Evaluation of the Correlation Between Articular Disc Displacement and the Lateral Pterygoid Muscle Using Magnetic Resonance Imaging

Background The lateral pterygoid muscle (LPM) plays a critical role in the biomechanics of the temporomandibular joint (TMJ), particularly through its superior (SLPM) and inferior (ILPM) heads. Recent studies have suggested anatomical variations in LPM morphology and its attachment patterns, potentially contributing to internal derangements and temporomandibular joint disorders (TMJD). This study aimed to evaluate the correlation between LPM attachment types and articular disc displacement using magnetic resonance imaging (MRI). Material and Methods This retrospective study included 266 TMJs from 133 patients (108 female, 25 male) who presented with TMJ-related symptoms. MRI scans were categorized based on LPM attachment types into three groups: Type I (ILPM attached to condyle, SLPM to disc), Type II (ILPM to condyle, SLPM to both disc and condyle), and Type III (ILPM and medial fibers to condyle, SLPM to disc). Disc position was classified as normal, disc displacement with reduction (DDwR), or disc displacement without reduction (DDwoR). Statistical analyses, including Chi-square and Fisher’s Exact Test, were conducted using SPSS v26, with a significance level set at p < 0.05. Results The distribution of LPM attachment types was as follows: Type I in 27.8% of joints, Type II in 62.4%, and Type III in 9.8%. Regarding disc positions, 36.4% of joints had normal disc position, 35.7% had DDwR, and 27.9% had DDwoR. No statistically significant correlation was found between LPM attachment types and disc displacement (Chi-square = 8.586, p = 0.072). Conclusion Although anatomical variations in LPM attachments were observed, no significant correlation was identified between these variations and the presence or type of disc displacement. These findings suggest that while LPM morphology is diverse, its role in the pathogenesis of TMJD requires further investigation with advanced imaging modalities and functional analysis.