From Amanda's very early writing (1990s to early 2000s), shared as it was originally written.
In the last couple of weeks we talked about the anatomy of the back and causes of injury and about muscle spasm. This week I wanted to cover ‘slipped discs’.
Most people think that this is the most common form of back injury and that it immediately leads to chronic invalidity! Wrong!
In fact, discs don’t ‘slip’. The actual disc is shaped like a jam doughnut - with a jelly inside and a fibrous layer outside. This fibrous layer is like a cricket ball - if you peel off the skin of a cricket ball, there a zillions of layers of string like material going in all sorts of directions. This string arrangement gives the outside of the disc flexibility and allows it to absorb a lot of torsion (medical jargon for twisting).
When we are young, our discs are wonderfully squashy and pliant and resilient. As we grow older, they lose some of this elasticity and become more rigid. They also get tired! We abuse our backs (not to mention bodies!) and the discs often take the brunt of the load so they become tired , worn out and damaged and more susceptible to injury.
In reality, the older we are the less likely we are to ‘slip the disc’ because it has become like an old cricket ball inside and the jelly has gone.
So what does slip a disc mean? Between any two bones in our vertebral column (medical jargon for back) is a disc. It is held in place by ligaments (medical jargon for strong elastic bands)- two big ones that run all down the anterior (medical jargon for front) and all down the posterior ( medical jargon for back!) of the bones. These ligaments help to protect the disc and keep it intact. (medical jargon for ‘in one piece’)
At either side of the back of the spine (the medical way of saying this is posterolateral ) there is a gap where no ligament surrounds the disc. Uh oh - yes you are right! The disc can bulge out here because there is no big strong elastic band holding it in place.
When we twist, we ring the disc out like we ring out a wet towel. It is the best way to damage a disc. If you want to be permanently disabled then all you have to do is bend AND twist at the same time! And keep doing it. Or stay in that position for more than a few minutes. See, it’s easy isn’t it? To really damage your spine.
In fact, discs do not ‘slip’. What people call a slipped disc refers to a situation where the jelly part of the disc is squeezed out of it’s central hole. If it’s a minor disc bulge as we call it, the jelly (the ‘nucleous pulposis’ if you are reading an X ray report and can’t understand it) is squeezed out into the fibrous layer (called the ‘annulus fibrosis’ if you want to impress people) , which causes the whole doughnut (or disc) to bulge out the side the jelly is leaking.
If you do a really great job and put huge amounts of pressure on the disc ( it doesn’t take that much) then you will rupture (medical jargon for rip apart) the outside fibrous layer and the jelly will go squirting out into your spinal canal. (medical for small bony hole at the back of the backbones in which the spinal cord sits) , press on the spinal cord and give you severe pain. With or without neurological involvement. (medical jargon meaning you can’t use your muscles any more or you are in deep trouble and better do something serious about looking after yourself SOON).
A relatively small proportion of back injuries are actually disc ruptures. And they most frequently occur in strong, young men, who, like my brother, try to lift things like fridges the size of the house with their necks!
One of the characteristic signs that a disc is damaged is that if you stand in front of a mirror and look at yourself, you will notice that your shoulders are several inches to the right or left of your hips. You are not bent sideways necessarily, but if you dropped a line from your shoulder to the floor it would miss your hips by a couple of inches. If you notice this , GET HELP SOON! Visit a medical specialist and a great physiotherapist. ??Maree can I plug physios here? You need serious treatment.
Sitting is rotten for discs - when we lie down there is about 25mm mercury pressure on the discs in our backs. When we stand up there is about 100mm mercury pressure. When we sit down there is 400mm Mercury pressure on our backs!
