Accessory Articulation of Elongated Anterior Tubercles of the Transverse Processes at C5-C6 in a Young Adult Female Patient: A Case Report.

Elongation of the anterior tubercle of the cervical transverse process with formation of an accessory articulation between adjacent vertebrae is a rare anatomical variant. Recognition of this variant is important to avoid misidentification as an acute fracture fragment in the trauma setting. In this report, a 22-year-old female patient presented to the emergency department following a motor vehicle collision (MVC). Per patient self-report, there was no known prior cervical spine pathology or previously identified congenital anomalies. Non-contrast computed tomography (CT) of the cervical spine with multiplanar reformatted images in the axial, coronal, and sagittal planes and three-dimensional surface-shaded display (SSD) reconstructions revealed no acute fracture, subluxation, or listhesis. An incidental finding demonstrated unilateral elongated left C5-C6 anterior tubercles of the transverse processes with a well-corticated accessory articulation between them. The articulation exhibited smooth, sclerotic articular surfaces morphologically consistent with a synovial-type articulation, although histological confirmation was not available. Transverse foramina were patent bilaterally without osseous narrowing. Vertebral artery patency was not directly assessable on this non-contrast examination. No cervical rib was identified at C7 on either side. This case was interpreted via teleradiology with limited access to clinical history, prior imaging, and follow-up. Recognition of this rare anatomical variant is important for radiologists and emergency physicians to avoid misidentification as an acute fracture fragment in the trauma setting. Well-corticated margins and sclerotic articular surfaces distinguish this congenital variant from fracture fragments. CT with multiplanar reformations provides detailed characterization of this variant.