Histochemical localization of the extracellular matrix components in the annular ligament of rat stapediovestibular joint with special reference to fibrillin, 36-kDa microfibril-associated glycoprotein (MAGP-36), and hyaluronic acid.

The annular ligament across the stapediovestibular joint connects the stapes footplate and the vestibular window and plays an important role in the sound conductive system of the ear. In this study, we investigated the distribution of extracellular matrix components in the ligament by histochemical methods at light and electron microscopic levels. As results, light microscopic immunohistochemistry of fibrillin and 36-kDa microfibril-associated glycoprotein (MAGP-36) showed intense immunoreactivities in the annular ligament between the stapes footplate and vestibular window. In addition, the histochemical localization of hyaluronic acid by using biotinylated hyaluronic acid-binding protein (HABP) clarifi ed the presence of hyaluronic acid in the annular ligament. At the electron microscopic level, the immunogold labeling of fibrillin showed intense labeling on the periphery of the electron-dense mantle. Furthermore, the labeling of fibrillin was preferentially seen on the fibrous components among the electronlucent amorphous substance. The immunogold labeling of MAGP-36 was seen on the electron-dense mantle and scattered on the electron-lucent amorphous substance. The gold labeling with biotinylated HABP clearly showed a distribution of hyaluronic acid throughout the amorphous space in the ligament. The present results provide a histochemical profile of the annular ligament of the rat stapediovestibular joint that may provide clues to elucidation of pathological changes in the ligaments and conductive hearing loss in humans.

Different crimp patterns in collagen fibrils relate to the subfibrillar arrangement.

Collagen fibril ultrastructure and course were examined in different connective tissues by PLM, SEM, TEM, and AFM. In tendons, collagen fibrils were large and heterogeneous with a straight subfibrillar arrangement. They ran densely packed, parallel, and straight changing their direction only in periodic crimps where fibrils showed a local deformation (fibrillar crimps). Other tissues such as aponeurosis, fascia communis, skin, aortic wall, and tendon and nerve sheaths showed thinner uniform fibrils with a helical subfibrillar arrangement. These fibrils appeared in parallel or helical arrangement following a wavy, undulating course. Ligaments showed large fibrils as in tendon, with fibrillar crimps but less packed. Thinner uniform-sized fibrils also were observed. Fibrillar crimps seem to be related to the subfibrillar arrangement being present only in large fibrils with a straight subfibrillar arrangement. These stiffer fibrils respond mainly to unidirectional tensional forces, whereas the flexible thinner fibrils with helical subfibrils can accommodate extreme curvatures without harm, thus responding to multidirectional loadings.

Periarticular ligament changes following ACL/MCL transection in an ovine stifle joint model of osteoarthritis.

Anterior cruciate ligament (ACL) injuries often lead to significant functional impairment, and are associated with increased risk for induction of degenerative joint disease. However, few studies have described the effect of ligament transection on the remaining intact knee ligaments. This study sought to determine specifically what impact combined ACL/medial collateral ligament (MCL) transection had on the remaining intact knee ligaments, particularly from the histological, biochemical, and molecular perspectives. Twenty weeks post-ACL/MCL transection, the cut ends of sheep MCLs were bridged by scar, while the posterior cruciate ligaments (PCLs) and lateral collateral ligaments (LCLs) seemed gross morphologically normal. Water content and cell density increased significantly in the MCL scars and the intact PCLs but were unchanged in the LCLs. Collagen fibril diameter distribution was significantly altered in both MCL scar tissue and uninjured PCLs from transected joints. MMP-13 mRNA levels in MCL scars and PCLs from ligament transected joints were increased, while TIMP-1 mRNA levels were significantly decreased in the PCLs only. This study has shown that some intact ligaments in injured joints are impacted by the injury. The joint appears to behave like an integrated organ system, with injury to one component affecting the other components as the "organ" attempts to adapt to the loss of integrity.

Effect of GDF-5 on ligament healing.

The effects of growth and differentiation factor-5 (GDF-5) on ligament healing were studied using a gap injury model of the medial collateral ligament in rat knee joints. The administration of GDF-5 once at the time of surgery significantly improved the mechanical properties of the femur-ligament-tibia complex. At 3 weeks after surgery, 30 microg of GDF-5 improved the ultimate tensile strength of the complex by 41%, and the stiffness by 60%, compared with the vehicle control (p < 0.05 for both; Fisher's PLSD test). The observation with a transmission electron microscopy revealed that GDF-5 increased the diameter of collagen fibrils in the repair tissue, which was considered to be a possible mechanism for the positive result in the biomechanical testing. Quantitative PCR and in situ hybridization revealed enhanced type I procollagen expression by GDF-5, and the PCR analysis also revealed that the GDF-5 treatment reduced the expression of type III procollagen relative to type I procollagen. The PCR analysis further showed that the expression of decorin and fibromodulin was relatively reduced against type I procollagen by the growth factor, which was considered to be responsible for the increase of collagen fibril diameter in the repair tissue. No adverse effects were observed, and the use of GDF-5 was considered a promising approach to facilitate ligament healing.

