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PubMed1992

Development of functionally distinct fibrocartilages at two sites in the quadriceps tendon of the rat: the suprapatella and the attachment to the patella.

This paper describes the post-natal development of two fibrocartilages in the quadriceps tendon of the rat. The compression-resisting fibrocartilage of the suprapatella was derived from a cell population present in neonates and positioned on the deep surface of the tendon of vastus intermedius. The cells secreted a metachromatic, coarsely fibrous extracellular matrix that was rich in chondroitin sulphate but lacked keratan sulphate or type II collagen. The cells themselves accumulated large quantities of vimentin. The adult form of the suprapatella was attained 8 weeks after birth. The fibrocartilage of the attachment zone of the quadriceps tendon to the patella was formed in a different manner. In animals up to 4 weeks of age, the quadriceps tendon inserted directly into the cartilage model of the patella. When later this was resorbed, and replaced by bone, the cartilage at the attachment zone remained, along with that of the articular surface of the patella. Attachment-zone fibrocartilage was therefore rich in type II collagen, unlike that of the suprapatella. Thus two functionally different fibrocartilages have been shown to have different origins, even when separated by only a short distance within the same tendon. The compositional differences between attachment-zone and compressive region fibrocartilages are also due to their different origins.

Animals↗
PubMed1992

Development and ageing of phenotypically distinct fibrocartilages associated with the rat Achilles tendon.

We describe by routine histology and by immunohistochemistry three phenotypically and developmentally distinct fibrocartilages associated with the Achilles tendon of the rat. All the fibrocartilages develop after birth and show significant age-related changes in the composition of their extracellular matrix. Attachment-zone fibrocartilage occurs at the insertion of the tendon on the calcaneus. It derives from the cartilage rudiment of the calcaneus and from the region where the tendon merges with the perichondrium. The extracellular matrix contain type II collagen and chondroitin sulphate. Compressive tendon fibrocartilage occurs in the deep part of the tendon where it presses against the calcaneus, and is derived by metaplasia of tendon cells. The cells label strongly for the intermediate filament vimentin, and the extracellular matrix contains chondroitin and keratan sulphates, but type II collagen only in very old animals (> 2 years). Calcaneal fibrocartilage covered the posterior surface of the calcaneus where it was in contact with the Achilles tendon. It labelled intensely for type II collagen and contained chondroitin and keratan sulphates. The cells were rich in vimentin. This fibrocartilage was derived from the calcaneal perichondrium.

Achilles Tendon↗
PubMed1996

Triangular fibrocartilage injury: a laboratory model.

A potential injury mechanism for triangular fibrocartilage tears and ulnar styloid fractures was investigated in cadaver specimens. The distal radioulnar joint was distracted to failure, thus applying a tensile force to the triangular fibrocartilage. During distraction, strains in the triangular fibrocartilage and the anatomic site of disruption were recorded with an image analysis system. Complete avulsion of the triangular fibrocartilage from the ulnar head occurred in 7 of 10 specimens. No ulnar styloid fractures occurred. Although strains were high in the radial portion of the disk (28%), no tears occurred in the substance of the disk or at its attachment to the radius. These findings suggest that distal radioulnar joint distraction can cause avulsion of the triangular fibrocartilage. However, ulnar styloid fractures and tears within the disk are more likely caused by injury mechanisms that include shear or compressive forces. Since complete avulsions of the triangular fibrocartilage occurred without a fracture, the absence of a fracture does not rule out a destabilizing injury to the distal radioulnar joint.

Adult↗
PubMed2003

Effects of condylar fibrocartilage on the biomechanical loading of the human temporomandibular joint in a three-dimensional, nonlinear finite element model.

