Study on Lateral Pterygoid Muscle Attachment Type is Related to the Pathogenesis of Anterior Disc Displacement, Disc Degeneration and Articular Surface Degeneration: A Magnetic Resonance Imaging Assessment

Aim: The aim of this study was to investigate the correlation between Lateral pterygoid muscle (LPM) attachment type and Anterior disc displacement (ADD), disc degeneration or articular surface degeneration among the population of central India.

Methods: Patients with complaint of pain, clicking, locking in the Temporomandibular Joint (TMJ) region were evaluated. TMJ dysfunctions were classified as normal disc position, ADD with reduction and ADD without reduction. LPM attachment types to the condyle disc complex were classified into three different types. Statistical analysis was conducted using the R version 3.2.0. Statistical correlation analysis was used to investigate the correlation between TMJ dysfunction and LPM attachment types to the disc condyle complex, disc degeneration and articular surface degeneration.

Results: Of the 108 TMJ’S in 54 patients (42 males and 66 females, mean age 32.20 years) 25 TMJ’S(23.14%) were evaluated as normal in terms of disc status, 61TMJ’S (56.48%) had an ADD with reduction and 22 (20.37%) had ADD without reduction. Arthritis was seen in 104 TMJ’S (96.30%) suggesting a high prevalence (96.3%) of TMJ osteoarthritis among young patients (mean age 32.2 years). LPM attachment types to the disc condyle complex were Type I (87.03%), Type II (11.11%) and Type III (1.85%). Statistically significant difference was found between the type of LPM attachment and ADD (P value 0.0285). No statistically significant difference was found between LPM attachment type and disc degeneration or articular surface degeneration.

Conclusion: LPM attachment type is related to the pathogenesis of ADD, but not related to disc degeneration and articular surface degeneration. It can be concluded that lateral pterygoid muscle attachment type is related to the pathogenesis of anterior disc displacement and hence to the internal derangement of TMJ disorders.