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.
DiGiovanni DL, Rademacher N, Riggs LM, Baumruck RA, Gaschen L.Palmar/plantar annular desmitis is a common disease that may be associated with adhesions and structures affecting the flexor tendons, which requires tenoscopy to diagnose. The purpose of this descriptive study was to develop a dynamic sonographic technique for evaluating the motion of normal equine flexor tendons in relation to the palmar/plantar annular ligament and to compare findings with horses previously diagnosed with palmar/plantar annular desmitis. Ten healthy adult horses were examined prospectively and the images of four horses diagnosed with palmar/plantar annular desmitis were ret...
Witte S, Dedman C, Harriss F, Kelly G, Chang YM, Witte TH.Superficial digital flexor (SDF) tendonitis is a common injury in Thoroughbred racehorses. Injuries require prolonged rehabilitation, with unpredictable outcomes and a high incidence of re-injury. This observational case-control study aimed to compare race outcomes after commonly advocated treatments for tendon healing. Clinical and racing records were evaluated for 127 National Hunt racehorses treated between 2007 and 2011 for an SDF tendon injury. Two age- and sex-matched control horses were selected for each case horse to analyse the effect on post-injury racing outcomes of pre-injury data,...
Thorpe CT, Riley GP, Birch HL, Clegg PD, Screen HRC.Tendon is composed of rope-like fascicles, bound together by interfascicular matrix (IFM). Our previous work shows that the IFM is critical for tendon function, facilitating sliding between fascicles to allow tendons to stretch. This function is particularly important in energy storing tendons, which experience extremely high strains during exercise, and therefore require the capacity for considerable inter-fascicular sliding and recoil. This capacity is not required in positional tendons. Whilst we have previously described the quasi-static properties of the IFM, the fatigue resistance of the...
Choi RK, Smith MM, Martin JH, Clarke JL, Dart AJ, Little CB, Clarke EC.Both mechanical and structural properties of tendon change after injury however the causal relationship between these properties is presently unclear. This study aimed to determine the extent of biomechanical change in post-injury tendon pathology and whether the sulphated glycosaminoglycans (glycosaminoglycans) present are a causal factor in these changes. Equine superficial digital flexor tendons (SDF tendons) were surgically-injured in vivo (n=6 injured, n=6 control). Six weeks later they were harvested and regionally dissected into twelve regions around the lesion (equal medial/lateral, pr...
Russell JW, Russell TM, Vasey JR, Hall MS.To evaluate a treatment protocol whereby superficial digital flexor (SDF) tendonitis in Thoroughbred and Standardbred racehorses was treated with autologous bone marrow aspirate (ABMA) obtained from the sternebrae. This treatment was combined with desmotomy of the accessory ligament of the SDF tendon (DAL-SDFT) in selected cases. Medical records of 105 horses treated using the reported protocol were reviewed. Signalment, history and details of treatment were recorded. Racing records were reviewed and performance recorded. Of Thoroughbreds, 82 per cent had one or more starts within the follow-u...
Jordana M, Cornillie P, Oosterlinck M, Simoens P, Pille F, Martens A.During endoscopy (tenoscopy) of the distal aspect of the equine digital flexor tendon sheath (DFTS), the digital manica flexoria can be visualized connecting the distal branches of the superficial digital flexor tendon. However, this structure has been inconsistently described and variably named in the veterinary literature. The objectives of this study were to describe the presence, configuration and variability of the digital manica flexoria in the equine distal limb. Dissection of 144 equine cadaveric limbs revealed the presence of this structure in all the feet, although different types an...
Thorpe CT, Karunaseelan KJ, Ng Chieng Hin J, Riley GP, Birch HL, Clegg PD, Screen HR.Although the predominant function of all tendons is to transfer force from muscle to bone and position the limbs, some tendons additionally function as energy stores, reducing the energetic cost of locomotion. To maximise energy storage and return, energy-storing tendons need to be more extensible and elastic than tendons with a purely positional function. These properties are conferred in part by a specialisation of a specific compartment of the tendon, the interfascicular matrix, which enables sliding and recoil between adjacent fascicles. However, the composition of the interfascicular matr...
