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The cricoarytenoid joint capsule and its relevance to endotracheal intubation.

UNLABELLED: Impaired movement of the cricoarytenoid joint with hoarseness and immobility of the vocal ligament may occur as a consequence of endotracheal intubation. Little is known about the cricoarytenoid joint capsule and its role in intubation. We investigated the joint capsules of 48 cricoarytenoid joints by means of gross anatomy microscopy, histology, and scanning electron microscopy; 30 unfixed cadaver larynges were also subjected to attempts to simulate traumata such as those that may occur during intubation trials. The larynges were intubated with the arytenoid tip entering the lumen of the tracheal tube or extubated with the cuff of the tube only partially deflated. Subsequently, i.e., after dissecting the left and right cricoarytenoid joint from each larynx, the morphologic changes induced experimentally were analyzed by using histologic methods. The cricoarytenoid joint was found to be lined by a wide joint capsule. Unexpectedly large and intensively vascularized synovial folds projected into the joint cavity. After simulation of intubation and extubation, histologic analysis revealed injuries to the synovial folds and joint surface impressions, but no trauma or rupture of the outer joint capsule. We conclude that laxity of the joint capsule and the large synovial folds are predisposing factors for intubation trauma of the cricoarytenoid joint, potentially leading to hemarthros and finally to cricoarytenoid joint dysfunction. IMPLICATIONS: The present study illustrates by morphological investigations and intubation experiments that laxity of the joint capsule and large synovial folds are predisposing factors for intubation trauma of the cricoarytenoid joint, potentially leading to hemarthrosis and finally to cricoarytenoid joint dysfunction.

Adult↗

[On the etiology of the loose shoulder--biochemical studies on collagen from joint capsules].

In order to investigate the etiology of loose shoulder, biochemical characteristics of collagens from four major joint capsules of extremities and from joint capsules of loose shoulder have been investigated. Joint capsules of normal shoulder were found to synthesize less collagen fibers comparing to those of other major joints. Furthermore formation of inter-molecular cross-links of collagen from shoulder joint capsule was relatively lower than that of collagens from other major joints. Noteworthy was the fact that collagen fibers from joint capsules of loose shoulder were more soluble and contain less amount of the reducible cross-links than those from joint capsules of the normal shoulder. These data suggest that collagen synthesis and formation of collagen fibers vary with the differences in joint structures, functions and movements. It may also be implied that the joint capsules of loose shoulder produce immature collagen fibers which may reflect the clinical feature of the disease.

Adolescent↗

Immunohistochemical approach for the investigation of nerve distribution in the shoulder joint capsule.

Twenty six shoulder joint capsules obtained from 13 autopsy cases were studied to evaluate the nerve distribution using immunohistochemical techniques. Immunohistochemical staining of polyclonal S-100 protein or protein gene product 9.5 was more sensitive, specific, and reproducible compared with conventional gold chloride methods. A small number of clustered nerve fibers were found in the superficial layer, and many nerve fibers with large diameters were found in anteroinferior portions of the deep layer. Nerve fibers of various sizes were more numerous in posterosuperior and anterosuperior portions of the boundary zone between labrum and capsule. A Pacinian corpuscle was clearly recognized in a capsule. In the central portion of the long head of some biceps brachii tendons, relatively large nerve fibers continued from capsules. The results suggest that the capsule and long head of the biceps brachii tendon may play a partial role in the stability of the shoulder joint through afferent feedback.

Aged↗

Material properties of the human lumbar facet joint capsule.

The human facet joint capsule is one of the structures in the lumbar spine that constrains motions of vertebrae during global spine loading (e.g., physiological flexion). Computational models of the spine have not been able to include accurate nonlinear and viscoelastic material properties, as they have not previously been measured. Capsules were tested using a uniaxial ramp-hold protocol or a haversine displacement protocol using a commercially available materials testing device. Plane strain was measured optically. Capsules were tested both parallel and perpendicular to the dominant orientation of the collagen fibers in the capsules. Viscoelastic material properties were determined. Parallel to the dominant orientation of the collagen fibers, the complex modulus of elasticity was E*=1.63MPa, with a storage modulus of E'=1.25MPa and a loss modulus of: E" =0.39MPa. The mean stress relaxation rates for static and dynamic loading were best fit with first-order polynomials: B(epsilon) = 0.1110epsilon-0.0733 and B(epsilon)= -0.1249epsilon + 0.0190, respectively. Perpendicular to the collagen fiber orientation, the viscous and elastic secant moduli were 1.81 and 1.00 MPa, respectively. The mean stress relaxation rate for static loading was best fit with a first-order polynomial: B (epsilon) = -0.04epsilon - 0.06. Capsule strength parallel and perpendicular to collagen fiber orientation was 1.90 and 0.95 MPa, respectively, and extensibility was 0.65 and 0.60, respectively. Poisson's ratio parallel and perpendicular to fiber orientation was 0.299 and 0.488, respectively. The elasticity moduli were nonlinear and anisotropic, and capsule strength was larger aligned parallel to the collagen fibers. The phase lag between stress and strain increased with haversine frequency, but the storage modulus remained large relative to the complex modulus. The stress relaxation rate was strain dependent parallel to the collagen fibers, but was strain independent perpendicularly.

