TMJ autopsy specimens were studied macroscopically and arthrographically with respect to the disc position in the sagittal and the coronal planes. After single-contrast arthrography of the lower joint space, the specimens were cryosectioned. The arthrographic findings were correlated with the morphological findings. Anterior disc position was found in about two thirds and sideways disc displacement in about one third of the joints. Some of the sideways displaced discs also exhibited an anterior displacement, hence a rotational disc displacement. Superior disc position was associated with biconcave disc configuration and anterior disc position with disc deformation (p<0.001). Perforation of the disc or posterior attachment was more frequent in joints with complete anterior disc position than in other joints (p<0.03). The diagnostic outcome of arthrography in diagnosing anterior disc position in the sagittal plane was high, with a positive predictive value of 0.88 and a negative predictive value of 0.78. In diagnosing a perforation, the corresponding figures were 0.80 and 1. The diagnostic outcome of arthrography in diagnosing sideways and rotational disc displacement was low, both in the sagittal and in the anteroposterior projection. Studies on imaging of TMJ disc position published from 1978 to 1994 were reviewed. More than 400 studies on arthrography, CT and MRI were found. Only about 7 % of the studies presented the diagnostic outcome of the method described. In diagnosing anterior disc position, arthrography exhibited the highest likelihood ratio for a positive test, 4.5 as compared with 2.3 for MRI and 2.1 for CT. In diagnosing sideways and rotational disc displacement, MRI showed the highest outcomes, with a likelihood ratio for a positive test of 9.3, as compared with 3.8 for arthrography. (Less)

OBJECTIVES:To review the literature and evaluate the evidence for the diagnostic outcome of arthrography, computed tomography (CT) and magnetic resonance imaging (MRI) in the assessment of temporomandibular joint (TMJ) disc position.METHODS:A literature search from 1978 to 1994 was conducted. Data on sensitivity, specificity, predictive values and likelihood ratios were collected and, if not available, calculated for each imaging method. Measures of observer performance were also recorded.RESULTS:In total, more than 400 publications were retrieved on imaging of TMJ disc position, 219 on arthrography, 99 on CT and 147 on MRI, with a marked decrease in recent years. The majority of the publications (54%) presented series of patients. The diagnostic outcome cold be obtained from only 7% of the studies and the observer performance from only two of these. Arthrography had the highest diagnostic outcome for the diagnosis of anterior disc position; sensitivity 0.90, specificity 0.80, positive predictive value 0.88 and negative predictive value 0.82. Corresponding figures for CT were 0.66, 0.68, 0.66 and 0.74 and for MRI 0.86, 0.63, 0.67 and 0.83. The diagnostic outcomes expressed as the likelihood ratios for positive test outcome were 4.5 for arthrography, 2.3 for MRI and 2.1 for CT. The outcomes in diagnosing sideways and rotational displacements were higher for MRI (sensitivity 0.81, specificity 0.87, positive predictive value 0.82, negative predictive value 0.88) than for arthrography (0.64, 0.83, 0.70, 0.79). The likelihood ratios were 6.2 for MRI and 3.8 for arthrography. The interobserver performance ranged between moderate to substantial for arthrography and was almost perfect for MRI.CONCLUSIONS:Based on current evidence on the diagnostic outcome, MRI seems to be the method of choice for diagnosing TMJ disc position. Arthrography has a higher diagnostic outcome for anterior disc position but the disadvantage of being an invasive method. We suggest that the quality of the evidence should be improved and that an analysis of the impact of the imaging methods on patient treatment should be performed.

The purpose of this investigation was to determine whether it is possible to diagnose medial and lateral disk displacements by single-contrast lower-compartment arthrography with an anteroposterior projection. Contrast medium was injected into the lower joint space of 29 fresh temporomandibular joint autopsy specimens. Anteroposterior arthrograms and anteroposterior arthrotomograms were obtained. Enlargement of the medial or lateral recess of the lower joint space was considered an arthrographic indication of medial or lateral displacement of the disk. After arthrography the joints were deep frozen and cryosectioned in the coronal plane. Imaging findings were correlated to observations in the cryosections in a blind fashion. The anteroposterior arthrograms were 48% accurate in determining the position of the disk in the coronal plane. The anteroposterior arthrotomograms were 59% accurate. It was concluded that anteroposterior lower joint space arthrography as well as arthrotomography is not reliable for diagnosis of medial or lateral disk displacement.

Arthrography and arthrotomography were performed on 29 fresh temporomandibular joint autopsy specimens to diagnose medial and lateral disk displacement. A horizontal contrast medium margin crossing over the condyle (edge sign) and the relative size of the anterior recess of the lower joint compartment in the lateral and medial parts of the joints were used as indicators of the mediolateral position of the disk. Arthrographic findings were compared with coronal cryosections in a blinded fashion. The edge sign underdiagnosed all the joints with lateral disk displacement and about 50% of the joints with medial disk displacement. The assessment of the relative size of the anterior recess of the lower joint compartment underdiagnosed 50% of the joints with medial disk displacement and overdiagnosed lateral disk displacement by 100%. It was concluded that arthrographic diagnosis of medial and lateral disk displacement may be difficult and includes substantial risks of both overdiagnosis and underdiagnosis. Other diagnostic methods should be considered when these types of disk displacement are suspected.

