Displaced fracture through the anterior atlantal synchondrosis. 
In the acute setting, accurate radiological interpretation of paediatric cervical spine trauma can be difficult due to a combination of normal variants and presence of multiple synchondroses.  We present a rare case of a fracture through the anterior atlantal synchondrosis in a paediatric spine.  A five-year-old boy, who fell backwards onto the top of his head while swinging across on a monkey bar frame, presented with neck pain, cervical muscle spasm and decreased right lateral rotation and extension of his neck.  Computed tomography showed a displaced diastatic fracture through right anterior atlantal synchondrosis.  There are only 12 cases of paediatric C1 fractures reported in the world literature.  The importance of considering this diagnosis in the appropriate clinical setting, and the normal variants in the paediatric atlas that can cause diagnostic dilemma to the interpreting radiologist, are discussed in this case report.