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Topic:Tendons
Tendons in horses are fibrous connective tissues that attach muscles to bones, facilitating movement and providing stability to the musculoskeletal system. They are composed primarily of collagen fibers, which confer strength and flexibility, allowing horses to perform various physical activities. Equine tendons are subject to significant mechanical stress during locomotion, making them susceptible to injury, particularly in performance horses. Common tendon injuries include strains, tears, and tendinitis, which can impact a horse's mobility and performance. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and pathology of tendons in horses, as well as advancements in diagnostic and therapeutic approaches for tendon injuries.
Practical management of superficial digital flexor tendinitis in the performance horse. The authors of this section represent a broad range of practice experience with horses that perform in rigorous and varied sport competitions. Each breed and performance application represent unique challenges of diagnosis and uncompromising demands on rehabilitated tendon injuries. This article will serve to guide, stimulate, and encourage veterinarians to apply scientific criteria to the evaluation of tendinitis therapy in the years to come so that we can arrive at a more valid consensus as to the "best" means of tendon and ligament injury management.
Treatment of superficial digital flexor tendinitis. This article reviews the research and clinical findings relevant to the treatment of acute tendinitis in the horse. The goals of treatment are to reduce inflammation, minimize scar tissue formation, and promote restoration of normal tendon function. A wide variety of treatments have and still are being used to treat tendinitis, which indicates that there is no uniformly successful way to return a horse to full athletic function after injury. Therapy depends on the severity of tendinitis and duration of injury and can be divided into treatment during the inflammatory, repair, and maturation pha...
Functional anatomy of tendons and ligaments in the distal limbs (manus and pes). Tendons and ligaments of the equine distal limbs have a prominent anatomic, functional, and clinical importance. This article reviews the descriptive and topographic anatomy of these structures in details. Special information is given about the mechanical properties and functional anatomy of the flexor tendons, accessory ligaments, and third interosseous muscle, as well as about their roles during the standing position and gaits.
Differential scanning calorimetric studies of superficial digital flexor tendon degeneration in the horse. Differential scanning calorimetry (DSC) of equine superficial digital flexor tendons revealed the presence of a small exothermic peak at 23 degrees C of unknown origin, and a large endothermic peak at 70 degrees C due to denaturation of cross-linked collagen fibres. In the central degenerated core of damaged tendons the denaturation temperature remained at 70 degrees C but the enthalpy decreased in relation to the extent of degeneration of the tendon. We suggest that this reduction in enthalpy is due to depolymerisation and denaturation of the collagen fibres. This contention is supported by t...
In vitro mechanical properties and failure mode of the equine (pony) cranial cruciate ligament. In vitro failure modes and mechanical properties of the equine cranial cruciate ligament (CCL) were evaluated in 15 stifle joints from 10 ponies. Ponies were from 3 to 25 years of age and weighed from 122 to 208 kg. Femur-CCL-tibia specimens were mounted in 48 degrees of flexion, distracted until a 500-g tensile preload was achieved, and then tested by tensile loading to failure. Specimens failed by complete midsubstance CCL rupture (n = 9), combined tibial insertion avulsion fracture and midsubstance CCL rupture (n = 4), and combined femoral origin avulsion fracture and midsubstance CCL ruptu...
Exercise-induced hyperthermia as a possible mechanism for tendon degeneration. Mathematical modelling of tendon thermodynamics predicted that the temperature of the central core of the equine superficial digital flexor tendon would plateau at 11 degrees C above the tendon surface temperature during a sustained gallop. A mean temperature differential (between tendon core and surface) of 5.4 (S.E. +/- 1.0) degrees C was demonstrated in vivo in four horses. Peak intra-tendinous temperatures in the range 43-45 degrees C were recorded. Temperatures above 42.5 degrees C are known to result in fibroblast death in vitro [Hall (1988) Radiobiology for the Radiologist, 3rd Edn., pp...
