Low-field magnetic resonance imaging of the canine stifle joint: normal anatomy

Low-field magnetic resonance imaging (MRI) was performed on the stifle joints of four normal adult mongrel dogs using a 0.064 Tesla scanner. Markers were placed on each stifle joint to serve as reference points for comparing gross sections with the images. A T1-weighted sequence was used to image one stifle joint on each dog in the sagittal plane and the other stifle joint in the dorsal plane. The dogs were euthanized immediately following MRI and the stifle joints frozen intact. Each stifle joint was then embedded in paraffin, again frozen, and sectioned using the markers as reference points. On T1-weighted images, synovial fluid had low signal intensity (dark) compared to the infrapatellar fat pad which had a high signal intensity (bright). Articular cartilage was visualized as an intermediate bright signal and was separated from trabecular bone by a dark line representing subchondral bone. Menisci, fibrous joint capsule, and ligamentous structures appeared dark. In the true sagittal plane, the entire caudal cruciate ligament was often seen within one image slice. The patella was visualized as an intermediate bright signal (trabecular bone) surrounded by a low intensity signal (cortical bone). The trochlea and the intercondylar notch were difficult areas to analyze due to signal volume averaging of the curved surface of these areas and the presence of several types of tissues.

MR-guided joint puncture and real-time MR-assisted contrast media application

OBJECTIVE

To develop, in MR arthrography of the shoulder joint, an MR-guided technique for localizing the needle puncture and confirming the intracapsular needle-tip position by visualization of the contrast media inflow.

MATERIAL AND METHODS

Three unfixed human shoulder specimens were examined on a 1.0 T MR unit. On the basis of MR-compatible markers, the optimal entrance point for puncturing the joint was determined. The precise localization of the needle tip (MR-compatible 0.7-mm needle) in the shoulder joint was determined with rapid localizer GRE sequences in 2 orthogonal planes. To confirm the intracapsular position of the needle tip, diluted Gd-DTPA was applied via a long connecting tube and contrast medium inflow into the joint space was controlled on an LCD screen in real-time MR imaging (local-look technique).

RESULTS

MR-compatible markers on the skin allowed the rapid determination of the optimal entrance point for needle puncture. An adequate localization of the intra-articular needle-tip position was possible in all specimens although significant artifacts were present on rapid localizer GRE sequences which resulted in an increase in the apparent width of the needle shaft. Real-time MR imaging of the contrast medium inflow was made possible by the local-look technique and LCD screen on the MR unit and this allowed confirmation of the intracapsular position.

CONCLUSION

In MR arthrography of the shoulder, an MR-guided technique in conjunction with the LCD screen and real-time MR imaging would seem to be a practical alternative to conventional fluoroscopic guidance.

A microscopic survey of the human temporomandibular joint disc

The articular disc of the temporomandibular joint was studied in a foetuses and children group (GI), a dentate group of adults (GII) and an edentulous, elderly group of humans (GIII) by light microscopy. The main, constituent bundles of type I collagen fibres are stratified and are orientated sagittally, transversely and obliquely in the middle portion of the disc. In the thick, posterior portion, transverse bundles constitute the main feature. In the anterior portion of the disc, the fibres are sagittally and obliquely orientated. Type III collagen fibres, intermingled with type I collagen fibres are present in all groups. The disc is cellular in nature in foetuses and children, becoming more fibrous with age. Chondroid cells are observed in all portions of the discs in groups GII and GIII. Elastic fibres are numerous in GI discs and decrease in number in the disc with age. These fibres lie parallel to the collagen fibres in all three portions of the three groups.

Perspectives on the role of the lateral pterygoid muscle and the sphenomandibular ligament in temporomandibular joint function

The lateral pterygoid muscle plays an important role in the movement of the mandible and has been studied from several points of view, including structural and functional anatomy. What matters clinically is the relative position of the muscle fibers attached medially to the mandibular condyle. In the following study, we observed not only the attachment of the lateral pterygoid muscle fibers to the articular disk, but also the relative position of the mandibular condyle to a base line set up on the mandibular condyle. According to our observations, the lateral pterygoid muscle fibers attach to the articular disk at the inner point of the medial pole. Based on this finding, we can say that the muscle fibers can both draw the articular disk anteriorly and balance it by supporting it posteriorly. That is to say, the lateral pterygoid muscle has two actions: to elevate the articular disk anteriorly and to support the articular disk. Furthermore, the sphenomandibular ligament has continuity with the articular disk tissue medially. This relationship suggests that the ligament fibers attached to the articular disk draw the disk posteriorly in its course of mandibular closing, thus enabling the articular disk to move smoothly.

