Topic:Articular Cartilage
Articular cartilage in horses is a specialized connective tissue found at the ends of bones within joints. It provides a smooth, lubricated surface for articulation and facilitates the transmission of loads with a low frictional coefficient. Articular cartilage is primarily composed of chondrocytes, collagen fibers, and proteoglycans, and it lacks blood vessels, nerves, and lymphatics. This avascular nature contributes to its limited capacity for self-repair following injury. The health and integrity of articular cartilage are essential for maintaining joint function and mobility in horses. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and pathological changes of articular cartilage in equine species, as well as advancements in diagnostic and therapeutic approaches for cartilage-related disorders.
Functional adaptation of articular cartilage from birth to maturity under the influence of loading: a biomechanical analysis. The concept of functional adapatation of articular cartilage during maturation has emerged from earlier biochemical research. However, articular cartilage has principally a biomechanical function governed by joint loading. Objective: To verify whether the concept of functional adaptation can be confirmed by direct measurement of biomechanical properties of cartilage. Objective: Fetuses have homogeneous (i.e. site-independent) cartilage with regard to biomechanical properties. During growth and development to maturity, the biomechanical characteristics adapt according to functional (loading) de...
Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 1. Study design, and clinical, nutritional, radiological and histological observations. This is the first in a series of papers reporting studies in 2-year-old Thoroughbred racehorses that aimed to determine the response of musculoskeletal tissues to early training on grass and sand racetracks. In this paper, the experimental set-up of the whole study is described, and nutritional, workload, and clinical, radiographic and pathological outcomes are reported, including semi-quantitative assessment of macroscopic changes in articular cartilage. Methods: The study group comprised 14 two-year-old Thoroughbred fillies reared entirely at pasture. Of these, seven were selected by a licen...
Overload arthrosis: strain patterns in the equine metacarpal condyle. An overload arthrosis occurs consistently in the palmar region of the metacarpal condyle of the equine fetlock (metacarpophalangeal) joint characterized by subchondral bone sclerosis, devitalization and mechanical failure leading to collapse of the overlying articular cartilage. Samples were selected of joints with mild, moderate, and severe subchondral sclerosis, in which cartilage collapse had not yet occurred. An additional group that had severe sclerosis with focal rarefaction suggesting impending collapse was also studied (n=5/group). Parasagittal slices were milled to 2.0 mm thickness an...
Inhibition of adenosine kinase attenuates interleukin-1- and lipopolysaccharide-induced alterations in articular cartilage metabolism. To investigate the effect of adenosine kinase inhibition on interleukin (IL)-1beta- and lipopolysaccharide (LPS)-induced cartilage damage. Methods: Articular cartilage was obtained from the metacarpophalangeal joints of 10 young adult horses. Following a stabilization period, weighed cartilage explants were exposed to IL-1beta (10 ng/ml) or LPS (50 microg/ml) to induce cartilage degradation. To test the potential protective effects of adenosine, these explants were simultaneously exposed to adenosine (100 microM), the adenosine kinase inhibitor 5'iodotubercidin (ITU, 1 microM) or to both adeno...
Cytokine induced metalloproteinase expression and activity does not correlate with focal susceptibility of articular cartilage to degeneration. To determine whether the focal susceptibility to cartilage degeneration in joints is related to a differential response to cytokine stimulation. Methods: Compare aggrecan and collagen catabolism in in-vitro models of cartilage degradation induced by retinoic acid (RA), interleukin-1 (IL-1), tumor necrosis factor alpha (TNF) and IL-1 plus oncostatin M (OSM). Glycosaminoglycan (GAG) and hydroxyproline (HyPro) quantification and Western immunoblot analyses of aggrecan and collagen degradation products were undertaken in explant cultures of normal cartilage from regions of equine joints with a kno...
