Stage 5: The Final Stage of Segmental Breakdown

Lumbar instability is often diagnosed, even though in reality it is not common. Also known as segmental instability, it is Stage 5 of degenerative breakdown of a lumbar segment as described by Sarah Key.

A Spinal Segment Works Itself Loose in Three Ways:

1. The intervertebral disc dehydrating and losing pressure
   
   
2. Erosion of  facet joint cartilage, making the locking mechanism sloppy
   
   
3. The degenerative process weakening all the soft tissues binding the spinal link

How Does the Pathology of Lumber Instability Worsen?

The dehydrated disc cannot spring-load its vertebra as the spine bends. With each bending movement the unstable segment goes to shear forward, tugging at the walls of its disc as it goes. The trauma here gradually causes the disc to self-destruct.

In the typical fashion of the body doing the best it can, extra bone grows out from the the vertebra-disc margins and facet joint surfaces to try to stabilise the segment. These are called osteophytes, or bony spurs, and they should never be removed by surgery. 

How Do You Know if You Have an Unstable Segment?

The main feature of lumbar instability is a 'painful arc' on bending. It is referred to as the 'broken reed back' as the back feels stable enough - even too stiff - when standing, only to give way painfully at the slightest bend forward. Active bending may also present as a 'circular trunk movement' as if the body is rolling around the rim of the vertebra below as a means of preventing shear.  

Instability is the final stage of breakdown of a spinal segment. You can read about it in depth in Chapter 6 of Back Sufferers' Bible. Better still, you can download the video Lower Back Strengthening Exercises where Sarah discusses instability and other internal weaknesses of the back - and also takes you through what you can do about it to avoid a surgical spinal fusion.