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.
Horstmeier C, Ahrberg AB, Berner D, Burk J, Gittel C, Hillmann A, Offhaus J, Brehm W.The magic angle effect increases the MRI signal of healthy tendon tissue and could be used for more detailed evaluation of tendon structure. Furthermore, it could support the discrimination of hypointense artefacts induced by contrast agents such as superparamagnetic iron oxide used for cell tracking. However, magic angle MRI of the equine superficial digital flexor tendon has not been accomplished in vivo in standing low-field MRI so far. The aim of this in vivo study was to evaluate the practicability of this magic angle technique and its benefit for tracking superparamagnetic iron oxide-lab...
Ribitsch I, Gueltekin S, Keith MF, Minichmair K, Peham C, Jenner F, Egerbacher M.Aging is hypothesized to be associated with changes in tendon matrix composition which may lead to alteration of tendon material properties and hence propensity to injury. Altered gene expression may offer insights into disease pathophysiology and thus open new perspectives toward designing pathophysiology-driven therapeutics. Therefore, the current study aimed at identifying naturally occurring differences in tendon micro-morphology and gene expression of newborn, young and old horses. Age-related differences in the distribution pattern of tendon fibril thickness and in the expression of the ...
Recent advances in tendinopathy research have focused on tendon vascularization detected with Color Doppler (CD) ultrasound. The use of CD has also been described in horses in a study on chronic lesions of superficial digital flexor tendon and suspensory ligament. The aim of this study was to investigate the occurrence and distribution of power Doppler (PD) signal in horses with superficial digital flexor tendinopathy. Twenty-five horses with tendinopathy were included and 10 healthy horses with no lameness and no ultrasonographic abnormalities were used for comparison. In all horses with tend...
Roth SP, Brehm W, Groß C, Scheibe P, Schubert S, Burk J.Transforming growth factor beta 3 (TGFβ3) promotes tenogenic differentiation and may enhance tendon regeneration in vivo. This study aimed to apply TGFβ3 absorbed in decellularized equine superficial digital flexor tendon scaffolds, and to investigate the bioactivity of scaffold-associated TGFβ3 in an in vitro model. TGFβ3 could effectively be loaded onto tendon scaffolds so that at least 88% of the applied TGFβ3 were not detected in the rinsing fluid of the TGFβ3-loaded scaffolds. Equine adipose tissue-derived multipotent mesenchymal stromal cells (MSC) were then seeded on scaffolds loa...
Muñoz A, Saitua A, Becero M, Riber C, Satué K, de Medina AS, Argüelles D, Castejón-Riber C.In recent years, exercise on a water treadmill has come to have great relevance in rehabilitation and training centres for sport horses. Its use exploits certain physical properties of water, related to the fundamental principles of hydrodynamics, such as buoyancy, viscosity, hydrostatic pressure, and water temperature. These properties together with deliberate specification of the depth of the water and the velocity of the treadmill provide a combination of parameters that can be varied according to the purpose of the rehabilitation or training programme, the disease to rehabilitate, or the h...
Shojaee A, Parham A.Tendon injuries, as one of the most common orthopedic disorders, are the major cause of early retirement or wastage among sport horses which mainly affect the superficial digital flexor tendon (SDFT). Tendon repair is a slow process, and tendon tissue is often replaced by scar tissue. The current treatment options are often followed by an incomplete recovery that increases the susceptibility to re-injury. Recently, cell therapy has been used in veterinary medicine to treat tendon injuries, although the risk of ectopic bone formation after cell injection is possible in some cases. In vitro teno...
Daniel AJ, Leise BS, Selberg KT, Barrett MF.Injuries to the structures within the digital flexor tendon sheath (DFTS) can lead to lameness with a variable degree of effusion in horses. In some cases, effusion is absent or minimal, and this may be related to the chronicity and type of injury, or veterinary interventions. The purpose of this study was to determine if saline injection into the DFTS would improve ultrasonographic and magnetic resonance imaging of the distal limb without introducing artifact. Nine normal equine cadaver forelimbs were collected. Non-weight-bearing ultrasonographic and magnetic resonance imaging (MRI) examinat...
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...
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 ...