Ex vivo investigation of the use of hydrothermal energy to induce chondrocyte necrosis in articular cartilage of the metacarpophalangeal and metatarsophalangeal joints of horses. To evaluate the use of hydrothermal ablation of articular cartilage for arthrodesis in horses through investigation of the effects of joint lavage with physiologic saline (0.9% NaCI) solution (80 degrees C) for various treatment times on chondrocyte viability in the articular cartilage of the metacarpophalangeal and metatarsophalangeal joints of cadaveric horse limbs. Sample Population-7 pairs of metacarpophalangeal and 8 pairs of metatarsophalangeal joints from 8 Thoroughbreds. Methods: The horses were euthanatized for reasons unrelated to musculoskeletal disease. On a random basis, 1 joint o...
Effects of sodium hyaluronate and methylprednisolone acetate on proteoglycan synthesis in equine articular cartilage explants. To determine effects of sodium hyaluronate (HA) on corticosteroid-induced cartilage matrix catabolism in equine articular cartilage explants. Methods: 30 articular cartilage explants from fetlock joints of 5 adult horses without joint disease. Methods: Articular cartilage explants were treated with control medium or medium containing methylprednisolone acetate (MPA; 0.05, 0.5, or 5.0 mg/mL), HA (0.1, 1.0, or 1.5 mg/mL), or both. Proteoglycan (PG) synthesis was measured by incorporation of sulfur 35-labeled sodium sulphate into PGs, and PG degradation was measured by release of radiolabeled PGs...
Modulation of articular chondrocyte activity by pirfenidone. Pirfenidone is under investigation as an anti-inflammatory and anti-fibrotic agent in several organs including lung. Since important features of arthritic conditions include inflammation and long-term damage to articular cartilage, we have investigated whether PD can suppress chondrocyte responses to bacterial lipopolysaccharide (LPS) and interleukin 1 (IL-1); modulators that induce a cascade of inflammatory responses that lead to articular joint tissue damage. PD (0 - 5microM) showed no effect on cell number or viability when incubated with high density primary equine chondrocyte cultures for...
Autologous osteochondral grafting (mosaic arthroplasty) for treatment of subchondral cystic lesions in the equine stifle and fetlock joints. To describe treatment of equine subchondral bone cysts (SBCs) by reconstruction of the articular surface with osteochondral grafts. Methods: Case series of horses with SBCs unresponsive to conservative therapy. Methods: Eleven horses (1-12 years). Methods: SBCs were identified in 4 locations: medial femoral condyle (5 horses), lateral femoral condyle (1), distal epiphysis of the metacarpus (4), or metatarsus (1). Osteochondral autograft transplantation (mosaic arthroplasty) was performed, taking grafts from the abaxial border of the medial femoral trochlea of the unaffected limb. Graft implant...
Three-dimensional kinematic analysis of horses with induced tarsal synovitis. Techniques for 3D analysis have recently been developed. This study applied 3D kinematic analysis to describe the effects of lameness in the distal intertarsal (DIT) and tarsometatarsal (TMT) joints; complex joints such as this may show measurable amounts of movement outside the sagittal plane that may change in response to pathological conditions. Objective: Three-dimensional motions of the tarsal joint change after the induction of synovitis at the DIT and TMT joints. Methods: Twelve retroreflective markers, attached on the skin over the right limb, were used to develop 3D coordinate systems...
Age-related changes in serum insulin-like growth factor-I, insulin-like growth factor-I binding protein-3 and articular cartilage structure in Thoroughbred horses. Structural changes in articular cartilage associated with the ageing process require definition for investigators performing developmental and age-related studies, for which information is lacking. Objective: To 1) determine the onset and end of puberty as defined by serum insulin like growth factor (IGF-I) and IGF-binding protein-3 (IGFBP-3) concentrations and 2) correlate articular-epiphyseal cartilage complex structural changes with the onset and end of puberty. Methods: IGF-I and IGFBP-3 were measured in serum samples from normal female and male horses age 9-715 days to determine peak and ...
