A Slipped Disc – Disc problems explained
A Slipped Disc – Disc problems explained
Back pain, sciatica and neck pain are often caused through an injury to a disc. Everyone knows someone who has “slipped disc”, your Mum did hers after having your sister, John down the road has one and Sarah at work did hers putting the rubbish out. But what is a slipped disc and how does it happen? Contrary to the belief the disc doesn’t actually slip anyway! Before clearing up this common misconception it is worth discussing what the disc is what it does and how it causes pain.
What is a disc?
Our spine consists of a series of bones (in medical speak – vertebrae) that are connected to each other by softer spongy “bits” called discs (which in reality don’t actually look much like a disc). The discs make up approximately 30% of the overall length of our spine and made of a substance known as fibrocartilage. In its simplest terms a disc has a soft “jelly” like centre (similar to toothpaste) which we refer to as the Nucleus and a firmer tough outer ring or casing known as its Annulus which effectively holds the nucleus within it.
What does it do?
The disc essentially joins the vertebrae together and allows movement to occur. The nucleus of the disc acts to transfer load and force between the vertebrae while keeping the vertebra apart. Because the nucleus is soft it moves within the annulus. If you squash the front of the disc (bending forwards in standing) the nucleus moves backwards if you squash the back of the disc (bending backwards) it moves forwards, all the time being contained by the annulus.
Bulging, prolapsed, herniated, dehydrated or degenerate discs!
What on earth does this mean? Breakdown and weakening of the annulus (the outer part) due to excessive, sustained or repeated straining or loading can occur. This weakening allows the nucleus to “bulge” into the weakened annulus normally in a backward/sideways direction. If this bulge progresses and the annulus tears the nucleus pushes through this torn outer ring to become “herniated” or “prolapsed”.
If the nucleus starts to lose its water content or dehydrate (which co-incidentally is part of the normal ageing process) it limits its ability to take load and force. As such the annulus begins to take more of the load which over time causes gradual structural deterioration or wear and tear of the whole disc. This wear and tear process is referred to as disc degeneration. Eventually the joints of the back are also overloaded leading to degeneration or arthritic change within these as well.
Why is this painful?
When the disc is damaged chemicals released as part of the inflammation process irritate the nerves within or near the disc. This causes a pain message to travel up the spinal cord to the brain where it is registered as a warning (or as we know it, pain). Alternatively the disc bulge can cause pain by pressing on pain sensitive structures such as ligaments, spinal nerves (this is often the cause of sciatica) or on rare occasions the spinal cord.
Despite the injury to our disc we continue to load our spine (unless we are non-weight bearing, lying down or in outer space!) because we need to function and as a result we continue to feel some degree of pain. The good news is that the outer part of the annulus has a good blood supply and can repair itself over time. Unfortunately the deeper layers of the annulus and the nucleus itself don’t so healing here is restricted. This is why some people recover from disc injury and some do not.
What can I do to prevent or manage this problem?
Living a healthy lifestyle is vitally important, this includes taking part in regular exercise or activity, eating a balanced diet and keeping within your ideal weight range. Health and Safety and Risk Assessment in the work place are essential in prevention and the management of disc disorders.
Research indicates that Physiotherapy which includes a mixture of general exercise as well as specific exercise drills are useful in the management of disc related back pain. We also know that spinal manipulation and mobilisation (the hands on part that us Physiotherapists do) is of benefit in the early stages of spinal pain (more about this soon!).
When all the above options have been unsuccessfully tried, spinal injections, nucleoplasty, disc removal and disc replacement are some of the more commonly known medical procedures used.