Current concepts: the stabilizing structures of the glenohumeral joint

Significant contemporary advances have permitted a more comprehensive understanding and development of some interesting concepts about the glenohumeral joint. The purpose of this review paper was to discuss current concepts related to the anatomic stabilizing structures of the shoulder joint complex and their clinical relevance to shoulder instability. The clinical syndrome of shoulder instability represents a wide spectrum of symptoms and signs which may produce various levels of dysfunction, from subtle subluxations to gross joint instability. The glenohumeral joint attains functional stability through a delicate and intricate interaction between the passive and active stabilizing structures. The passive constraints include the bony geometry, glenoid labrum, and the glenohumeral joint capsuloligamentous structures. Conversely, the active constraints, also referred to as the active mechanisms, include the shoulder complex musculature, the proprioceptive system, and the musculoligamentous relationship. The interaction of the active and passive mechanisms which provide passive and active glenohumeral joint stability will be thoroughly discussed in this paper.

Anatomy of the Lisfranc joint complex

The authors studied the Lisfranc joint complex using gross dissection and examination of anatomical sections of frozen samples in the frontal and sagittal planes. They distinguished a medial compartment, a central compartment, a lateral compartment, the secondary joint line, and the connections with the cuneoscaphoid articulation. The ligaments were divided on the basis of topography (dorsal, interosseous, and plantar) and course (longitudinal, oblique, and transverse). The dorsal and plantar ligaments reinforce the articular capsules. The interosseous ligaments are the strongest. A common characteristic of these ligaments is that they vary considerably in course, number, and insertions.

The medial capsule of the human temporomandibular joint

PURPOSE

Attachments of the medial capsule of the temporomandibular joint (TMJ) to structures other than the medial fossa wall are thought to exist and to have functional significance. This study evaluated these relationships.

MATERIALS AND METHODS

The anatomic relationships between the medial capsule and other medial structures, the sphenomandibular ligament, discomalleolar ligament, and auriculotemporal nerve, were examined in 14 cadaver heads.

RESULTS

The results showed that the sphenomandibular ligament attaches separately from the medial capsule of the TMJ and therefore has no functional significance to the biomechanics of the joint. The discomalleolar ligament was found to be a continuation of the retrodiscal tissues and minimally associated with the medial capsule. The auriculotemporal nerve was not found to be in a relationship with the medial aspect of the condyle to the extent that mechanical irritation is possible during TMJ movement or disc displacement.

Structural peculiarities of the tissue formed in modelling of the articular surface

A model of articular cavity with smooth cover was produced by influence of shape-forming element on regenerating bone tissue. Morphological, ultrastructural, histochemical, and biochemical peculiarities of the tissue of the formed articular surface are described.

A morphological study of the fibrous capsule of the human lumbar facet joint

STUDY DESIGN

Macroscopic and microscopic investigations of the human lumbar facet joint capsule were undertaken.

OBJECTIVE

To describe the morphologic characteristics of the fibrous capsule of the lumbar facet joints.

SUMMARY OF BACKGROUND DATA

Previous biomechanical and neurophysiologic studies by the authors have shown that the lumbar facet joint capsule may be a source of low back pain.

METHODS

Macroscopic investigation was performed on the facet joint capsules dissected from five fresh adult cadavers. For microscopic studies, facet joint capsules obtained from cadaver dissection and spinal surgeries were stained by the hematoxylin and eosin method and the Elastica-Van Gieson method.

RESULTS

The outer layer of the fibrous capsule is a dense regular connective tissue that is composed of parallel bundles of collagenous fibers. The inner layer of the fibrous capsule consists of bundles of elastic fibers, similar to the ligamentum flavum. In the superior and middle part of the joint, the fibers run in the medial to lateral direction, crossing over the joint gap. In the inferior part of the joint, the fibers are relatively long and run in a superior-medial to inferior-lateral direction, covering the inferior articular recess. They are thicker than the layer in the superior and middle parts of the joint.

CONCLUSIONS

Anatomical and histologic features of the lumbar facet joint capsule are different between its outer layer and inner layer. This complex of morphologic factors can affect the biomechanics and neurophysiology of the lumbar facet joint.