Hagen J, Kojah K, Geiger M, Vogel M.Corrective shoeing is used to change hoof angulation with the intention to influence the angulation of the digital joints to reduce strain on associated tendons. The objective of this study is to examine how gradual changes in hoof angulation affect the dorsal metacarpophalangeal joint (DMPJ) angulation and cross-sectional areas (CSAs) of the deep digital flexor tendon (DDFT) and superficial digital flexor tendon (SDFT) concerning the individual toe conformation. Forelimbs of 30 horses were examined barefoot and equipped with 5°, 10° and 20° toe wedges (TWs) and heel wedges (HWs). Phalangea...
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 (...
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...
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...
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...
Ali OJ, Comerford EJ, Clegg PD, Canty-Laird EG.BiTendons are constructed from collagenous fascicles separated by endotenon/interfascicular matrix (IFM). Tendons may be specialised for precision movement or to store energy during locomotion and for the latter the elasticity of the endotenon/IFM is particularly important. The equine superficial digital flexor tendon (SDFT) is a dedicated energy-storing tendon with a similar function to the human Achilles tendon. Classical anatomical descriptions portray fascicles as longitudinally arranged distinct anatomical structures. In the present study, using three-dimensional reconstruction from whole...
Alzola Domingo R, Riggs CM, Gardner DS, Freeman SL.Superficial digital flexor tendon (SDFT) tendinopathy is an important musculoskeletal problem in horses. The study objective was to validate an ultrasonographic scoring system for SDFT injuries. Ultrasonographic images from 14 Thoroughbred racehorses with SDFT lesions (seven core; seven diffuse) and two controls were blindly assessed by five clinicians on two occasions. Ultrasonographic parameters evaluated were: type and extent of the injury, location, echogenicity, cross-sectional area and longitudinal fibre pattern of the maximal injury zone (MIZ). Inter-rater variability and intra-rater re...
De Gasperi D, Dzierzak SL, Muir P, Vanderby R, Brounts SH.OBJECTIVE To assess the effects of sedation on results of acoustoelastography of the superficial digital flexor tendons (SDFTs) in clinically normal horses. ANIMALS 27 clinically normal horses. PROCEDURES For each horse, the pathology index (PI) for the SDFT of each thoracic limb was determined by use of acoustoelastography at 4 locations (5, 10, 15, and 20 cm distal to the accessory carpal bone). Horses were evaluated before and after they were sedated with a combination of detomidine hydrochloride (0.01 mg/kg, IV) and butorphanol tartrate (0.01 mg/kg, IV). A repeated-measures ANOVA was used ...
Kovac M, Litvin YA, Aliev RO, Zakirova EY, Rutland CS, Kiyasov AP, Rizvanov AA.In this clinical study, for the first time we used the direct gene therapy to restore severe injuries of the suspensory ligament branch and superficial digital flexor tendon in horses (). We injected the plasmid DNA encoding two therapeutic species-specific growth factors: vascular endothelial growth factor 164 and fibroblast growth factor 2 at the site of injury in the suspensory ligament branch and tendon. Treatment effects were evaluated with the use of clinical observation and ultrasound imaging during a period of a few months. We showed that gene therapy used within a period of 2-3 mont...
Beerts C, Suls M, Broeckx SY, Seys B, Vandenberghe A, Declercq J, Duchateau L, Vidal MA, Spaas JH.Poor healing of tendon and ligament lesions often results in early retirement of sport horses. Therefore, regenerative therapies are being explored as potentially promising treatment for these injuries. In this study, an intralesional injection was performed with allogeneic tenogenically induced mesenchymal stem cells and platelet-rich plasma 5-6 days after diagnosis of suspensory ligament (SL) (n = 68) or superficial digital flexor tendon (SDFT) (n = 36) lesion. Clinical, lameness and ultrasonographic evaluation was performed at 6 and 12 weeks. Moreover, a survey was performed 12 ...