Hatazoe T, Endo Y, Iwamoto Y, Korosue K, Kuroda T, Inoue S, Murata D, Hobo S, Misumi K.Aim of this study was to evaluate the relationships of exercise and tendon injury with Doppler flows appearing in the superficial digital flexor tendon (SDFT) of young Thoroughbreds during training periods. The forelimb SDFTs of 24 one- to two-year-old Thoroughbreds clinically free of any orthopaedic disorders were evaluated using grey-scale (GS) and color Doppler (CD) images during two training periods between December 2013 to April 2015. Twelve horses per year were examined in December, February, and April in training periods that began in September and ended in April. The SDFT was evaluated...
Geburek F, Mundle K, Conrad S, Hellige M, Walliser U, van Schie HT, van Weeren R, Skutella T, Stadler PM.Adipose tissue-derived mesenchymal stromal cells (AT-MSCs) are frequently used to treat equine tendinopathies. Up to now, knowledge about the fate of autologous AT-MSCs after intralesional injection into equine superficial digital flexor tendons (SDFTs) is very limited. The purpose of this study was to monitor the presence of intralesionally injected autologous AT-MSCs labelled with superparamagnetic iron oxide (SPIO) nanoparticles and green fluorescent protein (GFP) over a staggered period of 3 to 9 weeks with standing magnetic resonance imaging (MRI) and histology. Methods: Four adult warmbl...
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...
Tucker R, Jacklin BD, Gillespie S, Vaughan L, Fiske-Jackson AR, Smith RK.Injury to the superficial digital flexor tendon (SDFT) is common in equids, with a high risk of re-injury associated with changes in tendon stiffness. In vivo measurement of limb stiffness has been shown to correlate with tendon stiffness after injury [1] but requires kinematic analysis which is impractical in a clinical setting. We have developed a simple system for measuring limb stiffness statically, which could be used as a tool for monitoring SDFT healing. Objective: To validate a goniometric measurement of limb stiffness. Methods: Cross sectional study. Methods: Initially, forelimb stiff...
McMaster MA, Munsterman AS, Weimar WH, Barrett EJ, Hanson RR.To compare the load to ultimate failure, load to a 2 mm gap, mode of failure, and gap at failure (mm) of the Teno Fix(®) (TF) to the 3-loop pulley (3LP) for repair of equine tendon lacerations. The use of 4TF devices versus 5TF devices on load to ultimate failure and load to a 2 mm gap was also compared. Methods: Ex vivo biomechanical study; unbalanced incomplete block (horse) design. Methods: Cadaveric equine forelimb superficial digital flexor tendon (n = 20 paired tendons). Methods: Ten tendon pairs were selected randomly and repaired with a 3LP and 4TF pattern, and 10 tendon pairs...
Geburek F, Lietzau M, Beineke A, Rohn K, Stadler PM.Autologous blood-derived biologicals, including autologous conditioned serum (ACS), are frequently used to treat tendinopathies in horses despite limited evidence for their efficacy. The purpose of this study was to describe the effect of a single intralesional injection of ACS in naturally occurring tendinopathies of the equine superficial digital flexor tendon (SDFT) on clinical, ultrasonographic, and histological parameters. Methods: Fifteen horses with 17 naturally occurring tendinopathies of forelimb SDFTs were examined clinically and ultrasonographically (day 0). Injured tendons were ran...
Aim of this study was to document the normal computed tomographic tenography findings of digital flexor tendon sheath. Six ex vivo normal equine forelimbs were used. An axial approach was used to inject 185 mg/mL of iopamidol in a total volume of 60 mL into the digital flexor tendon sheaths. Single-slice helical scans, with 5 mm thickness, spaced every 3 mm, for a pitch of 0.6, and with bone algorithm reconstruction, were performed before and after injections of contrast medium. To obtain better image quality for multiplanar reconstruction and 3D reformatting, postprocessing retrorecon...
Thorpe CT, McDermott BT, Goodship AE, Clegg PD, Birch HL.Advancing age is a well-known risk factor for tendon disease. Energy-storing tendons [e.g., human Achilles, equine superficial digital flexor tendon (SDFT)] are particularly vulnerable and it is thought that injury occurs following an accumulation of micro-damage in the extracellular matrix (ECM). Several authors suggest that age-related micro-damage accumulates due to a failure of the aging cell population to maintain the ECM or an imbalance between anabolic and catabolic pathways. We hypothesized that ageing results in a decreased ability of tendon cells to synthesize matrix components and m...