Adult↗

Regional material properties of the human hip joint capsule ligaments.

The hip joint capsule functions to constrain translation between the femur and acetabulum while allowing rotational and planar movements. Despite the crucial role it plays in the pathogenesis of hip instability, little is known about its biomechanical properties. The goal of this study was to determine the regional material properties of the iliofemoral and ischiofemoral ligaments of the capsule. Ten human cadaveric specimens of each ligament were tested to failure in tension. The stress at failure, strain at failure, strain energy density at failure, toe- and linear-region elastic moduli, and the Poisson's ratio were measured for each ligament. The strain to failure was greatest in the ischiofemoral ligament, while no significant difference was noted in failure stress by region or ligament. The Young's moduli of elasticity ranged from 76.1 to 285.8 MPa among the different ligaments, and were generally consistent with properties previously reported for the shoulder capsule. The elastic moduli and strain energy density at failure differed by region. No significant differences in Poisson's ratio were found by region or ligament. The average Poisson's ratio was approximately 1.4, consistent with anisotropic behavior of ligamentous tissues. Understanding the material properties of the hip capsule may help the orthopaedic surgeon better understand normal ligament function, and thereby choose a surgical approach or strategy of repair. Furthermore, knowledge of the normal mechanical function of the hip capsule ligaments could assist in the evaluation of the success of a repair.

Aged↗

Mechanical states encoded by stretch-sensitive neurons in feline joint capsule.

1. The sensitivity of group II joint afferents innervating cat knee joint capsule to in-plane stretch was studied in vitro. Single afferents were recorded from teased filaments of the posterior articular nerve. The capsule was stretched by applying forces through tabs along the edges of the capsule (3 tabs/edge) with the use of an apparatus that allowed for independent control of each load. The relationships between the neural responses of these afferents and the local continuum mechanical state of the joint capsule have been investigated. By appropriately loading the tissue margins, it was possible to establish states of uniaxial and biaxial tension, including shear. 2. Plane stress was calculated from the loads along the tissue margins. Stress at the location of the mechanoreceptor ending was estimated by interpolation. Strain was calculated from deformations of the capsule measured by tracking markers on its surface. Full characterization of tissue stress and strain made it possible to determine strain energy density and the magnitudes of other coordinate invariant mechanical quantities. 3. Individual afferents (n = 15) exhibited pronounced selectivity to the direction of applied stress and strain. There was no overall preferred orientation across neurons, and simple correlation of individual stress or strain components with the neuronal response revealed no consistent relationship between neuronal response and any single tensor component. However, linear multiple regression of the combined stress and strain components with the neuronal response revealed high correlation (mean R = 0.91), indicating that the measured mechanical states strongly determine the neuronal response. There was a much stronger relationship between neuronal response and stress variables than with strain variables. Simple correlation of the first invariant of the stress tensor with neuronal response had the highest mean correlation of the tensor quantities (R = 0.51). On average, strain energy density was only modestly correlated with the neural response (R = 0.28). 4. These findings indicate that capsule mechanoreceptors are encoding the local continuum mechanical state in the joint capsule. The neural response of these mechanoreceptors is more strongly correlated to local stress than to local strain.

Adaptation, Physiological↗

The enthesis of the elbow-joint capsule of the dog humerus.