Ashraf Kharaz Y, Zamboulis D, Sanders K, Comerford E, Clegg P, Peffers M.Exploring the tendon proteome is a challenging but important task for understanding the mechanisms of physiological/pathological processes during ageing and disease and for the development of new treatments. Several extraction methods have been utilised for tendon mass spectrometry, however different extraction methods have not been simultaneously compared. In the present study we compared protein extraction in tendon with two chaotropic agents, guanidine hydrochloride (GnHCl) and urea, a detergent, RapiGest™, and their combinations for shotgun mass spectrometry. An initial proteomic analysi...
Geburek F, Roggel F, van Schie HTM, Beineke A, Estrada R, Weber K, Hellige M, Rohn K, Jagodzinski M, Welke B, Hurschler C, Conrad S, Skutella T....Adipose tissue is a promising source of mesenchymal stromal cells (MSCs) for the treatment of tendon disease. The goal of this study was to assess the effect of a single intralesional implantation of adipose tissue-derived mesenchymal stromal cells (AT-MSCs) on artificial lesions in equine superficial digital flexor tendons (SDFTs). During this randomized, controlled, blinded experimental study, either autologous cultured AT-MSCs suspended in autologous inactivated serum (AT-MSC-serum) or autologous inactivated serum (serum) were injected intralesionally 2 weeks after surgical creation of cen...
Romero A, Barrachina L, Ranera B, Remacha AR, Moreno B, de Blas I, Sanz A, Vázquez FJ, Vitoria A, Junquera C, Zaragoza P, Rodellar C.Several therapies have been investigated for equine tendinopathies, but satisfactory long term results have not been achieved consistently and a better understanding of the healing mechanism elicited by regenerative therapies is needed. The aim of this study was to assess the separate effects of autologous bone marrow (BM) and adipose tissue (AT) derived mesenchymal stem cells (MSCs), and platelet rich plasma (PRP), for treating lesions induced in the superficial digital flexor tendon (SDFT) of horses. Lesions were created surgically in both SDFTs of the forelimbs of 12 horses and were treated...
Tamura N, Nukada T, Kato T, Kuroda T, Kotoyori Y, Fukuda K, Kasashima Y.The objective assessment of the mechanical properties of the superficial digital flexor tendon (SDFT) could provide useful information for the rehabilitation of horses with SDFT injuries. Assessment of strain ratio (the strain of a standard reference divided by that of lesions) is a quantitative method in sonoelastography for evaluating tissue stiffness in vivo. As yet, no longitudinal studies have used strain ratio to evaluate the progression of stiffness in SDFT injuries. Objective: To test the hypothesis that strain ratio can evaluate the recovery of stiffness during the healing of SDFT inj...
Roth SP, Glauche SM, Plenge A, Erbe I, Heller S, Burk J.Decellularization of tendon tissue plays a pivotal role in current tissue engineering approaches for in vitro research as well as for translation of graft-based tendon restoration into clinics. Automation of essential decellularization steps like freeze-thawing is crucial for the development of more standardized decellularization protocols and commercial graft production under good manufacturing practice (GMP) conditions in the future. In this study, a liquid nitrogen-based controlled rate freezer was utilized for automation of repeated freeze-thawing for decellularization of equine superficia...
Tamura N, Kuroda T, Kotoyori Y, Fukuda K, Nukada T, Kato T, Kuwano A, Kasashima Y.Sonoelastography can assess the inner stiffness of tissues. Sonoelastographic evaluation of injured equine superficial digital flexor tendons (SDFTs) is considered to be useful for assessing the stiffness of a lesion even during late-stage rehabilitation. The purpose of this study was to investigate and compare the sonoelastographic appearance of injured SDFTs over time from the onset of the injury. Eighteen horses were classified into three groups according to the length of time from injury onset: group A, within two weeks after injury; group B, approximately five months after injury; and gro...
Nazem MN, Sajjadian SM.Palmar region of metacarpus in the horses and donkeys is an important region because of its tendons and ligaments which contribute to stay apparatus. This study was done on forelimbs of 6 healthy Miniature donkeys to detect the tendons, ligaments and their accessories on the palmar surface of metacarpus in this animal. Methods: Based on that magnetic resonance imaging (MRI) is a good technique to evaluate the soft tissues such as tendons and ligaments, palmar aspects of metacarpus in 6 euthanatised Miniature donkeys were prepared for anatomical and trans-sectional MRI studies to determine the ...