Spinella G, Loprete G, Castagnetti C, Musella V, Antonelli C, Vilar JM, Britti D, Capitani O, Valentini S.The aims of this research were to evaluate mean echogenicity (ME) of the deep and superficial digital flexor tendons (DDFT and SDFT), the interosseous muscle (IM), and the accessory ligament of the deep digital flexor tendon (ALDDFT) of the metacarpal region in neonatal foals, and determine the effect of sex, side and body weight on this quantitative ultrasonographic evaluation. Thirteen orthopedically sound neonatal foals were examined. Four areas of study (1A, 1B, 2A, 2B) were identified. Transverse scans of the DDFT, SDFT, IM and ALDDFT were obtained, recorded, and analyzed. The most echoge...
Freeman KD, Barrett JG, Youngstrom DW, White NA.The 6-strand Savage (SSS) tenorrhaphy pattern is biomechanically superior to the commonly employed 3-loop pulley (3LP); however, its effects on intrinsic tendon vasculature remain unknown. The objective of this study was to compare perfusion of intrinsic vasculature of the equine superficial digital flexor tendon (SDFT) after 3LP and SSS tenorrhaphies. We hypothesized that the SSS technique would significantly decrease vascular perfusion compared to the 3LP technique. Methods: Ex vivo, randomized, paired design. Methods: Horses (n = 9) METHODS: Under general anesthesia, 9 pairs of forelimb...
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...
Hill AE, Blea JA, Arthur RM, McIlwraith CW.Private-practice racetrack veterinarians in southern California recorded non-fatal injuries meeting defined criteria in Thoroughbreds for 1 year. Injury incidence was 2.29 injury events per 100 horse-months, which was lower than other studies where trainer reported injury data were collected. Of 477 injuries recorded, 344 (72.1%) were acute and 133 (27.9%) were chronic. Fractures were common (47.6% of injuries), with stress fractures accounting for 14% of injuries. Superficial digital flexor tendonitis and suspensory ligament desmitis accounted for 15.3 and 11.5% of injuries, respectively. Agr...
Nelson BB, Kawcak CE, Ehrhart EJ, Goodrich LR.To compare intra and postoperative clinical features of desmotomy of the accessory ligament of the superficial digital flexor tendon (ALSDFT) using the Saber radiofrequency (SaberRF) electrosurgical probe versus sharp transection with a tenotomy knife. Methods: Randomized, controlled, blocked (horse) design. Methods: Adult horses (n = 6). Methods: Each horse received bilateral, tenoscopic-guided ALSDFT desmotomy with a SaberRF and tenotomy knife, randomly assigned to left, or right limb. The desmotomy duration and intraoperative hemorrhage grades were recorded. Postoperatively, the grades ...
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 ...
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...
Conze P, van Schie HT, van Weeren R, Staszyk C, Conrad S, Skutella T, Hopster K, Rohn K, Stadler P, Geburek F.To investigate whether autologous adipose tissue-derived mesenchymal stem cells (AT-MSCs) treatment of tendon lesions increases neovascularization during tendon healing. Methods: A standardized surgical model was used to create lesions in both front limb superficial digital flexor tendons (SDFTs) of nine horses. Either AT-MSCs or control substance was injected intralesionally 2 weeks post-surgery. Color Doppler ultrasonography of SDFTs was performed at regular intervals. Horses were euthanized 22 weeks post-treatment and SDFTs were harvested for histology. Results: The color Doppler ultrasonog...
Bourzac CA, Koenig JB, Link KA, Nykamp SG, Koch TG.To evaluate the efficacy and effects of labeling equine umbilical cord blood (UCB)- and bone marrow (BM)-derived multipotent mesenchymal stromal cells (MSCs) with an ultrasmall superparamagnetic iron oxide (SPIO) contrast agent and the detection of labeled MSCs by use of MRI. Methods: UCB MSCs from placental tissues of 5 foals and BM MSCs from 5 horses. Methods: UCB and BM MSC cultures were seeded in duplicate (5,000 cells/cm(2)). One duplicate was incubated with SPIO (50 μg/mL); the other was processed identically, but without SPIO. Mesenchymal stromal cells were expanded in triplicates for ...
