atlantoaxial subluxationOrthopedics An upper cervical spine subluxation which is either rotatory or anterior; rotatory AAS is more common in children, often due to apparently trivial injury; torticollis may be seen Imaging On an open mouth film, the odontoid is not equidistant between lateral masses of C1 Management Reduce subluxation and brace; recurrent or chronic cases can be treated with C1-C2 fusion; anterior AAS is due to traumatic disruption of transverse ligament Imaging Abnormal atlanto-dental interval; if anterior AAS is suspected, a CT rules out fracture; an MRI is used to evaluate the transverse ligament which, if disrupted, requires fusion; a cervical brace suffices for fracture without disruption. See Atlantodental interval.
pertaining to the atlas and axis.
the articulation between the first two cervical vertebrae.
the fibrous sheet which closes the interarcual space between the atlas and the axis.
degeneration or malformation of the dens is seen mainly in toy breeds of dogs predisposing to displacement of the axis. Fracture of the dens can occur in any animal. Compression of the cervical cord is a common sequel that causes neck pain and varying degrees of spastic tetraparesis. Treatment is surgical stabilization. Also reported in Holstein cattle.