Teaching Case

A 23-year-old man presented following an alleged assault, where he was repeatedly kicked to the vertex of the head. He complained about neck pain.

A 23-year-old previously fit and well young man was admitted to A+E following an assault during which he was repeatedly kicked on the vertex of his head. He complained of pain at the back his of neck and had full cervical immobilisation in a collar, no neurological deficit was present. Plain film was performed (Fig. 1), the AP odontoid peg view showed the lateral masses of C1 overhanging the lateral masses of C2 in keeping with a Jefferson Fracture. CT was subsequently performed (Fig. 2) demonstrating a fracture through the anterior arch of C1 with a congenital cleft in the posterior arch. The patient had a halo device fitted and follow-up CT did not demonstrate any healing of the fracture at 3 months (Fig. 3). MR was performed to assess the ligaments of the atlanto-axial joint (Fig. 4). The right transverse ligament was seen to be ruptured, this, in combination with the congenital bone cleft, meant that the fracture was not stable and the patient was listed for posterior atlanto-axial fusion.

Jefferson fractures are caused when an axial force is transmitted between the occipital condyles and the surface of the axis vertebra causing the atlas to be compressed, resulting in a burst fracture to either the anterior or posterior arch [1], they were first described together by Geoffrey Jefferson in 1920 [2]. They account for up to 30% of all fractures to the atlas [3] and as many as 3% of all cervical spinal injuries [4] [5].

Posterior mid-line clefts of the atlas or spina bifida occulta are well recognised and are attributed to the defective or absent development of the cartilaginous preformation of the arch. They are present in approximately 4% of the population, 97% of these are median clefts [6]. These cleft defects can present diagnostic challenges as they can easily be mistaken for fractures. They also, as demonstrated in this case, can coexist with fractures and result in instability and non-union [7] leading to difficult management and necessitate further imaging during protracted treatment.

Here we present a case study of a patient who presented with both a congenital failure of fusion of the posterior arch of the atlas and a concomitant Jefferson fracture of the anterior arch following trauma. This combination has not previously been reported in the literature.