40 patients with chronic polyarthritis were investigated prospectively. The TMJ was investigated to detect clicking, crepitation, and pain. High resolution ultrasound (HR-US) assessed destructive changes, effusion, and disc dislocation. The results of the clinical investigation and the HR-US investigation were compared using the χ 2 test. The statistical calculation of the correlation between the HR-US results and the clinical TMJ investigation by the χ 2 test showed a significant correlation between TMJ sounds, destructive changes and disc dislocation. A significant correlation between TMJ joint effusion, TMJ pathology and TMJ pain was detected using the χ 2 test. Pain on palpation of the masseter and temporal muscle correlated significantly with TMJ effusion. There was significant correlation between TMD and the HR-US diagnosis of destructive changes and effusion. The significant correlation between TMJ effusion and actual TMJ pain and TMJ pain on palpation shows the ability of HR-US to detect acute TMJ affection with high significance. There was a significant correlation between effusion and pain on palpation of the masticatory muscles, which could be interpreted as the ability of HR-US to determine acute TMD. That any TMD correlated significantly with destructive changes and TMJ effusion suggests that HR-US could detect chronic and acute TMD.
In the literature, temporomandibular diseases (TMDs) are described in patients with chronic polyarthritis (CP) . According to the CDC/TMD scale , the most important symptoms of TMD are clicking, crepitation and reduction or closed lock of mouth opening movement. TMJ pain and/or pain of the masticatory muscles, such as the masseter and temporal muscle, can occur.
An early diagnosis of TMD is essential but clinical symptoms of TMD appear only at a late stage . A sufficient imaging diagnosis should be the goal of TMD investigation. Panoramic radiography is available in nearly every dental practice, but destructive changes and erosion also appear in a late stage of the disease. Computed tomography (CT) is sufficient for imaging bony structures, but soft-tissue imaging is lacking. Magnetic resonance imaging (MRI) is the gold standard for the detection of effusion, destructive changes and disc dislocation, but availability and high cost limit its use as a screening method. Ultrasound (US) is described as a helpful tool, but 7.5 MHz and 10 MHz transducers did not show sufficient resolution of the superficial structures of the TMJ . Recently, the sensitivity, specificity and accuracy of high resolution US (HR-US), using 12–15 MHz transducers, has been assessed for the imaging diagnosis of TMD, to detect effusion, destructive changes and disc dislocation . The aim of the current study was to determine any correlation between the US diagnosis and the pathological clinical parameters of the TMJ.
Patients and methods
40 patients with CP were investigated prospectively. They were selected randomly from the outpatients department of the Departments of Rheumatology and Cranio-, Oral- and Maxillofacial Surgery of the Medical University of Innsbruck. Inclusion criteria were active CP, stage 1–3, using the classification of the American College of Rheumatology (ACR) .
The clinical investigation of the TMJ included the detection of clicking, crepitation, pain (actual and by palpation), and pain on palpation of the masticatory muscles (masseter and temporalis). An eventual closed lock of the TMJ and/or pain in the past were documented.
The HR-US investigation ( Fig. 1 ) was performed by an experienced oral and maxillofacial surgeon with the transducer overlying the zygomatic arch in a vertical position with the mouth closed and at maximum mouth opening. The position of the disc was detected in the closed mouth position. The patient was then asked to open his mouth to the maximum mouth opening position when the position of the disc was detected again. The HR-US investigation was performed regarding the following criteria: destructive changes ( Fig. 2 ); effusion; disc dislocation ( Fig. 3 ) at closed mouth and maximum mouth opening positions; and disc dislocation with reduction (disc dislocation in closed mouth position and no disc dislocation in maximum mouth opening position). The investigator performing the HR-US investigation was blinded to the results of the clinical investigation of the TMJ.
The results of the clinical investigation of the TMJ and the HR-US investigation were compared by a χ 2 test. A result was considered to be significant if it reached a value of p < 0.05.
29 (73%) of 40 patients were female and 11 (28%) were male. The mean age of all patients was 60.5 years (median 63 years). 12 patients ( Table 1 ) (30%) reported TMJ pain in the past, and 9 patients (3%) reported a closed lock of the TMJ in the past. 23 patients (58%) showed at least one pathological clinical finding of the TMJ. 8 of 80 TMJs (10%) showed actual pain, and pain on palpation, whilst in 4 cases (5%) pain on palpation of the left or right temporal and masseter muscle was determined. 26 TMJs (33%) showed clicking and 16 TMJs (20%) crepitation ( Table 2 ). 8 (20%) patients had ACR stage 1, 19 (48%) had stage 2 and 13 (33%) had stage 3. 7 (88%) of the patients with stage 1 showed at least one of the pathological symptoms of the TMJ whilst 9 (48%) patients with stage 2 showed pathological findings of the TMJ. In 13 (33%) of the patients with stage 3 at least one pathological symptom of the TMJ was diagnosed.