The present study was undertaken to test a hypothesis that the addition of articular fibrocartilage in the condyle of the temporomandibular joint reduces three-dimensional stress distribution in the condyle, the disc and articular eminence. A three-dimensional, nonlinear finite-element model was developed for analysis of joint loading before and after the addition of condylar fibrocartilage to the osseous mandibular condyle reconstructed from spiral computer topography data. In the model, each of the disc, condyle and articular eminence was arbitrarily divided into five regions: the anterior, posterior, medial, lateral and central. Von Mises stresses that in virtually all regions of the disc, condyle and articular eminence became lower after the addition of condylar fibrocartilage. Especially remarkable was the approximately four-fold reduction in von Mises stresses in the anterior, central and medial regions of the mandibular condyle. In comparison, only slight to moderate stress reductions occurred in the disc and articular eminence, suggesting that condylar fibrocartilage absorbs considerable stresses and likely dampens more loads than the disc and articular eminence. The mandibular condyle demonstrated the largest total displacement in all directions after the addition of articular fibrocartilage, followed by the disc and articular eminence. We conclude that the addition of articular fibrocartilage primarily reduces loading of the mandibular condyle, rather than the disc and articular eminence. These findings lead to a hypothesis that the mandibular condyle more likely functions as a shock absorber than the disc.

Adult↗
PubMed1995

Distribution of calcification in the triangular fibrocartilage region in 181 patients with calcium pyrophosphate dihydrate crystal deposition disease.

PURPOSE: To investigate the occurrence of calcification around the triangular fibrocartilage complex in calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. MATERIALS AND METHODS: The radiographs of 316 wrists in 181 patients with a definite or probable diagnosis of CPPD disease were reviewed to determine the occurrence of calcification in the inferior radioulnar joint cartilage, triangular fibrocartilage, lunotriquetral ligament, lunotriquetral cartilage, and triquetral cartilage. RESULTS: The distribution of calcification in the 316 wrists was as follows: inferior radioulnar joint cartilage, 87 wrists (28%), triangular fibrocartilage, 233 (74%); lunotriquetral ligament, 244 (77%); lunotriquetral cartilage, 167 (53%); and triquetral cartilage, 66 (21%). Forty-nine wrists had calcification in the lunotriquetral ligament or cartilage but not in the triangular fibrocartilage; 30 wrists had calcification in the triangular fibrocartilage but not in the lunotriquetral ligament or cartilage. This difference in prevalence was statistically significant (P = .0429). CONCLUSION: Radiologic diagnosis of CPPD crystal deposition disease in the wrist necessitates careful evaluation of the lunotriquetral ligament as well as the triangular fibrocartilage.

Aged↗
PubMed2004

High-resolution sonography of the triangular fibrocartilage: initial experience and correlation with MRI and arthroscopic findings.

OBJECTIVE: The aim of our study was to compare the findings of high-resolution sonography of the triangular fibrocartilage with those of MRI and arthroscopy. SUBJECTS AND METHODS. Thirteen patients with clinically suspected triangular fibrocartilage tears prospectively underwent sonography, followed by MRI, of their wrists. Triangular fibrocartilage tears were classified as predominantly ulnar or predominantly radial. Only the surgeon was aware of the results of both studies, and eight patients subsequently underwent arthroscopy. The findings of the different techniques were compared. RESULTS: For the presence or absence of a tear, seven (87.5%) of eight sonographic examinations correlated with arthroscopy, and 11 (84.6%) of 13 sonographic examinations correlated with MRI. Sonography missed one small radial tear that was detected at arthroscopy and MRI, but sonography showed an ulnar tear in triangular fibrocartilage that appeared normal on MRI. CONCLUSION: High-resolution sonography shows good correlation with MRI and arthroscopy for the evaluation of triangular fibrocartilage tears. Sonography has the potential to be a rapid and cost-effective means of diagnosing tears of the triangular fibrocartilage, particularly those involving the ulnar aspect of the cartilage.

Adolescent↗
PubMed2002

Microvascularization of the hypermineralized calcified fibrocartilage and cortical bone in the sheep proximal femur.

