Evaluating Morphology of the Pterygomaxillary Junction and Its Association With the Orbit in Different Facial Skeletal Relationships

Purpose: The etiology for blindness after Le Fort I osteotomy is poorly understood. The authors propose that a study of the morphology and anatomical relationship of the pterygomaxillary junction to orbital vital structures may be crucial for understanding the possible etiology. Materials and Methods: This retrospective observational study involved analysis of data procured from computed tomography scans of individuals who were categorized into 4 groups based on their skeletal characteristics: skeletal Class I, II, and III and cleft lip and palate (CLP). The outcome variables included i) the height, width, and thickness of the pterygomaxillary junction (PTMJ) which represent its morphology and ii) distance of the PTMJ to the superior orbital fissure and optic canal, to demonstrate its proximity to orbital vital structures. Primary outcome measures were to i) compare variance of the outcome variables across groups, ii) determine association between PTMJ morphology and its proximity to the orbit, and iii) determine association between skeletal morphology and the outcome variables. Data were analyzed using descriptive and inferential statistics to study variance and association. Results: Forty patients (80 sides) were divided into 4 groups. The CLP group demonstrated maximum height and thickness of the PTMJ, whereas the Class II group demonstrated the minimum (P<.001 and P=.001, respectively). The CLP group demonstrated the closest proximity of the PTMJ to orbital vital structures (P<.001), with Class II being the farthest (P<.001). There was a weak positive correlation between the PTMJ height and its thickness and width, whereas a moderate negative correlation was seen between the PTMJ height and its distance from the optic canal and superior orbital fissures (P<.001). Conclusions: Morphology of the PTMJ varies with facial skeletal relationship and also influences the relationship of the PTMJ with the orbital vital structures. This may be critical in understanding the pathophysiology of blindness after Le Fort I osteotomies. (C) 2021 American Association of Oral and Maxillofacial Surgeons