What are spondylolysis and spondylolisthesis? Spondylolisthesis
is when one of the bones of the spine (vertebrae) slips forward
compared to the one below it. It can occur for a number of
reasons which will be reviewed below. One reason is due to
spondylolysis which is when there is a break in one or both
sides of the posterior ring of a vertebrae. The part of the
vertebrae that breaks is called the pars. This condition is most
common in the fourth and fifth lumbar vertebrae which are near
the bottom of the spine. How does it occur? Spondylolisthesis
(forward slipping) can occur for a number of reasons including:
It can be congenital (born with predisposition due to angle of
joints) – most often shows up during adolescent growth spurt It
can be degenerative- more common in women It can be due to bone
disease such as tumor, infection, osteoporosis etc. It can be
due to surgical procedures removing portions of the posterior
vertebral structure Spondylolysis (breakage in the portion of
vertebrae called the pars)