Rotational injuries of the cervical spine

Injuries which are caused in part by a rotational mechanism include atlantoaxial rotatory fixation (AARF), traumatic isolation of the articular pillar (TIAP), and unilateral interfacetal dislocation (UID). The anatomy, classification, radiographic findings, and frequency of neurological signs are reviewed. Key points include: AARF: (1) Mild injury is not diagnosed radiographically since the appearance is the same as for physiologic rotation. More significant injuries demonstrate widening of the atlanto-dens interval ( > 3 mm in adults) and/or abnormal rotation ( > 45 °) of C1 on C2. (2) AARF refers to an inability to return the head to a neutral position. This may be due to trauma resulting in subluxation or dislocation or may be due to muscle spasm in torticollis. TIAP: (1) Radiographic diagnosis depends on visualizing ipsilateral pedicle and lamina fractures. (2) Rotation of an articular mass from its normal orientation on radiographs implies the presence of this injury. However, rotation of the articular mass is not always present, and the ipsilateral pedicle and lamina fractures must be seen on radiographs or CT. UID: (1) Less rotational discrepancy than expected can occur in two circumstances: articular mass fracture with dislocation or significant subluxation on the contralateral side. (2) Less anterolisthesis than expected can occur if there is articular mass fracture with dislocation.