Ultrastructural immunolocalisation of bone sialoprotein in the osteocartilagenous interface of the equine third carpal bone. One of the most common causes of lameness in racehorses is osteoarthritis (OA). Pathogenesis is not clear and pathological processes of the different joint tissues interact in often progressive events. The interface between cartilage and newly synthesised bone has been shown to be particularly enriched in bone sialoprotein (BSP), a cell-binding matrix protein. Objective: To establish whether changes in the concentration of BSP may serve as a marker for early biochemical changes of the subchondral bone. Methods: Articular cartilage, cartilage/bone interface and subchondral bone of the proximal ...
Relationship between synovial fluid levels of glycosaminoglycans, hydroxyproline and general MMP activity and the presence and severity of articular cartilage change on the proximal articular surface of P1. Osteoarthritis (OA) is one of the most prevalent and disabling chronic conditions affecting horses and leads to degeneration of articular cartilage. Diagnosis is based on clinical signs in combination with radiography, which is relatively insensitive and provides only an indication of accumulated damage. Alternative methods, such as molecular markers, are therefore needed that can quantitatively, reliably and sensitively detect osteoarthritic changes in the joints at an early stage of the disease. If such markers are to be used reliably, it is important to know the relationship between marker ...
Articular calcified cartilage canals in the third metacarpal bone of 2-year-old thoroughbred racehorses. We describe morphological aspects of the articular calcified cartilage mineralizing front 'tidemark' in the distal joint surface of the third metacarpal bone from 14 horses. Compositional backscattered electron scanning electron microscopy and confocal scanning light microscopy were conducted on polymethylmethacrylate (PMMA)-embedded medio-lateral slices. After maceration, scanning electron microscopy (SEM) was used to study the calcified cartilage surface in the 'wedges' intervening between the slices. An anatomically reproducible clustering of canals in the calcified cartilage was found at o...
Repeated intraarticular injections of triamcinolone acetonide alter cartilage matrix metabolism measured by biomarkers in synovial fluid. Although intraarticular (IA) corticosteroids are frequently used to treat joint disease, the effects of their repeated use on articular cartilage remains controversial. The aim of our study was to determine the effects of a clinically recommended dose of IA triamcinolone acetonide (TA), on synovial fluid (SF) biomarkers of cartilage metabolism. Ten adult horses, free of osteoarthritis (OA) in their radiocarpal joints, were studied. One radiocarpal joint of each horse was randomly chosen for treatment and the contralateral anatomically paired joint acted as the control. Aseptic arthrocentesis w...
Dual transduction of insulin-like growth factor-I and interleukin-1 receptor antagonist protein controls cartilage degradation in an osteoarthritic culture model. This study evaluated the potential of gene induced synoviocyte expression of a combination of insulin-like growth factor-I (AdIGF-I) and interleukin-1 receptor antagonist protein (AdIL-1Ra) to control articular cartilage degradation in vitro. Cartilage explants and synovial membrane were harvested from young mature horses. Synovial monolayers were established and either (1) maintained as untransduced controls; (2) transduced with AdIGF-I at 200 MOI in 500 microl serum-free medium; (3) transduced with AdIL-1Ra at 100 MOI; or (4) transduced with a combination of AdIGF-I (200 MOI) and AdIL-1Ra (1...
Differences in the topographical distribution of articular cartilage degeneration between equine metacarpo- and metatarsophalangeal joints. The equine metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints, although having virtually the same geometrical appearance, differ in the prevalence of joint pathologies, such as osteochondral fragmentation, and in biomechanical behaviour. The recently developed cartilage degeneration index (CDI) technique offers a possibility to assess quantitatively differences in cartilage degeneration between these joints and to compare these with known differences in biomechanics and clinical observations. Objective: To compare the topographical distribution of articular cartilage degeneration a...