Avulsion of the origin of the peroneus tertius tendon in a foal. A 3-month-old foal was examined because of lameness and fracture of the left lateral trochlear ridge of the femur. Arthroscopy of the left femoropatellar joint was elected. After induction of general anesthesia and placement of the foal in dorsal recumbency, it was noticed that the left hind limb was extended at the tibiotarsal joint and flexed at the femorotibial joint. Avulsion fracture at the origin of the peroneus tertius tendon was diagnosed. Fracture fragments were excised. The horse had mild left hind limb lameness at the time of follow-up evaluation 1 year after discharge.
Ultrasonographic evaluation and long-term follow-up of flexor tendonitis/desmitis in the metacarpal/metatarsal region in Dutch warmblood horses and standardbred racehorses. Over a 2 year-period, the ultrasonographic localization and distribution of flexor tendinous and ligamentous injuries, the long-term follow-up, and the outcome were studied in 101 Dutch Warmblood horses (DW) with a mean age of 8.7 years and in 71 Standardbred racehorses (ST) with a mean age of 5.2 years. The ratio between forelimb and hind limb flexor tendonitis/desmitis in the DW-group was 4:1 and in the ST-group group 4:3. In the DW-group, tendonitis/desmitis of the suspensory ligament (32%), the superficial digital flexor tendon (29%), the distal carpal check ligament (17%) of the forelimb ...
Arthroscopic approach and intra-articular anatomy of the plantar pouch of the equine tarsocrural joint. Arthroscopic examination of structures within the plantar pouch of the tarsocrural joint was accomplished via portals in both the plantaromedial and plantarolateral aspects of the joint. Flexion and extension of the tarsus while examining the joint through either portal allowed observation of the proximal and plantar aspects of the lateral and medial trochlear ridges, the trochlear groove, the caudal aspect of the distal tibia, and the deep digital flexor tendon (DDFT) in its sheath. From a plantarolateral portal, the plantar talocalcaneal ligament and the plantar aspect of the lateral malleol...
Clinical and force plate evaluation of the effect of a high plantar nerve block in lameness caused by induced mid-metatarsal tendinitis. To answer the question whether it is possible to differentiate, by means of a high plantar nerve block in the hind limb, flexor tendon lameness from a suspensory ligament lameness, mid-plantar tendinitis or desmitis was induced with collagenase in five Standardbred horses in two trials. Before the induction of lameness, and on the fourth (D4) and fourteenth day (D14) after the induction of lameness the horses were evaluated subjectively (clinical lameness score), objectively (ground reaction force (GRF) measurements), and ultrasonographically. Clinical evaluation and GRF measurements were also...
Structure of equine type I and type II collagens. Collagen type I was purified from equine skin and flexor tendon, and type II collagen was purified from equine articular cartilage. The proteoglycans in these tissues were extracted, using guanidine HCl; the collagens were solubilized, using pepsin digestion, then were selectively precipitated with NaCl. Gel electrophoresis indicated that the precipitates contained only type I or type II collagen. Amino acid analysis indicated that collagen constituted > 97% of the total protein in the precipitates. Hydroxylation of proline was 42.0 +/- 0.6% (mean +/- SEM) in alpha 1(I) and alpha 2(I), and ...
Scintigraphic and ultrasonographic diagnosis of soft tissue injury in a thoroughbred horse. A 2.5-year-old female Thoroughbred horse was referred to the veterinary teaching hospital for right front limb lameness of 1 year duration. Physical examination and diagnostic nerve blocks failed to localize the origin of the lameness. Scintigraphy with 99mTc-MDP suggested increased radionuclide uptake in the palmar metacarpal soft tissues of the right front limb. Ultrasonographic examination revealed hypoechoic lesions in the superficial digital flexor tendon and the suspensory ligament, suggesting tendinitis and desmitis. Combined imaging modalities improved detection and characterization of...