Garvican ER, Salavati M, Smith RKW, Dudhia J.The purpose of this study was to investigate the effect of normal synovial fluid (SF) on exposed endogenous tendon-derived cells (TDCs) and engrafted mesenchymal stem cells (MSCs) within the tendon extracellular matrix. Methods: Explants from equine superficial digital flexor (extra-synovial) and deep digital flexor tendons (DDFTs) from the compressed, intra-synovial and the tensile, extra-synovial regions were cultured in allogeneic or autologous SF-media. Human hamstring explants were cultured in allogeneic SF. Explant viability was assessed by staining. Proliferation of equine monolayer MSC...
Sherlock CE, Mair TS.Recognition of artefacts is an essential component of the accurate interpretation of diagnostic images. This study aimed to investigate the presence of magic angle effect in the superficial digital flexor tendon (SDFT) in the equine proximal pastern region. The proximal pastern of four cadaver limbs was imaged using a 0.27 Tesla magnet with high-resolution sequences that are commonly utilised in clinical equine practice. The limbs were imaged in a neutral position and positions that simulated the horse 'leaning in', 'leaning out' and having internal and external rotation of the distal limb. Si...
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...
Schramme M, Hunter S, Campbell N, Blikslager A, Smith R.Tendon injuries are common in all athletic activities in both humans and horses. Research of treatment modalities for this disease has typically been performed on a model of collagenase-induced tendonitis. This model has several disadvantages. Our hypothesis was that a reproducible core lesion could be created surgically in superficial digital flexor tendons (SDFT), which could then be evaluated consistently using ultrasonography. Methods: Four horses free of forelimb lameness were used in this study. Each horse underwent general anaesthesia and a synovial resector was used to create a core le...
O'Brien C, Marr N, Thorpe C.The forelimb superficial digital flexor tendon (SDFT) is an energy-storing tendon that is highly susceptible to injury during activities such as galloping and jumping, such that it is one of the most commonly reported causes of lameness in the performance horse. This review outlines the biomechanical and biothermal effects of strain on the SDFT and how these contribute to the accumulation of microdamage. The effect of age-related alterations on strain response and subsequent injury risk is also considered. Given that tendon is a slowly healing and poorly regenerative tissue, prompt detection o...
Roth SP, Brehm W, Groß C, Scheibe P, Schubert S, Burk J.Transforming growth factor beta 3 (TGFβ3) promotes tenogenic differentiation and may enhance tendon regeneration in vivo. This study aimed to apply TGFβ3 absorbed in decellularized equine superficial digital flexor tendon scaffolds, and to investigate the bioactivity of scaffold-associated TGFβ3 in an in vitro model. TGFβ3 could effectively be loaded onto tendon scaffolds so that at least 88% of the applied TGFβ3 were not detected in the rinsing fluid of the TGFβ3-loaded scaffolds. Equine adipose tissue-derived multipotent mesenchymal stromal cells (MSC) were then seeded on scaffolds loa...
van Schie HT, Bakker EM, Cherdchutham W, Jonker AM, van de Lest CH, van Weeren PR.To evaluate quantitative ultrasonography for objective monitoring of the healing process and prognostication of repair quality in equine superficial digital flexor (SDF) tendons. Methods: 6 horses with standardized surgical lesions in SDF tendons of both forelimbs. Methods: Healing was monitored for 20 weeks after surgery by use of computerized ultrasonography. Pixels were categorized as C (intact fasciculi), B (incomplete fasciculi), E (accumulations of cells and fibrils), or N (homogenous fluid or cells). Four scars with the best quality of repair (repair group) and 4 scars with the lowest q...
Patterson-Kane JC, Parry DA, Birch HL, Goodship AE, Firth EC.The superficial digital flexor tendon is the most commonly injured tendon in the racing Thoroughbred. Despite the clinical significance of this structure, only limited data exist regarding normal age-related morphology of the tensile units, the collagen fibrils. The age at which these collagen fibrils become mature in composition and structure may be of importance. Consequently, the association of age and collagen fibril crosslink composition, diameter distribution and crimp morphology in the superficial and deep digital flexor tendons of Thoroughbreds up to and including three years of age ha...