It is well known that the incidence of hip fractures is increasing as the population ages, and that vascularity is one of the most important characteristics for any tissue (the proximal femur being no exception). Additionally, calcified fibrocartilage from tendon and ligament insertions comprises a significant portion of the fractional area of the proximal femur's cortical shell. The goal of the present investigation was to quantify and compare the microvascularity of the cortical bone and calcified fibrocartilage of the proximal femur in a sheep model. There were no regional differences in the vascular density of the cortical bone. However, the calcified fibrocartilage from tendon and capsular insertions were determined to be avascular, and regions of the proximal femur with insertions lacked a vascularized periosteum. If a vessel was present in the calcified fibrocartilage, it was located within an isolated region of bone tissue or osteoid. Since blood vessels appear to be a significant contributor to the health and remodeling of mineralized tissue, it is hypothesized that the large areas of avascular calcified fibrocartilage present on the elderly femoral neck may predispose these regions to damage accumulation. Therefore future research should examine the role of the vascularity to the proximal femur in the mechanisms of numerous pathological conditions, such as avascular necrosis, osteopenia, and hip fractures.

Animals↗
PubMed2001

Regional structural and viscoelastic properties of fibrocartilage upon dynamic nanoindentation of the articular condyle.

Fibrocartilage,a tissue with macromaterial properties between dense fibrous tissue and hyaline cartilage, is not well understood in its ultrastructure and regional viscoelastic properties. Here nanoindentation with atomic force microscopy was performed on fresh fibrocartilage samples of rabbit jaw joint condyles. Each sample was divided into anteromedial, anterolateral, posteromedial, and posterolateral regions for probing and topographic imaging in 2 x 2 microm and 10 x 10 microm scan sizes. Young's moduli differed significantly among these regions in a descending gradient from the anteromedial (2.34 +/- 0.26 MPa) to the posterolateral (0.95 +/- 0.06 MPa). The Poisson ratio, defined as lateral strain over axial strain, had the same gradient distribution: highest for the anteromedial region (0.46 +/- 0.05) and lowest for the posterolateral region (0.31 +/- 0.05). The same four regions showed a descending gradient of surface roughness: highest for the anteromedial (321.6 +/- 13.8 nm) and lowest for the posterolateral (155.6 +/- 12.6 nm). Thus, the regional ultrastructural and viscoelastic properties of fibrocartilage appear to be coregulated. Based on these region-specific gradient distributions, fibrocartilage is constructed to withstand tissue-borne shear stresses, which likely propagate across its different regions. A model of shear gradient and concentric gradient is proposed to describe the region-specific capacity of fibrocartilage to sustain shear stresses in tendons, ligaments, joints, and the healing bone across species.

Animals↗
PubMed1989

Work in progress: postarthrography computed tomography of the wrist: evaluation of the triangular fibrocartilage complex.

This report reviews a work in progress evaluating the use of postarthrography computed tomography (CT) of the wrist in assessing triangular fibrocartilage complex abnormalities. Twenty-two triangular fibrocartilage complex perforations in 119 patients were identified with both multiple compartment arthrography and postarthrography CT. To obtain a double contrast image of the triangular fibrocartilage complex, the postarthrography CT examinations were performed after multiple compartment arthrography and the injection of air into the radiocarpal compartment. The site of triangular fibrocartilage complex perforation could be identified (radial versus peripheral) as could degenerative changes and internal derangements such as chondrocalcinosis. We did not, however, find any information not provided by arthrography that would have changed the course of management. At this time there is no clinical role for postarthrography CT in the evaluation of triangular fibrocartilage complex derangements.

Arthrography↗
PubMed1996

Meniscal repair by fibrocartilage in the dog: characterization of the repair tissue and the role of vascularity.

Lesions in the avascular part of 20 canine menisci were repaired by implantation of a porous polyurethane. Seven menisci were not repaired and served as controls. The repair tissue was characterized by biochemical and immunological analysis. The role of vascularity in healing was studied by perfusion of menisci with Indian ink. Histologically, repair tissue inside the implants initially consisted of fibrous tissue containing type I collagen. After 2 months, fibrocartilaginous tissue developed inside the implants, whereas control defects only showed repair with fibrous tissue. Both type I and type II collagen, the two major collagen types of normal meniscal fibrocartilage, could be detected in this newly formed fibrocartilage. The implant guided vascular tissue from the periphery towards the lesion resulting in healing of the tear. After fibrocartilage had formed, vascularity decreased and was completely absent in mature fibrocartilage. Control defects remained filled with vascular connective tissue. Two-thirds of the longitudinal lesions were found to be healed partially or completely. It is concluded that implantation of a porous polymer does enhance vascularity sufficiently to result in healing of meniscal lesions extending into the avascular part. Healing takes place by repair tissue strongly resembling normal meniscal fibrocartilage.

