Back Sufferers' Bible: Understanding Is Half the Cure. You Can Treat Your Own Back! - Brossura

Key, Sarah

Brossura

ISBN 10: 1741751896 ISBN 13: 9781741751895

Casa editrice: Allen & Unwin, 2008

Riassunto

Providing concise yet comprehensive coverage of why back pain occurs as well as a range of instructions, advice, and exercises to cure its many forms, this analysis encourages patients to actively contribute to their own back-pain management. With a new reference section, this updated handbook clearly shows how each stage of back pain manifests, sets out a logical course of treatment programs, explains when patients need medications or simply rest, and describes curative exercises. Anyone who suffers from back pain or who wants to understand how to manage it will benefit from this essential resource that shows what has gone wrong with the spine and the steps to take and keep the back healthy and pain-free.

Su questo libro

Informazioni sull?autore

Sarah Key is a trained physiotherapist and the author of Back in Action and Body in Action. She was made a Member of the Victorian Order acknowledging her many years of service treating members of Britain's Royal Family.

Estratto. © Ristampato con autorizzazione. Tutti i diritti riservati.

Back Sufferers' Bible

By Sarah Key

Allen & Unwin

Copyright © 2007 Sarah Key
All rights reserved.

ISBN: 978-1-74175-189-5

Contents

Foreword, 
Introduction, 
1 How a normal spine works, 
2 The stiff spinal segment, 
3 Facet joint arthropathy, 
4 The acute locked back, 
5 The prolapsed 'slipped' intervertebral disc, 
6 The unstable spinal segment, 
7 Treating your own back, 
Reference reading, 

CHAPTER 1

How a normal spine works

This chapter describes the nuts and bolts of how the spine works. Parts of it are quite technical, particularly the mechanics of bending and the function of the various muscles, but I'm afraid there is no way around this. It is simply not possible to understand how things go wrong without first seeing how they should work. More to the point, the information lets you know what you are doing when it comes to fixing your back.

WHAT IS A SPINE?

Figure 1.1 The human spine is a slender segmented column made up of 24 segments sitting atop the narrow sacral base.

The human spine is an upright bendy column. It consists of 24 separate segments called vertebrae which sit atop each other in a vertical stack. There are seven in the neck (cervical), twelve in the middle back (thoracic) and five in the low back (lumbar). The base of the spine sits on the sacrum, which is a solid triangular block of bone at the back of the pelvis. The sacrum tilts down at the front to an angle of approximately 50 degrees below the horizontal, making a concavity in the low back as the spine arches to compensate.

The spine rises out of the pelvis in three gentle curves like a cobra from a basket. Its 'S' shape helps hold it upright, and by arching back and forth over a central line of gravity it balances the top-heavy torso over its narrow base. With perfect spinal alignment (posture) a straight line can be drawn through the ear, the tip of the shoulder, the spine at waist level, the front of the knee joint and the back of the ankle.

The hollow in the low back is called a lumbar lordosis. This is followed by a gentle hump the other way in the chest region, called the thoracic kyphosis, and another arch in the neck called the cervical lordosis. The lumbar lordosis lessens with sitting when the pelvis tips backwards on the sitting bones (the ischial tuberosities) and increases with standing.

Figure 1.2 A lumbar hollow (lordosis) is critical for spinal health; it allows the spine to sink and spring to absorb impact while walking and also stacks the spine in equilibrium during sitting.

Perfect lumbar alignment achieves two important ends: it ensures the correct distribution of bodyweight through the front and back compartment of each lumbar segment, and allows your lower back to bow forward slightly to absorb impact during walking. As you might imagine, the right amount of lumbar lordosis is an important factor in avoiding back pain.

The following discussion highlights the anatomy which allows the spine to move in its free-flowing way — guiding it and controlling it so it doesn't go too far.

The lumbar vertebrae

The vertebrae are the individual building blocks of the spine. Each has a front and back compartment. The front compartment consists of the circular vertebral body, shaped like a cotton reel, which is specifically designed to stack easily and bear weight. The back compartment protects the spinal cord and hooks the spinal segments together so they stay in place.

