage, and a limited adaptive ability may increase the risk of fatigue failure. Studies evaluating treatment regi...
Gerard MP, Hodgson DR, Rose RJ, Walsh WR.To determine whether recombinant equine growth hormone (rEGH) would alter the in vitro biomechanical properties of the forelimb superficial digital flexor tendon (SDFT) in exercising young Standardbred horses. Methods: Randomized complete block design. Methods: Twelve Standardbred yearlings. Methods: Horses were trained for 12 weeks on a high-speed treadmill (10% positive incline). rEGH was administered intramuscularly (IM) daily (10 microg/kg during week 4; 20 microg/kg for weeks 5-9) to 6 horses (treated group), whereas 6 horses (control group) were administered an equivalent daily volume of...
Lin YL, Brama PA, Kiers GH, van Weeren PR, DeGroot J.The objectives of the present study were to test the hypotheses that: (1) the composition of the extracellular matrix of the equine superficial digital flexor tendon (SDFT) shows great functional similarities with articular cartilage, i.e. that significant differences exist in biochemical composition of differently loaded areas (which in the case of tendons may be more apparent as tendon shows more obvious differences than cartilage); and (2) that, as in articular cartilage, no substantial alterations in biochemical composition take place during ageing once adulthood has been attained. Tendon ...
Pourcelot P, Defontaine M, Ravary B, Lemâtre M, Crevier-Denoix N.The ability to measure the forces exerted in vivo on tendons and, consequently, the forces produced by muscles on tendons, offers a unique opportunity to investigate questions in disciplines as varied as physiology, biomechanics, orthopaedics and neuroscience. Until now, tendon loads could be assessed directly only by means of invasive sensors implanted within or attached to these collagenous structures. This study shows that the forces acting on tendons can be measured, in a non-invasive way, from the analysis of the propagation of an acoustic wave. Using the equine superficial digital flexor...
Gibson KT, Burbidge HM, Robertson ID.To determine the effect of polyester (terylene) fibre implants on normal equine superficial digital flexor (SDF) tendon structure. Methods: Normal forelimb SDF tendons (n=24) of 12 horses were divided into unoperated, sham-operated, and implanted (terylene fibre implant) groups. Horses were assessed for lameness and ultrasonographic changes to SDF tendons at intervals up to 48 weeks post-operatively. After euthanasia, SDF tendons were collected for histological and ultrastructural examination. Histological sections were examined for alcian blue staining intensity, cellularity, fibril bundle al...
Perkins NR, Reid SW, Morris RS.To investigate risk factors for injury to the superficial digital flexor tendon (SDFT) and suspensory apparatus (SA) of the forelimbs in Thoroughbred racehorses in New Zealand. Methods: Poisson and negative binomial regression, with exposure time represented by cumulative training days for each horse, were used to relate explanatory variables to the incidence rate (IR) of cases of inflammation of the SDFT (n=51), and injuries involving the SA (n=48) in a population of 1,571 commercially- trained racehorses over 554,745 study days. Only the first occurrence of an injury for any one horse was el...
Firth EC, Rogers CW, Anderson BH.To determine the weight, volume, density and cross-sectional area (CSA) of the digital flexor tendons, common digital extensor tendon (CDET) and suspensory ligament (SL) of the forelimb of young Thoroughbred horses in early training, and to assess the response to a training programme of known parameters of superficial digital flexor tendon (SDFT) tissue at mid-metacarpal level. Methods: The tendons of seven 2-year-old Thoroughbred horses in training were inspected, transected into segments of known length, and compared with those from seven untrained horses matched for age, sex and breed. The ...
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...
Kicker CJ, Peham C, Girtler D, Licka T.Support boots are thought to reduce tension on the superficial digital flexor tendon (SDTF) of the horse and are frequently recommended for horses convalescing after tendonitis, but evidence of their effectiveness is conflicting. Objective: To document the effects of 4 different types of support boots on fetlock joint angle in comparison to the unprotected fetlock. Methods: In 26 horses, the kinematics of the forelimb fetlock joint angle was measured at walk and trot on a treadmill when wearing 3 different types of support boots and 1 protective boot, as well as without boots. As outcome param...