Barker WH, Wright IM.Accurate description of the calcaneal insertions of the superficial digital flexor tendon (SDFT) is lacking and inconsistent. The aim of this study was to undertake morphologic and morphometic evaluations of these structures to assist in elucidating their functional and pathogenic roles in displacement of the SDFT from the calcaneal tuber. Methods: Dissections were performed on 10 normal cadaveric hindlimbs. The anatomy was photographed to allow measurements at repeatable locations and differences in SDFT dimensions at the various locations were compared using a paired student t-test. Results:...
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...
Hu AJ, Bramlage LR.To assess postoperative probability of racing, career longevity, and convalescent time in Thoroughbred racehorses with moderate to severe superficial digital flexor tendonitis (SDFT) in the forelimbs treated by desmotomy of the accessory ligament of the superficial digital flexor tendon (ie, superior check ligament desmotomy [SCLD]). Methods: Retrospective case series. Methods: 332 Thoroughbred racehorses with SDFT consecutively treated by means of SCLD. Methods: Medical records and racing records were reviewed to assess return to racing, number of races completed, time to first race, and life...
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, Mukai K, Ohmura H, Aida H, Hiraga A.The purpose of this study was to create a lower forelimb model of the Thoroughbred horse for measuring the force in the superficial and deep digital flexor tendons (SDFT and DDFT), and the suspensory ligament (SL) during a trot. The mass, centers of gravity, and inertial moments in the metacarpus, pastern, and hoof segments were measured in 4 Thoroughbred horses. The moment arms of the SDFT, DDFT, and SL in the metacarpophalangeal (fetlock) and distal interphalangeal (coffin) joints were measured in 7 Thoroughbred horses. The relationship between the fetlock joint angle and the force in the SL...
Barrett EJ, Munsterman AS, Hanson RR, Jackson RL.To compare in vitro strength and failure characteristics of a tendon implant against a 3 loop pulley suture pattern for equine superficial digital flexor tendon (SDFT) laceration repair. Methods: Experimental. Methods: Cadaveric equine forelimb SDFT (n = 16). Methods: One tendon of each of 8 pair of SDFT was randomly selected for repair with either the 3-loop pulley (3LP) suture pattern using 2 polydioxanone or with 4 stainless steel suture and anchor implants (SA). Ultimate load to failure, mode of failure, gap at failure, and load to 2 mm gap were obtained using a materials testing sys...
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,...
Watanabe T, Imamura Y, Hosaka Y, Ueda H, Takehana K.By using ultramorphological and biochemical methods, we analyzed the regional differences between the three parts of the equine superficial digital flexor tendon (SDFT), namely, the myotendinous junction (MTJ), middle metacarpal (mM), and osteotendinous junction (OTJ). Cross-sectional images showed unique distributions of collagen fibrils of varying diameters in each region. Small collagen fibrils (diameter 200 nm). In the mM region, the collagen fibrils were intermediately distributed between the MTJ and OTJ. The results indicate a graded arrangement of collagen fibrils in the tendon. Type V ...
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...
Meershoek LS, Schamhardt HC, Roepstorff L, Johnston C.Lameness in athletic horses is often caused by forelimb tendon injuries, especially in the interosseus tendon (TI) and superficial digital flexor tendon (SDF), but also in the accessory ligament (AL) of the deep digital flexor tendon (DDF). In an attempt to explain the aetiology of these injuries, the present study investigated the loading of the tendons during landing after a jump. In jumping horses, the highest forces can be expected in the trailing limb during landing. Therefore, landing kinematics and ground reaction forces of the trailing forelimb were measured from 6 horses jumping singl...
van Schie HT, Bakker EM, Jonker AM, van Weeren PR.To evaluate effectiveness of computerized discrimination between structure-related and non-structure-related echoes in ultrasonographic images for quantitative evaluation of tendon structural integrity in horses. Methods: 4 superficial digital flexor tendons (2 damaged tendons, 2 normal tendons). Methods: Transverse ultrasonographic images that precisely matched histologic sections were obtained in fixed steps along the long axis of each tendon. Distribution, intensity, and delineation of structure-related echoes, quantitatively expressed as the correlation ratio and steadiness ratio , were co...