The enthesis of the elbow-joint capsule in the dog is described histologically in relation to the specific mechanical forces that operate in different regions along its line of attachment. Special attention is given to the collagen fibre-bone interface in those parts of the capsule that are highly affected by mechanical stress. The histological features of the enthesis are heterogeneous along the entire circumference of the attachment site. Three types of collagen fibre-bone interconnections can be distinguished: (1) periosteal insertion: attachment to the periosteum of the humerus; (2) bony insertion: attachment directly to peripheral osteons; (3) fibrocartilaginous insertion: attachment to the bone via fibrocartilage. The periosteal insertion covers the greatest part of the joint capsule attachment line, along the peripheral borders of the radial and olecranon fossae. In contrast, bony insertions and fibrocartilaginous insertions are focally arranged: bony insertions in the caudoproximal aspect of the olecranon fossa, related to nutrient foramina; fibrocartilaginous insertions in combination with the attachment of distinct ligaments. This distribution reflects a strict relation between the type of enthesis and the biomechanical stress at the attachment site. The periosteal insertion type is predominant in entheses adjacent to pouches of a loose joint capsule -- i.e., regions less dependent on the high tensile strength of collagen fibres. Fibrocartilaginous insertions characterise areas of the joint capsule which are subjected to high biomechanical traction during joint movement. Both structurally and functionally, the entheses of the fibrous layer of the joint capsule are similar to those of tendons and ligaments.

Animals↗

Quantitative examination of calcitonin gene-related peptide immunoreactive nerve fibres in the cat knee joint capsule.

The knee joint of the cat has been used extensively to study the morphology and function of primary afferents in a deep somatic tissue. A proportion of these neurones synthesizes various neuropeptides, with calcitonin gene-related peptide being the most prominent. In the present study we examined the distribution and density of nerve fibers immunoreactive for calcitonin gene-related peptide within the medial articular capsule. The fibres were predominantly located in the superficial layer of the capsule. They formed a dense innervation pattern, mainly accompanying blood vessels. Electron microscopy showed that most fibres were in close proximity to small arteries. The highest innervation density was found in parts of the capsule that were located over the epicondyle of the femur with 21 +/- 12 fibres per mm2 (mean +/- SD). In the tissue over the joint cleft this density was lower, with 11 +/- 6 fibres per mm2. In conclusion, the high innervation density of the knee joint capsule by nerve fibres containing calcitonin gene-related peptide supports the hypothesis of an important regulatory function of this peptide in normal tissue.

Animals↗

Detection of synovial macrophages in the joint capsule of dogs with naturally occurring rupture of the cranial cruciate ligament.

OBJECTIVE: To test the hypotheses that the densities of macrophages in the synovial membranes and capsules of stifle joints in dogs with ruptured cranial cruciate ligaments are greater than those of normal joints and that those densities in affected joints are positively correlated with the chronicity and severity of the disease. ANIMALS: 17 dogs with naturally occurring rupture of the cranial cruciate ligament and 5 healthy control dogs. PROCEDURE: All dogs underwent orthopedic and radiographic evaluations. In affected dogs, duration of clinical signs was used as an indicator of disease chronicity and the severity of osteoarthritis in the stifle joint was determined radiographically. Joint capsule specimens were evaluated histologically; macrophages, interleukin-6, and tumor necrosis factor-alpha were identified by use of immunocytochemical techniques. RESULTS: Compared with unaffected joints, macrophage density was increased in all affected joints. Duration of disease was significantly associated with radiographic severity of osteoarthritis and synovial macrophage density. Synovial macrophage density was significantly associated with severity of osteoarthritis and with the presence of interleukin-6 and tumor necrosis factor-a. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that synovial macrophages may be involved in the development of pathologic changes (including osteophyte formation) in the stifle joints of dogs with osteoarthritis secondary to rupture of the cranial cruciate ligament. Determination of the importance of synovial macrophages in the development of changes in osteoarthritic joints may result in new treatment strategies that involve elimination of the deleterious effects of those cells.

Animals↗

Distribution of A-delta and C-fiber receptors in the cervical facet joint capsule and their response to stretch.

BACKGROUND: It has been proposed that cervical facet joint capsules are a major source of whiplash pain. However, there is a paucity of neurophysiologic data to support this hypothesis. The purposes of this study were to determine the distribution of A-delta and C-fiber sensory receptors in the facet joint capsule and to test their patterns of response to stretch and related sensory function. METHODS: Laminectomy from C4 to C7 was performed in seventeen goats, while they were under general anesthesia, to expose the C6 nerve roots. Customized dual bipolar electrodes were used to record neural activity from one of the C6 branches. An 8 or 15-V electrical stimulus was used to provoke receptor activity in nine designated areas on the dorsal part of the C5-C6 facet joint capsule. Receptors were classified on the basis of conduction velocities. The waveform of an identified receptor was set up as a template to determine its neural activity in response to capsular stretch. The characteristics of each single receptor's response to capsular stretch were analyzed to determine its sensory function as a mechanoreceptor or nociceptor. RESULTS: Two hundred and forty-eight receptors on the dorsal part of the C5-C6 facet joint capsule were evoked by electrical stimulation in the seventeen goats. More C-fiber receptors were found on the dorsolateral aspect of the facet joint capsule, where tendons and muscles were attached. The response to stretch of 120 receptors, from twelve goats, were analyzed to classify them into one of four categories (high-threshold mechanoreceptors, non-saturated low-threshold mechanoreceptors, saturated low-threshold mechanoreceptors, and silent receptors) or as unclassified receptors. CONCLUSIONS: The existence of receptors in the facet joint capsule indicates that the capsule has pain and proprioceptive sensory functions.