Cross-validation of cyanogen bromide-peptide ratios to measure the proportion of type II collagen in pepsin digests of equine articular cartilage, meniscus, and cartilage repair tissue. Collagen type I and type II were purified from equine flexor tendon and articular cartilage, respectively. Equal amounts of these collagens were cleaved with cyanogen bromide, and 11 mixtures containing increasing proportions of type II collagen were separated in seven identical sodium dodecyl sulfate-polyacrylamide gels. The density of bands was measured in wet gels and the peak areas were used to form six ratios of peptide bands that had polynomial relationships with the known proportions of type I and type II collagen in the mixtures. Calibration curves for determining the proportion of typ...
Sonographic brightness of the flexor tendons and ligaments in the metacarpal region of horses. Sonographic observations were made of the image mean gray scale (MGS) of the flexor tendons and ligaments in the left and right metacarpal regions of each of 10 clinically normal horses. In images made in the dorsal and sagittal planes, the MGS was measured at multiple sites in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), accessory ligament (AL), and suspensory ligament (SL), and at single sites in the medial and lateral limbs of the SL, and the palmar ligament. Relative sonographic brightness of each tendon and ligament was calculated by dividing the value ...
Short echo time magnetic resonance imaging of tendon. Current clinical magnetic resonance (MR) imaging studies provide almost no useful signal from normal tendon and have no clear advantage over other imaging modalities in the evaluation of tendon injuries. The authors believe that tendon MR signal may be T2-limited, and, if so, could be enhanced by short echo time (TE) pulse sequences. The relationship of tendon signal intensity and tendon infrastructure conspicuity to TE was assessed at three different field strengths. Methods: Magnetic resonance imaging studies were performed on samples of normal equine tendon at 3 different field strengths wi...
The correlation between the dose and distribution of intratendinous fluid injections in the flexor tendons/ligaments of the horse. An in vitro study was carried out to define the correlation between the dose and distribution of intratendinous fluid injections in the different flexor tendons/ligaments of the palmar/plantar, metacarpal/metatarsal region of the horse. Injection of 0.1-0.2 ml resulted in a local intratendinous fluid depot showing minimal abaxial spreading and more extensive proximodistal expansion. If 0.3-0.5 ml was injected the abaxial spreading remained minimal but the proximodistal expansion increased significantly, the depots in the axial proximal, mid and distal region flowing together. Also minimal peri...
Ultrasonographically detected changes in equine superficial digital flexor tendons during the first months of race training. The forelimb superficial digital flexor (SDF) tendons of 6 Thoroughbreds were examined clinically and ultrasonographically during the first 4 months of race training. Sonograms were interpreted clinically and by use of computer-aided analysis. Tendon tissue from all horses was examined histologically at the end of the study. Computer-aided analysis of sonograms of the SDF tendons revealed trends toward an increase in mean cross-sectional area and a decrease in mean echogenicity over time with training. An inverse relation was found between increase in cross-sectional area and decrease in mean ...
Endoscopically assisted annular ligament release in horses. An endoscopically assisted technique for internally dividing the palmar or plantar annular ligament was developed in six cadaver limb specimens and two anesthetized horses. Under arthroscopic view, a slotted cannula was inserted into the digital sheath through a stab wound proximal to the annular ligament and advanced through the fetlock canal superficial to the flexor tendons with the slot oriented toward the fibers of the annular ligament. Division of the annular ligament by 90-degree tipped open and guarded blades was observed and verified by direct arthroscopic view. At necropsy, complete ...
Extensor tendon lacerations in horses: 50 cases (1982-1988). Medical records of 50 horses with extensor tendon lacerations affecting 53 limbs over 7 years (1982 to 1988) were reviewed to determine the clinical features and prognosis for athletic soundness after treatment. Mean and median ages were 4.8 and 3 years, respectively. Eighty-nine percent of the injuries involved the hind limbs, with approximately equal distribution between the right and left limbs. Hind limb lacerations involved the long digital extensor tendon (28 limbs), lateral digital extensor tendon (3 limbs), or both tendons (16 limbs). Forelimb lacerations involved the common digital ex...
Ultrasonographic appearance of ruptured peroneus tertius in a horse. Ultrasonography was a valuable diagnostic tool for examination of a ruptured peroneus tertius in a horse, because it allowed visualization of the extent of the injury and evaluation of healing prior to return of the horse to athletic activity.
