Spodylolisthesis - Slip Slide and Away...

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this is the article the author referred to in the last article I posted

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Spodylolisthesis - " Slip Slide and Away... "

Spondylolisthesis is the slippage of one vertebra on the

vertebrae below. The word is derived from Greek: spondylo-

defined as spinein Greek and listhesis- defined as to slip or

slide. Most spondylolisthesis occurs in the low lumbar spine

and the most common spinal levels involved are either

L5-S1 and L4-L5

TYPES OF SPONDYLOLISTHESIS:

CONGENITAL SPONDYLOLISTHESIS is caused by an anomaly of the bones

of the spine. It is estimated that this is the cause in up to 20%

of patients with spondylolisthesis. An individual is born with

an abnormality of the posterior bones of the spine. Because of

the abnormal orientation of the bones, the normal ability of the

spine to resist slippage is lost and the vertebral body of L5

slips forward on S1. People usually present when they are in

their adolescent growth spurt.

ISTHMIC SPONDYLOLISTHESIS is caused by a defect in a part of the

bone called the pars interarticularis. The pars bone connects

the upper joint of one vertebra to the lower joint. Isthmic

spondylolisthesis is usually caused by a stress fracture

of the pars. This is thought to occur due to repetitive

stresses such as bending backwards, on the pars. The pars that

incursa stress fracture most likely has a hereditary

predisposition to fracture. This means that the patient is born

with some minor abnormality or weakness of the pars such that

repetitive bending causes a fracture.

DEGENERATIVE SPONDYLOLISTHESIS is a forward slippage caused by

arthritis of the spine. Spinal stenosis is highly associated

with this process. As the disc in front of the spine ages, it

loses water and loses its ability to resist motion. To

compensate, the joints in back

of the spine increase in size and develop extra soft tissue and

bone spurs. This extra tissue and bone presses on the nerve

roots and actually can weaken the joints in the back of the

spine, causing slippage. The most common level for this type of

spondylolisthesis is L4-5. The reason is

that L5-S1 has ligaments which run from the pelvis to the spine

that help to minimize slippage.

DIAGNOSIS:

The diagnosis of spondylolisthesis is made by plain xrays. An

oblique view will outline the spine and if you trace the

structures you will have a picture that resembles a scottish

terrier or " scottie dog " . The " collar " of the scottie dog is the

fracture line in the pars. If xrays are taken when you are

bending fowards and backwards then the amount of slippage of one

vertebrae on the other can be measured. If the top one slips

about 25% it is called a grade 1. If it slips almost all the way

it is a grade 4. The amount or grade of the slippage helps the

surgeon determine the best mode of treatment.

The most common treatment is surgical. The roof of the spine is

removed along with all of the abnormal tissue so the nerve roots

can be freed. Once there is no tissue the bone are fused to

prevent further slippage and pain. The type of fusion and

materials used is a topic for another time...

J Houle, MD

Copyright 2000

If you would like to see xrays of spondylolisthesis visit the

website:

http://www.spinetimes.com/spondy.html