Animals↗
PubMed2004

Endostatin/collagen XVIII--an inhibitor of angiogenesis--is expressed in cartilage and fibrocartilage.

UNLABELLED: Aim of the study was to get a deeper insight in the mechanisms regulating avascularity of cartilaginious tissues. In the center of our interest was the expression of the anti-angiogenic fragment of collagen XVIII and its potency to inhibit angiogenesis. We observed a strong endostatin/collagen XVIII production in articular and fibrocartilage and an inhibitory potency concerning the VEGF-signalling pathway. INTRODUCTION: Cartilaginous tissue is mainly avascular and shows a limited intrinsic capacity for healing. Aim of this study was to investigate the expression of the antiangiogenic peptide endostatin/collagen XVIII in cartilage and fibrocartilage. RESULTS: In fetal epiphyseal cartilage of humans high endostatin/collagen XVIII levels could be detected by ELISA whereas significantly lower levels were found in articular cartilage of adults. In the fibrocartilaginous tissue of the menisci, there was no significant difference in the endostatin/collagen XVIII concentrations between samples of fetuses and adults. But in the menisci of adults, endostatin/collagen XVIII concentrations were higher in the internal avascular two thirds of the meniscus whereas in the fetal menisci higher endostatin/collagen XVIII concentrations were found in the external third. Endostatin/collagen XVIII immunostaining of rat articular cartilage shows that endostatin/collagen XVIII downregulation starts soon after birth. In fetal cartilage and fibrocartilage of rats and humans, endostatin/collagen XVIII could be immunostained in the extracellular matrix and in the pericellular matrix of endothelial cells, fibrochondrocytes and chondrocytes. In adult cells, weak endostatin/collagen XVIII immunostaining was restricted to the pericellular matrix of fibrochondrocytes and chondrocytes. The detection of endostatin/collagen XVIII could be verified by in situ hybridization. Chondrocytes in vitro released measurable amounts of endostatin/collagen XVIII into culture supernatants. Stimulation of chondrocytes with EGF, as an example of a growth factor, or dexamethasone had no influence on endostatin/collagen XVIII expression. Endostatin inhibited VEGF-induced phosphorylation of MAPK in chondrocytes. CONCLUSIONS: The spatial and temporal expression of endostatin/collagen XVIII in cartilaginous tissue and its potency regarding inactivation of VEGF signalling suggests that this antiangiogenic factor is important not only for the development but also for the maintenance of avascular zones in cartilage and fibrocartilage. EXPERIMENTAL PROCEDURES: We analyzed the spatial and temporal expression of endostatin/collagen XVIII--an endogenous angiogenesis inhibiting factor--in cartilage and fibrocartilage of humans and rats by immunohistochemical and biochemical (ELISA) methods and by in situ hybridization. To elucidate possible factors responsible for the induction or suppression of endostatin/collagen XVIII in cartilaginous tissues, chondrocytes (cell line C28/I2) were exposed to EGF and dexamethason. To study the possible interaction of endostatin/collagen XVIII with angiogenic factors, the immortalized human chondrocytes (C28/I2) have been incubated with VEGF and the phosphorylation of the MAPK Erk 1/2 (extracellular-regulated kinases), a known signal transduction pathway for VEGF has been determined under the influence of endostatin.

Aging↗
PubMed1991

The microvasculature of the triangular fibrocartilage complex: its clinical significance.

The microvascular anatomy of the triangular fibrocartilage complex was investigated in 10 cadaver specimens by histology and tissue clearing (Spalteholz) techniques. It was found that the triangular fibrocartilage of the wrist is supplied by small vessels that penetrate the triangular fibrocartilage complex in a radial fashion from the palmar, ulnar, and dorsal attachments of the joint capsule and supply the peripheral 10% to 40%. The inner (horizontal) portion is avascular, and no vessels cross the radial attachment of the triangular fibrocartilage complex. The results of this study suggest that tears in the periphery of the triangular fibrocartilage complex may have sufficient blood supply to mount a reparative response and, in theory, can be repaired. However, tears that occur in the center and along the radial attachment do not have immediate access to a blood supply and are not likely to heal.