Animals↗

High rate of joint capsule matrix turnover in chronic human elbow contractures.

The joint capsule is a key component in posttraumatic joint contractures. The capsule is described as thickened, but little data exist supporting the observation. Our hypotheses were that mRNA levels of (1) collagen; (2) decorin and biglycan; (3) matrix metalloproteinases; and (4) tissue inhibitors of matrix metalloproteinases were significantly elevated in anterior joint capsules obtained from 11 patients having surgery for posttraumatic contractures when compared with nine elbows, from organ donors, that were free of contractures. Reverse transcription-polymerase chain reaction was used to evaluate mRNA expression normalized to a housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase. In the joint capsules of the patients with elbow contractures, relative mRNA levels were increased for: collagen Types I, III, and V (1.5-2.5 times); biglycan (1.5 times); and matrix metalloproteinases-1, -2, -9, -13, and -15 (1.6-3.9 times). In contrast, expression of tissue inhibitors of matrix metalloproteinases-1, -2, and -4 were decreased (1/3-3/4 times) in the capsules of patients with contractures. There was no difference between the groups in relative mRNA expression for decorin, matrix metalloproteinases-8, -14 and -16, and tissue inhibitor of matrix metalloproteinase-3. The results indicate that joint capsule matrix molecule mRNA levels are altered in the chronic stages of posttraumatic elbow contractures in humans, potentially creating an environment with high matrix turnover rates.

Adolescent↗

Sensory receptors in ankle joint capsules of normal and arthritic rats.

The responses of afferent fibers innervating the capsule of the ankle joint have been investigated in 34 normal and 19 arthritic anaesthetised rats. Afferent fiber diameter and conduction velocity were in the same range in normal and arthritic rats. All receptors examined were excited by mechanical stimulation of the joint capsule and the majority adapted slowly. A resting discharge was absent in normal rats in contrast to the arthritic animals where it was present in about 25% of the sample. The mechanical thresholds of the responses, measured using either von Frey hairs or the force transducer, ranged from 4.6 mN to 65 mN for 11 units recorded in normal and exceeded 80 mN for 11 others. For 30 units recorded in arthritic animals the thresholds ranged from 0.4 to 46 mN. When tested, pressure on the ankle or small degrees of flexion or extension produced a high rate of discharge in receptors of arthritics while similar stimuli were ineffective in normals. Repeated indentation at short intervals caused a progressive reduction in response to 10 to 15% of control values in normal and almost to extinction in arthritic rats. Recovery occurred within minutes in normals but was delayed in arthritics. These results suggest that the changes in responsiveness of somatosensory neurons and in behaviour, previously described in arthritic rats, can be partly accounted for in terms of the altered properties of the joint capsule receptors.

Adaptation, Physiological↗

Histologic evaluation of the glenohumeral joint capsule after the laser-assisted capsular shift procedure for glenohumeral instability.

Glenohumeral joint capsule obtained from 42 patients who had undergone an arthroscopic laser-assisted capsular shift procedure was evaluated histologically. A total of 53 samples from the anterior inferior glenohumeral ligament of the joint capsule were collected before and at various times after the procedure (range, 0 to 38 months). Despite glenohumeral instability, joint capsule of the patients before the procedure showed no significant histologic lesions. Laser treatment significantly altered the histologic properties of the tissue as evidenced by hyalinization of collagen and necrotic cells (time 0). Tissues sampled during the short-term period (3 to 6 months) after the procedure demonstrated fibrous connective tissue with reactive cells and vasculature. Collagen and cell morphology returned to normal in the middle- to long-term period (7 to 38 months) after the procedure, while the number of fibroblasts remained elevated. Joint capsule collected from the shoulders of six patients who experienced stiffness after the procedure showed persistent synovial, cellular, and vascular reaction even after 1 year postoperatively, the cause of which is unclear. This study revealed histologic evidence of robust tissue healing and maturation after thermal treatment by the laser-assisted capsular shift procedure, although mechanical and biochemical characterization of the tissue was not evaluated. Correlation with clinical follow-up must be performed to further clarify the advantages and disadvantages of this procedure.