Swanstrom MD, Zarucco L, Stover SM, Hubbard M, Hawkins DA, Driessen B, Steffey EP.The superficial (SDF) and deep digital flexor (DDF) muscles are critical for equine forelimb locomotion. Knowledge of their mechanical properties will enhance our understanding of limb biomechanics. Muscle contractile properties derived from architectural-based algorithms may overestimate real forces and underestimate shortening capacity because of simplistic assumptions regarding muscle architecture. Therefore, passive and active (=total - passive) force-length properties of the SDF and DDF muscles were measured directly in vivo. Muscles from the right forelimbs of four Thoroughbred horses we...
Hosaka Y, Sakamoto Y, Kirisawa R, Watanabe T, Ueda H, Takehana K, Yamaguchi M.Although tumor necrosis factor (TNF) alpha is an important key factor in degeneration of equine superficial digital flexor tendon (SDFT), the dynamism of TNF receptors and associated factors on tendinocytes has not been elucidated. To reveal signaling events mediated by TNF-receptors (TNF-Rs) in tendinocytes, we focused on four signaling factors, TNF-R1, TNF-R2, TNF-R-associated factor 2 (TRAF2) and nuclear factor-kappa B (NF-kappaB), and investigated the distribution and production of these factors. Cultured tendinocytes were obtained from SDFTs of thoroughbred horses. The tendinocytes were t...
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 ...
Crevier-Denoix N, Ruel Y, Dardillat C, Jerbi H, Sanaa M, Collobert-Laugier C, Ribot X, Denoix JM, Pourcelot P.The objective of this study was to test the hypothesis that tendon echogenicity is associated with the material properties of the corresponding tendon site, especially in case of lesions, due to local changes in tendon matrix composition. Four normal and nine spontaneously injured equine superficial digital flexor tendons (SDFT) were isolated then ultrasonographically examined under tension, in a special device placed in a water bath. Ultrasonographic transversal images (7.5MHz linear transducer) of five segments along each tendon were digitized, and analyzed in order to measure the mean cross...
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...
Watanabe T, Hosaka Y, Yamamoto E, Ueda H, Tangkawattana P, Takehana K.The Golgi tendon organ (GTO) is an encapsulated fusiform mechanoreceptor siding in the musculo-tendinous junction of many animal species. Inhibitory function of afferent nerve fibers distributed from nearby motor units, the organ responds to active tension exerted onto the muscle. The morphological features of the equine GTO have not yet been elucidated. Additionally, there is some controversy regarding to the existence of the GTO in the equine superficial digital flexor tendon (SDFT). Therefore, immunohistochemistry and immunoelectron microscopy using alcian blue (pH 2.5) staining and the sil...
Dyson SJ.There is a lack of long-term follow-up data for outcome of medical treatment of superficial digital flexor (SDF) tendonitis. Objective: To determine whether intralesional injection of hyaluronan, beta aminoproprionitrile fumarate (BAPN) or polysulphated glycosaminoglycans (PSGAG) or systemic administration of PSGAG yielded better results than a controlled exercise programme alone in the management of SDF tendonitis, with a minimum follow-up period of 2 years after resumption of full work; and to determine whether reinjury rate was related to sports discipline and whether fibre alignment score ...
Takahashi T, Kasashima Y, Ueno Y.To determine whether race history, including the number of races and total race distance, was associated with risk of superficial digital flexor tendon (SDFT) injury in Thoroughbred racehorses in Japan. Methods: Matched case-control study. Methods: 515 Thoroughbred racehorses (case horses) that sustained an SDFT injury during training or racing in Japan during 2002 and 951 horses (control horses) without SDFT injury that were matched with case horses on the basis of age and month of the latest race. Methods: Variables related to race history were compared between case and control horses by mea...