Vergari C, Pourcelot P, Holden L, Ravary-Plumioën B, Gerard G, Laugier P, Mitton D, Crevier-Denoix N.Excessive 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 qua...
Ashraf Kharaz Y, Zamboulis D, Sanders K, Comerford E, Clegg P, Peffers M.Exploring the tendon proteome is a challenging but important task for understanding the mechanisms of physiological/pathological processes during ageing and disease and for the development of new treatments. Several extraction methods have been utilised for tendon mass spectrometry, however different extraction methods have not been simultaneously compared. In the present study we compared protein extraction in tendon with two chaotropic agents, guanidine hydrochloride (GnHCl) and urea, a detergent, RapiGest™, and their combinations for shotgun mass spectrometry. An initial proteomic analysi...
Marr CM, Love S, Boyd JS, McKellar Q.Ultrasonographic examination was used to define the severity of injuries to the superficial digital flexor tendon in 73 National Hunt or point-to-point racehorses and the factors influencing the outcome of the cases were examined. Thirty-four of the horses (46 per cent) returned to work with an average time out of training of 13.5 months. The rate of recurrence of the injury was 35 per cent. The severity of the lesions was related to the outcome; all the mildly affected horses returned to work, with 63 per cent of them racing and an average time out of training of 10.2 months; 50 per cent of t...
Bosch G, René van Weeren P, Barneveld A, van Schie HT.The effectiveness of new therapies to treat tendon injuries is difficult to determine and is often based on semi-quantitative methods, such as grey level analysis of ultrasonographic images or subjective pain scores. The alternatives are costly and long-lasting end-stage studies using experimental animals. In this study, a method of ultrasonographic tissue characterisation (UTC), using mathematical analysis of contiguous transverse ultrasonographic images, was used for intra-vital monitoring of the healing trajectory of standardised tendon lesions treated with platelet rich plasma (PRP) or pla...
Georg R, Maria C, Gisela A, Bianca C.This case report describes the intralesional application of autologous conditioned plasma (ACP) in seven horses as treatment of severe tendinitis of the superficial digital flexor tendon, deep digital flexor tendon, or desmitis of the inferior check ligament. Follow-up data of the horses revealed a positive outcome in 10 to 13 months post injury. All horses treated with ACP were either performing in their previous work-load or were back in full training. Further studies with long-term follow-up will have to be performed to support these clinical intermediate-term observations.
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...
Patterson-Kane JC, Wilson AM, Firth EC, Parry DA, Goodship AE.This study was undertaken to test the hypothesis that collagen fibrils, the submicroscopic units of strength in tendon, would hypertrophy in response to a specific defined training programme. Fibril diameters were measured in central and peripheral regions of superficial digital flexor tendon (SDFT) samples from five 18-month-old horses which underwent a subsequent 18 month training programme and 6 age- and sex-matched controls. Central region fibrils from the trained horses had a mass-average diameter (MAD) of 105.3 nm, which was significantly lower (P < 0.01) than that of 131.7 nm for the...
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 ...
amnion-derived stem cells are considered a promising alternative source for tendon tissue regeneration. Objective: aims of this paper were to illustrate the ultrasound and histological outcomes following the treatment of acute and chronic superficial digital flexor tendon spontaneous lesions in horses with ovine amniotic epithelial cells xenotransplantation. Methods: six adult horses suffering from unilateral acute (4 cases) and chronic (2 cases) tendinopathy (clinical and ultrasound diagnosis) were enrolled. At baseline, ovine amniotic epithelial cells were grafted, in sterile conditions and ...
Riemersma DJ, Schamhardt HC.The mechanical properties of the deep digital flexor tendon (DDFT), the superficial digital flexor tendon (SDFT) and the suspensory ligament (SL) of the hindlimb of the horse were studied in vitro. The tendons were observed at several morphologically distinct sites. The loaded tendon is homogeneously strained, in spite of large variations in cross-sectional area. Consequently the modulus of elasticity was inversely proportional to the corresponding cross-sectional area and ranged from 738 MPa (megaPascal, N mm-2) to 1398 MPa within the DDFT, from 1000 MPa to 1282 MPa within the SDFT and from 5...