Age-related changes of the retrodiscal tissues in the temporomandibular joint

PURPOSE

This study compares the histologic features of the lateral capsule and lateral and central posterior disc attachment of temporomandibular joints (TMJs) in young and elderly persons.

MATERIAL AND METHODS

Samples were removed from 36 joints belonging to young persons (mean age, 30 years; age range, 16 to 39 years) and 29 joints belonging to elderly persons (mean age, 69 years; age range, 58 to 78 years). Twelve joints from elderly persons had altered disc position, whereas none of the young joints had this condition. Six-micrometer-thick sections were stained with hematoxylin-eosin and the Fränkel method (for elastic fibers). Logistic regression analysis using a likelihood-ratio test was applied for comparisons between groups and to avoid the confounding effect of differences in disc position and gender.

RESULTS

A significantly lower density of fibroblasts was observed in elderly persons in all the three areas investigated. In addition, elderly persons demonstrated a significantly lower distribution of vascular tissue and a significantly higher presence of dense connective tissue in the central third of the posterior disc attachment.

CONCLUSION

This study shows that retrodiscal tissues, which may eventually function as an articular disc during altered disc position, are susceptible to age-related connective tissue changes.

Soft tissue attachments of the ulnar coronoid process. An anatomic study with radiographic correlation

Regan and Morrey proposed a 3-type coronoid fracture classification observing that the incidence of concommitant elbow dislocation was proportional to fragment size. Elbow instability associated with coronoid fractures presumably is related to disrupted bony architecture and ineffective stabilizers attached to the free fragment. Twenty cadaveric elbows were dissected, measuring medial collateral ligament, anterior capsule, and brachialis muscle insertion loci on the coronoid. Radiographs were taken after radiopaque labeling of the stabilizer insertions. The anterior bundle of the medial collateral ligament insertion averaged 18.4 mm dorsal to the coronoid tip. Only in Type III fractures would it be attached to the free fragment. The capsule inserted an average of 6.4 mm distal to the coronoid tip. Rarely should Type I fractures result from a capsular avulsion, because only 3 of 20 specimens had the capsule inserting on the tip. The brachialis had a musculoaponeurotic insertion onto the elbow capsule, coronoid, and proximal ulna. The bony insertion averaged 26.3 mm in length, with its proximal margin averaging 11 mm distal to the coronoid tip. In only Type III fractures is the fragment large enough to include the brachialis bony insertion.

[Normal and pathological MRI aspects of the posterolateral corner of the knee]

The purpose of the study is to compare normal PLC anatomy and its MRI appearance, with the various lesions observed in MRI, from the simple popliteus tendinous contusion to the complete PLC rupture. For this specific work on PLC lesions, we selected 61 examinations among the traumatic knees explored during the last 3 years. Surgical correlation is obtained for the 61 patients. MRI examinations are performed on a 0.5 T. unit with gradient echo T1, T1 and T1 GD-DOTA IV. Normal PLC anatomy is compared to the dissection of 4 anatomic subjects. Normal MRI slices are evaluated with this reference analysis. The principle anatomical structures of the PLC include the lateral collateral ligament, the popliteus tendon, the arcuate ligament, the fabello fibular ligament, the posterolateral condylar capsule, and the posterior horn of the lateral meniscus. Surgical findings confirm PLC lesion for 58 patients with 3 false positive. Diagnosis of these lesions is important because chronical posterolateral laxity is secondary to the destabilisation of lateral condyle. Unrecognised and untreated posterolateral instability may result in failure of ACL reconstruction. When clinical tests are doubtful or complex, or the examination very painful, MRI evaluates completely the traumatic knee and particularly the PLC.

Capsular restraints to anterior-posterior motion of the abducted shoulder: a biomechanical study

