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A case is reported of a 7 year-old girl who suffered a central luxation of the mandibular condyle into the middle cranial fossa. The management and previously reported cases are discussed.
As several morphological parameters of cancellous bone express more or less the same architectural measure, we applied principal components analysis to group these measures and correlated these to the mechanical properties. Cylindrical specimens (n = 24) were obtained in different orientations from embalmed mandibular condyles; the angle of the first principal direction and the axis of the specimen, expressing the orientation of the trabeculae, ranged from 10 degrees to 87 degrees. Morphological parameters were determined by a method based on Archimedes' principle and by micro-CT scanning, and the mechanical properties were obtained by mechanical testing. The principal components analysis was used to obtain a set of independent components to describe the morphology. This set was entered into linear regression analyses for explaining the variance in mechanical properties. The principal components analysis revealed four components: amount of bone, number of trabeculae, trabecular orientation, and miscellaneous. They accounted for about 90% of the variance in the morphological variables. The component loadings indicated that a higher amount of bone was primarily associated with more plate-like trabeculae, and not with more or thicker trabeculae. The trabecular orientation was most determinative (about 50%) in explaining stiffness, strength, and failure energy. The amount of bone was second most determinative and increased the explained variance to about 72%. These results suggest that trabecular orientation and amount of bone are important in explaining the anisotropic mechanical properties of the cancellous bone of the mandibular condyle.
This paper describes a patient in whom a huge osteochondroma of the mandibular condyle was mistakenly treated as temporomandibular joint syndrome for approximately 6 months before an accurate diagnosis was made. While clinical and pathologic features of this lesion are discussed, further emphasis is placed on the surgical management and immediate reconstruction with autogenous costochondral grafting.
Three cases of rare cystic tumors of the mandibular condyles are described: One case concerned a young 17-year-old girl with pain and joint crepitation due to an aneurysmal cyst. In the second case the presence of pain and a swelling led to the discovery of an eosinophil granuloma, with similar lesions in two other locations. A mandibular metastasis from a bronchial epithelioma was present in the third case.
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INTRODUCTION: Aneurysmal bone cyst (ABC) is a pseudotumor of bone consisting of a septated cystic cavity filled with blood. CASE: We report a case of aneurysmal bone cyst of the left mandibular condyle discovered in a 10-year-old child with a history of mandibular trauma which had occurred one year earlier. The treatment consisted in surgical excision of the lesion and reconstruction using a chondro-costal graft. The post operative development led to a chondral hyperplasia. DISCUSSION: We discuss the pathogenesis of the ABC centered on three theories, traumatic, vascular and tumoral of primary lesion. There are several complementary examinations to establish the diagnosis of ABC but the histopathological examination is the only way to confirm the diagnosis. The differential diagnosis of ABC is not an easy task. Surgical management with removal followed by immediate reconstruction is preferred.
Osteochondroma is one of the most common benign tumors of the axial skeleton, but is rarely found in the facial bones. When present, the tumor is most often reported to affect the mandibular coronoid process. Osteochondroma of the mandibular condyle is extremely rare. A case is presented of a massive osteochondroma of the mandibular condyle leading to facial asymmetry and disturbed occlusion. The diagnosis was confirmed by radiological and histological examination.
OBJECTIVE: The purpose of the study was to develop a method of multiplanar CT reconstruction in fractures of the mandibular condyle in order to evaluate the feasibility of lag screw osteosynthesis. STUDY DESIGN: Angulated axial and sagittal images of the mandibular ramus were calculated using collected CT data. In 183 mandibular rami the optimal position of the screw axis was determined retrospectively. The thickness of the covering bone as well as the degree of screw exposure were measured. RESULTS: Application of the method led to medial (28.4% of cases) or lateral (3.8% of cases) correction of the usual screw axis. In 1.6% of cases an extraosseous position of screws could not be avoided by this correction. CONCLUSIONS: Evaluation of the feasibility of lag screw osteosynthesis by this method is possible. Medial or lateral change of the axis ensures the optimal intraosseous screw position. Intraosseous screw placement is almost always possible.