Cartilage, Articular↗
PubMed2001

The role of radiocarpal injection arthrography and magnetic resonance imaging in the diagnosis of triangular fibrocartilage complex injuries.

OBJECTIVE: To investigate the radiocarpal joint injection arthrography and magnetic resonance imaging for diagnosis of the triangular fibrocartilage complex (TFCC) injuries. METHODS: Thirteen cases whose main complaints were ulnar wrist pain were given radiocarpal joint arthrography and eight of them were also given magnetic resonance imaging for evaluating the integrity of the triangular fibrocartilage complex. RESULTS: Ten of thirteen cases presented the leakage of contrast medium to distal radioulnar joint from the radiocarpal joint, in whom, 8 were demonstrated triangular fibrocartilage tear on magnetic resonance imaging, and 3 located at radial side, 2 at central, 3 at ulnar side. One of three cases which were demonstrated without the leakage of contrast medium in arthrography were displayed with marked TFCC tear on magnetic resonance imaging. CONCLUSIONS: The wrist arthrography can provide a definite diagnosis for triangular fibrocartilage disruption with higher sensitivity. magnetic resonance imaging not only demonstrates the site of triangular fibrocartilage disruption as the same value as wrist arthrography, but also displays the other related bony and soft tissues changes.

Adult↗
PubMed1995

Variations in the quality of uncalcified fibrocartilage at the insertions of the extrinsic calf muscles in the foot.

It has been suggested that fibrocartilage at entheses (tendon-bone junctions) prevents collagen fibres bending at the hard tissue interface. We have investigated this function by exploring the relationship between the presence or amount of fibrocartilage at the attachments of the major extrinsic muscles in the foot, and the extent to which these tendons bend near their entheses during movement. The tendons were taken from each of 5 formalin-fixed dissecting room cadavers and prepared for routine histology, and sections were collected systematically throughout the blocks. Tendons that attached to the tarsus and metatarsus had fibrocartilaginous entheses, but those attached to the phalanges had fibrous entheses. In all tarsal and metatarsal tendons, the fibrocartilage was significantly thicker (P < 0.05) in the deepest part of the enthesis. Here the greatest amount of fibrocartilage was in the Achilles tendon (mean thickness +/- S.E.M.: 1560 +/- 161 microns). There were moderate amounts at the medial cuneiform attachment of tibialis anterior (533 +/- 82 microns), peroneus brevis (472 +/- 64 microns) and tibialis posterior (454 +/- 26 microns), small quantities at the first metatarsal attachment of tibialis anterior (104 +/- 14 microns) and peroneus longus (21 +/- 8 microns), but only traces at the attachments of the flexor and extensor tendons of the phalanges. The differences can be related to variations in the freedom of movement of the tendons near their attachments. This depends on the extent to which the tendons are bound by retinacula and the range of movement of the joint nearest the enthesis. The results suggest that more 'mobile' tendons have more fibrocartilage.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1997

Changes in the expression of type-X collagen in the fibrocartilage of rat Achilles tendon attachment during development.

This study histologically and immunohistochemically demonstrated developmental changes in cell morphology and expression of type-X collagen in the attachment of the Achilles tendon to the calcaneus in the rat. Although the site of attachment in the mature rat showed a well organized, direct insertion that was composed of tendon, fibrocartilage, calcified fibrocartilage, and bone, this four-zone structure was not observed in the immature 1-week-old rat. Formation of fibrocartilage was observed at 2 weeks, together with the hypertrophy of chondrocytes and the appearance of the secondary center of ossification. Type-X collagen was not detected either in chondrocytes in the attachment area at 1 week or in hypertrophic chondrocytes at the attachment at 2 weeks. In the 3-week-old rat, the secondary center of ossification extended to the area of attachment and type-X collagen was detected both in cartilage spicules within the secondary center of ossification and in cells found at the attachment adjacent to the secondary center of ossification. A four-zone structure had been established by 6 weeks and remained through 20 weeks. After 6 weeks, type-X collagen was identified both in the attachment of the tendon and beneath the calcaneal fibrocartilage. Type-X collagen is produced by cells in transitional zones between calcified and noncalcified tissue, such as the interface between articular cartilage and subchondral bone. In these areas, the expression of this protein persists through maturity and is not transient.