Zarucco L, Taylor KT, Stover SM.To provide a quantitative description of the architecture of superficial digital flexor (SDF) and deep digital flexor (DDF) muscles in adult horses to predict muscle-tendon behavior and estimate muscle forces. Methods: 7 forelimb specimens from 7 adult Thoroughbreds. Methods: Muscle and tendon lengths and volumes were measured from 6 fixed forelimbs. After processing, fiber bundle and sarcomere lengths were measured. Optimal fascicle lengths and muscle length-to-fascicle length, muscle length-to-free tendon length, and fascicle length-to-tendon length ratios were calculated, as were tendon and...
Kasashima Y, Takahashi T, Smith RK, Goodship AE, Kuwano A, Ueno T, Hirano S.Overstrain injuries to the superficial digital flexor tendon (SDFT) and suspensory ligament (SI) are among the most common musculoskeletal injuries which contribute to the considerable wastage of racing Thoroughbreds. Many epidemiological studies have demonstrated the prevalence of and risk factors for tendon injury when racing but have not included those injuries sustained during training. However, since tendon injury during training is seen commonly in clinical practice, it is appropriate to determine the overall prevalence of tendon injury sustained during both training and racing. Objectiv...
Yoon JH, Brooks RL, Khan A, Pan H, Bryan J, Zhang J, Budsberg SC, Mueller PO, Halper J.Fluoroquinolone antibiotics have been used widely in humans and domestic animals, including horses, because of their broad-spectrum bactericidal activity, and relative safety. The use of fluoroquinolones, however, is not without risk. Tendonitis and spontaneous tendon rupture have been reported in people during or following therapy with fluoroquinolones. We have studied the effects of enrofloxacin, a fluoroquinolone antibiotic used commonly in domestic animals, on tendon cell cultures established from equine superficial digital flexor tendons. Effects on cell proliferation and morphology were ...
Crowson CL, Jann HW, Stein LE, Claypool LP, Moll HD, Blaik MA.To compare effects of the locking-loop suture pattern (LLP) and 3-loop pulley (3LP) suture pattern for tenorrhaphy on the intrinsic vasculature of the superficial digital flexor tendon (SDFT) of horses in vitro after surgery. Methods: 16 forelimbs obtained from 8 mature horses. Methods: Tenotomy and subsequent tenorrhaphy was performed in anesthetized horses. Following systemic administration of heparin, horses were euthanatized and the limbs were removed and placed under tension to load the flexor tendons. The intrinsic vasculature was then perfused with a mixture of barium sulfate and water....
Swanstrom MD, Stover SM, Hubbard M, Hawkins DA.To determine the relative contributions of the muscles, tendons, and accessory ligaments to the passive force-length properties of the superficial (SDF) and deep digital flexor (DDF) myotendinous complexes. Methods: 8 cadaveric forelimbs from 6 adult Thoroughbreds. Methods: In vitro, limb configurations during slack position and myotendinous lengths during subsequent axial loading of forelimbs were recorded before and after transection of accessory ligaments. Expressions were derived to describe the force-length behavior of each muscle, tendon, and accessory ligament-tendon unit; linear stiffn...
Zarucco L, Swanstrom MD, Driessen B, Hawkins D, Hubbard M, Steffey EP, Stover SM.To develop and test an experimental model for in vivo short-term recording of peak isometric forces of the digital flexor muscles in the forelimb of adult horses. Methods: In vivo experimental study. Methods: Four healthy, anesthetized, adult Thoroughbred horses (3 to 7 years old; 527 +/- 87 kg) Methods: In dorsal recumbency, ulnar and median nerves were exposed and instrumented with insulated bipolar cuff stimulation electrodes for later connection to an electrical stimulator. In left lateral recumbency, a biplanar fixator was applied to the right humerus and a custom-made, rigid, aluminum fr...