Twenty-three fresh-frozen cadaver shoulders free of degenerative arthritis or rotator cuff disease were tested biomechanically to quantitate the contribution of specific capsular structures to restricting anterior-posterior translation of the abducted shoulder. With the glenohumeral joint in 90 degrees of abduction on a servohydraulic control testing system, translation was measured in 30 degrees of forward flexion (with regard to the coronal plane of the scapula), 0 degree, and 30 degrees of extension while a 25 N anterior-posterior load was applied. Measurements were taken both in the intact (vented) shoulder and after selective cutting of different capsuloligamentous structures was performed. In the intact shoulder the largest anterior-posterior translation occurred in 0 degree of horizontal flexion and extension with regard to the scapular plane, with equal amounts of anterior and posterior translation noted. The primary anterior-posterior stabilizer of the abducted shoulder is the inferior glenohumeral ligament complex. The anterior band is the primary stabilizer in 30 degrees of horizontal extension and at 0 degree (neutral). The posterior band is the primary stabilizer in 30 degrees of horizontal flexion. This study quantifies for the first time the normal amount of anterior-posterior translation in the intact cadaveric shoulder model. In addition, it demonstrates the relative role of the anterior and posterior band of the inferior glenohumeral ligament complex in stabilizing the glenohumeral joint at 90 degrees of abduction, where most clinical instability of the shoulder occurs.

Sensory receptors situated in the interphalangeal joint capsule of the fingers of the bonnet monkey (Macaca radiata)

Using bonnet monkeys (Macaca radiata) the content, location and types of sensory endings with regard to interphalangeal joints of the fingers of the hand were studied. Use of the modification of Barker and Ip [J Physiol (Lond) 1963;124: 476-488] of the de Castros silver method showed that the Paciniform/Pacinian corpuscles are almost the exclusive encapsulated receptors in this tissue. Free nerve endings are present. Using serial paraffin sections stained with the May-Grünwald-Giemsa stain, the proximal interphalangeal joint capsules were reconstructed. This confirmed the results of the study using teased preparations stained by the Barker and Ip method. In addition it was shown that the encapsulated endings were situated exclusively in the lateral and ventral aspects of the joint capsule. The number of lamellae of these encapsulated endings varied from as few as three to more than fifty. It is suggested that the contribution of these various receptors to kinaesthesis can depend on such factors as their relationship with tendons and skin.

The joint capsule: structure, composition, ageing and disease

The joint capsule is vital to the function of synovial joints. It seals the joint space, provides passive stability by limiting movements, provides active stability via its proprioceptive nerve endings and may form articular surfaces for the joint. It is a dense fibrous connective tissue that is attached to the bones via specialised attachment zones and forms a sleeve around the joint. It varies in thickness according to the stresses to which it is subject, is locally thickened to form capsular ligaments, and may also incorporate tendons. The capsule is often injured, leading to laxity, constriction and/or adhesion to surrounding structures. It is also important in rheumatic disease, including rheumatoid arthritis and osteoarthritis, crystal deposition disorders, bony spur formation and ankylosing spondylitis. This article concentrates on the specialised structures of the capsule--where capsular tissues attach to bone or form part of the articulation of the joint. It focuses on 2 joints: the rat knee and the proximal interphalangeal (PIP) joint of the human finger. The attachments to bone contain fibrocartilage, derived from the cartilage of the embryonic bone rudiment and rich in type II collagen and glycosaminoglycans. The attachment changes with age, when type II collagen spreads into the capsular ligament or tendon, or pathology--type II collagen is lost from PIP capsular attachments in rheumatoid arthritis. Parts of the capsule that are compressed during movement adapt by becoming fibrocartilaginous. Such regions accumulate cartilage-like glycosaminoglycans and may contain type II collagen, especially in aged material.(ABSTRACT TRUNCATED AT 250 WORDS)

Age-related variability in elbow joint capsule thickness in asymptomatic children and adults

The purpose of this study was to establish normal ultrasonographic measurements for elbow joint capsule thickness in children. Transverse posterior ultrasonographic images of 53 elbow joints in asymptomatic patients were digitized, and off-line measurements were performed and compared to the corresponding scale present on each image to yield a reliable measurement in millimeters. Joint capsule thickness measurements regressed with age. Significant differences existed between three age groups. Joint capsule thickness is under 1 mm in children 1 month to 2 years of age, increased significantly to just over 1 mm from 2 to 15 years of age, and approached 2 mm in thickness at and after 15 years of age.

A histologic study of retrodiscal tissues of the human temporomandibular joint in the open and closed position

Specialized roles for the different components of the retrodiscal tissues have been previously postulated. This study compared the histologic features of the retrodiscal tissues of temporomandibular joints, taken from human cadavers, in the open and closed position; it was concluded that the primary role of these components was to provide a volumetric compensatory mechanism for pressure equilibration. This mechanism was still active in joints that demonstrated disc displacement and degenerative changes. Elastin was found in the upper and lower strata of the retrodiscal tissues, as well as in the central zone. The concept of an elastic upper stratum that has a recoil mechanism to control disc movement was not supported by this study, as the upper stratum was folded on itself in the closed position and only became stretched near maximal opening.

