Etiology of atlantoaxial dislocation

The causes of atlantoaxial dislocation can be divided into three categories: congenital, traumatic and congestive. Congenital atlantoaxial dislocation is mainly due to the development disorder of odontoid process of axis and/or the imperfection of transverse ligament of atlas, which is the pathological basis change of congenital atlantoaxial dislocation. Dentate dysplasia can be divided into the following types:

1. The odontoid bone, that is, the odontoid process, is not fused with the axis vertebral body.

2. The terminal bone, that is, the tip of odontoid process, has not fused with the root of odontoid process.

3. The odontoid process is underdeveloped, that is, there is no odontoid process.

4. The base of odontoid process is undeveloped, that is, only the tip of odontoid process.

5. The odontoid process tip is undeveloped, that is, there is only one short odontoid process root.