Achilles Tendon↗
PubMed1995

Understanding the biomechanics of tendon fibrocartilages.

A direct analogy with the function of large proteoglycans in articular cartilage has led to the assumption that the presence of such components in tendon fibrocartilages is a major factor enabling these structures to resist pressure. However, the association of collagen fibrils in bundles and their tensional state as verified through the existence of crimp under polarized light in tendon fibrocartilage raises doubts as to whether the large proteoglycans are kept under osmotic pressure, which is an essential condition for their physiological role in articular cartilage. This suggests that tendon fibrocartilage has distinct mechanisms to resist pressure. In tendon fibrocartilages, the compressive forces must be transferred to the inextensible collagen fibers which lie in many directions in different planes, before reaching the parallel fibers of the tension region. In this sense, the large proteoglycans are likely to have the function of providing a viscous and cohesive environment in which collagen fibers could get stretched to reinforce the tissue.

Animals↗
PubMed1995

The development of fibrocartilage in the rat intervertebral disc.

The development of fibrocartilage in rat lumbar intervertebral discs has been correlated with an immunohistochemical analysis of the changing distribution of extracellular matrix components. Disc anlagen were first recognised by embryonic day 14 as segmental cell condensations. By E16, the notochord formed a series of bulges, each representing a future nucleus pulposus, and the annulus fibrosus had differentiated in the disc anlagen. The inner part of the annulus was composed of cartilage which linked that of adjacent vertebral bodies. The outer part was fibroblastic, with layers of parallel fibroblasts. The long axes of the cells in successive layers lay at an angle of approximately 90 degrees to each other. This criss-cross orientation of cells preceded the oriented deposition of collagen fibres to form the lamellae. Disc anlagen were immunolabelled weakly for types I and III collagen, chondroitin 6-sulphate and dermatan sulphate. Later tissue differentiation was marked by the appearance of type II collagen, chondroitin 4-sulphate and keratan sulphate in the inner annulus. These components also appeared in the outer annulus, but only in adult animals, and indicated metaplastic change in the lamellar fibroblasts. Fibrocartilage in the nucleus pulposus was only seen in old animals, and the origin of the tissue was less clear. However, the fibrocartilage cells appeared to be derived from the cartilage end plate and/or from the inner annulus. We conclude that fibrocartilage in the intervertebral disc is derived from several sources and that the radial distribution patterns of extracellular matrix components in the adult disc are explained by the embryonic origins of its parts.

Animals↗
PubMed1999

A study of mechanoreceptors in fibrocartilage masses in the defect of pars interarticularis.

We investigated the origin of low back pain associated with lumbar spondylolysis and spondylolytic spondylolisthesis by removing fibrocartilage masses from the lytic sites in symptomatic patients and staining the masses by the Gairns gold chloride method to examine mechanoreceptors. The fibrocartilage masses were found to contain four types of mechanoreceptors: Pacinian corpuscles, Ruffini receptors, Golgi tendon organ-like receptors, and free nerve endings. All of these mechanoreceptors were present at the periphery of the specimens, and Ruffini receptors and free nerve endings were abundant. Some mechanoreceptors had a slightly atypical structure, in addition to those with typical morphology. Comparison with mechanoreceptors in normal lumbar facet joint capsules showed that there were more mechanoreceptors in the fibrocartilage masses and a greater proportion of atypical structures at lytic sites. The presence of mechanoreceptors at lytic sites suggests that the fibrocartilage masses are not simply scar tissue filling the defect. Rather, these masses also appear to play a protective role by sensing instability via mechanoreceptors and transmitting this information as pain, while at the same time acting as ligament-like tissue that connects and stabilizes the separated vertebral arches.

Adolescent↗