Ultrastructural cytochemical and ultrastructural morphological differences between human multinucleated giant cells elicited by wear particles from hip prostheses and artificial ligaments at the knee.

The authors investigated the ultrastructural cytochemical features of multinucleated and mononuclear cells in periprosthetic tissues associated with bone resorption (osteolysis) and those in tissues adjoining failed artificial ligaments having no relation to bone resorption. Clinical specimens of granulation tissue of each type, respectively numbering 4 and 3, were stained for tartrate-resistant acid phosphatase (TRAP) reactions and examined by light and electron microscopy. Both periprosthetic granulation tissues and those adjoining artificial ligaments contained TRAP-positive multinucleated and mononuclear cells. Near joint prostheses, multinucleated cells, including some giant cells, showed TRAP activity and cytoplasmic features resembling osteoclasts, while others had features consistent with foreign-body giant cells, and still others showed degenerative changes. Near artificial ligaments, TRAP-positive multinucleated cells lacked osteoclastic features. At both sites, TRAP-positive multinucleated cells had phagocytised wear particles. TRAP-positive mononuclear cells at both sites also showed phagocytic cytoplasmic features, but not osteoclastic cytoplasmic features. Human mononuclear phagocytes and multinucleated giant cells induced by wear particles possess TRAP activity. Those multinucleated giant cells at sites of osteolysis developed osteoclastic cytoplasmic features and have a phagocytic function.

New technology for assessing microstructural components of tendons and ligaments.

This study investigated the ability of optical coherence tomography (OCT), a recently developed technology with micron-scale resolution, to assess the microstructure of tendons and ligaments. In vitro structural- and polarization-sensitive OCT was performed on human ACL, Achilles tendon, and biceps tendon (obtained postmortem). Histology was performed on all imaged samples and compared to the corresponding OCT data. OCT images correlated well with histology. Most importantly, through polarization-sensitive OCT, the collagen in normal tissue was easily distinguished from the surrounding, supportive tissue due to the birefringent properties of organized collagen. Since the integrity of collagen is an important indicator of structural stability and pathologic state, the ability of OCT to assess collagen could be a powerful diagnostic tool in assessing tendon and ligament properties.

Anatomic variations of the coracoacromial ligament in neonatal cadavers: a neonatal cadaver study.

One of the most common causes of pain and disability in the upper limb is inflammation of the rotator cuff tendons. When no significant bony abnormality exists in the surrounding structures, the coracoacromial ligament has been implicated as a possible cause of impingement on the cuff tendons and various morphological variants of the ligament have so far been claimed to be either the cause or the result of impingement. In this study, 110 shoulders from 60 neonatal cadavers that were preserved in a preparation of formaldehyde were dissected. Anatomic variations of coracoacromial ligaments were investigated with metric and histologic analysis. Three main ligament types were identified: quadrangular, broad band and U-shaped. The multiple banded ligament was not found. Histologic analysis showed that in U-shaped ligaments a thin tissue existed in the central part of the ligament close to the coracoid. Comparing our data with the adult measurements of a previous study we suggest that the primordial ligament is broad shaped, but assumes a quadrangular shape due to the different growth rates of the coracoid and acromial ends. We also suggest that broad and U-shaped ligaments account for the primordial and quadrangular and Y-shaped ligaments account for the adult types of the single or double banded anatomic variants respectively. Our results show that various types of the coracoacromial ligament are present at the neonatal period and that the final shape of the ligament should be defined by developmental factors, rather than degenerative changes.

Physical characteristics of the axial interosseous ligament of the human sacroiliac joint.

