Low back pain – what goes wrong

Low back pain is said to affect 80% of the population at some stage in their life!

Whether it be your first experience of low back pain, or a reoccurrence of a more chronic problem Active Steps Physiotherapy have a caring, scientifically based treatment approach that will aim to minimise your pain and maximise the speed of your recovery.  Strongly influenced by the Sarah Key Approach the aim of treatment is to resolve your pain as quickly as possible and then get you back moving pain free.  It is important you gain a good understanding of what has happened to your back and identify factors that have contributed to this episode of pain so that future occurrences can be avoided.

The causes of low back pain are many and varied but a comprehensive explanation of what happens in our lumbar spine that can lead to pain and injury is made by Sarah Key and her “5 Stages of Spinal Breakdown”.  Here is brief summary:

Stage 1. Stiff spinal segment. 

A stiff spinal segment may develop because we injure it and then stop moving at that level because it hurts to move it, or in our sedentary daily life we may not require/demand movement of a certain segment/s and then over time this segment stiffens up, or as if often the case in the low back, L5 and L4 are compressed daily through prolonged sitting and over days/weeks/months/years they loose their mobility.  This lack of mobility at a spinal level greatly impedes the health of the intervertebral disc at that level.  The disc is an avascular structure (has no blood supply) that relies on pressure changes induced by movement of the segment to provide new nutrients to the disc and flush out old metabolites.  If this flush and flood mechanism does not occur then our discs can not remain healthy as they are starved of nutrition.  Movement/pressure changes within the disc also produces a protein called proteoglycans which have a very high osmotic effect which sucks new fluid into the discs and keeps them hydrated.

So without movement at a spinal level we end up with a degenerative/dehydrated disc that has a flow on effect.  This can all happen without any evidence of pain or awareness.

Stage 2.  Facet joint arthropathy

Develops as a result of a stiff spinal segment!  Facet joints unlike discs have a very good blood supply and are highly innervated which makes them very pain sensitive.  As the disc becomes dehydrated and unhealthy it becomes flatter which means the two bony surfaces of the facet joint sit closer together.  The dehydrated disc also changes the axis of movement of a spinal segment which means the load/movement occurring at the facet joint is altered and over time this will cause the facet joint to become inflamed and degenerative.

Stage 3.  Acute locked back.

Is when through an incidental movement (usually bending) you experience sudden excruciating pain and your back fells like it ‘seizes up’.  You may be unable to walk/stand and its an event that you remember years later.  The biomechanics of this event are quite detailed but basically because the disc is flatter, from the back having undergone the first 2 stages of breakdown, then the segment above can no longer move with the same control over the segment below and it tends to slide/shear rather than roll and pivot.  It is also thought that during stage 1 and 2 the multifidus muscle, which is essential in controlling the facet joint in the first part of bending, has become inhibited and therefore isn’t available to control the segment in bending.

When the brain realises that this shearing uncontrolled segmental vertebral movement has occurred it sends signals the the “big” back muscles in the area to tighten up/spasm to prevent any further ‘uncontrolled/shearing’ movement.  This is called protective muscle spasm and it generally won’t ease up until your brain is reassured that further ‘uncontrolled/shearing’ will not occur.  This is where we at Active Steps Physiotherapy can guide you through what you should and shouldn’t be doing to allow your brain to turn off this protective muscle spasm.

Stage 4.  The prolapsed intervertebral disc.

A true prolapsed disc is rare (estimated at <5% of low back pain).  The term is used loosely and more often than not is used to describe a disc bulge and not a true prolapsed disc.  A normal healthy disc (one well hydrated and full of fluid) is made to bulge, its how it absorbs and disperses load/shock.  But when the disc has became flat and de-hydrated this ability to bulge and absorb load is absent.  

Imagine a freshly blown up balloon that you sit on.  It bulges in all directions equally and takes a lot of compressive load before it would pop.  That same balloon 3 days later no longer has as much air within it, and it has become floppy and flatter, and now when you sit on it it will bulge and distort in different directions compared to 3 days previously and will not be able to absorb the compressive loads as well. 

This balloon is much more likely to pop at lower compressive loads than the freshly pumped up balloon.  Over time as this disc has started to degenerate as a result of the previous 3 stages, the strong outer walls of the disc have been under increased load and can develop small tears within their layers through repeated poor loading in a non-uniform direction (the floppy/saggy balloon scenario).  These outer walls are innervated so this process will be somewhat painful.  These small radial tears allow the nucleus of the disc to migrate outside of the centre of the disc and cause localised bulging of the disc wall. 

This localised bulging can cause mechanical pressure onto a nerve root, or can cause chemical irritation which then sensitises the nerve.  Once sensitised (either mechanically or chemically) the nerve causes referred pain, usually what people describe a ‘sciatica’.  If this abnormal loading within the disc continues then the outer wall of the disc can rupture and toxic disc material can migrate out of the disc and sensitise the nerve.

This is called a sequestrated or fenestrated disc and is extremely painful but the body will deal with this over many weeks if given the right environment to heal.  Quite often people feel their backs are better (despite horrendous leg pain) after this sequestration/fenestration as there has been a release of built up pressure within part of the disc wall which was causing local pain within the disc.  It is however something that you rather avoid through prevention or early treatment.

Stage 5.  The unstable spinal segment.

Is a result of long standing degeneration of the facet joints and the disc at a specific spinal level/s.  It is not common.  Because the disc is flatter and degenerated the vertebrae tend to slide/shear over each other rather than tilt and roll with control (like the difference between driving a car with a flat tyre and a pumped up tyre).

This sliding of the segment causes further wear and tear on the facet joint surfaces and often results in the development of extra bony ‘spurs’ (osteophytes) that develop to try and add bony constraints to this excess movement.  The flatter disc also means the capsule of the facet joints is looser, providing less restraint to the joint movement.

Also the pain local to this segment causes a reflex inhibition of the ‘core’ muscles controlling this level.  Some symptoms of an unstable segment include; clicking/grinding in the back on movement, a rigid spine that gives way when attempting to bend, or alternating sciatic pain.

At any stage in the process the symptoms are all treatable and the mobility of your spinal segment can be improved. At Active Steps Physiotherapy we treat spines by:

  1. Identifying and treating the stiff spinal level/s using manual mobilising techniques aimed at restoring movement to the spinal segment and facet joints
  2. Prescribing specific home mobilising/spinal decompressing exercises aimed at restoring/maintaining spinal mobility and improving disc hydration at that spinal level 
  3. Increasing the strength and activation of the deep stabilising (core) muscles and re-train your ability to move and use that spinal level on a day-to-day basis
  4. Depending on what ‘stage’ you present with will dictate the length of time you may need to attend treatment, but the ultimate goal is to enable you to manage your spine long term and independently.

So don’t leave a back to grumble along.  Low back pain and disability is something to be avoided if possible!

Kristen has completed Levels 1 (2007) and 2 (2010) of the Sarah Key method.  She has used the techniques for many years now and has seen the short and long term benefits of the approach in reducing the number of people living with low back pain both in the long and short term.

For further reading –

Causes of back pain – by Sarah Key

The science behind decompressive treatment for back pain – by Sarah Key