Adult↗

Elastic reinforcement and thickness of the joint capsules of the lower cervical spine.

Mechanical studies have shown the major strength of the joint capsules of the lower cervical spine, especially in its ventrolateral part. The aim of this study was to examine the structure of the joint capsules in order to discover if there is a correspondence between biomechanical properties and descriptive anatomy. Ten transverse sections and 4 sagittal sections obtained from 6 cadavers were observed under light microscopy at X 25 to X 250 magnification. Standard stains and specific elastic fiber stain were used for histologic preparation. The data were the thickness of the joint capsules in the different quadrants, and the topography and direction of the elastic fibers. The results showed that the ventrolateral part of the joint capsules is thick and reinforced by oblique elastic fibers. The dorsal part is thin. The authors suggest that the descriptive anatomy of the joint capsules confirms their mechanical properties. They note that the role of the ventrolateral part is supplemented by that of the posterior longitudinal ligament for the stability of the functional cervical spinal unit.

Aged↗

The surgical repair of a defect of tendinous distortion of the patella and of the joint capsule during an arthrolysis of the knee joint.

The suture of tissues resected during surgical tendomyolysis and arthrolysis of the knee joint required by its extension contracture is carried out during tibial flexion at an angle of 90 degrees. This can lead to the development of a diastasis of the tendinous distortion of the patella and of the joint capsule which prevents the suture of the wound. It is suggested to repair the resulting tissue defect with the use of a split flap of local tissues with a wide base situated in front of the defect. The flap is dissected from the lateral part of the tendinous distortion and of the capsule. The flap is turned by 180 degrees around its base and extended to cover the defect with its subsequent suture to the opposite edge of the defect. The described supplementary surgical procedure is technically uncomplicated and results in stable anterior and lateral joint structures, in a reduction of the risk of complications due to infection, and allows an early initiation of active kinesitherapy in the early postoperative period.

Contracture↗

Collagen gene expression during development of avian synovial joints: transient expression of types II and XI collagen genes in the joint capsule.

The developmental sequence of the embryonic joint has been well studied morphologically. There are, however, no definitive studies of cell function during joint development. In order to begin to understand the differentiation events that contribute to joint formation, we examined the expression of collagen mRNAs encoding types I, IIA, IIB, and XI. In situ hybridization was performed on chicken embryo hind limb buds and digits from day 7 to day 18 (Hamburger and Hamilton stages 31-44). In the day 7 (stage 31) limb bud, there was a condensation of mesenchyme forming the primitive tarsal and metatarsal bones that showed abundant expression of type IIA procollagen message, but no type IIB or type alpha 1(XI) message. By day 8 (stage 33), co-expression of types IIA, and type XI procollagen mRNAs was observed in the condensations, with expression of IIB restricted to early chondrocytes with metachromatically staining matrix. At this stage, DNA fragmentation characteristic of apoptosis was observed in cells near the midline of the interzone region between the developing anlagen, and in areas between and around the individual digits of the paddle. The presumptive apoptotic cells were more numerous at day 9 (stage 35), and were not found in the developing joint at subsequent time points, including the initiation of spatial cavitation of the joint. From days 11-18, type IIA procollagen mRNA was expressed in flattened cells at the surface of the anlagen, and in the perichondrium and in the developing joint capsule; type IIB mRNA message was found only in chondrocytes. Type XI mRNA was expressed by all type II-expressing cells. Alpha 1(I) mRNA was expressed early by cells of the interzone and capsule, but as cavitation progressed, the type I expressing cells of the interzone merged with the superficial layer of the articular surface. Thus, at the time of joint cavitation, there was a distinct pattern of expression of procollagen messages at the articular surface, with type I being outermost, followed by morphologically similar cells expressing type IIA, then chondrocytes expressing type IIB. The progenitor cells expressing type IIA message define a new population of cells. These cell populations contribute to the molecular heterogeneity of the articular cartilage, and these same populations likely exist in the developing joints of other species. The transient transcription of type II and type XI collagen genes, characteristic of chondrocytes, by cells in the joint capsule demonstrates that these cells may have chondrogenic potential.

Animals↗