Topic:Cartilage
Cartilage in horses is a specialized connective tissue found in joints, providing a smooth, lubricated surface for articulation and facilitating the transmission of loads with low friction. It is composed of chondrocytes embedded within an extracellular matrix rich in collagen fibers, proteoglycans, and water. Cartilage does not contain blood vessels or nerves, relying on diffusion for nutrient delivery and waste removal. This avascularity contributes to its limited capacity for repair and regeneration. Research on equine cartilage focuses on understanding its structure, function, and the biological processes involved in cartilage development, maintenance, and degeneration. Studies also explore the impact of various conditions, such as osteoarthritis, on cartilage integrity and investigate potential therapeutic approaches for cartilage repair and preservation. This page gathers peer-reviewed research and scholarly articles that delve into the biology, pathology, and treatment of cartilage-related conditions in horses.
Equine dyschondroplasia (osteochondrosis)–histological findings and type VI collagen localization. This study describes (1) the histological appearance of dyschondroplasia, the primary lesion of osteochondrosis, in articular cartilage of the horse and (2) the localization of type VI collagen which is an important constituent of the extracellular matrix (ECM). Dyschondroplastic cartilage was identified on the basis of the presence of cartilage cores (i.e., cartilage extending into the subchondral bone) and confirmed with subsequent histological examination. Full-thickness cartilage samples from 57 horses were collected and paraffin embedded. Histological examination was used to examine the n...
Cellular heterogeneity in cathepsin D distribution in equine articular cartilage. The distribution of cathepsin D in normal equine growth cartilage has been examined immunocytochemically using an antiserum raised against human cathepsin D. The cross-reactivity and specificity of the antiserum for equine cathepsin D was confirmed, and its lysosomal localisation was demonstrated in horse skin fibroblasts by confocal scanning microscopy. Cultured horse chondrocytes were heterogenous in their expression of cathepsin D. Heterogeneity of distribution of the enzyme was also seen in chondrocytes in cartilage from different anatomical sites. A high level of cathepsin D was observed ...
Evaluation of cartilage lesions on the medial femoral condyle as a cause of lameness in horses: 11 cases (1988-1994). To evaluate clinical findings and response to treatment in horses in which cartilage lesions on the medial femoral condyle were a cause of lameness. Methods: Retrospective case series. Methods: Medical records of 11 horses that had cartilage lesions on the medial femoral condyle detected during arthroscopy of the stifle. Methods: Signalment, history, lameness examination, response to intra-articular anesthesia, radiographs of the stifle, observations during diagnostic arthroscopy, and treatment were extracted from the medical record of each horse. Follow-up examinations and outcome were availa...
The effect of strenuous versus moderate exercise on the metabolism of proteoglycans in articular cartilage from different weight-bearing regions of the equine third carpal bone. Articular cartilage degeneration in the middle carpal joint is a common problem in racing horses. This study evaluated the effect of exercise on the in-vitro synthesis of the large aggregating proteoglycans (aggrecan) and two small proteoglycans, biglycan and decorin, in articular cartilage taken from three weight bearing regions of the third carpal bone of horses which were subjected to moderate or strenuous exercise. Twelve Standardbred horses free from clinical and radiographic disease of the middle carpal joint were subjected to an 8 week moderate exercise program. The horses were then ran...
Insulin-like growth factor 1 and corticosteroid modulation of chondrocyte metabolic and mitogenic activities in interleukin 1-conditioned equine cartilage. To evaluate potential stimulatory or matrix-sparing effects of insulin-like growth factor 1 (IGF-1), alone or in combination with a corticosteroid, in an interleukin 1 (IL-1)-induced model of cartilage degradation. Methods: Cartilage from the weightbearing surfaces of trochlea and condyles of clinically normal 2-year-old male horses. Methods: Triamcinolone acetonide and IGF-1 effects were evaluated by assessing: matrix responses by sulfated glycosaminoglycan (GAG) assay and [35S]sulfated GAG synthesis; collagen content by hydroxyproline assay; and mitogenic response by [3H]thymidine incorporat...
Nitric oxide production by equine articular cells in vitro. Recent research in several species has suggested nitric oxide (NO) as a mediator of articular cartilage damage and an inhibitor of cartilage matrix neosynthesis. This study investigated NO production by cultured equine articular chondrocytes in response to 2 arthritogenic molecules, namely lipopolysaccharide (LPS) and interleukin-1 beta (IL-1 beta), and compared NO production by cultured equine synoviocytes stimulated with LPS. Synoviocytes exhibited a low basal level of NO synthesis (measured as nitrite, a NO metabolite) that was neither significantly increased nor decreased by exposure to LP...
