A 28-year-old male presents to the emergency department following a motor vehicle accident with a dashboard injury to the chin. Clinical examination reveals pre-auricular swelling, pain on jaw movement, and deviation of the jaw to the right on mouth opening. An AP mandible X-ray is obtained. The structure marked **C** in the diagram is suspected to be fractured. Which imaging modality would be MOST appropriate to definitively visualize and characterize this fracture?

Explanation

## Why Orthopantomogram (OPG) and CT face is right The structure marked **C** is the mandibular condyle, which articulates at the temporomandibular joint (TMJ). Condylar fractures are the second most common site of mandibular fracture (after the angle) but are frequently missed on AP views alone because of the complex three-dimensional anatomy of the TMJ. According to Bailey & Love 28e, condylar fractures are best visualized on Towne's view, reverse Towne's view, orthopantomogram (OPG), or CT face. CT face is the definitive imaging modality for characterizing displacement, comminution, and associated injuries. OPG provides an excellent panoramic view of the entire mandible including both condyles, making it ideal for detecting bilateral condylar fractures (which are common with chin trauma due to bilateral force transmission). The clinical presentation of right-sided jaw deviation on opening, pre-auricular pain, and swelling following chin trauma is classic for condylar fracture, and the patient requires imaging that can reliably demonstrate this injury. ## Why each distractor is wrong - **Posteroanterior (PA) mandible X-ray alone**: While PA views are better than AP for some mandibular structures, they still do not adequately visualize the condylar head and TMJ articulation. Specialized views (Towne's, reverse Towne's) or cross-sectional imaging are required. - **Intraoral occlusal radiograph**: This view is useful for visualizing the anterior mandible and dental structures but provides no information about the posterior mandible or condylar region. - **Lateral skull X-ray only**: Although lateral views can show some condylar anatomy, they lack the specificity and detail needed for definitive diagnosis and characterization of condylar fractures; CT is superior. **High-Yield:** Condylar fractures are easily missed on AP/PA views alone—always request OPG or CT face when condylar injury is suspected clinically. [cite: Bailey & Love 28e]