Witte S, Dedman C, Harriss F, Kelly G, Chang YM, Witte TH.Superficial digital flexor (SDF) tendonitis is a common injury in Thoroughbred racehorses. Injuries require prolonged rehabilitation, with unpredictable outcomes and a high incidence of re-injury. This observational case-control study aimed to compare race outcomes after commonly advocated treatments for tendon healing. Clinical and racing records were evaluated for 127 National Hunt racehorses treated between 2007 and 2011 for an SDF tendon injury. Two age- and sex-matched control horses were selected for each case horse to analyse the effect on post-injury racing outcomes of pre-injury data,...
Smith RK, Jones R, Webbon PM.Fifty-two animals, comprising 22 Irish Draught crosses (Group A), 15 Thoroughbreds (Group B) and 15 ponies (Group C) were examined ultrasonographically using a 7.5 mHz linear array probe and stand-off pad. All animals were free of tendon disease as determined from clinical and ultrasonographical examination. The superficial (SDFT) and deep (DDFT) digital flexor tendons were scanned at 7 transverse (axial) levels between the carpus and metacarpophalangeal joint. Each transverse image was digitised using a commercially available frame grabber and the cross-sectional areas of each tendon at each ...
Zamboulis DE, Marr N, Lenzi L, Birch HL, Screen HRC, Clegg PD, Thorpe CT.Energy storing tendons such as the human Achilles and equine superficial digital flexor tendon (SDFT) are prone to injury, with incidence increasing with aging, peaking in the 5 decade of life in the human Achilles tendon. The interfascicular matrix (IFM), which binds tendon fascicles, plays a key role in energy storing tendon mechanics, and aging alterations to the IFM negatively impact tendon function. While the mechanical role of the IFM in tendon function is well-established, the biological role of IFM-resident cell populations remains to be elucidated. Therefore, the aim of this study was...
Salz RO, Elliott CRB, Zuffa T, Bennet ED, Ahern BJ.Overstrain of the superficial digital flexor tendon (SDFT) is a common Thoroughbred racehorse limb injury requiring treatment. Objective: To determine whether treatment of SDFT lesions in flat Thoroughbred racehorses with autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) or allogenic adipose-derived mesenchymal stem cells (A-MSCs) is associated with improved likelihood of returning to racing, when compared to racehorses managed with a controlled exercise rehabilitation program (CERP) alone. Methods: Retrospective cohort study combining clinical treatment records with race records...
Watanabe T, Hosaka Y, Yamamoto E, Ueda H, Sugawara K, Takahashi H, Takehana K.The distribution pattern of collagen fibril diameter in the equine superficial digital flexor tendon (SDFT) is known to differ in central and peripheral areas of some regions. This study reports the essence of collagen fibril differences among different regions of the equine SDFT by transmission electron microscopic (TEM) and high-voltage electron microscopic observations and biochemical analysis. The distribution of large collagen fibrils increased but the density of collagen fibrils decreased from the proximal metacarpal region to the distal metacarpal region. Large collagen fibrils with an ...
van Schie HT, Bakker EM, Jonker AM, van Weeren PR.To correlate quantitative analysis of ultrasonographic images of normal (injury-free) equine superficial digital flexor (SDF) tendons and equine SFD tendons that have pathologic changes with corresponding histologic sections. Methods: 4 SDF tendons, 2 of which had various stages of tissue integrity. The 2 ipsilateral tendons were used as points of reference. Methods: Tendons were mounted in a custom-made device that permitted sequential scanning, transversely and perpendicular to the tendon long axis. At precise steps of 0.5 mm, transverse ultrasonographic images were collected. Subsequently, ...
