Sonographic investigation of the temporomandibular joint in patients with juvenile idiopathic arthritis: A pilot study

Authors


Abstract

Objective

To evaluate whether there are any correlations between the clinical parameters of temporomandibular joint (TMJ) arthritis and pathologic ultrasound (US) findings of the TMJ in patients with juvenile idiopathic arthritis (JIA).

Methods

We conducted prospective clinical and US investigations of the TMJs of 48 patients with JIA. The US investigation was performed by a 12-MHz high-resolution transducer, which was positioned parallel to the ramus of the mandible overlying the zygomatic arch in a closed-mouth position and maximum open-mouth position.

Results

Patients with ≥5 peripheral affected joints showed significantly more sonographically diagnosed destructive changes in the TMJ than did patients with <5 affected joints. There was no significance between the number of affected peripheral joints and disc dislocation in the closed-mouth position. In the maximum open-mouth position, there was a significant correlation between the number of affected peripheral joints and disc dislocation. Patients with a JIA duration >23 months had a significantly higher rate of disc dislocation and destructive changes. Patients with a JIA duration >60 months had a significantly higher rate of destructive changes of the TMJ than patients with a disease duration <60 months, but no statistical significance was found concerning disc dislocation.

Conclusion

The significant correlation between pathologic sonographic findings, duration of JIA, and the number of affected peripheral joints make the technique interesting for use as a diagnostic screening method.

INTRODUCTION

The temporomandibular joint (TMJ) can be affected by rheumatoid arthritis (1–9). Temporomandibular diseases (TMDs) such as clicking, crepitation, and disc dislocation in patients with juvenile idiopathic arthritis (JIA) could lead to severe symptoms such as hypoplastic condyles, a convex facial morphology, and retrognathia (4, 10–13). Generally, TMDs do not appear very often in otherwise healthy juvenile patients (Figure 1) (14, 15). Therefore, JIA should be included in the differential diagnosis in juvenile patients with TMD. Clinical symptoms commonly appear very late in patients with TMD, whereas imaging diagnosis methods such as magnetic resonance imaging (MRI) and high-resolution ultrasonography (US) could detect destructive changes and disc dislocation at an earlier stage of the disease (12, 16). Furthermore, TMDs are often masked by antirheumatic therapy (12, 16). From the dentist's view, a therapeutic intervention, e.g., splint therapy, should start in an early stage of the TMD (14, 15). MRI is the gold standard in the diagnosis of TMD (17–23), but the availability and high costs do not allow the use of MRI as a screening method in juvenile patients with rheumatic diseases. Furthermore, especially in smaller children, a general anesthesia or conscious sedation is required for an MRI investigation. Recently, high-resolution US was shown to be an alternative method in the imaging diagnosis of TMD concerning destructive changes, disc dislocation, and effusion (24–33). The purpose of the present study was to evaluate whether there are any correlations between the clinical parameters of JIA and pathologic sonographic findings of the TMJ.

Figure 1.

Ultrasonic image of a temporomandibular joint without any pathologic changes. The articular eminence, the condyle, the capsular ligament, and the disc are marked. The double arrows show the joint space. The arrow shows the disc (marked with small dots).

PATIENTS AND METHODS

A total of 48 patients with JIA (34, 35) were investigated prospectively by high-resolution US. The sonographic investigation was performed by a well-experienced oral and maxillofacial surgeon. The following criteria were evaluated: destructive changes and disc dislocation in closed-mouth and maximum open-mouth positions. A 12-MHz linear-array transducer was used (HDI 5000 ATL; Advanced Technologies Laboratories, Bothell, Washington). The transducer was positioned vertically parallel to the ramus of the mandible. The number of affected peripheral joints (active) and duration of JIA were evaluated at the time of the US investigation. The clinical investigation of the TMJ included the following parameters: clicking, crepitation, deviation of the mouth-opening movement, and pain on palpation of the TMJ and/or the mandibular muscles.

Using a chi-square test, the correlation between JIA duration >23 months (and >60 months) and pathologic sonographic findings was calculated. Furthermore, the correlation between pathologic sonographic findings and a polyarticular joint involvement was evaluated. We considered a result to be significant if the P value was less than 0.05. SPSS for Windows, version 12.0 (SPSS, Chicago, IL) was used for all analyses.

RESULTS

Of the 48 patients, 29 (60.4%) were female and 19 (39.6%) were male. The mean ages of the female and male patients were 10.2 years and 11.5 years, respectively. The mean duration of the disease was 5.17 years (median 4 years). Patients had the following JIA subtypes: oligoarthritis (19 patients [39.6%]), enthesitis-related arthritis (7 patients [14.6%]), polyarthritis (11 patients [22.9%]), systemic arthritis (4 patients [8.3%]), psoriatic arthritis (1 patient [2.1%]), and undifferentiated arthritis (6 patients [12.5%]).