Relationship between ossification of the cartilages of the foot and conformation and radiographic measurements of the front feet in Finnhorses. One hundred Finnhorse cadaver front feet were measured and examined both radiographically and visually to report the incidence of various foot problems and their relationship to ossification of the cartilages of the foot. Ossification extending above the proximal border of the navicular bone and/or separate centres of ossification were found in 36 feet, and the lateral cartilages showed more ossification than the medial cartilages. The feet were generally broad with well developed frogs, but the long toe-low heel syndrome was a relatively common finding. Ossification of the cartilages correlat...
Effect of 19-norandrostenololylaurate on serum testosterone concentration, libido, and closure of distal radial growth plate in colts. The long-term effect of anabolic steroid was investigated in 3 experiments. In experiment I, 500 mg of 19-norandrostenololylaurate was given to 5 colts and a dose of 100 mg to another 5 colts every 3rd week. Six colts served as untreated controls. The animals were 12-16 months old at the start, and 24 months at the end of treatment. In experiment II, a dose of 1 mg/kg was given every 3rd week to 4 colts and 0.3 mg/kg every week to another 4 colts. Six colts served as controls. The colts were treated from 7 months to 12 months of age. In experiment III, 1 mg/kg of steroid was given every 3rd we...
Proteoglycan metabolism of equine articular chondrocytes cultured in alginate beads. Equine chondrocytes were cultured in vitro for 30 days in ionically gelled alginate beads. The alginate polymerises into a stable gel in the presence of divalent cations (calcium), and rapid depolymerisation in the presence of a calcium chelator releases the viable chondrocytes. The chondrocytes maintained a spherical appearance for 30 days in culture, in marked contrast to monolayer cultures, which develop a dedifferentiated fibroblastic morphology. The major proteoglycan molecule produced by the encapsulated chondrocytes was aggrecan, of similar hydrodynamic size to aggrecan molecules presen...
The structure of the keratan sulphate chains attached to fibromodulin isolated from articular cartilage. Fibromodulin has been isolated from bovine and equine articular cartilage and the attached keratan sulphate chains subjected to digestion by keratanase II. The oligosaccharides generated have been reduced and subsequently isolated by strong anion-exchange chromatography. Their structures have been determined by high-field 1H-NMR spectroscopy and high-pH anion-exchange chromatography. Both alpha(2-6)- and alpha(2-3)-linked N-acetylneuraminic acid have been found in the capping oligosaccharides, and, fucose which is alpha(1-3)-linked to N-acetylglucosamine has been found as a branch in both repe...
Atypical villonodular synovitis in a horse. A 4-year-old sexually intact male Standardbred trotter was evaluated for left forelimb lameness. A presumptive diagnosis of severe cartilage damage was made because the horse had a history of infectious arthritis involving the left metacarpophalangeal joint. Arthroscopic evaluation revealed what was presumed to be a large villonodular lesion. The mass was surgically removed, and the horse was treated with procaine penicillin G, trimethoprim-sulfamethoxazole, phenylbutazone, and polysulfated glycosaminoglycans and eventually returned to racing. Histologic examination of the mass revealed a bed ...
Effects of flunixin, tolfenamic acid, R(-) and S(+) ketoprofen on the response of equine synoviocytes to lipopolysaccharide stimulation. The objective of this study was to analyse the effects of 4 nonsteroidal anti-inflammatory drugs (NSAIDs) on the production of beta-glucuronidase (beta-glu), tumour necrosis factor alpha (TNF alpha), interleukin-6 (IL-6), interleukin-1 (IL-1) and prostaglandin E2 (PGE2) by lipopolysaccharide (LPS)-stimulated equine synoviocytes. The agents studied were flunixin, tolfenamic acid, S(+)ketoprofen (KTP) and R(-)ketoprofen. LPS-induced release of beta-glu from synoviocytes was inhibited in a concentration dependent manner by all 4 compounds, tolfenamic acid being the most potent. Of the 2 KTP enant...
Maintenance of equine articular cartilage explants in serum-free and serum-supplemented media, compared with that in a commercial supplemented medium. To evaluate the effects of a commercially defined, serum-free medium additive on equine articular cartilage explants, compared with effects of serum-free and serum-supplemented media. Methods: Articular cartilage from a 3-year-old, mixed breed horse euthanatized for reasons other than musculoskeletal disease or sepsis. Methods: Media were changed every 48 hours, and the glycosaminoglycan (GAG) content was determined in media collected at each time point. Glycosaminoglycan synthesis by explant chondrocytes, and residual GAG content of articular cartilage (as a measure of explant GAG loss) were ...
