The case is advanced ankylosing spondylitis as manifested by squaring of vertebral bodies , ossifications of the anterior longitidinal ligaments , multiple syndesmophytes causing multiple undulations , shiny corner signs are also seen at multiple levels. There is advanced osteoporosis. Due to the anterior vertebral body fusions as well as the facet joint fusions any minor trauma will lead to fracture. 

There is hyperextension type fracture that involve the fused and ossified disc space. It is also extending into the posterior arch.