Forty-five fresh temporomandibular joint autopsy specimens from elderly persons were studied with respect to the position of the disk in the sagittal and coronal planes. In the sagittal plane 80% of the joints showed superior disk position and 20% showed anterior disk position. In the coronal plane 62% showed superior disk position, 33% showed medial disk position, and 4% showed lateral disk position. There were no statistically significant associations between disk positions in the sagittal and coronal planes. The vertical distance from the central part of the condyle to the fossa was measured in the coronal sections and was smaller in joints with medial disk position than in joints with superior disk position. It was concluded that medial disk position is relatively frequent in elderly persons and that this condition might represent a variant of temporomandibular joint internal derangement.

The angle between the horizontal condylar long axis and the frontal plane was measured and correlated with arthrographic diagnosis in 364 consecutive temporomandibular joint patients. There were no statistically significant associations between the horizontal condylar angle and the arthrographic diagnosis. The condylar angle of the contralateral joint however, was, found to be larger in patients with unilateral anterior disk displacement than in patients with normal temporomandibular joints. There is no immediate explanation of this finding, but it supports previous observations and may contribute to the understanding of the etiology and the pathogenesis of internal derangement of the temporomandibular joint.

The diagnostic accuracy of upper compartment arthroscopy of the temporomandibular joint was evaluated in fifty fresh human cadavers. Arthroscopic observations of remodeling, arthrosis, adhesion, and perforation were compared with dissection findings. About half of the joints were arthroscopically diagnosed in agreement with subsequent dissection findings. In the other joints there were discrepancies between arthroscopic and morphologic findings. The discrepancies were, with only two exceptions, underdiagnosis of pathologic changes. This was most pronounced for perforation of the disk, since only three of fourteen perforations were seen through the arthroscope. The position of the disk was difficult to study arthroscopically, since the injected air and the thick arthroscope in the joint compartment altered the positional relationship between the joint components and made it difficult to reproduce joint function during the examination. In conclusion, arthroscopy of the upper compartment of the temporomandibular joint provides information about the articular surfaces that is not available by other methods, and this examination may therefore be a valuable supplement to other diagnostic methods, and this examination may therefore be a valuable supplement to other diagnostic methods. An arthroscopic diagnosis of pathologic changes seems to be reliable (high specificity), but an arthroscopic diagnosis of normality includes a substantial risk of underdiagnosing pathologic changes (low sensitivity).

Arthrography of the temporomandibular joint is widely performed in clinical practice. The diagnostic accuracy of this technique has not been systematically evaluated. Therefore, findings from transcranial single-contrast, lower-compartment videoarthrography of 58 temporomandibular joint autopsy specimens were correlated with postmortem morphology. Arthrographic diagnosis of disk position and perforation was confirmed in 47 joints (81%). Misinterpretations were made in 11 joints; nine concerned disk position and two concerned perforation. Analysis of the misinterpretations revealed that inability of arthrography to allow differentiation of lateral from medial resulted in four false-negative diagnoses and one false-positive diagnosis. Variation of joint anatomy with disk deformation resulted in four false-positive diagnoses of anterior disk position. The number of false diagnoses in clinical practice might be reduced if transcranial single-contrast, lower-compartment videoarthrography is followed by multilayer arthrotomography in cases with an unclear diagnosis.

The risk of complications occurring during arthroscopic examination of the temporomandibular joint is not well documented. We therefore performed arthroscopic examinations of the upper compartment of the temporomandibular joint of fresh cadavers and during subsequent dissection studied possible damage to the facial nerve, superficial temporal vessels, disk, and articular surfaces. Damage to the facial nerve was not seen in any joint. The distance between the puncture site and any branch of this nerve was 3 mm or more in all but one of the specimens. The puncture site was repeatedly located immediately adjacent to the superficial temporal vessels, but damage to these vessels was not seen in any case. Scratch marks on the articular surfaces resulting from intra-articular manipulations with the instrument were seen in more than half of the joints. It was concluded that the risk of damage to the facial nerve or the superficial temporal vessels during arthroscopy of the temporomandibular joint is small. There is, however, a risk of damage to the articular surfaces. The frequency of this type of injury can probably be reduced in patients by sufficiently distending the joint before the instrument is inserted.

Internal derangement of the temporomandibular joint has mainly been studied arthrographically from the standpoint of anterior disk displacement with or without reduction. Frequent clinical observations of disk deformation in joints with internal derangement implied the need for a systematic study of morphologic alterations associated with internal derangement. Therefore, morphology, internal derangement, and joint function were studied in 58 randomly selected autopsy specimens of the temporomandibular joint. The results showed that joints with superior disk position rarely demonstrated morphologic alterations. In joints with partially anterior disk position, disk deformation occurred somewhat more frequently (31%) and was consistently located in the part of the disk that was positioned anteriorly. Joints with completely anteriorly positioned disks showed disk deformation in 77% and irregularities of the articular surfaces in 65%. It appears that anterior disk position precedes disk deformation. Therefore, early causal treatment to correct symptomatic internal derangement appears indicated to decrease the possibility of development of disk deformation. Disk deformation was also closely associated with disturbed joint function and should therefore be an important consideration when one is planning treatment of internal derangement of the temporomandibular joint.

The condylar position at centric occlusion has been considered important in diagnosis of the temporomandibular joint. The present study describes inter- and intra-observer variation in radiographic assessment of condylar position. One radiogram obtained by using an individualized lateral oblique transcranial projection and three corrected sagittal tomograms from the lateral, central, and medial parts of the joint were selected from each of 31 patients. In the resulting 124 radiograms three observers assessed the position of the condyle as posterior, central, or anterior on two occasions, 3 months apart. Concordant reports for all three observers were found in 63%. The interobserver agreement two by two ranged between 69% and 79%, whereas the intraobserver agreement ranged between 81% and 90%. The observer variation and limitations of radiographic techniques should be considered when the therapeutic implication of condylar position is discussed.