Repair of temporomandibular joint disc perforation using a synovial membrane flap in Macaca fascicularis monkeys: light and electron microscopy studies.

Previous studies have demonstrated that experimentally produced perforations in the discs of Macaca fascicularis monkeys lead to osteoarthrosis. Synovial membrane hyperplasia also was demonstrated in monkey and human joints with disc perforations. The hypothesis was advanced that a synovial flap obtained from within the affected joint would be the most appropriate tissue to repair chronic disc perforation. To test this hypothesis, four adult M fascicularis monkeys were anesthetized and 4- to 6-mm perforations were made in the posterolateral aspects of the avascular discs bilaterally. The wounds were sutured leaving the perforations open, and the animals were fed their normal diet. After 4 weeks, one joint in each monkey was reopened and a repair was performed using a double-layered flap from the synovial lining of the superior and inferior recesses. Four weeks after repair, the animals were killed and the temporomandibular joints (TMJs) were removed en bloc and decalcified. The joints were sectioned into lateral, middle, and medial sections and were photographed using a stereomicroscope and then processed for light and electron microscopy. The same processing was done to four intact joints that were used as controls. Eight weeks following perforation, the joint components showed degenerative changes consistent with osteoarthritis. Close to the perforations the disc showed loss of collagen, vacuolation of extracellular matrix, accumulation of dense proteoglycan-like material, and the appearance within the disc of type A or macrophage-like cells of the synovium. The discal tissue away from the perforation showed high cellularity and vascularity. The temporal and condylar surfaces showed denudation, fibrillation, osteophytes, and chondrocytic clustering, all characteristics of osteoarthrosis. The surgically repaired discs were intact and the articular surfaces showed no degenerative changes. Discal collagen was restored and appearance of myofibroblasts and elastogenesis were a consistent feature of the repaired disc. The vascularity of the condylar cartilage of the repaired joints appeared similar to that of embryonic cartilage. The reversibility of the degenerative alterations following discal repair in this experimental model should provide the basis for a rational and useful method for surgical repair of TMJ disc perforation using intraarticular synovial tissue.

Light microscopic and ultrastructural study of thinned discal areas in patients with temporomandibular joint internal derangement.

It is generally believed that pathological destruction of the articular tissue occurs whenever articular remodeling does not maintain a balance between its structure and function. Remodeling is a natural cellular response contingent on the capability and availability of viable cells. Remodeling maintains the anatomic integrity of individual cells. Remodeling maintains the anatomic integrity of individual joint components that sustain the wear and tear occurring normally in the joint while accomplishing work. If the mechanical forces are within the physiological tolerance of the articular structures, cellular repair will keep up with destruction to protect the joint from deformation. It is hypothesized that the TMJ disc lacks the reserve remodeling capacity that characterizes the condyle and articular eminence. The lack of blood supply to the disc proper renders it dependent on nutrient diffusion from an intact synovial film. Many factors may change both the composition and the continuity of this nutritional source. Therefore, the synovial fluid may be the solitary source of nutrition for cellular healing and remodeling of the avascular part of the joint. Carlsson et al. felt that longstanding increased compressive forces on the disc may lead to cell necrosis and matrix degradation culminating in thinning of the disc and subsequent perforation.

Management of frontal sinus fractures. Review of the literature and clinical update.

The purpose of this article is to discuss and analyze the controversial treatment protocols that are currently recommended in the management of frontal sinus fractures. Embryology, anatomy, and diagnostic radiology of the frontal sinus are also discussed.

Fatty change in the human temporomandibular joint disc. Light and electron microscopy study.

Joint pain has been associated with fatty infiltration of the knee articulation. The purpose of this study is to report on the histopathological findings, especially fatty changes, that are seen in surgical specimens from the temporomandibular joints (TMJ) of patients that had persistent pain after non-surgical therapy. Forty plicated TMJ retrodiscal samples from 25 patients were used in this study. The patients were previously treated with splints for variable periods but not less than 2 months. The specimens were obtained by 2 surgeons using standard TMJ plication techniques. Control disc specimens were obtained from normal appearing cadaveric TM joints. Samples were immediately immersed in glutaraldehyde and processed for light and electron microscopic examination. The specimens were composed mainly of moderately dense tissue with cells that appeared fibroblastic and intermittent chondrocytic type cells. Fatty change, exclusively in association with the perivascular areas, was observed in 27 of 40 specimens. Electron microscopy showed fibroblasts, as well as large fat inclusions adjacent to elastin macroglobules. Fatty infiltration of the TMJ has been interpreted as a degenerative change. It is postulated that kinins and prostaglandins generated in the fat pads can pass freely in tissue fluid to adjacent, highly innervated structures thus leading to joint pain. It is further postulated that the finding of associated elastin with fatty deposition is similar to the atherosclerotic changes encountered in large blood vessels and the aorta.

Carotid-cavernous sinus fistula accompanying an isolated mandibular fracture.

A patient who developed carotid-cavernous sinus fistula associated with an isolated mandibular fracture is reported, and the etiology, diagnosis, and treatment of this condition and the associated abducens nerve palasy are discussed.

Histopathological study of human TMJ perforated discs with emphasis on synovial membrane response.

Fifteen perforated TMJ discs from human cadavers were studied histologically to examine the synovial membranes and to compare the findings with previous experimental results in monkeys. There were four with perforations in the bilaminar zone (these four discs were displaced anteriorly), three in the medial third of the disc, and eight in the lateral third of the disc. Histopathologically, there was an increase in vascularity and strong methyl pyronine-positive cellularity around the margins of the perforations. A young, loose, collagenous tissue lined the lateral margins of the perforated discs. Increased fibrous tissue content of the synovial subintimal territorial matrix and osteochondroid metaplasia were also seen. Severe synovial hyperplasia was visible in all joint recesses, but was greatest within those associated with displaced discs. There was patchy distribution of acidic glycoproteins, especially in the lateral parts of the perforated discs. As in the animal studies, human TMJ disc perforation was associated with a vigorous synovial reaction that was seen to form lateral bridges along the margins.

Synovial chondromatosis associated with experimental osteoarthritis in adult monkeys.

This report describes the synovial response to temporomandibular joint disc perforation in an experimental animal model. Histologic examination revealed the presence of marked synovial membrane hypertrophy in all experimental joint recesses. Gradual transformation of synovial islands from a cellular to a metaplastic stage, with chondroid or even osteochondroid-containing tissue also was seen. The cartilage was arranged in a lobular pattern with intervening fibrous septae within the synovial islands. These synovial islands were observed in the anterior recess of three joints and in the posterior recess of another joint. The experimental findings suggest a relation between synovial chondromatosis and osteoarthritis.