Murray SJ, Santangelo KS, Bertone AL.To evaluate early cellular influences of bone morphogenetic protein (BMP)12 and BMP2 on equine superficial digital flexor tenocytes (SDFTNs) and equine bone marrow-derived mesenchymal stem cells (BMDMSCs). Methods: 9 adult clinically normal horses. Methods: BMDMSCs and SDFTNs were cultured in monolayer, either untreated or transduced with adenovirus encoding green fluorescent protein, adenovirus encoding BMP12, or adenovirus encoding BMP2. Cytomorphologic, cytochemical, immunocytochemical, and reverse transcriptase-quantitative PCR (RT-qPCR) analyses were performed on days 3 and 6. Genetic pro...
Birch HL, Smith TJ, Poulton C, Peiffer D, Goodship AE.Partial rupture occurs most often to the superficial digital flexor tendon (SDFT) of the forelimb at the mid-metacarpal level. In this study, we tested the hypothesis that the mid-metacarpal region of the SDFT has the smallest cross sectional area (CSA) and a similar collagen content to other regions and, therefore, represents a weak point in the tendon. The SDFT was collected from the forelimbs of 9 horses. Each tendon was marked at 7 different levels from the origin of the accessory ligament to the phalangeal region. The CSA, water content and collagen content was measured at each level. The...
Montgomery L, Elliott SB, Adair HS.To (1) determine the temperature change in equine tendon and muscle during therapeutic ultrasound and (2) develop guidelines for treating horses for muscular or tendinous injury using therapeutic ultrasound. Methods: Experimental, in vivo study. Methods: Adult horses (n = 10). Methods: Thermistors were inserted in the superficial and deep digital flexor tendons (SDFT and DDFT) of the thoracic limbs of 10 adult horses. On the left, 3.3 MHz therapeutic continuous ultrasound was done for 10 minutes at an intensity of 1.0 W/cm(2) and for the right thoracic limb at 1.5 W/cm(2). Thermistors were pla...
Muttini A, Salini V, Valbonetti L, Abate M.The ideal strategy for tendon healing has not been identified to date. Recently, the use of stem cells based therapy has been proposed, due to their ability to proliferate and to differentiate towards specific connective tissues lineages. Embryonic stem cells should be considered the ideal cell source for regenerative therapies, but ethical factors limit their use in humans. Mesenchymal stem cells are more easily available and can be obtained by different sources. Amnion derived stem cells can differentiate towards all three germ layers, and can be used for allogeneic transplantation and store...
Crevier-Denoix N, Ravary-Plumioën B, Evrard D, Pourcelot P.A non-invasive ultrasonic (US) technique of tendon force measurement has been recently developed. It is based on the relationship demonstrated between the speed of sound (SOS) in a tendon and the traction force applied to it. The objectives of the present study were to evaluate the variability of this non-linear relationship among 7 equine superficial digital flexor (SDF) tendons, and the reproducibility of SOS measurements in these tendons over successive loading cycles and tests. Seven SDF tendons were equipped with an US probe (1MHz), secured in contact with the skin overlying the tendon me...
Kersh KD, McClure SR, Van Sickle D, Evans RB.Extracorporeal shock wave therapy (ESWT) is being used to treat desmitis and tendonitis in horses. This paper compares the clinical, ultrasonographic and histological characteristics of ESWT treated collagenase induced superficial digital flexor tendon (SDFT) lesions, versus untreated controls. This blinded study utilizes six mature, healthy horses where bilateral forelimb SDFT lesions were induced. One forelimb was treated while the other served as an untreated control. Three shock wave treatments were administered at three week intervals. At weekly intervals, ultrasonograms were used to meas...
Meershoek LS, van den Bogert AJ, Schamhardt HC.To describe a method to calculate flexor tendon forces on the basis of inverse dynamic analysis and an in vitro model of the equine forelimb and to quantify parameters for the model. Methods: 38 forelimbs of 23 horses that each had an estimated body mass of > or = 500 kg. Methods: Longitudinal limb sections were used to determine the lines of action of the tendons. Additionally, limb and tendon loading experiments were performed to determine mechanical properties of the flexor tendons. Results: The study quantified the parameters for a pulley model to describe the lines of action. Furthermo...
