Axial condyle morphology and horizontal condylar angle in patients with internal derangement compared to asymptomatic volunteers.

The purpose of this study was to evaluate the possible structural variations of axial condyle morphology and horizontal condylar angle between patients with internal derangement and asymptomatic volunteers. Forty-five symptomatic patients and 31 asymptomatic volunteers (AV) were included in this study. All subjects had bilateral high-resolution magnetic resonance imaging scans. Axial condyle morphology was evaluated using these images and classified into four diagnostic groups: convex, flat, and concave anterior surfaces, and tapered form. The angulation between the condylar long axis and the transversal plane was then measured. A Wilcoxon-Whitney-Mann-U-test demonstrated no significant differences in the horizontal angulation of the patients with disk displacement with reduction (DDR) (24.35+/-9.31) as compared to patients with displacement without reduction (DDN) (25.61+/-10.11) and asymptomatic volunteers (25.68+/-9.31) (AV). Eighty percent of the flat type condyles and 73.3% of the tapered type condyles belonged to the symptomatic patients with disk displacement with reduction (DDR) and without reduction (DDN). Chi-square test demonstrated significant differences between the diagnostic groups of condyle types (p<0.01). A comparison of the angular difference of right and left joints of asymptomatic volunteers and patients using the Wilcoxon-Whitney-Mann-U test showed that the results of the asymptomatic volunteers were significantly lower (p = 0.05). The conclusion that an increase in the horizontal condylar angle is a predisposing factor for the development of internal derangement or that the derangement develops during the prognosis of the disorder could not be clearly stated based on the results of this study. It is proposed that the difference between condyle morphology in patients with disk displacement and asymptomatic volunteers may be a result of the remodeling or degeneration caused by the disorder.

Morphology of the mandibular fossa and inclination of the articular eminence in patients with internal derangement and in symptom-free volunteers.

OBJECTIVE: The purpose of this study was to evaluate temporomandibular joint morphology and to compare possible structural variations in the temporomandibular joint anatomy of symptomatic anterior disk displacement patients with possible structural variations in the temporomandibular joint anatomy of symptom-free volunteers. STUDY DESIGN: Fifty-six symptomatic patients and 25 symptom-free volunteers were included in this study. All subjects had bilateral high-resolution magnetic resonance imaging scans performed in the sagittal (closed and open) positions. Disk positions were evaluated with these images, and the patients were accordingly classified into 4 diagnostic groups. The angulation between the Frankfort horizontal plane and the posterior slope of the articular eminence, as well as the width and depth of the glenoid fossa and the articular tuberculum, were automatically measured with the aid of a computer. RESULTS: The Mann-Whitney U test demonstrated significant differences in the angular and linear values obtained in disk displacement with reduction patients in comparison with the values obtained in patients with disk displacement without reduction and in symptom-free volunteers. CONCLUSION: It is proposed that a steeper posterior slope and higher tuberculum articulaire are predisposing factors for the development of disk displacement with reduction. Flattening of the eminence may progress in time, leading to the onset of disk displacement without reduction.

Magnetic resonance imaging-based joint space measurements in temporomandibular joints with disk displacements and in controls.

OBJECTIVE: Previous studies have discussed a posterior displacement of the condyle as a possible risk factor for the development of disk displacements (DDs) of the temporomandibular joint (TMJ). The objective of this study was to compare the posterior and anterior joint spaces in healthy TMJs with those of patients who present different forms of DDs. STUDY DESIGN: The anterior and posterior joint spaces from 58 patients with unilateral or bilateral DD with reduction (DDR) or without reduction (DDNR) and from 30 healthy volunteers were measured with 3 sagittal magnetic resonance images (MRIs) from each TMJ in the maximum intercuspid position. RESULTS: Measurements of anterior and posterior joint spaces showed a good interexaminer reproducibility (rank correlation coefficients ranging from 0.88 to 0.95). Patients with bilateral DDR demonstrated a significantly more posterior position of the condyle, as compared with controls and patients with bilateral DDNR. DDNR presented a significant reduction of the anterior and the posterior joint spaces, leading to a mean concentric position of the condyle. Patients with unilateral DDR or DDNR demonstrated a greater variability of anterior and posterior joint spaces, compared with patients with a bilaterally identical type of DD. CONCLUSIONS: The data of this MRI-based clinical study indicate that different stages of disk displacements are associated with significant changes of condylar position. The variation of anterior and posterior joint spaces was influenced by the diagnosis of the contralateral joint.

Variability of disk position in asymptomatic volunteers and patients with internal derangements of the TMJ.

This study determined the variability of temporomandibular joint (TMJ) disk position in medial, central, and lateral aspects of the joint using magnetic resonance imaging (MRI). Subjects had clinical evidence of reciprocal TMJ clicking (N = 123) or restricted mandibular motion (N = 52). Eighty-nine asymptomatic volunteers provided a control group. Disk position was quantified on MRI by measuring the angle formed by a line through the middle of the condyle and perpendicular to the Frankfort plane and a line through the same midpoint of the condyle and tangential to the posterior-most aspect of the disk. The disk position in asymptomatic TMJs varied considerably with a tendency toward farther anterior placement in more lateral images. In 47 TMJs from a total of 52 TMJ5 (90%), restricted mobility was associated with anterior disk displacement (ADD) without reduction. The disk position demonstrated a mean displacement of 77 degrees without significant differences at the medial and lateral aspects of the condyle. One hundred TMJs from a total of 123 TMJs (81%) with reciprocal clicking demonstrated ADD with reduction. Tomograms revealed larger lateral displacements or rotational displacements in these joints, whereas medial images frequently showed similar ranges of disk positions as compared with asymptomatic TMJs. The results suggest that disk positions of up to +15 degrees on medial tomograms and +30 degrees on lateral tomograms should be regarded as normal variations. Furthermore, multisection analysis of all parasagittal images improved the separation between disk displacement and asymptomatic TMJs.