Kasashima Y, Smith RK, Birch HL, Takahashi T, Kusano K, Goodship AE.Most skeletal tissues are thought to adapt to the mechanical environment they experience. While this has been demonstrated for muscle and bone, previous studies in the mature horse have failed to demonstrate adaptation in the superficial digital flexor tendon (SDFT), which suffers a high frequency of injury. This study tested the hypothesis that imposed exercise during growth would result in an increase in SDFT cross-sectional area (CSA). Fourteen Thoroughbred foals were divided into 2 sex-matched groups. A control group received 4 h pasture exercise and an exercise group had the same amount o...
Mitchell A, Rivas KA, Smith R, Watts AE.Equine superficial digital flexor tendon injury is a well-accepted model of human tendon injury and is routinely treated with local injections of autologous mesenchymal stem cells (MSCs). Identification of a clinically safe medium for short-term cryopreservation of MSCs prior to cell implantation would streamline laboratory and clinical procedures for autologous regenerative therapies. Veterinary experience with short-term (MSCs prepared after the injury has occurred) cryopreserved MSCs in naturally occurring injury in the horse will be of value to human practitioners. Methods: Equine bone mar...
Cohen ND, Peloso JG, Mundy GD, Fisher M, Holland RE, Little TV, Misheff MM, Watkins JP, Honnas CM, Moyer W.To describe and compare data from Thoroughbreds that sustained musculoskeletal injuries while racing with data from matched control horses. Methods: Matched case-control study. Methods: 216 Thoroughbreds that sustained a musculoskeletal injury while racing and 532 horses from the same races that were not injured. Methods: Data regarding racing history, race-entrant characteristics, racing events determined by analysis of videotapes of races, and results of prerace physical inspections were determined for all horses. Injured horses were compared with control horses by using conditional logistic...
Birch HL, Wilson AM, Goodship AE.Tendons that store energy during locomotion, such as the equine superficial digital flexor tendon (SDFT) and human Achilles tendon, suffer a high incidence of central core degeneration which is thought to precede tendon rupture. Although energy storage contributes to the efficiency of locomotion, tendons are not perfectly elastic and some energy is lost in the form of heat. Recent studies have shown that the central core of equine SDFT reaches temperatures as high as 45 degrees C during high-speed locomotion. In this study, we test the hypothesis that hyperthermia causes tendon cell death and ...
Cadby JA, David F, van de Lest C, Bosch G, van Weeren PR, Snedeker JG, van Schie HT.Injuries in energy-storing tendons are common in both horses and man. The high prevalence of reinjury and the relatively poor prognosis for returning to preinjury performance levels warrant further research, for which well characterised models would be very helpful. Objective: Given the clinical similarities in tendinopathy of energy-storing tendons, we hypothesised that a recently developed experimental model of equine tendon injury would display many of the characteristics of clinical tendinopathy and could therefore be of use for both species, thus providing comparative insight to the human...
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...
Riemersma DJ, van den Bogert AJ, Jansen MO, Schamhardt HC.Strains in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), accessory ligament of the deep digital flexor muscle (inferior check ligament [ICL]) and the interosseus medius muscle (suspensory ligament [SL]) in the right forelimb of 5 ponies were measured using mercury-in-silastic strain gauges a few hours after implantation. Tendon strains were recorded at the walk with normal flat shoes, egg-bar shoes, a 7 degrees increased hoof angle accomplished by application of a heel-wedge and a 7 degrees decreased hoof angle using a toe-wedge, consecutively. Ground reactio...
Clayton HM, Schamhardt HC, Willemen MA, Lanovaz JL, Colborne GR.To measure and correlate kinematic and ground reaction force (GRF) data in horses with superficial digital flexor tendinitis. Methods: 6 sound horses. Methods: Horses were evaluated before (sound evaluation) and after (lame evaluation) induction of superficial digital flexor tendinitis in 1 forelimb (randomized) by injection of collagenase. As each horse trotted, kinematic data were collected by use of an optoelectronic system, and GRF data were measured by use of a force plate. Three-dimensional kinematic and GRF data were projected onto a 2-dimensional sagittal plane. Results: Lame limbs had...