OBJECTIVES: The aim of this study was to comparatively evaluate the resistance of 3 plating rigid internal fixation techniques for mandibular condylar process fractures. MATERIALS AND METHODS: Synthetic hemi-mandible replicas made in polyurethane were used to evaluate a control, and 3 mandibular condyle plating techniques using 2-mm system plates and screws. The plating techniques were fixation with a 4-hole plate and 4 6-mm screws, fixation with a 4-hole plate and 4 8-mm screws and fixation with 2 4-hole plates with 4 6-mm screws each. Each group was subjected to linear loading in medial to lateral and anterior to posterior directions by an Instron 4411 servohydraulic mechanical testing unit (Instron Corp, Norwood, MA). Load peak value and peak displacement were measured. Means and standard derivations were derived and compared for statistical significance using an analyses variance (P < .05) and compared by Tukey test. RESULTS: Statistically significant differences were noted between fixation groups for the different mechanical measures evaluated under the different directions of linear loading. The 2-plate fixation system presented better behavior, followed by 1 plate with 4 8-mm screws and 1 plate with 4 6-mm screws. The fixation systems used were more resistant to antero-posterior load and the use of 8-mm screws improved the resistance of the fixation when compared with 6-mm screws only in the antero-posterior test. CONCLUSION: Under the conditions tested the 2-plate fixation system provided the most favorable mechanical behavior. We can suggest that lengthy screws, with bicortical engagement, can increase the stability at fixation of mandibular condylar process fractures.
The purpose of this study was to investigate the course of bone marrow edema pattern (decreased signal intensity on T1- or proton-density-weighted images and increased signal intensity on T2-weighted fat-suppressed images) in the mandibular condyle after improvement in clinical symptoms, and to clarify its relationship with temporomandibular joint (TMJ) pain. This study was based on 14 joints of 11 patients (all female, mean age 37.5 years) with TMJ disorders showing condylar bone marrow edema pattern on initial magnetic resonance (MR) images. All joints were re-evaluated clinically and using MR images after relief of joint pain following arthrocentesis combined with non-surgical treatment. The time interval between the initial and follow-up MR images ranged from 14 to 27 months (mean 17 months). Of the 14 joints, 4 joints (28.6%) showed a normal bone marrow signal, whereas 10 joints (71.4%) showed persistent bone marrow edema pattern on follow-up MR images (P = 0.125). Therefore, the reduction in TMJ pain did not correlate with resolution of bone marrow edema pattern in most joints. The results of this study suggest that the bone marrow edema pattern in the mandibular condyle does not always contribute to the occurrence of joint pain in patients with TMJ disorders.
A great deal of attention has been given over the years to the development of highly specialized x-ray equipment that, in many instances, has reduced the complex nature of the radiographic procedure. However, it is impossible, and probably always will be, to design equipment that will automatically produce the proper radiographic position. This will remain a distinct function of the technologist, and the individual's skill will have great bearing on the quality of the radiograph. One need only review the literature to realize how innovative our profession has been in developing countless numbers of radiographic positions for demonstrating specific anatomical regions. Moreover, many useful radiographic positions can be found that, for various reasons, never gained the level of acceptance perhaps anticipated by their originators. Consequently, the practical value of these positions often escapes our attention. To illustrate this point, I have selected a radiographic position described some thiry years ago for visualization of the mandibular condyle. It is my intent to demonstrate the practical value of this projection, as well as that of some others not usually thought of, for radiography of the mandibular condyle.
The purpose of this study was to evaluate the long-term radiological results obtained with open reduction and fixation of unilateral mandibular condyle fractures in 10 patients. CT images taken at the end of the follow-up period (average of 22 months, range 7 to 33 months), were traced and digitized, and the position and morphology of the fractured condylar process was statistically compared with those of the contralateral non-fractured condylar process in the coronal, transverse and sagittal planes. Little difference was observed in the position or morphology of the condylar process in the operated and non-fractured joints. This study shows that it is possible to anatomically reduce fractured condyles, and thereby to avoid postoperative disadvantageous joint changes.
