TMJ Disc Displacement Angle Analysis in MRI A New Proposal

摘要

Objective: To evaluate the co relation of clinical symptoms and MRI findings of TMJ in symptomatic Temporomandibular Dysfunction (TMD) patients. Material and Method: MRI TMJ scan of 25 patients were evaluated. The subjects had clinical evidence of reciprocal TMJ clicking or restricted mouth opening. This study determined the variability of temporomandibular joint (TMJ) disk position in antero-posterior aspect of the joint using magnetic resonance imaging (MRI). Disk position was evaluated on MRI by measuring the angle formed by a line through the middle of the condyle and tangential to the posterior-most aspect of the disk. Joint effusion was checked using T2 weighted image sequence. Thickness of superior and inferior head of lateral pterygoid muscle was measured. These MRI findings were then correlated statistically to clinical findings. Results: Out of 50 TMJ's (25 patients); 40% had biconcave shape (no deformity), 16% cases showed lengthened disc, 12% cases showed a flattened disc, 12% cases showed thick posterior band. Varying degrees of disc displacement was associated with disc shape deformity. Increased thickness of Inferior head of lateral Pterygoid had statistically strong association with pain. Conclusion: A strong positive co relation was seen between the clinical and MRI findings in symptomatic TMD patients. Further using this, a new Disc Displacement angle measurement method and classification of disc shape was proposed for better disc evaluation.