BACKGROUND CONTEXT: Although the sacroiliac joint has occupied a place in medical literature since at least the eighteenth century, its role in normal function and dysfunction of the back and hip remains controversial. The controversy persists, because there is still no suitable method to study the role of stability and mobility at the sacroiliac joints in vivo. One cost-effective approach to understanding such complex, deeply placed structures is biomechanical modeling. Unfortunately, very few data on the mechanical properties of tissues in this region are currently available to modelers. PURPOSE: The objective of this preliminary project was to determine some mechanical properties of the axial interosseous ligament (AIL), and to investigate the histology of the ligament. STUDY DESIGN/SETTING: A modified split plot design was used in conjunction with descriptive statistics to identify AIL characteristics. PATIENT SAMPLE: This was a cadaveric study. OUTCOME MEASURES: The study used descriptive statistics to categorize the ultimate failure strength of the AIL, and to describe the macro-constituents of the ligament. METHODS: Eighteen sacroiliac joints were harvested from nine fresh female cadavers (age range, 54 to 92). Data from 10 joints submitted to mechanical testing are reported. The eight remaining joints were used for histologic analysis of the AIL by light microscopy. RESULTS: The AIL proved to be relatively weak, with a mean failure load of 381 N (SD 43.7N) and a peak stress of 1.73 MPa (SD 0.99 MPa). Histologically, the AIL contained significantly less collagen than most other "typical" ligaments. CONCLUSIONS: The AIL failure loads are just slightly higher than those for the ligamentum flavum in the spine, a tissue composed mainly of elastic fibers. In contrast, the AIL has negligible elastin content. Because the AIL represents about 14% of the total area of interosseous sacroiliac ligaments, its mechanical properties should be useful to modelers of the joint. In addition, it appears that injury to the AIL would do little to compromise the mechanical integrity of the sacroiliac joint. Further study of this ligament seems warranted.

Quantitative analysis of collagen fibrils of human cruciate and meniscofemoral ligaments.

The ultrastructural anatomy of collagen fibril diameters in the cruciate and meniscofemoral ligaments, from four young human cadaver knees (mean age, 20 years, range, 17-22 years) was studied using transmission electron microscopy. Samples were harvested from the proximal, middle, and distal regions of the anterior and posterior cruciate ligaments, and the meniscofemoral ligament. Photomicrographs were taken and assessed quantitatively using image analysis software to determine the collagen fibril diameters and eccentricities, and the percentage of total cross sectional area occupied by collagen. The collagen fibril diameter for the anterior cruciate ligament was found to be largest in the distal region but it decreased as it moved proximally. The posterior cruciate ligament had an opposite trend because it decreased from the proximal to the distal region. For the meniscofemoral ligament, the fibrils of the middle region were larger than those of the proximal and distal regions. The percentage of total cross sectional area occupied by collagen, however, did not vary significantly between regions. Fibril eccentricity also varied little between ligament or location. The variability observed in fibril diameters may account for the different mechanical properties of the ligaments.

Morphology of the lateral ligament in the human temporomandibular joint.

The morphology of the lateral ligament of the human temporomandibular joint is of two types: ligamentous and without distinct structure. Under the scanning electron microscope, a sheath-like structure that contained bundles of collagen was mainly found in the posterior region of the lateral ligament. Analysis of macromolecular components revealed that type III collagen was mainly present on the collagenous framework of the sheath-like structure. Type I collagen, laminin, and tenascin were found in the framework of the sheath-like structure. Supported collagenous bundles and the distribution of macromolecular components might be related to the stability of the temporomandibular joint. The sheath-like structure and other components of the lateral ligaments store energy and protect the capsule from stress and tension during movements of the jaw.

Lesions of the alar ligaments. In vivo and in vitro studies with magnetic resonance imaging.

STUDY DESIGN: This study analyzed anatomic characteristics of the alar ligaments and the possibility of imaging them with magnetic resonance imaging. Also determined was whether artificial ruptures of the alar ligament can be recognized experimentally. OBJECTIVE: To determine the ability of magnetic resonance imaging to visualize normal, torn, resected alar ligaments. SUMMARY OF BACKGROUND DATA: There are no studies about computed tomography or magnetic resonance imaging findings of alar ligaments and after anatomic sections. Direct visualization of the complete ligament is not possible for computed tomography. No precise diagnostic method for showing a ruptured alar ligaments has been described. Magnetic resonance imaging seems to be the method of choice for distinguishing between normal and pathologic soft tissue. METHODS: Fifteen specimens from accident victims underwent anatomic dissection. In addition, ligaments from three groups were examined: 1) eight volunteers, 2) seven patients, and 3) 17 fresh cadaveric specimen before anatomic exploratory dissection. In seven of these specimens, one ligament was cut to simulate an artificial disruption and magnetic resonance imaging was repeated. RESULTS: Lesions of the alar ligaments were found in four of 15 prepared specimens. Using magnetic resonance imaging, the alar ligaments could be identified in all volunteers, patients, and specimen except one. No ruptures were found in the 17 specimens. Of the seven resected specimens, all cuts could be demonstrated by magnetic resonance imaging. CONCLUSION: Magnetic resonance imaging is useful for showing lesions of the alar ligaments because of a high soft tissue contrast, plane independence imaging, possibility of functional scans, and secondary reconstruction from three-dimensional data sets.