Petrov R, MacDonald MH, Tesch AM, Van Hoogmoed LM.To determine rate and degree of cooling for the superficial digital flexor tendon (SDFT) during a standard cryotherapy application in horses and evaluate in vitro effects of cooling on survival of tendon cells. Methods: 6 limbs of 5 adult horses and cultured cells obtained from SDFT of 3 adult horses during necropsy. Methods: In vivo data were acquired by use of a thermocouple temperature probe inserted into the SDFT of a forelimb of each standing sedated horse. After baseline temperatures were recorded, a commercial compression splint with circulating coolant was placed on each selected limb,...
van Schie HT, Bakker EM, Jonker AM, van Weeren PR.To describe a method of computerized ultrasonographic tissue characterization that includes structures below the size limits of resolution in equine superficial digital flexor tendons. Methods: 2 damaged and 2 structurally normal superficial digital flexor tendons. Methods: Transverse ultrasonographic images were collected along the tendon long axis. Stability of echo pattern was quantified by means of variation in gray levels of each pixel in contiguous images and expressed as correlation, entropy, and waviness ratios. Results: Normal young and normal old tissues were characterized by high co...
Zekas LJ, Forrest LJ.The purpose of this study was to describe ultrasonographic changes of the equine palmar metacarpal area attributed to the infiltration of local anesthetic solution and to determine whether these changes were noted immediately or at 24 h. The palmar metacarpal region of one forelimb in each of six horses was examined ultrasonographically with a 10-MHz linear array transducer and a 7.5-MHz curvilinear transducer. Transverse and longitudinal images were recorded at 5-cm intervals distal to the accessory carpal bone. High and low palmar and palmar metacarpal nerve blocks were performed with a 2% m...
Smith MA, Ross MW.To determine features of postoperative wound infection caused by Actinobacillus spp in horses undergoing clean, elective surgery and to evaluate bacterial susceptibility profiles of bacteria isolated. Methods: Retrospective study. Methods: 10 horses. Methods: Data were retrieved from medical records and the microbiology laboratory database. Results: 1,604 horses underwent clean, elective surgical procedures during the study period. Of these, 23 (1.43%) had postoperative wound infections, and Actinobacillus spp was isolated from 10 of these 23 (43%). Surgical procedures in these 10 horses inclu...
Hosaka Y, Kirisawa R, Yamamoto E, Ueda H, Iwai H, Takehana K.Although inflammatory activation of cytokines have been analyzed in various tissues, there have only been a few and as-yet-inconclusive studies on cytokines in equine tendons. In this study, the localizations of 4 cytokines (IL-1alpha, IL-1beta, TNFalpha and IFNgamma) in tendinocytes of the equine superficial digital flexor tendon (SDFT) were analyzed by the use of an immunohistochemical method. In inflamed tendons positive staining for all 4 cytokines antibodies were detected in endotedinieum cells and vascular epithelial cells. In contrast, negative or trace immunoreactions were obtained in ...
James S, Schuijers J, Daffy J, Cook J, Samiric T.Fluoroquinolones are an effective, broad-spectrum antibiotic used to treat an array of bacterial infections. However, they are associated with an increased risk of tendinopathy and tendon rupture even after discontinuation of treatment. This condition is known as fluoroquinolone-associated tendinopathy, the underlying mechanisms of which are poorly understood. While many factors may be involved in the pathophysiology of tendinopathies in general, changes in tenocyte metabolism and viability, as well as alteration of proteoglycan metabolism are prominent findings in the scientific literature. T...
Jorgensen JS, Genovese RL, Döpfer D, Stewart MC.Equine carpal sheath effusion has multiple etiologies. The purpose of this retrospective study was to describe the prevalence of distinct musculoskeletal lesions lameness in a sample of horses with a clinical diagnosis of carpal sheath effusion. A total of 121 horses met inclusion criteria. Seventy-four percent (89/121) of horses were lame at presentation; middle-aged (9-18 years, 80%) and older (> 18 years, 85%) horses were lame more frequently than young horses (< 9 years, 44%). Ninety-three percent (113/121) were diagnosed with osseous and/or soft tissue abnormalities. Of these 113 ho...