Patterson-Kane JC, Parry DA, Goodship AE, Firth EC.One of the current concepts with regard to equine superficial digital flexor tendonitis is that cumulative subclinical microscopic damage weakens the structure, predisposing the tendon to partial or complete rupture. This microtrauma is likely to affect the waveform or crimp of the collagen fibrils, which are the units of tensile strength. Collagen fibril crimp morphology characteristics were determined in superficial digital flexor tendons of 18 horses presented for necropsy. Horses were separated into exercised (n = 9) and non-exercised groups (n = 9), based on recent function. Five of the e...
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...
Johnson SA, Valdés-Martínez A, Turk PJ, Wayne McIlwraith C, Barrett MF, McGilvray KC, Frisbie DD.The range of diagnostic modalities available to evaluate superficial digital flexor tendon (SDFT) injury includes magnetic resonance imaging (MRI), computed tomography (CT) and ultrasonography (US). Direct, comprehensive comparison of multi-modality imaging characteristics to end-point data has not previously been performed using a model of tendinopathy but is required to obtain a better understanding of each modality's diagnostic capabilities. Objective: To compare CT, MRI and US evaluation to outcome measures for histologic, biochemical and biomechanical parameters using an equine surgical m...
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...
Patterson-Kane JC, Wilson AM, Firth EC, Parry DA, Goodship AE.Injury to the core of the mid-metacarpal region of the superficial digital flexor tendon in Thoroughbred racehorses is a very frequent but poorly understood condition. It has been suggested that subclinical changes induced by galloping exercise weaken the collagen in this region of the tendon, predisposing it to rupture. The longitudinally arranged collagen fibrils in tendon follow a planar waveform, termed the crimp. Fibril bundles with a smaller crimp angle fail at a lower level of strain than those with a larger crimp angle. This study tested the hypothesis that a specific 18 month exercise...
Gillis C, Pool RR, Meagher DM, Stover SM, Reiser K, Willits N.To assess tendon morphology and non-reducible crosslink concentration, and associations of these findings with horse age and previously reported mechanical and ultrasonographic findings. Methods: Superficial digital flexor tendon samples were obtained from 23 horses aged 2 to 23 years. The tendons had undergone ultrasonography and were submitted to biomechanical testing in the physiologic range prior to sample acquisition. Methods: Samples were sectioned in a transverse plane; then dorsal, palmar, central, lateral, and medial regions were evaluated for fascicle cross-sectional area (CSA), sept...
Thorpe CT, McDermott BT, Goodship AE, Clegg PD, Birch HL.Advancing age is a well-known risk factor for tendon disease. Energy-storing tendons [e.g., human Achilles, equine superficial digital flexor tendon (SDFT)] are particularly vulnerable and it is thought that injury occurs following an accumulation of micro-damage in the extracellular matrix (ECM). Several authors suggest that age-related micro-damage accumulates due to a failure of the aging cell population to maintain the ECM or an imbalance between anabolic and catabolic pathways. We hypothesized that ageing results in a decreased ability of tendon cells to synthesize matrix components and m...
Kang JG, Park SB, Seo MS, Kim HS, Chae JS, Kang KS.Tendinitis of the superficial digital flexor tendon (SDFT) is a significant cause of lameness in horses; however, recent studies have shown that stem cells could be useful in veterinary regenerative medicine. Therefore, we isolated and characterized equine umbilical cord blood mesenchymal stem cells (eUCB-MSCs) from equine umbilical cord blood obtained from thoroughbred mares during the foaling period. Horses that had tendinitis of the SDFT were treated with eUCB-MSCs to confirm the therapeutic effect. After eUCB-MSCs transplantation, the core lesion in the SDFT was found to decrease. These re...
Crevier-Denoix N, Collobert C, Sanaa M, Bernard N, Joly C, Pourcelot P, Geiger D, Bortolussi C, Bousseau B, Denoix JM.To assess histologic variations of the equine superficial digital flexor tendon (SDFT) according to site and to horse age and activity, and to correlate these data with reported segmental mechanical results. Methods: Superficial digital flexor tendons isolated from 42 horses 0.5 hour to 23 years old. Methods: 7 segments of each SDFT were delimited and submitted for conventional histologic examination. Each segment was examined and graded for fiber undulation, cellularity, number and size of interfascicular connective spaces (ICS), presence or absence of focal and diffuse chondroid metaplasia, ...
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...
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...
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...
