Blog Post: Spondylolysis or Pars Fracture 6-26-2021
Before we talk about what is Spondylolysis or Pars Fracture, we need to understand what is normal.
So, what is normal vertebral anatomy?
As you below in the two drawings the vertebra of 3 parts: the vertebral body (which is in the front), the posterior elements (in the back; red circles), and the pedicles (which connect the vertebral bodies in the front to the posterior elements in the back.
The spinal cord and nerve roots run in the blue areas below:
Notice the 3 parts of the vertebra create a full bony ring around the spinal cord and nerve roots (below):
What is a pars fracture/spondylolysis? A pars fracture/spondylolysis (red lines, below) is a break in this bony ring at the area called the pars interarticularis.
This means the back area is not attached, is loose and can wiggle back and forth with back motion.
What does spondylolysis mean? If you break down the word into its Latin roots, spondylo- means “vertebra” and –lysis means “break”. So the red lines are the place where the break in in the posterior elements.
Is there a difference between pars fracture and spondylolysis? No, they mean the same thing. I believe the main the phrase “pars fracture” is more commonly utilized is due to the difficulty in pronouncing “spondylolysis”, and its similarity of “spondylolysis” to the phrase “spondylolisthesis”, which is a more advanced/severe stage.
Can you be born with spondylolysis? There have been no reports of spondylolysis being present at birth, so they develop over time.
Why does it happen? Most likely all those pars that break did not develop normally. The pars area is very narrow and with motion gets stressed, then a crack develops. If this problem was simply due to sports or a particular activity, we would see this much more commonly.
The area then cracks…
We will continue to present this topic over the next several posts.