Biochemical and biomechanical alterations in equine articular cartilage following an experimentally-induced synovitis. The effects of inflammation on the biochemical and biomechanical properties of articular cartilage at two sites (dorsal and palmar) from the radial facet of the equine third carpal bone were examined in response to a synovitis induced with Escherichia coli lipopolysaccharide (LPS). Four groups were studied. In group 1 synovitis was induced at time zero and evaluated at week 6. Group 2 was the sham-treated control for group 1. In group 3 synovitis was induced at time zero and evaluated at week 2. Group 4 was the sham-treated control for group 3. There was a significant increase (P palmar). The...
Expression of types II, VI and X collagen in equine growth cartilage during development. The synthesis and expression of collagen types II, VI and X were investigated in growth cartilage selected from a group of 31 horses and ponies in the age range 157 days of gestation to 12 years. Collagen isolation, immunolocalisation and in situ hybridisation techniques were used in order to provide information on the pattern of synthesis of these 3 collagens during endochondral ossification in normal horses. Type II collagen immunoreactivity and mRNA expression was found in each of the 3 zones of growth cartilage chondrocytes in all samples studied, whereas the localisation of both collagen ...
Regulation of glycosaminoglycan metabolism by bone morphogenetic protein-2 in equine cartilage explant cultures. To investigate whether recombinant human bone morphogenetic protein-2 (rhBMP-2) regulates glycosaminoglycan (GAG) synthesis and release from equine articular cartilage explant cultures. Methods: Equine articular cartilage explants were maintained in vitro for 7 days in the presence of 0 (control), 1, 10, or 100 ng of rhBMP-2/ml. Synthesis and release of GAG were assessed as measures of production and degradation of the extracellular matrix, respectively. Methods: 6 horses (age range, 2 to 25 years old) without clinically detectable musculoskeletal abnormalities. Methods: Rate of synthesis of G...
Radiographic and arthroscopic findings associated with subchondral lucency of the distal radial carpal bone in 71 horses. Case records and radiographs of 71 horses with subchondral lucency, without radiographic evidence of fracture, located on the distal radial carpal bone were examined retrospectively. All horses had lameness and/or joint effusion referable to the carpus. Distal radial carpal bone subchondral lucency was found as a solitary lesion or as a lesion concurrent and symmetric to a contralateral distal radial carpal bone chip fracture. The lesion appeared radiographically as a lucency or shadow on the distal dorsal margin of the radial carpal bone and was most evident on the flexed lateromedial and dor...
The effects of irradiation dose on the stiffness of cartilage grafts. Various centers report irradiated cartilage graft absorption rates that differ quite widely. We postulated that a major factor governing this phenomenon might be irradiation dose. Irradiation produces collagen cross-binding and increased resistance to absorption of such material when implanted. Since cross-binding produces stiffening of collagen, cartilage grafts were exposed to increasing doses of irradiation and their elastic modulus was measured. The postulate was that increasing radiation doses will produce grafts of increasing stiffness. Sternal cartilage, harvested from horses, was cut i...
Effects of holmium: YAG laser energy on cartilage metabolism, healing, and biochemical properties of lesional and perilesional tissue in a weight-bearing model. Comparison of perilesional cartilage, lesional repair tissue, and subchondral bone activity 6 months after application of holmium-yttrium-aluminum-garnet (Ho:YAG) laser energy to chronic (10 week) induced 10-mm full-thickness (FT) circular articular cartilage craters followed by 6 months' intermittent active motion (IAM) in a free exercise environment was investigated. The 2.1-microns wavelength was delivered in hand-controlled near-contact mode by arthroscopic surgery in a saline medium. Bilateral arthroscopy was performed on normal antebrachiocarpal, intercarpal, and metacarpophalangeal join...
Transphyseal vessel involvement in repair of metaphyseal retained cartilage. A foal with retained cartilage in the distal metaphysis of the right and left radii and third metacarpal bones had abnormal physeal vasculature. In areas where cartilage was retained, vessels crossed the physis, and branched at the physeal-metaphyseal junction or at the site of retained cartilage. Vessels appeared to be involved in re-initiation of endochondral ossification and in the repair reponse to the presence of retained cartilage. In areas where the physis was radiographically and histologically normal, no vessels crossed the physis. A function of transphyseal vessels may be as a reserv...
The dose-related effects of phenylbutazone and a methylprednisolone acetate formulation (Depo-Medrol) on cultured explants of equine carpal articular cartilage. The dose-related effects of phenylbutazone and Depo-Medrol on chondrocyte viability and chondrocyte-mediated synthesis and depletion of proteoglycans were investigated using cultured explants of equine middle carpal joint articular cartilage. Explants from 12 horses (941 x 3 mm diameter) were cultured for a total of 5 days, which included 3 days' exposure to either phenylbutazone (0, 2, 20, 200 or 2000 micrograms/mL) or Depo-Medrol (0, 20, 200 or 2000 micrograms/mL). For each explant, amino sugar content was used as a measure of proteoglycan content, 35S incorporation as a measure of the rate ...