Tamura N, Kodaira K, Yoshihara E, Mae N, Yamazaki Y, Mita H, Kuroda T, Fukuda K, Tomita A, Kasashima Y.A retrospective cohort study was conducted to investigate risk factors for the failure of Thoroughbred racehorses to return to racing after an injury of the superficial digital flexor tendon (SDFT). Successful return was defined as the completion of five or more races after SDFT injury. The official Japan Racing Association (JRA) medical records of racehorses with a core-type SDFT injury were reviewed for clinical variables related to the characteristics of the horse and the severity of SDFT injuries at the time of diagnosis. Data on racing outcomes were obtained from the official JRA racing d...
Jaafar SE, Al-Bayti AAH, Abdullah SI.High-power laser therapy has been used as a treatment to cure sports injuries; however, there are no controlled standardized studies on its efficacy. Moreover, high-power laser therapy has been applied for the sport horses field. This study aimed to investigate whether high-power laser therapy can cure tendon disorders and reduce the pain in tendon lesions in injured horses and also to examine the effect of laser therapy on injured horses. This retroactive experiential clinical research was performed on50 racing horses between 5 and 15 years old. They were diagnosed with neither superficial di...
Haussler KK, Wilde SR, Davis MS, Hess AM, McIlwraith CW.Rehabilitation of tendon injuries in horses often involves cryotherapy to reduce inflammation and occasionally tissue heating to increase collagen extensibility. The application of alternating cold and hot (ie contrast therapy) is widely used in human physical therapy; however, its utility in equine rehabilitation is largely unknown. Objective: The objectives of this study were to (a) assess if the equipment could achieve therapeutic tissue temperatures (40°C) at different tissue depths relative to the digital flexor tendons and (b) evaluate the time-temperature profiles during serial heating...
Hosaka YZ, Takahashi H, Uratsuji T, Tangkawattana P, Ueda H, Takehana K.The aim of this study was to determine the characteristic differences in tendinocytes derived from tendons in the equine forelimb, superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT) and common digital extensor tendon (CDET), in morphology, proliferation, collagen production ability and ability for synthesis of matrix metalloproteinases (MMPs). Significant differences were observed in cell number in vivo. The cellular number was largest in the SDFT and smallest in the CDET. The values of in vitro proliferation ratios and ability for synthesis of collagen and MMPs were l...
Raes EV, Vanderperren K, Pille F, Saunders JH.Ultrasonographic findings from 100 horses (103 joints) diagnosed with tarsal region pathology are described. Results of standard orthopaedic, radiographic and ultrasonographic examination of the tarsal region were analysed retrospectively. Periarticular swelling and/or synovial effusion was present in 100% of the joints, a wound was observed in 14.5% and 76.7% of the horses that were lame. Abnormalities were detected in 69.7% of joints using radiography and in 100% with ultrasonography. Our results show that the main disease process can affect all aspects of the tarsus. The most common ultraso...
Plevin S, McLellan J, van Schie H, Parkin T.Injuries to the superficial digital flexor tendon (SDFT) are one of the leading causes of Thoroughbred (TB) wastage. Increasingly, the aim is to prevent injury rather than treat it. Conventional ultrasonography is not sufficiently sensitive to accurately monitor tendon and predict injury. Ultrasound tissue characterisation (UTC) is a relatively new technique, which improves tendon characterisation by providing a 3-dimensional (3D) SDFT reconstruction and objective calculation of fibre alignment by classifying fibres into one of 4 echo-types. Objective: To report a reference range of echo-types...
Estrada RJ, van Weeren PR, van de Lest CH, Boere J, Reyes M, Ionita JC, Estrada M, Lischer CJ.Even though equine multi-limb tendinopathy models have been reported, it is unknown if fore- and hindlimb tendon healing behave similarly. The aim of this study was to compare the healing process of surgically induced superficial digital flexor tendon (SDFT) core lesions of fore- and hindlimbs in horses. Methods: Tendon core lesions were surgically induced in the SDFT of both fore- and hindlimbs in eight horses. One randomly assigned forelimb and one randomly assigned hindlimb were injected with saline one and two weeks post-surgery. The healing process was monitored clinically and ultrasonogr...
