What are the causes of anterior subluxation and facet joint arthritis?

Age, degeneration, . Vertebral body may shift over another below it due to incompetence/laxity of facet joints at that level due to degeneratiion of joints which may become arthritic. This is seen with increasing age particularly in post menopausal girls & has a higher association in females than males & may be related to lower bone density developing in addition to degeneration. Also seen with rheumatoid arthritis.
Ligament damage. In the neck (cervical spine) anterior subluxation results from a flexion and rotation injury. This tears the ligaments behind the vertebral bodies. It changes the relationships of the articulating facets which can lead to arthritis. Assessment of the degree of instability is essential, best evaluated by a spine surgeon.