The human posterior cruciate ligament complex: an interdisciplinary study. Ligament morphology and biomechanical evaluation.

To study the structural and functional properties of the human posterior cruciate ligament complex, we measured the cross-sectional shape and area of the anterior cruciate, posterior cruciate, and meniscofemoral ligaments in eight cadaveric knees. The posterior cruciate ligament increased in cross-sectional area from tibia to femur, and the anterior cruciate ligament area decreased from tibia to femur. The meniscofemoral ligaments did not change shape in their course from the lateral meniscus to their femoral insertions. The posterior cruciate ligament cross-sectional area was approximately 50% and 20% greater than that of the anterior cruciate ligament at the femur and tibia, respectively. The meniscofemoral ligaments averaged approximately 22% of the entire cross-sectional area of the posterior cruciate ligament. The insertion sites of the anterior and posterior cruciate ligaments were evaluated. The insertion sites of the anterior and posterior cruciate ligaments were 300% to 500% larger than the cross-section of their respective midsubstances. We determined, through transmission electron microscopy, fibril size within the anterior and posterior cruciate ligament complex from the femur to the tibia. The posterior cruciate ligament becomes increasingly larger from the tibial to the femoral insertions, and the anterior cruciate ligament becomes smaller toward the femoral insertion. We evaluated the biomechanical properties of the femur-posterior cruciate ligament-tibia complex using 14 additional human cadaveric knees. The posterior cruciate ligament was divided into two functional components: the anterolateral, which is taut in knee flexion, and the posteromedial, which is taut in knee extension. The anterolateral component had a significantly greater linear stiffness and ultimate load than both the posteromedial component and meniscofemoral ligaments. The anterolateral component and the meniscofemoral ligaments displayed similar elastic moduli, which were both significantly greater than that of the posteromedial component.

Age-related distribution of elastic fibers in the rabbit knee.

The distribution and histochemical properties of elastic fibers in the knee of newborn, young, adult, and old New Zealand White rabbits were studied. In the growing rabbit, elastic fibers, especially oxytalan fibers, are abundant in the perichondrium and the fibrous layer of the periosteum. They are homogeneously distributed in tendons, ligaments, and menisci, and are absent in the epiphyseal cartilage and growth plate and at the enthesis. In mature rabbits, the articular capsule, the synovial membrane, the peritenon, the periosteum, the perimysium, and the perivascular connective tissue are rich with elastic fibers. They are rarer in the tendon and are absent at the enthesis, in bone and articular cartilage. In the meniscus, the fibers are distributed centripetally. The distribution of elastic fibers is probably related to the different functional role and biomechanical behavior of each tissue. Finally, the type of elastic fiber in the various tissues changes with age; younger animals have more oxytalan fibers than adult animals. A gradual process of maturation and specialization of the network of elastic fibers takes place with age.

[Clinical aspects and therapy of carpal tunnel syndrome]. / Klinik und Therapie des Karpaltunnelsyndroms.

In a retrospective study the clinical symptomatology and the clinical results of carpal tunnel syndrome is evaluated by means of 1000 patients. The results of 1047 operated hands assessed by the patients were rated as very good 72%, good 21.2% and satisfactory 5.6%.

The interosseous membrane of the forearm: structure and its role in Galeazzi fractures.

A cadaveric study was performed to anatomically describe and mechanically document the interosseous membrane of the forearm using gross, histologic, scanning electron microscopic, and mechanical testing. The membrane was found to be a complex structure composed of nerves and vessels but mainly of collagen fibers that thicken to form bands coursing from radius to ulna. Strain-gauge studies demonstrated that the load transfer occurs from the radius to the ulna via the membrane and changes with supination or pronation. With specimens under a specific test load, sectioning of the membrane allowed the fractured radius to shorten by 6.25 mm and sectioning of the triangular fibrocartilage complex resulted in shortening of 7.7 mm. Total shortening after osteotomy and sectioning of the complex structure and membrane ranged from 15 to 40 mm. In Galeazzi fractures, the interosseous membrane acts as a constraint to radial shortening. Anatomic reduction with internal fixation is indicated for this fracture-dislocation.