Dowling BA, Dart AJ, Hodgson DR, Rose RJ, Walsh WR.To evaluate the effect of recombinant equine growth hormone (rEGH) on the in vitro biomechanical properties of normal adult equine superficial digital flexor tendon (SDFT). Methods: Completely randomized design. Methods: Nine Standardbred horses, 6 to 9 years of age with ultrasonographically normal forelimb SDFT. Methods: Six horses were administered intramuscular (IM) rEGH at 10 microg/kg/day for 1 week, and then 20 microg/kg/day for another 5 weeks; 3 horses (control subjects) were administered an equivalent daily volume of sterile water IM. Horses were killed at the end of the 6-week treatm...
Ellison ME, Duenwald-Kuehl S, Forrest LJ, Vanderby R, Brounts SH.To evaluate the feasibility and repeatability of in vivo measurement of stiffness gradients by means of acoustoelastography in the superficial digital flexor tendons (SDFTs) of clinically normal horses. Methods: 15 clinically normal horses. Methods: For each horse, stiffness gradient index and dispersion values for SDFTs in both forelimbs were evaluated in longitudinal orientation by use of acoustoelastography at 3 sites (5, 10, and 15 cm distal to the accessory carpal bone) by 2 observers; for each observer, data were acquired twice per site. The left forelimb was always scanned before the ri...
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...
Ripollés-Lobo M, Perdomo-González DI, Azor PJ, Valera M.Abnormalities in hoof shape are usually connected with limb conformation defects. The role of angular hoof deviations is important for longevity in sports competitions and is increasingly recognized as a factor associated with lameness in performance horses. In this paper, we measured the prevalence of four defects related to the angulation of the hoof in the Pura Raza Española horse (PRE): splay-footed forelimb (SFF), pigeon-toed forelimb (PTF), splay-footed rear limb (SFR), and pigeon-toed rear limb (PTR). A total of 51,134 animals were studied, of which only 15.75% did not have any of the ...
Aßmann A, Ohlerth S, Hartmann S, Torgerson P, Bischofberger A.Tenosynovitis of the digital flexor tendon sheath (DFTS) is diagnosed using ultrasonography and contrast tenography. Nevertheless, making a precise preoperative diagnosis is challenging. This study aimed to determine and compare the sensitivity and specificity of low-field MRI and MRI tenography (MRIt) to detect artificially created soft-tissue lesions in the DFTS. In 21 DFTSs, 118 lesions were made tenoscopically in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), manica flexoria (MF) and proximal scutum. MRI and MRI, following intrathecal gadolinium administra...
Lin YL, Moolenaar H, van Weeren PR, van de Lest CH.To determine effects of microcurrent electrical tissue stimulation (METS) on equine tenocytes cultured from the superficial digital flexor tendon (SDFT). Methods: SDFTs were collected from 20 horses at slaughter. Methods: Tenocytes were isolated following outgrowth from explants and grown in 48-well plates. Four methods of delivering current to the tenocytes with a METS device were tested. Once the optimal method was selected, current consisting of 0 (negative control), 0.05, 0.1, 0.5, 1.0, or 1.5 mA was applied to cells (8 wells/current intensity) once daily for 8 minutes. Cells were treated ...
Hale MJ, Zellner EM, Naiman JH, Kraus KH.To determine the influence of suture patterns on resistance to gap formation after tendon plating STUDY DESIGN: Ex vivo study SAMPLE POPULATION: Suspensory ligament and superficial and deep digital flexor tendons harvested from 16 neonatal cadaver foal limbs. Methods: Each tendon/ligament from a given limb was randomly assigned to one of three treatment groups consisting of a 7-hole veterinary cuttable plate fixed with alternating simple interrupted, figure-8, or hybrid suture patterns. The constructs were distracted at a rate of 1.0 mm/s to failure, as determined by the formation of a 1 m...
