Diagnostic value of clinical signs for detecting temporomandibular joint disc displacement: a single-center cross-sectional diagnostic accuracy study using magnetic resonance imaging as the reference standard.

BACKGROUND: Temporomandibular joint (TMJ) internal derangement is a common cause of orofacial pain and functional limitation. Clinical symptoms such as joint pain, clicking sounds, and limited mouth opening are frequently used in the initial assessment of temporomandibular disorders (TMD). However, the diagnostic accuracy of these clinical signs in predicting disc displacement remains uncertain. Magnetic resonance imaging (MRI) is considered the gold standard for evaluating TMJ disc position and morphology. This study aimed to assess the diagnostic value of common clinical symptoms for detecting TMJ disc displacement using MRI as the reference standard. METHODS: A cross-sectional study was conducted between August 2023 and August 2024. A total of 178 patients, contributing 267 temporomandibular joints, were included. Clinical symptoms including joint pain, joint clicking, and limited mouth opening were recorded during standardized clinical examination. All participants underwent MRI evaluation of the temporomandibular joints. Disc displacement identified on MRI served as the reference standard. Because both joints of a patient could be included, observations were clustered within patients; diagnostic performance (sensitivity, specificity, PPV, NPV, accuracy, likelihood ratios, and diagnostic odds ratios with 95% confidence intervals) and multivariable generalized estimating equation models accounted for this clustering. RESULTS: Disc displacement was present in 206 of 265 analyzed joints (77.7%). Joint pain showed the highest sensitivity (92.7%, 95% CI 88.3-95.5) but low specificity (33.9%), together with the most useful negative likelihood ratio (0.21) and the strongest discrimination (diagnostic odds ratio 6.53, 95% CI 3.08-13.86). Limited mouth opening had the highest specificity (69.5%), whereas joint clicking did not discriminate displaced from normally positioned discs (diagnostic odds ratio 1.34, 95% CI 0.74-2.42). In multivariable analysis, joint pain (adjusted odds ratio 4.06, 95% CI 1.83-9.03) and younger age were the only independent clinical predictors of disc displacement; joint effusion and condylar abnormality were additionally associated when MRI findings were included. CONCLUSION: Clinical symptoms provide useful preliminary information in the evaluation of TMJ disorders. However, clinical examination alone has limited diagnostic accuracy for identifying disc displacement. MRI remains the most reliable imaging modality for confirming TMJ internal derangement and should be considered when clinical findings are inconclusive.