Lawson SE, Chateau H, Pourcelot P, Denoix JM, Crevier-Denoix N.The sagittal alteration of hoof balance is a common intervention in horses, with corrective shoeing being one of the most frequently applied methods of managing tendonitis. However, the effect of toe or heel elevation on tendon strains is poorly understood. This study aimed to examine the effect of toe and heel wedges on the superficial digital flexor tendon, deep digital flexor tendon, and the third interosseous muscle or suspensory ligament strains using in vivo data and an accurate subject-specific model. Kinematic data were recorded using invasive markers at the walk and trot. Computerized...
Ribitsch I, Gueltekin S, Keith MF, Minichmair K, Peham C, Jenner F, Egerbacher M.Aging is hypothesized to be associated with changes in tendon matrix composition which may lead to alteration of tendon material properties and hence propensity to injury. Altered gene expression may offer insights into disease pathophysiology and thus open new perspectives toward designing pathophysiology-driven therapeutics. Therefore, the current study aimed at identifying naturally occurring differences in tendon micro-morphology and gene expression of newborn, young and old horses. Age-related differences in the distribution pattern of tendon fibril thickness and in the expression of the ...
Birch HL, Wilson AM, Goodship AE.This study explores the hypothesis that high-intensity exercise induces degenerative changes in the injury-prone equine superficial digital flexor tendon (SDFT), but not in the rarely injured common digital extensor tendon (CDET). The horse represents a large-animal model that is applicable to human tendon and ligament physiology and pathology. Twelve age-matched female horses undertook galloping exercise three times a week with trotting exercise on alternative days (high-intensity group, n = 6) or only walking exercise (low-intensity group, n = 6) for 18 mo. The SDFT, suspensory ligament, dee...
Watkins JP, Auer JA, Gay S, Morgan SJ.Full-thickness defects were surgically created in the superficial digital flexor tendons of the front limbs of 20 horses. Tissues formed within the defect were evaluated histologically, and the collagen composition of the tissue was determined by immunofluorescence. Transformation occurred from loose fibrillar areas of types I and III collagen and pericellular types IV and V collagen to dense bundles of type I collagen fibers. Loose fibrillar areas of types I and III collagen were present after 24 weeks. Histologically, in horses killed after 2 weeks, the tissue within the defect was a randoml...
Williamson KA, Lee KJ, Humphreys WJ, Comerford EJ, Clegg PD, Canty-Laird EG.The aim of this study was to characterize stem and progenitor cell populations from the equine superficial digital flexor tendon, an energy-storing tendon with similarities to the human Achilles tendon, which is frequently injured. Using published methods for the isolation of tendon-derived stem/progenitor cells by low-density plating we found that isolated cells possessed clonogenicity but were unable to fully differentiate towards mesenchymal lineages using trilineage differentiation assays. In particular, adipogenic differentiation appeared to be restricted, as assessed by Oil Red O stainin...
Rajpar I, Barrett JG.Tendon injury is a significant clinical problem due to poor healing and a high reinjury rate; successful treatment is limited by our poor understanding of endogenous tendon stem cells. Recent evidence suggests that adult stem cells are phenotypically diverse, even when comparing stem cells isolated from the same tissue from the same individual, and may in fact exist on a spectrum of proliferation and differentiation capacities. Additionally, the relationships between and clinical relevance of this phenotypic variation are poorly understood. In particular, tenogenic capacity has not been studie...
Carvalho AM, Yamada AL, Golim MA, Álvarez LE, Hussni CA, Alves AL.Mesenchymal stem cells (MSCs) have been used to treat equine tendonitis with promising results; however, little is known about the potential migration of these cells. Objective: To assess the possible migration of MSCs from an implantation site in the superficial digital flexor tendon (SDFT) to a lesion in the SDFT of the contralateral limb. Methods: In vivo experimental study. Methods: Adipose-derived MSCs were isolated from 4 healthy horses. Lesions were induced in the SDFTs of both forelimbs, followed by intralesional implantation of autologous adipose-derived MSCs labelled with nanocrystal...
