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Answer to your Health Question

Question (02/14/2011):

My doctor said I have grade one spondylolisthesis because of a cartilage bulge, is that possible?



Dear Matthew,

Disc bulge or protrusion results when the disc bulges out from between two vertebrae without rupturing its surrounding envelope, the annulus fibrosis.

The causes of a bulging disc include:


Spondylolisthesis can be caused by:

- a birth defect
- fractures
- spondylolysis (a defect or fracture in the pars interarticularis)
- degeneration due to age or overuse
- tumors
- surgery

There are different types of spondylolisthesis. It all depends on the original cause: what made your vertebra slip forward.

Spondylolisthesis Type II also called isthmic, is the most common kind of spondylolisthesis. With type II spondylolisthesis, there's a problem with the pars interarticularis, a particular region of your vertebra.

In Spondylolisthesis Type II A, gymnasts, weight lifters, and football linemen are especially prone to this kind of spondylolisthesis. It's caused by multiple micro-fractures on the pars interarticularis-micro-fractures that occur because of hyperextension (overarching) and overuse. The pars interarticularis fractures completely in type II A.

Pseudodisc bulging without disc herniation is the most common type in isthmic spondylolisthesis.

However, in cases of disc herniation, extreme lateral disc herniation occasionally occurs; therefore, every isthmic spondylolisthesis patient should be examined carefully for extreme lateral disc herniation with thin-cut axial CT or MRI, especially when the patients complain of lateralizing symptom.

Normally the facet joints in the back of the spine protect the disc from shear as they act to limit the shear force.

When there is a pars interarticularis fracture the facet joints cannot limit shear.

Discs work well as a shock absorber but they are susceptible to being damaged if they have to resist shear.

When a disc is damaged, it may bulge.

Degenerative spondylolisthesis is an acquired condition related to chronic degenerative disc disease and the associated changes that may lead to segmental instability. The pars interarticularis is not affected in degenerative spondylolisthesis.

The degeneration of intervertebral discs (degenerative disc disease) results in narrowing of the disc space, which allows the supporting structures to become lax and can lead to segmental instability, most common at L4-L5.

Bulging of the discs is possible for degenerative disc disease

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