At the time of this investigation, nearly half of the patients (46.3%) experienced a polyarticular course of JIA (Table 1). As shown in Table 2 and Figure 2, the TMJs of 53 (55.2%) patients exhibited destructive changes. In 41 (42.7%) patients, TMJ disc dislocation in the closed-mouth position was diagnosed, but was not present during mouth-opening movement in 17 (17.7%) patients (Figure 3).

Table 1. Affection of peripheral joints in juvenile patients with rheumatic diseases
Affected peripheral joints, no.No. (%) of patients
01 (2.1)
13 (6.25)
2–417 (35.4)
5–914 (29.2)
>913 (27.1)
Table 2. Results of the sonographic investigation of the temporomandibular joints (TMJs) in juvenile patients with rheumatic diseases (double nomination is possible)
Sonographic diagnosisNo. (%) of TMJs
Destructive changes53 (55.2)
Disc dislocation (closed-mouth position)41 (42.7)
 Disc dislocation in closed-mouth position/no dislocation in maximum open-mouth position17 (17.7)
 Disc dislocation in closed-mouth position and maximum open-mouth position24 (25.0)
Disc dislocation (maximum open-mouth position)25 (26.0)
 Disc dislocation in closed-mouth position and maximum open-mouth position24 (25.0)
 Disc dislocation in maximum open-mouth position/no dislocation in closed-mouth position1 (1.0)
Figure 2.

Ultrasonic image of a temporomandibular joint with a destructive erosion of the condyle (arrow). The capsular ligament and the articular eminence are marked.

Figure 3.

Ultrasonic image of a temporomandibular joint with a lateral dislocation of the disc. The articular eminence, the condyle, the capsular ligament, and the disc are marked. The arrows show the dislocated part of the disc.

The results of the clinical investigation are shown in Table 3. The most common pathologic finding was a history of TMJ lock in the closed-mouth position in 12 (27.1%) patients, pain on palpation of the TMJ in 11 (22.9%), and crepitation in 11 (22.9%).

Table 3. Results of the clinical investigation of the temporomandibular joint (TMJ; double nomination is possible)
Clinical diagnosisNo. (%) of patients
Pain on palpation (TMJ)11 (22.9)
Crepitation11 (22.9)
Clicking8 (14.5)
History of closed lock of the TMJ12 (27.1)
Pain on palpation (masseter muscle)10 (20.8)
Pain on palpation (temporal muscle)2 (4.2)
Deviation of mouth-opening movement10 (20.8)

There was a significant correlation between sonographically diagnosed destructive changes of the TMJ and patients with ≥5 peripheral affected joints (P = 0.002) (Table 4). No significant relationship was found between the number of affected peripheral joints and disc dislocation in the closed-mouth position (P = 0.144). In the maximum open-mouth position, there was a significant correlation between the number of affected peripheral joints and disc dislocation (P = 0.021). Patients with duration of JIA >23 months had a significantly higher rate of disc dislocation and destructive changes (P < 0.0001 for both). Patients with a duration of JIA >60 months were found to have a significantly higher rate of destructive changes of the TMJ than patients with a disease duration <60 months (P < 0.0001), but no statistical significance was found concerning disc dislocation (P = 0.059 and P = 0.070 for closed-mouth position and maximum open-mouth position, respectively) (Table 4).

Table 4. Statistical relationships (P values) between clinical findings of the temporomandibular joints and imaging diagnosis by high-resolution ultrasonography calculated by the chi-square test
Investigated parametersDestructive changesDisc dislocation
Closed-mouth positionMaximum open-mouth position
Duration since diagnosis of the rheumatic arthritis >23 months< 0.0001< 0.00010.0004
Duration since diagnosis of the rheumatic arthritis >60 months< 0.00010.0590.070
No. of affected peripheral joints (≥5)0.0020.1440.021

DISCUSSION

The literature reports a 12–13% prevalence of TMD in juvenile patients (14, 15), whereas in the current investigation 55% of patients had destructive changes of the TMJ diagnosed by US. These results imply that rheumatic diseases lead to a higher number of TMDs than in the normal population. It is difficult to compare the clinical results of our TMJ investigation with those of the literature because there exists no standardized scheme for juvenile patients, such as the Clinical Diagnostic Criteria for Temporomandibular Diseases classification (36), which refers to adult patients. A literature review demonstrates that clicking, crepitation, and pain are the most evaluated parameters for the investigation of the juvenile TMJ (10, 15, 16, 37). Furthermore, the clinical symptoms of juvenile TMD change during the growth of the patients (38–41), which makes a comparison difficult because previously published studies did not divide patients into different age groups (10, 15, 16, 37).

