Diagnostic Accuracy of Dynamic High-Resolution Ultrasonography in Assessing Anterior Disc Displacement in Temporomandibular Joint Disorders: A Prospective Observational Study

Abstract

Objective: The objective of this study was to assess the diagnostic efficacy of dynamic high-resolution ultrasonography (HRUS) in detecting anterior disc displacement with reduction (ADDWR) and anterior disc displacement without reduction (ADDWoR) in the temporomandibular joint (TMJ). Methods: A total of 144 TMJs was categorized into three groups according to the magnetic resonance imaging (MRI) findings, which served as the reference standard: the normal disc position (NDP) group, the ADDWR group, and the ADDWoR group. Static images of the TMJ in full opening and maximum intercuspal positions, along with dynamic sequences during jaw opening, were obtained utilizing a 14 MHz L-shaped linear array transducer. The diagnostic efficacy of dynamic HRUS for identifying ADDWR and ADDWoR was evaluated in terms of accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), diagnostic odds ratio (DOR), and the Youden index. Results: According to the MRI findings, the NDP, ADDWR, and ADDWoR groups consisted of 42 (29.2%), 47 (32.6%), and 55 (38.2%) TMJs, respectively. HRUS data revealed 54 TMJs (37.5%) in the NDP group, 26 TMJs (18.1%) in the ADDWR group, and 64 TMJs (44.4%) in the ADDWoR group. With MRI as the reference standard, HRUS exhibited a diagnostic accuracy of 71.4%, sensitivity of 51.4%, and specificity of 91.4% for ADDWR. For the ADDWoR, HRUS attained a diagnostic accuracy of 86.5%, sensitivity of 90.0%, and specificity of 82.1%. Conclusions: With MRI serving as the reference standard, dynamic HRUS has high diagnostic value for ADDWoR, with better diagnostic accuracy than ADDWR. Ultrasonography has the potential to be used as a highly effective and non-invasive imaging modality for the early screening of ADD in future clinical practice.

Keywords: anterior disc displacement; diagnostic efficacy; dynamic high-resolution ultrasonography; temporomandibular joint disorders.

Figure 1

Schematic illustration of the US examination: (A) the L-shaped ultrasonographic transducer was positioned transversely anterior to the tragus; (B,C) the corresponding anatomical schematic and ultrasonographic schematic.

Figure 2

Ultrasonographic image depicting a normal TMJ. (A) Maximum intercuspal position; (B) full opening position. In panel (A), the dotted line denotes the joint capsule, depicted as a hyperechoic (white) line. The white triangle indicates the articular eminence, whereas the white arrow indicates the condyle, with the condyle surface manifesting as a hyperechoic line. In panel (B), (1) denotes the masseter, depicted as hypo-to-isoechoic, with white lines outlining the masseter boundary. (2) denotes the articular disc, which appears as a thin hypo-to-isoechoic band, with the dotted line delineating the joint capsule.

Figure 3

Ultrasonographic image depicting a normal TMJ. (A) Maximum intercuspal position; (B) full opening position. In panel (A), the dotted line denotes the joint capsule, manifesting as a hyperechoic (white) line. The white triangle denotes the articular eminence, whereas the white arrow represents the condyle, where the condyle surface appears as a hyperechoic line. The region between the condyle and the articular eminence corresponds to the articular disc. In panel (B), (1) denotes the masseter, depicted as hypo-to-isoechoic, with white lines outlining the masseter boundary. The dotted line denotes the joint capsule, whereas the white arrow indicates the condyle. The articular disc appears as a thin hypo-to-isoechoic band encircling the anterior, superior, and posterior sections of the condyle.

Figure 4

Ultrasonographic image of a TMJ with ADDWR. (A) Maximum intercuspal position; (B) full opening position. In panel (A), the dotted line denotes the joint capsule, depicted as a hyperechoic (white) line. The white triangle denotes the articular eminence, while the white arrow indicates attention to the condyle, with the condyle surface illustrated as a hyperechoic line. The interval between the condyle and the articular eminence pertains to the region of the articular disc. In panel (B), (1) denotes the masseter, depicted as hypo-to-isoechoic, with white lines outlining the border of the masseter; and (2) denotes the articular disc, which appears as a thin hypo-to-isoechoic band, with the dotted line illustrating the joint capsule and the white arrow signifying the condyle.

Figure 5

Ultrasonographic image of a TMJ with ADDWR. (A) Maximum intercuspal position; (B) full opening position. In panel (A), the dotted line denotes the joint capsule, depicted as a hyperechoic (white) line. The white triangle indicates the articular eminence, whereas the white arrow indicates the condyle, with the condyle surface manifesting as a hyperechoic line. The interval between them pertains to the articular disc. In panel (B), (1) denotes the masseter, depicted as hypo-to-isoechoic, with white lines delineating the masseter border. The dotted line denotes the joint capsule, whereas the white arrow represents the condyle. The articular disc is illustrated as a thin hypo-to-isoechoic band situated anteriorly, superiorly, and posteriorly to the condyle.

Figure 6

Ultrasonographic image of a TMJ with ADDWR. (A) Maximum intercuspal position; (B) full opening position. In panel (A), the dotted line signifies the joint capsule, illustrated as a hyperechoic (white) line. The white triangle denotes the articular eminence, whereas the white arrow indicates the condyle, where the condyle surface manifests as a hyperechoic line. The interval between the condyle and the articular eminence is occupied by the articular disc. In panel (B), (1) denotes the masseter, depicted as hypo-to-isoechoic, with white lines delineating the border of the masseter; and (2) denotes the articular disc, observed as a hypo-to-isoechoic narrow band, with the dotted line indicating the joint capsule and the white arrow directing attention to the condyle.

Figure 7

Ultrasonographic image of a TMJ with ADDWoR. (A) Maximum intercuspal position; (B) full opening position. In panel (A), the dotted line denotes the joint capsule, depicted as a hyperechoic (white) line. The white triangle denotes the articular eminence, whereas the white arrow indicates the condyle, where the condyle surface manifests as a hyperechoic line. The interval between the condyle and the articular eminence corresponds to the articular disc. In panel (B), (1) denotes the masseter, depicted as hypo-to-isoechoic, with white lines outlining the border of the masseter; and (2) denotes the articular disc, depicted as a thin hypo-to-isoechoic band, with the dotted line indicating the joint capsule and the white arrow directing attention to the condyle.

Figure 8

Ultrasonographic image of a TMJ with ADDWoR. (A) Maximum intercuspal position; (B) full opening position. In panel (A), the dotted line denotes the joint capsule, depicted as a hyperechoic (white) line. The white triangle denotes the articular eminence, whereas the white arrow indicates the condyle, where the condyle surface manifests as a hyperechoic line. In panel (B), (1) denotes the masseter, depicted as hypo-to-isoechoic, with white lines delineating the border of the masseter. The dotted line denotes the joint capsule, whereas the white arrow indicates the condyle. The white region between the two denotes the articular disc, which is situated anterior to the condyle.

Figure 9

Flowchart of the TMJ inclusion process.

Figure 10

Bar chart depicting the findings of the US examination.