Structure on the capsular ligaments of the facet joints.

Microscopic studies showed that the capsular ligaments were mostly composed of collagenous tissue. The collagen fiber bundles were found to be crimped at right angles to their long axis. The collagen fibrils were connected transversely by proteoglycan filaments which were regularly associated with their periodicity. Among the collagen fiber bundles were varying quantities of elastic fibers and numerous fibroblasts. The highest concentration of elastic fibers was found in the posterior and inferior aspects of the capsular ligaments. These findings are discussed in relation to the mechanical behavior of the capsular ligaments.

Detection of Luse bodies, spiralled collagen, dysplastic collagen, and intracellular collagen in rheumatoid connective tissues: an electron microscopic study.

BACKGROUND: Rheumatoid arthritis is a chronic inflammatory disease leading to alterations of the extracellular matrix in tendons, ligaments, and cartilage. The structural changes of the collagenous systems in rheumatoid connective tissues are largely unknown, however. METHODS: Thirty four samples of menisci, 36 cruciate ligaments, and four tendons were taken during joint surgery in patients with rheumatoid arthritis. Eighteen menisci, 35 ligaments, and 30 tendons obtained at necropsy served as a control group. The extracellular matrix in the two groups was analysed by the combined use of transmission and scanning electron microscopy, immunohistochemistry with monoclonal antibodies recognising collagen types IV and VI, and ultramorphometry. RESULTS: Normal tendons and ligaments predominantly showed a unidirectional fibril arrangement. Whereas type IV collagen showed a positive staining pattern along all basement membranes, type VI collagen formed fine, filaments aligned in parallel. In patients with rheumatoid arthritis a significant reduction of the mean diameter of the collagen fibrils was found owing to the presence of thin collagenous fibrils 20-60 nm in diameter. Most of these fibrils showed considerable changes in their arrangement with irregular courses (so-called interfibrillar dysplastic collagen). Up to 410 nm thick frayed fibrils with irregular outlines (spiralled collagen) and intracellular collagen forms were found in rheumatoid tissues. In addition, atypical thick collagenous structures with 41 nm periodicity (Luse bodies) were detected in the matrix. The upregulation of type IV collagen in rheumatoid arthritis was associated with an increase in the vascular density. The expression of type VI collagen was upregulated in fibrotic zones. CONCLUSIONS: The dramatic ultrastructural collagen changes lead to a structural and functional insufficiency of the extracellular matrix in rheumatoid connective tissues. The results suggest that collagen alterations may contribute to the development of tendon and ligament ruptures in rheumatoid arthritis.

Rigid immobilization alters matrix organization in the injured rat medial collateral ligament.

The effects of mobilization on matrix reorganization and density after ligament injury were studied in rat medial collateral ligaments using scanning electron microscopy (SEM). Both medial collateral ligaments of 14 Sprague-Dawley rats were sharply incised transversely at their midpoint. A 1.14-mm threaded Kirschner wire was driven through the tibia and into the femur of the right leg (through the knee) to immobilize that knee at 90 degrees of flexion. Four additional rats were used as controls. The right medial collateral ligament of the control rats was exposed in the same manner as the experimental rats and the wound closed without damaging the ligament. Rats were sacrificed on the 7th and 14th days postinjury and the ligaments evaluated by SEM. The electron micrographs from this study demonstrated that early on, the tissue at the injury site is disorganized on a gross scale with large bundles of poorly organized matrix. Large "defects" were present between bundles in the substance of the ligament and appeared as holes in the ligament around the injury site. As healing progressed, the matrix in the mobilized specimens appeared to bridge the injury site more rapidly and completely with fewer "defects" and thus higher density than the immobilized specimens.

A comparative evaluation of the mechanical properties of the rabbit medial collateral and anterior cruciate ligaments.

The biomechanical properties of the medial collateral and anterior cruciate ligaments from 30 New Zealand White rabbits were measured. Because of its complex geometry, the ACL was divided into two portions (medial and lateral) to provide uniform loading. This allowed an examination of the intra-ligamentous properties. A laser micrometer system was used to measure the cross-sectional area for tensile stress and a video dimension analyzer was used to measure the strain. The mechanical properties (stress-strain curves) of the MCL and ACL were different, with the modulus (determined between 4 and 7% strain) in the MCL (1120 +/- 153 MPa) more than twice that of either portion of the ACL (516 +/- 64 and 516 +/- 69 MPa for the medial and lateral portions, respectively). This higher modulus correlated with the more uniform and dense appearance of the collagen fibrils examined with scanning electron microscopy (SEM).