Ultrasonographic observations of the flexor tendons and ligaments of the metacarpal region of horses. Observations were made in dorsal and sagittal planes of the ultrasonographic mean gray scale of the flexor tendons and ligaments of the metacarpal regions of 5 Thoroughbred geldings, during weight bearing and nonweight bearing. In images made when the horses were nonweight bearing, the mean gray scale of the superficial and deep digital flexor tendons and accessory ligament was significantly reduced, but that of the interosseous medius muscle (suspensory ligament) was not. When relaxed, collagen fiber bundles in the tendons and ligaments acted as diffuse, rather than specular, reflectors of ul...
Mechanical implications of collagen fibre orientation in cortical bone of the equine radius. Mechanical test specimens were prepared from the cranial and caudal cortices of radii from eight horses. These were subjected to destructive tests in either tension or compression. The ultimate stress, elastic modulus and energy absorbed to failure were calculated in either mode of loading. Analysis was performed on the specimens following mechanical testing to determine their density, mineral content, mineral density distribution and histological type. A novel technique was applied to sections from each specimen to quantify the predominant collagen fibre orientation of the bone near the plane...
[The laterocranial fascia structures in the upper and forearm and the differences in the insertion of the M. biceps brachii in domestic mammals]. The laterocranial fascia of the upper arm and forearm, as well as aponeurotic relationships of the Musculus biceps brachii were investigated on each of ten forelimbs from horses, cattle and swine. Ten canine biceps were also investigated. Equine and bovine fascia contain elastic components. An as-yet undescribed ligament-like aponeuroses of the laterocranial forearm fascia to the Fossa radialis humeri was seen in all three species studied. The laterocranial fascia of the upper and forearm form a common passage for the Musculi brachialis et extensor carpi radialis. In the case of the horse, the...
In vivo tendon forces in the forelimb of ponies at the walk, validated by ground reaction force measurements. The load distribution over tendinous structures in the equine forelimb was studied by computing forces from in vivo signals of implanted liquid-metal strain gauges in 5 ponies. For validation, these tendon forces were converted to joint moments, which were summed and compared to the calculated joint moments caused by the ground reaction force. Mean peak forces per kilogram body weight (n = 5) amounted to 5.2 N/kg for the superficial digital flexor tendon, 3.8 N/kg for the deep digital flexor tendon, 7.3 N/kg for the distal accessory (check) ligament and 8.4 N/kg for the third interosseous musc...
Analgesic effects of detomidine in thoroughbred horses with chronic tendon injury. This study was undertaken to assess the analgesia provided by detomidine (20 micrograms kg-1 intravenously) in thoroughbred horses. Pain thresholds to a mechanical noxious stimulus were measured before and after a period of mild chronic pain in one foreleg. Detomidine was a good analgesic in control animals; their pain thresholds were significantly elevated for about 60 minutes. After injury, the injured leg had a significantly lower pain threshold and the intensity and duration of analgesia provided by detomidine were significantly reduced. The analgesia in the opposite (sound) leg was also r...
Ultrasonographic and histopathological findings in equine superficial digital flexor tendon injury. The ultrasonographic and histopathological findings in 12 normal and 28 injured superficial digital flexor tendons, with lesions ranging in duration from 2 days to 15 months, were compared. A consistent relationship between the ultrasonographic and histological findings was demonstrated. The echogenicity of lesions, the distinctness of their delineation from the surrounding tissue, and the presence and arrangement of the linear echoes were useful features by which to assess the ultrasonograms. Acute lesions were anechoic, a complex mixture of anechoic and hypoechoic areas, or diffusely hypoech...
A method to estimate the initial length of equine tendons. A procedure is described by which the length of a tendon at the onset of loading is determined objectively. The procedure includes the fitting of third-order polynomial functions on the load-elongation data. The onset of loading is detected by an increasing fit of the polynomial by selective data reduction of the initial part of the load-elongation curve. The procedure results in an objective and reproducible definition of the zero strain level of a tendon.
