Worn discs are extremely common, including in people with no pain at all. But there are four situations where a disc genuinely is the culprit.
Have you been wondering whether your lower back pain is coming from a worn disc?
In previous videos I have stressed how common worn discs are, including in people with no back pain whatsoever. That remains true. But it is not the whole story, and I want to give the other side of it here.
There are four scenarios where your back pain could be coming directly from a disc, or where the disc is contributing to it indirectly.
A note before I start: this is about how discs cause back pain specifically, not leg pain. Leg pain arises when the nucleus herniates out of its space and pinches a nerve, which is sciatica, and I have covered that separately.
How a disc is built
The discs are the cushions between the vertebrae, acting as shock absorbers.
Each has an inner substance called the nucleus. When we operate on it, the nucleus looks very much like crab meat, which is how the textbooks describe it. It is the shock-absorbing component.
Holding it in place is an outer lining of many layers, the annulus.
1. A tear in the outer lining
This is a cause of acute lower back pain that comes directly from the disc.
It typically happens when the outer lining weakens over time, often with a sedentary lifestyle: hours each day sat slumped in an office chair. The lining gradually wears thin.
Patients then tell me the pain came on suddenly after something entirely trivial, such as loading the dishwasher.
Why it hurts so much. The disc material contains a great deal of water, and that liquid also contains inflammatory chemicals called cytokines. Tested in a laboratory it has an acidic pH.
When the lining tears, that liquid leaks out. You do not see it on an MRI, but it stings the surrounding structures and sets off an inflammatory cascade. That is what produces the acute pain.
The pattern is characteristic: sudden onset, severe for a day or two, then gradually settling over the following days or couple of weeks.
Treatment. In the acute phase, simple painkillers, and walking through the pain as far as you are able.
Then, as it settles, the real treatment begins. We build a muscular brace around that segment to stabilise it further and prevent the tear happening again. During the healing period your body lays down scar tissue and almost, though not quite, reforms the annulus, because the annulus is made of collagen and collagen is what scar tissue is.
2. The end plates
This is an often overlooked cause.
The end plates are the bony surfaces in direct contact with the discs.
If a disc is worn, the shock absorption along the surface of the bone can become uneven, causing microfractures. Substances from the disc then leak into the bone, producing localised inflammation and pain.
On particular MRI sequences, such as the STIR sequence, this appears as glowing of the end plates adjacent to the worn disc. These are Modic changes.
I have discussed a full treatment protocol for this separately. It includes desensitising the nerves supplying the end plates, a procedure to stabilise the segment, and specific physiotherapy to strengthen and reinforce it. Followed properly, that protocol often allows surgery, the final stage, to be avoided.
3. Discitis
A rare but important cause of chronic lower back pain is discitis, an infection of the disc.
Healthy discs have no blood supply. If you have an infection elsewhere in the body and bacteria enter the bloodstream, they may reach the disc space, which is effectively somewhere they can hide from your immune system and continue to grow.
On MRI you see a bright disc area with erosion of the end plates above and below it.
This is a serious condition requiring fairly urgent treatment, usually a prolonged course of antibiotics. Sometimes surgery is needed to wash out the disc space, or to protect nerves being compressed by material that has leaked from the disc.
4. Disrupted movement between the bones
Finally, a worn disc can upset the way the vertebrae move relative to one another.
Healthy discs and facet joints, the joints at the back of the spine, allow a small amount of movement between each bone. If a disc is worn, it can disturb those dynamics, causing pain or strain in the surrounding structures supporting the spine.
So the pain may come from the facet joints themselves, or from muscles working overtime to stabilise that segment.
Here we must be especially cautious in interpreting MRI scans, because worn discs are such common findings. And in this scenario, surgery is certainly not an option.
The answer is physiotherapy: strengthening the muscles surrounding the spine, and also a form of physiotherapy I believe in strongly called cognitive functional therapy.
The key takeaway
A worn disc on a scan is usually incidental. But it is not always.
The four situations above are where a disc genuinely can be responsible, and each has a different pattern and a different treatment. Telling them apart is the work of a proper clinical assessment, not a scan report.