Lawson SE, Chateau H, Pourcelot P, Denoix JM, Crevier-Denoix N.As equine musculoskeletal models become common, it is important to determine their sensitivity to the simplifications used. A subject-specific distal forelimb model was created using bones extracted from CT scans to examine movement from in-vivo invasive-marker motion capture. The movements of the sesamoid bones were simulated using the constraints of maintaining an isometric virtual ligament and maintaining contact between the appropriate articular surfaces, creating a variable moment arm for the tendons. The simulation of the proximal sesamoid bones was compared to movement recorded in-vitro...
Kicker CJ, Peham C, Girtler D, Licka T.Support boots are thought to reduce tension on the superficial digital flexor tendon (SDTF) of the horse and are frequently recommended for horses convalescing after tendonitis, but evidence of their effectiveness is conflicting. Objective: To document the effects of 4 different types of support boots on fetlock joint angle in comparison to the unprotected fetlock. Methods: In 26 horses, the kinematics of the forelimb fetlock joint angle was measured at walk and trot on a treadmill when wearing 3 different types of support boots and 1 protective boot, as well as without boots. As outcome param...
Takahashi T, Kasashima Y, Eto D, Mukai K, Hiraga A.One cause of overstrain injury to the superficial digital flexor tendon (SDFT) in horses is the force loaded on the SDFT during repeated running. Therefore, decreasing this force may reduce SDFT injury. It has been reported that strain on the SDFT decreases with a toe-wedge shoe. Uphill courses are used for training of racehorses, and the angle of hoof-sole to the horizon during uphill running is similar to that of the toe-wedge shoe. Objective: To determine the effects of uphill exercise on the force on the SDFT during trotting and cantering. Methods: Arthroscopically implantable force probes...
Dyson SJ.Desmitis of the accessory ligament of the deep digital flexor tendon (ALDDFT) was diagnosed in 27 horses between September 1986 and December 1990. The first observed clinical sign in four horses was localised swelling in the proximal metacarpus. Twenty horses became lame suddenly during a work period and most developed swelling within 24 h of exercise. The injury was confirmed by ultrasonographic examination. Ten of 13 horses with uncomplicated desmitis of the ALDDFT resumed full work, within three to nine months of the onset of clinical signs, without recurrence of clinical signs in the perio...
Zarucco L, Swanstrom MD, Driessen B, Hawkins D, Hubbard M, Steffey EP, Stover SM.To develop and test an experimental model for in vivo short-term recording of peak isometric forces of the digital flexor muscles in the forelimb of adult horses. Methods: In vivo experimental study. Methods: Four healthy, anesthetized, adult Thoroughbred horses (3 to 7 years old; 527 +/- 87 kg) Methods: In dorsal recumbency, ulnar and median nerves were exposed and instrumented with insulated bipolar cuff stimulation electrodes for later connection to an electrical stimulator. In left lateral recumbency, a biplanar fixator was applied to the right humerus and a custom-made, rigid, aluminum fr...
Schade J, de Souza AF, Vincensi LC, Fonteque JH.The objective of this study was to assess the influence of the metacarpophalangeal (MCP) joint angle on the transversal area (TA) and mean echogenicity (ME) of the superficial digital flexor tendon (SDFT) and suspensory ligament (SL) in gaited horses. Ultrasound images were obtained from 50 healthy adult horses of the Mangalarga Marchador (MM; n=25) and Campeiro (n=25) breeds. Static and dynamic angles of the MCP joint were measured from photographs and video recordings. Higher ME values were evinced for the SL only in the group with the smaller dynamic angles of the MCP joint in the MM horses...