Five lumbar vertebrae make up the low back. At the base of the spine the bottom vertebra (L5) sits on the sacrum and the junction between the two is called the lumbo-sacral or L5-S1 joint. As the most compressed level in the spine it is the most problematic. A high percentage of back trouble is caused by dysfunction of the front or back compartment (sometimes both) at this level.

The back compartment is a ring of bone, which barely takes weight, extending backwards from the vertebral body. In standing it bears approximately 16 per cent of bodyweight, but less if the spine is more humped in the sitting position where the facets are less engaged. With severe disc narrowing — the primary form of breakdown of the spine — the facets may be forced to take much more weight (up to 70 per cent), which is tremendously destructive.

Each back compartment has small projections of bone sprigging from the outside corners: two wings out either side, called the transverse processes and a fin projecting out the back called the spinous process (these are the spinal knobs you can see through the skin running down the back). All these bony bars serve as levers for the attachment of muscles which make the vertebrae move.

Figure 1.3 The vertebral bodies of the front compartment are designed to stack easily and bear weight, while the bony ring of the back compartment protects the cord and notches the segments together at the facet joints.

The 'cotton reels' superimposed on one another at the disc– vertebra union make up the beautifully bendable neurocentral core, and the junctions between are often called the interbody joints. The bony inter -notching either side at the back makes a chain of mobile juicy apophyseal or facet joints, running down the entire length of the spine. Together, the two different types of joints of the front and back compartment make up the total 'motion segment' at each spinal level.

All the muscles working the segments exert a downward pull as they bring about movement. If you bear in mind how much time we spend upright, fighting the weighing-down effects of gravity, you can see there are two factors at the start — our weight plus the muscular strings working the vertebrae — contributing to spinal compression. But there is also a third: sitting. Long periods of heavy sitting slumped in a 'C'-shaped posture loads up the discs and is particularly compressive; even more so as the facet joints at the back disengage and the belly lets go at the front. This is noteworthy, because I believe lumbar compression is the background cause of most low-back problems.

The vertebral bodies are prevented from grinding on one other by the intervertebral discs. These are high-pressure fibrous sacks containing an unsquashable sphere of fluid in the centre, called the nucleus. The 24 bony segments interspersed with discs makes the spine into a dancing resilient column, readily able to carry load and absorb extraneous forces from all directions.

The actual shape of the vertebral bodies helps spread the load. They have a narrow waist which flares out to a broad weight-bearing upper and lower surface. Unlike the other lumbar vertebrae, L5 is thinner at the back, which helps to form the lumbar lordosis. Its disc is also slightly wedge -shaped although it is still the fattest disc in the spine, helping it to bear the load of the rest of the body towering above.

Each 'cotton reel' is made up of a layer of hard cortical bone on the outside and honeycomb bone (or cancellous bone) on the inside. This is sometimes called the 'spongiosa' because it resembles a sponge and stores a rich supply of blood. The presence of the blood inside the bones is an ingenious way of dispersing forces through the bone.

Figure 1.4 The honeycomb cancellous bone (spongiosa) is really a three-dimensional internal scaffolding which stops the vertebral body crumbling under load. The blood reservoirs in the vertebrae also help absorb shock.

Apart from being a handy reservoir, the fluid inside helps absorb the impact of shock passing through the vertebrae. These box-like bodies, literally bursting with blood, transmit the forces of compression in all directions throughout the fluid, thereby dissipating the direct downward pressure. As well as reducing strain, this functions as a useful engine for shunting nutrient-bearing fluids into the disc, which does not have its own blood supply.

The line of demarcation between the vertebra and the upper and lower surfaces of the disc is called the vertebral endplate. It is a thin cartilaginous interface about 2 mm thick and although each one is cushioned by the disc in between, it is still the weakest part of the spine. With rigorous impact, each endplate can seem like a semi-destructible membrane caught between two thundering fluid-transmitted systems: the vertebral body on one side and the disc on the other. Sometimes, impact through the spine can blow a tiny vent in an endplate, like blowing a hole through hide stretched over a drum.

The honeycomb bone inside the vertebra is actually a gridwork of tiny struts and spars, like internal scaffolding. Its three-dimensional structure prevents the roof of the vertebra caving in and the walls collapsing inwards like a cardboard box being flattened. It is a brilliant way of making the bones strong yet light. If the vertebrae were solid it would be much harder for our spines to operate. Not only would the bone tend to cleave off in chunks when subjected to compression and torsional strains but we would hardly be able to move for our own weight.