Site- and exercise-related variation in structure and function of cartilage from equine distal metacarpal condyle. Determine (1) the site-associated response of articular cartilage of the equine distal metacarpal condyle to training at a young age as assessed by changes in indentation stiffness and alterations in cartilage structure and composition, and (2) relationships between indentation stiffness and indices of cartilage structure and composition. Methods: Experimental animals (n=6) were trained on a track (increasing exercise to 1km/day by 5 months); controls (n=6) were pasture-reared. Animals were euthanized at 18 months and four osteochondral samples were harvested per metacarpal condyle from dorsal...
Engineered articular cartilage: influence of the scaffold on cell phenotype and proliferation. Articular cartilage defects do not heal. Biodegradable scaffolds have been studied for cartilage engineering in order to implant autologous chondrocytes and help cartilage repair. We tested some new collagen matrices differing in collagen type, origin, structure and methods of extraction and purification, and compared the behavior of human chondrocytes cultured on them. Human chondrocytes were grown for three weeks on four different equine type I collagen matrices, one type I, III porcine collagen matrix and one porcine type II collagen matrix. After 21 days, samples were subjected to histoche...
Extracellular matrix changes in early osteochondrotic defects in foals: a key role for collagen? Osteochondrosis (OC) is the most important developmental orthopaedic disease in the horse. Despite some decades of research, much of the pathogenesis of the disorder remains obscure. Increasing knowledge of articular cartilage development in juvenile animals led to the presumption that the role of collagen in OC might be more important than previously thought. To study collagen characteristics of both cartilage and subchondral bone in young (5 and 11 months of age) horses, samples were taken of subchondral bone and articular cartilage from a group of 43 Dutch Warmblood foals and yearlings that...
An integral biochemical analysis of the main constituents of articular cartilage, subchondral and trabecular bone. In articular joints, the forces generated by locomotion are absorbed by the whole of cartilage, subchondral bone and underlying trabecular bone. The objective of this study is to test the hypothesis that regional differences in joint loading are related to clear and interrelated differences in the composition of the extracellular matrix (ECM) of all three weight-bearing constituents. Methods: Cartilage, subchondral- and trabecular bone samples from two differently loaded sites (site 1, dorsal joint margin; site 2, central area) of the proximal articular surface of 30 macroscopically normal equ...
Viability of equine articular chondrocytes in alginate beads exposed to different oxygen tensions. Ischaemia and reperfusion are suspected to alter chondrocyte metabolism. Here, we studied the effects of three oxygen (O2) tensions on the viability of equine articular chondrocytes isolated from the cartilage of the distal interphalangeal joint of horses. Chondrocytes were cultured in alginate beads under 1%, 5% or 21% gas phase O2 concentration for 14 days, cellular growth kinetics were measured (n=6), and the cells were observed by light microscopy after staining for necrotic and apoptotic cell detection. For information about the metabolic status, the intracellular adenosine triphosphate (...
Aquaporin water channels AQP1 and AQP3, are expressed in equine articular chondrocytes. Chondrocytes exist in an unusual and highly variable ionic and osmotic environment in the extracellular matrix of articular cartilage. Alterations to the ionic and osmotic environment of chondrocytes influence the volume and ionic content of the cells, which, in turn, modifies the rate at which extracellular matrix macromolecules are synthesized and degraded. Thus, regulation of the water and solute content of chondrocytes will profoundly affect their anabolic and catabolic functions. The water content of cells is effectively influenced by the abundance of aquaporin (AQP) water channels. Recen...
Effect of matrix depleting agents on the expression of chondrocyte metabolism by equine chondrocytes. This study was carried out to investigate the effect of two enzymes (collagenase and chondroitinase) and two cytokines/metabolites (interleukin-1beta and retinoic acid) of known catabolic activity on the expression of cartilage metabolism/phenotype in equine articular cartilage. Articular cartilage explants from 11 horses (5-13 years old) were treated for 48 h and assayed for total sulphated glycosaminoglycan (GAG), the incorporation of 35S-sulphate, collagen degradation and mRNA expression of the proteoglycans collagen II, collagen IIA, collagen III, collagen IX, collagen X, collagen XI and g...