Sese M, Ueda H, Watanabe T, Yamamoto E, Hosaka Y, Tangkawattana P, Takehana K.The superficial digital flexor tendon (SDFT) is one of the longest tendons in the horse. In racehorses, disturbance of the locomotor functions of the SDFT occurs most frequently in the central area of the mid-metacarpal region. While many studies have investigated the equine SDFT, there are no reports to date of the morphological characteristics of collagen fibrils in the central and peripheral areas of each of the three regions that comprise the entire tendon: the myotendinous junction (MTJ), the mid-metacarpal region (mM) and the osteotendinous junction (OTJ). Mass average diameter (MAD), wh...
Takahashi T, Kai M, Hada T, Eto D, Muka K, Ishida N.It has been reported that a small decrease in the strain in the superficial digital flexor tendon (SDFT) occurs if the toe is raised during walking. Although walking on a slope appears similar to raising the toe, it is unclear whether uphill exercise decreases the strain in the SDFT. Because the force or strain on tendons is one of the important factors leading to tendon stress injury, we hypothesised that reducing the force in the SDFT during exercise may prevent tendinitis. The purpose of this study was to determine the effects of treadmill inclination on the force in the SDFT in the walking...
James S, Daffy J, Cook J, Samiric T.Fluoroquinolone antibiotics are associated with increased risk of tendinopathy and tendon rupture, which can occur well after cessation of treatment. We have previously reported that the fluoroquinolone ciprofloxacin (CPX) reduced proteoglycan synthesis in equine tendon explants. This study aimed to determine the effects of CPX on proteoglycan catabolism and whether any observed effects are reversible. Equine superficial digital flexor tendon explant cultures were treated for 4 days with 1, 10, 100 or 300 µg/mL CPX followed by 8 days without CPX. The loss of [S]-labelled proteoglycans and che...
The objectives of this prospective, experimental study were to describe changes in the stiffness of the equine superficial digital flexor tendon (SDFT) after induced injury, deep digital flexor tendon (DDFT), accessory ligament (AL-DDFT), and suspensory ligament (SL) during 90 days of healing using acoustic radiation force impulse (ARFI) elastography. Eight healthy horses were selected. Preinjury B mode and ARFI evaluations were performed bilaterally in the palmar metacarpal region. Injury was induced only on the left forelimb (G2) by a single injection of collagenase in SDFT, 15 cm distal to ...
Secchi V, Masala G, Corda A, Corda F, Potop E, Barbero Fernandez A, Pinna Parpaglia ML, Sanna Passino E.Early diagnosis of tendon injuries and accurate long-term monitoring of the healing process are key for equine veterinarians that use conventional ultrasonography. The development of strain elastography could improve the management of clinical cases. The aim of the study was to assess the intraobserver repeatability and interobserver reproducibility of manual measurements of the colored areas of the tendons within elastograms and to standardize this manual modality by comparing the analysis of the images with ImageJ. Twenty elastograms of the injured superficial digital flexor tendons (SDFTs) ...
Watkins JP, Auer JA, Morgan SJ, Gay S.The effect of pulsing electromagnetic field (PEMF) therapy on the healing of surgically created defects in equine superficial digital flexor tendons was evaluated. Defects were created in both front superficial digital flexor tendons of 20 horses. The defect in 1 limb was exposed to a PEMF for 2 hours daily. The other limb served as a control. Histologic and immunofluorescent evaluations were done in horse killed at postsurgical weeks 2, 4, 8, 12, and 24. Therapy with the PEMF significantly (P less than 0.05) delayed the maturation of the tissue formed within the defect at postsurgical weeks 8...
Gillis C, Meagher DM, Cloninger A, Locatelli L, Willits N.Fifty Thoroughbred horses were examined. All horses had been in race training for a minimum of 4 months before examination and had worked at racing speed; 24 horses had raced. All horses were clinically sound at the time of examination. Ultrasonography was performed, using a 7.5-MHz transducer with built-in fluid offset. Videotaped images of the palmar soft tissue structures were obtained at 4, 8, 12, 16, 20 and 24 cm distal to the base of the accessory carpal bone (DACB). Images were digitized, and each image was calibrated. Values for cross-sectional area (CSA) and mean echogenicity (ME) wer...