When the vertebrae are superimposed on one another, the consecutive bony rings at the back make a hollow tube inside the spine called the spinal canal. The canal houses the fragile spinal cord of the central nervous system which hangs down from the base of the brain like a long plait of hair. Filaments of nervous tissue branch off either side all the way down and become the spinal nerve roots. The cord itself actually ends at the level of the second lumbar vertebra. The roots then continue on inside the spine, hanging down like strands of a horse's tail (hence the name 'cauda equina') until they make their exit either side through their designated intersegmental level.

Whereas the role of the front compartment is fairly straightforward as a weight-bearing strut, the workings of the back compartment are more complex. Apart from acting as casing to protect the spinal cord it has two other important functions: to guide the movement of the vertebrae — favouring some and keeping other more troublesome ones to a minimum — and helping to lock the vertebrae together to stop them slipping off one another.

Figure 1.5 The spinal cord ends at the level of L2 and the nerves continue on down inside the spine as the cauda equina. Each set of nerve roots exits the spine at its designated level.

The spinal ligaments

The spinal ligaments are a very important backup system to keep the spinal segments together. Between the bony locking mechanism and the muscular system they guide and restrain the movements of the vertebrae. The most important group is 'the posterior ligamentous system' made up of the capsular ligaments, the ligamentum flavum, the inter-spinous ligament, the supraspinous ligament, and the posterior longitudinal ligament. They make a dense festoonery of fibrous reinforcement connecting the bony parts of the spine at the back and the whole system comes into its own when the spine bends and lifts.

The capsular ligaments are really the facet joint capsules and they, together with the discs themselves, do the bulk of the ligamentous restraint in holding the segments secure when the spine bends. Researchers have removed the discs from cadavers in a laboratory and shown that half the body's weight can be suspended by facet capsules alone.

The ligamentum flavum is a thick short ligament covering the front of the facet joints at each segmental level. Each one has a smooth surface to help create a safe, comfortable lining for the back of the spinal canal with the delicate spinal cord inside.

In its healthy state, the ligamentum flavum is unusual because unlike other ligaments it has more muscle tissue (elastin 80 per cent) than fibrous (collagen 20 per cent), making it in reality a 'muscular' ligament. The purpose of this may be for ligamentum flavum to maximally shrink itself, thus avoiding physical runkling into the highly sensitive spinal cord. In the degenerative process, it is not uncommon for ligamentum flavum to calcify and become so bulky that it affects the very blood supply to the spinal cord itself. This is part of the process called vertebral stenosis.

While the ligamentum flavum covers the front of the facet joints, the multifidus muscle (about which you will read a great deal in this book) covers the back. With both muscles right at the nexus of forward movement of a segment, they are intimately involved in controlling it. In particular, they guard the laxity of the facet joints — which are the most likely part of the spine to come undone. They stand like muscular sentries front and back, controlling how much they pay out to let facets open for the spine to bend.

Figure 1.6 The collection of ligaments at the back of the spine constitutes the 'posterior ligamentous lock' which generates greatest holding tension when the back is rounded. Easy to see why we should lift with a humped lower back. (Note: Capular ligaments not shown.)

Both 'muscles' do an equally important job during bending by pressurising the disc. Through the facets they generate a tension at the back of the interspace which primes or pre-tenses the disc and stops unwanted wobble of the segment as the spine leaves the safety of vertical. It is a vitally important role and you will see in Chapter 4 how sometimes this mechanism falters. If the spine goes to bend before having worked up sufficient holding power in the multifidus muscle — usually due to bending with a weak tummy, or with the back arched instead of humped — there can be a fluke mishap where the upper vertebra slips imperceptibly at one of its facets.

The interspinous ligament is situated between the tails of the vertebrae with its fibres aligned in such a way as to resist opening of the backs of the vertebrae. The supraspinous ligament links the tips of the spinous processes (the tails), and also helps them to resist splaying open. There is no supraspinous ligament between L5-S1 interspace, presumably because this is taken care of by the massively strong ilio-lumbar ligament.