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An investigation with respect to position of the mandibular condyles in relation to maximal vertical mouth opening was undertaken. For this purpose, 51 subjects of different nationalities were examined. None of the 51 persons had a TMJ disorder. The mobility of the mandible in different directions was clinically measured. With the use of two different reference lines (Methods A and B), the amount of the movement of the condyle from closed to maximal mouth opening position was measured in the sagittal plane on lateral tomograms. All of the measurements were recorded, and the means, SD, and range of variation were calculated. Statistical analysis was subsequently performed. The clinical results are comparable to those of other previous clinical studies. As seen in the lateral tomograms, the condyle in 41 out of 51 subjects moved beyond the articular eminence during maximal mouth opening. It was occasionally situated higher than the eminence. In only ten subjects, the condyle reached only the top of the articular eminence during maximal mouth opening. A moderate degree of dependency and correlation was found between maximal vertical movement of the mandible and the amount of movement of the right and left condyles from closed to maximal open position of the mouth, as seen in tomograms. None of our subjects had any sign of luxation despite the position of the condyle beyond the articular eminence with maximal mouth opening. Therefore, the diagnosis of condylar luxation cannot be established by radiologic investigation alone.
Chondrocytes may control the mineralization of the extracellular matrix of condylar cartilage by several mechanisms including the release of microvesicles involved in the initial nucleation, the creation or modification of the local matrix to help propagate or restrict mineralization, and the regulation of the ionic environment at the calcifying foci within the matrix. The plasma membrane Ca2+-Mg2+ ATPase (Ca2+ pump) is known to play a part in the vectorial efflux of calcium in a variety of cells including chondrocytes. The purpose here was to study the distribution of Ca2+-pump protein in mandibular condyles from growing and adult rabbits, and compare the expression of that protein in progressively differentiating chondrocytes whose final stage is associated with a mineralized extracellular matrix. Ca2+-pump antigen was identified immunohistochemically in six growing and six adult rabbit mandibular condyles with a Ca2+ pump-specific monoclonal antibody. The presence of Ca2+-pump antigen was established in hypertrophic chondrocytes, and in osteoblasts and osteoclasts of subchondral bone. Slot-blot analysis of nitrocellulose-immobilized chondrocyte homogenates showed that the amount of Ca2+ pump in growing cartilage was more than twice that in adult cartilage (p < 0.05). The demonstration of Ca2+-pump antigen in the hypertrophic chondrocytes of growing rabbit condyles is consistent with a role for the plasma-membrane Ca2+ pump in the calcification of mandibular condylar cartilage.
In recent years, temporomandibular disorder (TMD) is occasionally found among orthodontic patients and has become a great concern in orthodontics. From this point of view, a certain technique has been hopefully anticipated for diagnosis and treatment planning. The purpose of this study was to develop a new method for evaluating three-dimensional position of the mandibular condyle relative to the glenoid fossa and also to investigate its clinical application. Seven-layered tomograms were taken and contours of the condyle and glenoid fossa were traced on an acetate paper. These contours were entered into a personal computer by use of a digitizer and were equally divided into 9 parts for the condyle and 15 parts for the glenoid fossa, consisting of 10 and 16 points on the contours of condyle and glenoid fossa. Three-dimensional configuration of the TMJ was thus constructed by 108 triangles for the condyle and 180 triangles for the glenoid fossa. The shortest distance between the condyle and the glenoid fossa (CGFD) was then calculated along a perpendicular line to center of gravity of a triangle on the condyle. For evaluating the position of the condyle to the glenoid fossa easily in a three dimensional space, surface of the condyle was divided into five areas, i.e. anterior, posterior, middle, lateral and medial areas. In order to investigate whether or not the CGFD is accurate enough to identify the distance between surface of the condyle and glenoid fossa, a model of hemi-spherical solid shell was made, of which the thickness is 3.0 mm. Tomograms of the model were taken to analyze the thickness. Direct measurement of the same area was also made by calipers. Two means were approximately 3.0 mm, which is the thickness itself and no significant differences were indicated at 5% level of confidence. The present technique was applied to diagnosis of an orthodontic patient with painful clicking as TMD. The analyzed CGFDs were coincident with clinical symptom. It is shown that the present approach provides an availability and a possibility to evaluate positional relationship between the mandibular condyle and the glenoid fossa of patients with TMDs.
The growth rate of the cartilage of the mandibular condyle in the young rat exhibits: - a circadian cycle with a maximum of the 3H-thymidine labelled cells around 13(00) and a minimum around 01(00); with a maximum in the number of mitoses around 21(00) and a minimum around 09(00). - a circannual cycle with a maximum in May and a minimum between November and January, and with a difference in rhythms between May and November. The condylar cartilage growth in response to orthopaedical appliances of the mandible is modified and exhibits: - circadian variations. - circannual variations. The responsiveness of the condylar cartilage to orthopaedic appliances is greater when the condylar cartilage growth rate is higher.
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