The Mechanics of Acute Low Back Pain – Why are you in spasm?

Written by Stephen Sacks – Medically reviewed by Stephen Sacks – Last updated May 27, 2014

Perhaps, the most common and anxiety-provoking back pain is the one that comes on so suddenly. You bend over to brush you teeth, you put a dish in the dishwasher, you feed you baby …AND…it’s gone, it’s stuck, you can’t move!

You can be an old hand at this or you can say like so many others do, “I have never suffered from back pain”.
We feel old when it happens and fragile and embarrassed and desperate.
When they come to my waiting room and I call them in, the desperation if often palpable. Some prefer to stand, some want to sit, all want it to stop! Many don’t know how it happened while some do. Some feel it was a question of time before it ‘hit’ whilst for some it comes out of the blue. For all it is one sided – even for those who feel it is in ‘the middle’. Often, when I ask the patient where the pain is, they use one hand to show that it is in the middle. I figured out a while ago that the hand used to demonstrate is most commonly the side that the pain is on. I.e. a right-hand-dominant person will comfortably use his left to point to his back and say that it is in the middle when indeed, it is on the left. Most commonly, it is felt around the base of the spine around the ‘venus dimple’ or sacra-illiac joint (SIJ).

But first let me explain what, I think, mechnically happens to you and in doing so enable you to understand your pain and self-solve it to an extent.

Mechanics of the spine

The upper and lower back have to different functions: the upper back is much better at rotating and because there are ribs wedging between the thoracic vertebrae, not so great at side-bending. The lower back is different, it is not great at rotating because the structure of the joint doesn’t allow it but, as a unit, much better at side-bending.

Joining the upper spine to the lower, we find the thoraco-lumbar junction (TLJ) which is the interplay between the two. Joining the last rib to the pelvis is a muscle called the quadratus lumborum – some call it the QL.

Now, this is how you hurt your back – let’s say the left. 1. You bent forward, even if ever so slightly. 2. You rotated to the side, probably right, even if ever so slightly. 3. and then you side-bent to the right.
As a result, your thoraco-lumbar junction is put under tension, it is having to flex, rotate and side bend under unfavourable circumstances. Unfavourable because it is, for some reason at that specific time, not ready for the mixture of movement. Precarious at best! The quadratus lumborum (which Dr. Janet Travell called the Joker of back pain) needs to protect the area (that is what a muscle spasm is – the body’s overly enthusiastic response to protect and try and prevent pain) and sudenly pulls back- mainly on the coming back up from the bend.

The spasm pulls up on the ilium (the attachment on the pelvis), jams the sacra-iliac joint and you, my friend, can’t move! All sorts of things then happen, the pelvis rotates, you stand up like the tower of Pisa, you limp with an apparently shorter leg from the rotated pelvis. Sneezing hurts in the lower back (the sudden action of last rib and it’s accessory breathing muscle – the QL), we can have an upet tummy due to visceral referral. We have to use our hands to lift ourselves from a chair because teh pelvis is stuck and it takes a few steps before we are upright.

Ease Your Pain

First, stretch out your QL by doing some side bending exercises. Be careful that you are only stretching the lower back. Pushing your hips to the side or dropping the shoulder does not constitute side stretching – be specific. Rotate the upper back – do not rotate the pelvis too. by separating these two, the TLJ will marry up and loosen.
Even though the pain is lower at the SIJ, if you can start with the TLJ area and QL, some pressure will release from the SIJ.

I will, hopefully put some specific stretches on here at some point when I have time and a more pleasant model than myself.

Then, if you are no better, pop in for a visit!