At the 'critical point' in bending, restraint passes from the spinal muscles to the posterior ligamentous system. Muscle activity ceases at full bend when you literally 'hang on your straps' with the back held stable by the passive tension of the ligaments. In the controversial area of correct lifting techniques it should be obvious that there are sound biomechanical reasons for slightly humping (rather than arching) the lower back to lift. This simple measure brings the critical point forward and makes the spine more stable earlier in range. (Though I fly in the face of convention here, I welcome — with some temerity — the debate opening up and ultimately benefiting our instructions to industry on manual handling.)

The ilio-lumbar ligament provides the main shoring for the base of the spine. It is a broad star-shaped band of fibrous thickening which passes from the inside bowl either side of the pelvis and converges upwards on the lowest vertebra, attaching itself strongly through the two huge transverse processes which curve downwards to meet it like tusks.

Incidentally, to provide extra strength in lashing the base of the spine to the sacral table, the transverse processes of L5 are built in a pyramidal shape with a broader base to receive the two strong ropes of the ilio -lumbar ligament. Handy as this may be in providing a better base for attachment, it does somewhat occlude the diameter of the intervertebral foraminae. These are the two small holes below the transverse processes at every spinal level through which the nerve roots issue. If you bear in mind that the L5 root is also the thickest, you can see at the start why the lumbo -sacral level is so prone to being inflamed by pathological processes affecting either the front or back compartment (or both).

Figure 1.7 The star-shaped ilio-lumbar ligament attaches to the tusk-like transverse processes and binds the base of the spine to the sacrum, deep within the pelvis.

The long tube of 'cotton reels' making up the neurocentral core is reinforced front and back by two strap-like ligaments called the anterior and posterior longitudinal ligaments. The anterior longitudinal ligament is the strongest ligament in the spine and by interlinking the front of the vertebrae it stops your spine bending back too far. It also prevents the lower back sinking too deeply into an arch (or lordosis) as the spine takes weight.

The posterior longitudinal ligament runs down the back of the cotton reels, spreading out over the back of each disc in a crosshatching of fibres to reinforce this part of the disc wall. More than the other ligaments, it has a highly developed nerve supply and is extremely sensitive to stretch. Significantly, in the case of a prolapsed intervertebral disc when escaping nuclear material squeezes out — between chinks in the disc wall (see Chapter 5), the cause of irritation can be twofold: stretching both the outer layers of disc wall and the ultra-sensitive posterior longitudinal ligament lying on top of it.

Figure 1.8 The strap-like anterior and posterior longitudinal ligaments encase the front and back of the 'cotton reels' like a ligamentous strait-jacket.

At its simplest, the spine gets most of its movement from the cotton reels sitting on their discal pillows and careening about in all directions. The role of the back compartment of each motion segment is to control that movement.

The intervertebral discs

The intervertebral discs are resilient, water-filled pillows between the vertebrae. They have scant nerve supply and no blood supply; indeed discs are the largest avascular structures in the body. This also means that other mechanisms must be utitilised to transport raw materials and waste products to keep the discs alive, which will be discussed below, but even at the best of times discs struggle to remain viable.

Discs are designed to give us flexibility at low load and stability at high load and it is significant that our vertical posture helps achieve this by enhancing the tensile strength of the disc walls. It adds to the pressurising of the fluid sacks and converts the spine into a whippy spring-loaded rod of many segments which can flip up straight again after bending.

Figure 1.9 The disc's nucleus acts like an hydraulic sack distributing forces outward and evenly in all directions. The greater the pressure, the greater the tensile strength generated in the outer disc walls.

Without these tensile properties, the human back would not be the long slender thing it is. We would need a hugely muscular apparatus to haul us up straight again once we had doubled over. However, vertical posture does have its down side. It means the segments at the bottom of the stack are always more loaded by the weight of the rest of the body towering above.

(Continues...)

Excerpted from Back Sufferers' Bible by Sarah Key. Copyright © 2007 Sarah Key. Excerpted by permission of Allen & Unwin.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Dettagli dell'edizione

• Editore: Allen & Unwin
• Data di pubblicazione: 2008
• Lingua: Inglese
• ISBN 10: 1741751896
• ISBN 13: 9781741751895
• Rilegatura: Copertina flessibile
• Numero di pagine: 244
• Contatto del produttore: non disponibile
• Persona responsabile: non disponibile