Histologic appearance of axial osteochondral fragments from the proximoplantar/proximopalmar aspect of the proximal phalanx in horses. Osteochondral fragments from the axial proximoplantar/proximopalmar region of the proximal phalanx were removed from 38 joints in 30 horses. Ninety-three percent of the horses were Standardbreds, and 28 of the 30 had a low-grade lameness. All but 1 of the horses had hind limb involvement. A total of 43 fragments were removed. Most (71%) of the fragments involved the medial aspect of the joint and had to be dissected from a covering of synovial tissue. Histologically, the circumference of most fragments consisted of a transition zone at the attachment of the joint capsule, a region of nonarticu...
Localisation of alkaline phosphatase in equine growth cartilage. The aim of this study was to localise alkaline phosphatase (ALP) activity in equine growth cartilage both histochemically and ultrastructurally. For histochemical studies, full thickness growth cartilage samples were obtained from 6 anatomical sites from 16 horses and ponies ranging in age from 90 d postconception to 12 years of age. For ultrastructural studies, samples were obtained from the lateral trochlear ridge of the distal femur of 3 animals ranging in age from 157 d postconception to 12 months of age. Alkaline phosphatase in histological sections was localised using a substituted napht...
Complete primary sequence of equine cartilage link protein deduced from complementary DNA. Investigation of the structure of the equine articular cartilage link protein (LP) from individuals ranging in age from 1 to 15 years identified 3 distinct isoforms having molecular weights of 46,000, 43,000 and 41,000. The relative amounts of each of the 3 isoforms altered with age. The largest form did not change with age; however, amounts of the Mr 43,000 and 41,000 forms increased with increasing age. The results suggested that an accumulation, in the extracellular matrix of cartilage, of these 2 smaller products may have arisen from proteolytic cleavage. The complete amino acid sequence o...
Local and remote matrix responses to chondrocyte-laden collagen scaffold implantation in extensive articular cartilage defects. Chondrocyte-laden collagen scaffolds were evaluated in extensive cartilage defects in an equine model. Arthroscopic techniques were used to implant a chondrocyte-collagen culture product in 15-mm defects in the lateral trochlear ridge of the femoropatellar joint of 12 horses. Ungrafted control defects were formed in the opposite joint. Groups of six horses were terminated at 4 and 8 months after implantation and the repair sites, adjacent cartilage, and remote cartilage within each femoropatellar joint examined biochemically. Eight months following surgery the relative proportions of type II c...
Case report: acute joint destabilization in the equine demonstrating early pathology in osteoarthritis. A case of acute destabilization of the right stifle joint associated with rupture of the anterior cruciate ligament and avulsion fracture of the tibial spine in a horse is reported. The diagnosis was obtained by scintigraphy and radiography. Post mortem investigations 6 weeks after injury demonstrated fibrillation of surface cartilage in regions unprotected by tibial menisci. No pathological change was demonstrated in the subchondral bone of the tibia in regions associated with loss of cartilage integrity.
Long-term fate and effects of exercise on sternal cartilage autografts used for repair of large osteochondral defects in horses. Bilateral osteochondral defects (10 mm2 x 3 mm deep) were created on the distal articular surface of the radial carpal bone of ten, 2- to 3-year-old horses. One defect of each horse was repaired, using a sternal cartilage autograft (treated), and the other was left untreated (control). The horses were exercised on a high-speed treadmill at incrementally increased speed and duration over the course of 12 months. Horses were evaluated arthroscopically at 6 to 7 weeks, and clinical examinations were conducted weekly at exercise. Twelve months after surgery, carpuses of each horse were radiographe...
Crystals in equine articular cartilage. Crystal deposits have been observed in equine articular cartilage and identified by scanning electron microscopy and X-ray diffraction as octacalcium phosphate and calcium pyrophosphate dihydrate. Of 89 equine fetlock joints examined 10 contained evidence of calcification visible by eye. It is suggested that the deposition of crystals may be a mediator of arthritis in horses and may also cause damage directly.
Chondrocyte-fibrin matrix transplants for resurfacing extensive articular cartilage defects. Cartilage resurfacing by chondrocyte implantation, with fibrin used as a vehicle, was examined in large (12 mm) full-thickness articular cartilage defects in horses. Articular chondrocytes, isolated from a 9-day-old foal, were mixed with fibrinogen and injected with thrombin, in a 1:1 mixture, into 12 mm circular defects on the lateral trochlea of the distal femur of eight normal horses. The contralateral femoropatellar (knee) joint served as a control in which the defect was left empty. Synovial fluid from the femoropatellar joints was sampled on days 0, 4, 7, 30, 120, and 240 postoperatively...
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 was...