Congenital fusion of C2 - C3, Radiology Case

Fusion of adjacent vertebral segments is not an unusual isolated abnormality and should not be confused with the far less common Klippel Feil syndrome. 

Congenital fusion of C2 - C3, Radiology Case

Neurospine

Congenital variants - vertebrae, Radiology Case

Block vertebra, Radiology Reference Article

Radiographic Assessment of Congenital C2–3 Synostosis

Klippel-Feil Syndrome - Spine - Orthobullets

Klippel Feil Syndrome

Cureus, Images in Spine: A Rare Abnormal Bony Fusion

Figure 3 from Radiographic Assessment of Congenital C2–3 Synostosis

Figure 5 from Radiographic Assessment of Congenital C2–3 Synostosis

Traumatic C2-C3 subluxation with atlanto-axial dislocation managed by posterior approach — A rare case report - ScienceDirect

Congenital fusion of C2 - C3, Radiology Case

Congenital fusion of C2 - C3, Radiology Case