The Way the Spine Works

Each segment of the spine is made up of the intervertebral disc in the front compartment and a pair of facet joints in the back. Both mechanisms operate as a sort of hinge to give the segment mobility yet stability, and they work in very different ways. The additional specific functions of disc and facet means they suffer very different strains and a segment becomes painful when either [or both] mechanism malfunctions. Wear and tear of either structure manifests as its own idiosyncratic type of back pain.

The role of the front compartment of a motion segment is to take most of the weight. It does this through the cotton-reel shaped vertebral bodies and the intervertebral discs sandwiched between. The discs are water filled fibro-elastic pillows that slowly lose water through the day under the effects of gravity and muscular contractions, so that by evening we are all about 2cm shorter. Only the outer layers of the disc wall [the annulus] are innervated and this is also the only part of the disc with a blood supply.

Disc nutrition is transacted by a stately exchange of fluid pressed out by day and drawn in again overnight. Small gulps of fluid - sucked in during the day by spinal movements that pull the segments apart - are critical in retarding disc deflation and aiding disc nutrition. As you might imagine, typical sedentary lifestyles provide little in the way of expansive spinal activity during daylight hours. Indeed, prolonged sitting and low activity levels, coupled with high-impact sporting endeavours, all contribute to the back pain pandemic. It is important to note that intervertebral discs degenerate sooner in life than other soft tissue in the body, and the rate is picking up.

Unlike the discs, the notching-together facet joints at the back of the spine take very little weight [approximately 16% in the standing position]. Their role is to minimise twisting strain of the lumbar segments and prevent them sliding forward off one another as the spine bends. Also unlike the discs, the facet joints have a prolific blood and nerve supply.

What Goes Wrong?

The front compartment develops trouble when excessive compression (usually through indolent Western lifestyles) further reduces disc metabolism. As a disc loses metabolic vigour it loses its ability to attract and retain water. Over time, the nucleus at the centre of the disc dehydrates and the disc loses height. As the shrinkage becomes permanent, the walls of the disc start bearing load, like resting a cement slab on a wicker basket [see left]. Since the outer wall is innervated, this becomes painful. I believe this is the most common cause of simple back pain.

The disc absorbs impact badly and also stretches poorly; the two segments cannot pull apart freely as the spine moves. Both factors - compression and stretch - cause pain and in Chapter 2 of 'Back Sufferers' Bible' I have named this very common, pre-pathology 'stiff spinal segment' [SSS]. Once the condition starts to show up on scans it takes the name of 'degenerative disc disease' [DDD].

Loss of disc height causes trouble for the facet joints at the same level. As the upper joint surfaces ride down the lower ones (see left) there is bony abrasion of the opposing cartilage interfaces which causes pain. The condition, known as 'facet joint arthropathy' [FJA], is described in Chapter 3 of 'Back Sufferers' Bible'. As the disc continues to lose height the roof of the spinal nerve's exit hole - the intervertebral foramen - also comes down and the passing nerve may be irritated. This may cause leg pain or sciatica. I believe facet arthropathy is the second most common cause of back pain.

In the book 'Back Sufferers' Bible' I propose that most lumbar problems originate as a 'stiff spinal segment'. I also postulate that backs get worse 'developmentally' as they acquire more widespread dysfunction of the problem segment. I also believe that improving the function and hence the nutrition of an ailing disc must be the first and foremost aim of all 'therapy', no matter what stage of degeneration the segment is in.  

We know that pressure changes through discs stimulate their metabolism and specifically promote the synthesis of proteoglycans - and thus the disc's ability to hold and circulate water. 'Mechanobiology' - or therapeutically induced pressure changes - aims to improve discal fluid flow and ultimately disc height as it slowly gets healthier and rehydrates.

Both the front and back compartments of a spinal segment work more effectively if the disc is fully hydrated and buoyant. Another important benefit is that a puffier disc allows the segment-to-segment deep spinal muscles to work more efficiently. 'Higher' discs afford these muscles their optimal angle of pull so they can better control their segment as the spine bends.

 

The Tools of Self Treatment:
The BackBlock

The first principle in treating low back problems is the daily lumbar traction or decompression to distract the lumbar segments. All patients treated by the Sarah Key Method are taught to use a BackBlock because they can effectively do this at home [it can be done over a 7cm stack of books]. The regime should be carried out in the evening, when the spine is most compressed, because that helps the discs imbibe fluid to their maximum during the night hours when the spine is unweighted. The local stretching also makes the disc walls more elastic, which allows them to accommodate more fluid. This makes the back less brittle and better able to ride out the jolts and bangs during the upright hours. A more compliant spine is an important factor in stopping further breakdown.

The BackBlock is about the size of a shoebox. When sited under the pelvis like a fulcrum, the body drapes passively backwards, which distracts the lumbar segments and makes them pull apart. This unusual 'anti-sitting posture' stretches the discs and also stretches the soft tissues at the front of the spine and hips, which have adaptively shortened through many hours spent crumpled forward in working postures. By easing the entire skeleton backwards, over several weeks, the BackBlock also creates better alignment of the upper body over the spine's narrow base. In other words, it makes you stand straighter which is critically important for recovery.

The Ma Roller

The second wooden tool you can use in treating your own spine is the Ma Roller which specifically targets the facet joints. It is shaped like a convoluted rolling pin, with two rounded prominences either side of a central gully. These mounds are exactly sited to roll over the chain of facet joints running down either side of the spine from the base of the skull to the pelvis.

The purpose of the Ma Roller is to ease apart facet joints which have become rusty through excessive wear and tear. You use it by placing it under your lumbar area, lowering your weight onto it and then moving minutely back and forth over the sore spots. An inflamed joint is apparent by its sweet pain but it also feels agreeable, as if the troublemaker craves the contact. It takes a bit of getting used to doing it properly - and you have to relax as much as possible so the roller can pierce through the muscle bulk. You must not use the Ma Roller more than once a week because too much hurting the back can keep it quietly inflamed.

In the UK you can purchase
BackBlocks - £28 plus £10 post and package and
Ma Rollers - £20 and £5 post and package from:
Blenheim Estate Office,
Blenheim Palace,
WOODSTOCK,
Oxfordshire, OX20 1PS,
United Kingdom
email: cmccormack@blenheimpalace.com
fax: (+44) 01993813107

In Australia, you can purchase both items
BackBlock - $66:00 inclusive of GST and post and package
Ma Roller - $46:00 inclusive of GST post and package through:
The Sarah Key Physiotherapy Centre,
Level 6, 44 Bridge Street
Sydney 2000
email: net@sarahkey.com
fax: 02 9221 8103

Please note: We despatch plastic BackBlocks only to destinations outside Australia