Low Back Pain and Sciatica: Do Discs Really Slip Out?

Disc Picture

Sciatica is not a diagnosis but a term that medical professionals use to describe ‘pain in the back of the thigh, typically the hamstring and calf area’. One of the many reasons for low back pain and sciatic pain be an irritated nerve root, but what is the cause? Many people are told, often incorrectly, that it is likely that they have a ‘slipped disc’ that is causing their leg pain.

Most people given such a diagnosis would naturally be concerned and consequently stop moving in an effort to protect their spine. Inevitably this will usually make their pain worse, increase spinal stiffness, reduce  spinal range of movement and lead to muscle weakness (atrophy).

There are a number of reasons why discs do not ‘slip out of place’, and in fact might not even be responsible for some case of sciatic pain:

(1) Research using MRI scans has shown that 25-30% of the general population have confirmed evidence of a lumbar intervertebral disc (IVD) bulge but surprisingly don’t have any leg pain; therefore in some cases a disc bulge can be a normal age related finding;

(2) Spinal disc are incredibly strong structures, and very rarely protrude or bulge and certainly don’t ‘slip in and out’ as we are often told. The terms that we tend to use are ‘prolapse’,  ‘herniation’ or ‘sequestration’. These all mean slightly different things;

(3) The bony blocks of the spine (so called vertebral bodies) contain ‘endplates’ which are structures that provide an anchor point for the collagen fibres of the disc, thus helping to hold discs in place.

(4) Disc pathology, even when symptomatic, doesn’t always relate to a prolapse or herniation; thinning, loss of IVD height and most importantly the position of the pathology in relation to the exiting nerve root are key factors to consider.

In summary, a comprehensive clinical assessment at PhysioDoc can help to determine if your symptoms are coming from a disc. Although an MRI scan can be helpful for some patients, it will inevitably show a number of age related findings (grey hair!) that does not usually alter your management plan or rate of recovery. One thing for certain; DISCS DO NOT SLIP OUT OF PLACE!

Dr Jamie Bell