In vivo evaluation of collagen-coated Dacron fiber in bone

To evaluate the influence of type I collagen and hydroxyapatite coatings on the ability of Dacron fiber to achieve biologic fixation to bone, tows with the following coatings were evaluated in vivo: avian collagen (A); an avian collagen/hydroxyapatite composite (AH); bovine tendon collagen (B); a bovine tendon collagen/hydroxyapatite composite (BH); and plain (uncoated) Dacron tow (C). The Dacron tows were placed unstressed in the cancellous bone of both lateral femoral condyles of rabbits. Tissue reaction to each kind of Dacron tow was evaluated histopathologically, histomorphometrically and biomechanically. Inflammatory reaction was apparent around the AH and BH Dacron fibers at 2 weeks. There was no such reaction in the A, B, and C specimens, thus implicating the hydroxyapatite particles as the cause. At later time periods specimens A, B, and C all induced new bone formation. Direct contact between the Dacron fibers and trabecular bone was apparent in A and B. The pull-out strength of the B fibers was higher than the controls at a statistically significant level, but there was no significant difference between any of the other specimens and C (controls). There was no significant difference between any coating and controls at 8 or 16 weeks. Dacron fibers coated with bovine tendon collagen exhibited the best biocompatibility to bone and improved the anchoring to bone in the early time intervals by maintaining direct contact between Dacron fibers and trabecular bone.(ABSTRACT TRUNCATED AT 250 WORDS)

The articular-synovial lining tissue system in temporomandibular joints of young adults

The histologic character of the articular surfaces and synovial tissues in the temporomandibular joints of 20 young adults was described. Each joint compartment had a continuous connective-tissue lining that was fibrous on the articular surfaces, went through a transition, and was continuous with the lining tissue in the recesses. Areolar synovial tissue was found only in the upper posterior recess of the temporomandibular joint, fibrous synovial tissue was predominantly found in the upper anterior and lower posterior recesses, and an intermediate type of synovial tissue was found in the lower anterior recess. There was no distinct boundary between articular and synovial tissue. The structure and continuity of these lining tissues suggest that they constitute a continuous tissue system, here termed the "articular-synovial lining tissue system," that has a histologic character which depends on location and functional demands. It is hypothesized that all of the lining tissues should be considered synovial, based on a functional definition of nonadherence.

Histometric study of synovial cavity dimensions of human temporomandibular joints with normal and anterior disc position

To evaluate effects of internal derangement, the sagittal lengths of the condylar, temporal, and disc articular surfaces, as well as those of the disc attachments, were measured in histologic sections of human temporomandibular joints obtained at autopsy, mainly from adolescent, young adult, and middle-aged subjects. While the upper joint compartment appeared little affected, anterior disc position was significantly associated with comparatively long inferior disc attachments and a short condylar articular surface, indicative of possibly aberrant insertions of the attachments. Such discrepancies in size or alignment between condyle and disc complex could primarily reflect a constitutional deviation or result secondarily from remodeling.

Anatomy of the human temporomandibular joint. An updated comprehensive review

This article is an in-depth review of the current knowledge on human temporomandibular joints (TMJ's). All aspects of joint anatomy are described with emphasis on adaptability to biochemical stimuli throughout life. Each TMJ is a pressure-bearing compound double synovial joint. TMJ's are unique in having a movement not only controlled by the morphology of the joint per se but also by the dentition at the other end of the lever system. During life the temporal, condylar and discal articular surfaces undergo remodelling. The synovium is an important joint component which contributes to nourish and lubricate the avascular surfaces and has bactericidal properties. The joint capsule has privileged relationships anteriorly with the lateral pterygoid muscle. This muscle has two heads that show functionally reciprocal activation. The exact insertion and role of the superior head of the lateral pterygoid muscle remains controversial. The disc has a very low coefficient of friction and compensates for the lack of congruence between articular surfaces. Biomechanically it is stabilized between condyle and articular eminence by its thick rim which has special viscoelastic properties. Apart from the viscoelastic deformations the other important mechanism of disc stabilization seems to be related with the structure of some of the disc attachments.

Arthrography of the shoulder

Arthrography of the shoulder is a simple, safe, and relatively painless diagnostic procedure that is used to demonstrate the integrity, shape, and capacity of the glenohumeral joint space.