Type | Definition |
---|---|
Type I (dynamic stable type) | It is characterized with the typical radiological changes, such as vertebral vacuum sign, intervertebral cleft, and/or pseudarthrosis. The D-value of VKA is less than 11°. |
Type II (dynamic unstable type) | The D-value of VKA is greater than 11°. |
Type III (spinal stenosis type) | MRI reveals backward displacement of the bone fragments that leads to spinal canal stenosis and neurological deficit. |
Type IV (kyphotic deformity type) | The CKA is greater than 30° on both flexion and extension lateral radiography. |
Type V (mixed type ) | Among the 3 aforementioned morphological changes from type II to IV, at least 2 types existed. |