Occipito-cervical fusion (OCF) is required when the junction is rendered unstable by a 

variety of pathological conditions including congenital abnormalities, inflammatory diseases, 

trauma, tumours and infections.

Occipito -cervical instability ,neurological deficit intractable pain,atlanto-axial 

osteomyelitis ,Trauma ankylosing spondylitis , atlanto- occipital osteoarthritis.