Accuracy of diagnostic arthroscopy for the assessment of cartilage damage in the equine metacarpophalangeal joint. There are many noninvasive diagnostic methods used for evaluating chronic progressive joint disease, but each has severe limitations in the detection of early articular cartilage damage. Objective: To evaluate the accuracy of arthroscopy as a diagnostic method for the assessment of the severity of cartilage surface damage on the proximal articular margin of the equine first phalanx (P1). Objective: That arthroscopic assessment of the visible cartilage provides 1) a good indication of the integrity of the cartilage surface and 2) a good estimation of the status of the cartilage surface of the e...
Assessment of subchondral bone mineral density in equine metacarpophalangeal and stifle joints. Functional relationships between articular cartilage and underlying subchondral bone have been shown to be associated with the progression of osteoarthritis (OA). However, quantifiable factors substantiating this relationship do not exist. Therefore, the study objective involved quantifying subchondral bone mineral density (BMD) of the equine metacarpophalangeal (MCP) and stifle joints as a step in determining if regional subchondral BMD may be associated with OA changes. BMD was bilaterally quantified using dual energy xray absorptiometry (DEXA) for four subchondral regions: palmer and dorsal...
An assessment of equine cartilage degeneration. Millions of Americans suffer from osteoarthritis, a joint disease characterized by cartilage degradation and subchondral bone sclerosis. However, little is known about its pathology. It remains to be discovered which comes first in the progression of osteoarthritis: subchondral bone remodeling or cartilage degeneration. This study assessed equine cartilage degeneration, based upon measurements of cartilage thickness and Indian ink stain uptake. By gaining a greater understanding of the determining factors in cartilage degeneration, we may be able to better understand the pathomechanics of oste...
Effects of insulin-like growth factor-II on the mitogenic and metabolic activities of equine articular cartilage with and without interleukin 1-beta. To investigate the effects of insulin-like growth factor-II (IGF-II) on DNA and glycosaminoglycan (GAG) synthesis and the expression of matrix-related genes in equine articular cartilage explants and chondrocytes, respectively, with and without interleukin 1-beta (IL1-beta). Methods: Articular cartilage from 12 adult horses. Methods: Articular cartilage was incubated in standard media with and without equine IL1-beta (10 ng/mL) containing various concentrations of IGF-II for 72 hours. Synthesis of DNA and GAG was determined by incorporation of thymidine labeled with radioactive hydrogen (3H) a...
Repair of extensive articular cartilage defects in horses by autologous chondrocyte transplantation. Damaged adult articular cartilage has very limited capacity to heal. Autologous chondrocyte transplantation (ACT) has been used clinically and studied in experimental animals in an attempt to provide biologically based cartilage regeneration. This study evaluated cartilage repair following ACT in a large animal model over a period of 2 years. Articular cartilage defects (10 mm in diameter, full-thickness) were created in the minor load-bearing area on the lateral talus of tibiotarsal joints of eight adult horses. In each animal, the right joint was repaired using autologous chondrocytes inject...
Effect of radiosynovectomy with holmium-166 ferric hydroxide macroaggregate on adult equine cartilage. To analyze the effect of radiosynovectomy with holmium-166 ferric hydroxide macroaggregate (166Ho-FHMA) on articular cartilage in 6 adult horses. Methods: Arthritic changes and mechanical properties of articular cartilage were evaluated with arthroscopy and postmortem microscopic analyses. Glycosaminoglycan content was measured by safranin-O staining combined with digital densitometry, uronic acid analyses, and dimethylene blue binding assay. 35S-sulfate labeling and autoradiography were used to localize proteoglycan synthesis and to characterize proteoglycan structures using SDS-agarose gel e...