Bipartite atlas mimicking traumatic atlantoaxial instability following a rugby tackle.

We report a very rare case of a congenital cervical spine anomaly. The low occurrence rate of this anatomic variant combined with the high frequency of cervical injuries in sports medicine made this case a diagnostic challenge on both emergency and orthopaedic departments. After reading, it should give the clinician a more consistent view in differentiating the traumatic or congenital origin of the disorder seen on radiographs, as well as what can be expected in the future when diagnosis is set.