The clinical evaluation of the TMJ was difficult, especially in small children, because symptoms such as pain could often be evaluated only indirectly by asking the parents of the juvenile patients. Furthermore, clinical symptoms could be masked by antirheumatic therapy. Early treatment of TMD could prevent severe malfunctions of the TMJ caused by hypoplastic condyles and growth alterations of the mandible (16).

MRI is accepted in the literature as the gold standard in the imaging diagnosis of the TMJ (17–23), but the availability and high cost make the use of MRI as a screening method impossible. Conventional radiographs such as the panoramic radiograph, which is normally available at every dentist, show destructive changes in the TMJ only in a late stage, and computed tomography (CT) is not able to visualize soft-tissue structures such as the articular disc (3, 18). Furthermore, the radiation exposure of a CT investigation does not allow the use of CT as a screening method 1 or 2 times a year. Therefore, an inexpensive and quick imaging diagnosis that is widely available would be an improvement in the diagnosis of TMD in patients with JIA. US is a widely used diagnostic imaging tool in patients with rheumatic diseases and nearly every high-quality ultrasound machine could be adapted to a high-resolution transducer. Recent studies using MRI as a reference demonstrated that high-resolution US can be used as an alternative method in the diagnosis of destructive changes, effusion, and disc dislocation in the TMJ (24–33). The dynamic investigation of the TMJ by high-resolution US especially resulted in a large improvement concerning sensitivity, specificity, and accuracy regarding MRI as a reference (33). The diagnosis of disc dislocation and destructive changes should not be the only goal of US investigation of the TMJ, because effusion and synovitis should be investigated as well. The use of US in TMJ imaging diagnosis implies that effusion and synovitis should also be included in the diagnosis. Further investigations have to be performed to evaluate the potential of US to diagnose effusion and synovitis in the TMJ in patients with JIA. Of course conventional radiography is important, especially if the initial diagnosis of TMD is made by the dentist, who normally does not use ultrasound in his or her practice.

There is a significant correlation between duration of rheumatoid arthritis and clinical symptoms of TMD (7, 12). The current study demonstrated a correlation between the duration of JIA and destructive changes of the TMJ and disc dislocation in the maximum open-mouth position. These results imply that high-resolution US could be used as a screening method for the evaluation of the TMJ in patients with JIA. Former studies regarding the same cohort of patients as the current investigation (32) demonstrated no significant correlation between TMD and the number of affected peripheral joints, whereas the current study found a significant correlation between the number of affected peripheral joints and the sonographic diagnosis of destructive changes and disc dislocation in the maximum open-mouth position. These results imply that high-resolution US is able to detect TMD earlier than clinical symptoms appear. High-resolution US is interesting as a screening method, because an early intervention is essential for successful treatment of TMD (41, 42).

In the current study, no significant correlation was found between the number of affected peripheral joints and disc dislocation in the closed-mouth position, whereas such a correlation was detected in the maximum open-mouth position. One reason for this difference could be that most patients show an anterior disc dislocation in the closed-mouth position and an undislocated disc in the maximum open-mouth position. During the mouth-opening movement, the condyle normally jumps onto the disc, which causes the clicking in the TMJ. If the patient then closes his or her mouth the condyle moves backwards and the disc remains in an anterior position. If a disc remains in the anterior position, the range of mouth opening is normally limited. Therefore, the results of the current study imply that high-resolution US is able to detect severe disc dislocations in the maximum open-mouth position before the awareness of clinical symptoms.

This study demonstrated that patients with ≥5 affected peripheral joints have significantly more pathologic sonographic findings than patients with <5 affected peripheral joints. Now the question is whether the diagnosis of the destructive change of both TMJs by high-resolution US in a patient with an oligoarticular course would lead to a change of the diagnosis into a polyarticular course. An undiscovered destructive change of one or both TMJs could lead to a false classification of JIA. Therefore, a destructive change of the TMJ within the first 6 months of the disease would change the classification of the disease as well (onset type). Further studies with more patients divided into different age groups are needed to obtain more information about TMJ destruction in patients with JIA; statistical correlations between the US results and the clinical results of the TMJ investigation could especially be evaluated with a larger number of patients. The significant correlation between pathologic sonographic findings, the duration of the rheumatic disease, and the number of affected peripheral joints make the technique interesting for use as a diagnostic screening method.

AUTHOR CONTRIBUTIONS

Dr. Jank had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study design. Jank, Schroeder.

Acquisition of data. Michels, Häfner.

Analysis and interpretation of data. Jank, Missman, Schroeder.

Manuscript preparation. Haase, Mur.

Statistical analysis. Strobl, Schroeder.

Radiology. Bodner.

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