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Lower Back Pain in Adults – Non-specific Mechanical Low Back Pain

Lower back pain is extremely common, about 80% of people have one or more episodes of back pain during their life. Even though in most cases the precise cause of the back pain is not clear, the vast majority of back pain episodes are not due to anything serious wrong with the back, such as cancer or other important diseases.

Current advice is to maintain as normal a level of physical activity as you can without suffering too much pain, take painkillers and wait until the pain settles down. Returning to fully normal activity is encouraged as soon as possible but it is quite likely that the pain episode will recur at times. A small number of people develop long term or chronic back pain, which may need management by an orthopaedic surgeon or a pain clinic.

Further useful information about back pain is available at NHS Choices and the back pain pages at PatientUK.

Understanding Your Lower Back

The low back region consists of the lumbar vertebrae (spinal bones) and the sacrum which is the large triangular bone at the bottom which connects at each side with the pelvis. The whole area is referred to as the lumbosacral spine.

There are five lumbar vertebrae sitting on top of each other to form the lumbar spine. These are an inch or more high each and roughly of a circular shape, with a disc in between each one. Discs have a tough, more fibrous outer layer (annulus) and a softer centre which behaves like a gel (nucleus). The discs allow movement of the spine and larger discs are present in areas of greater movement in the spine. They also absorb loads and transmit them equally to the bones above and below. Discs are extremely strong and rarely fail unless they have had trauma and time to change – doctors call this disc degeneration.

The discs are tightly bound to the vertebrae above and below and are unable to “slip out” so a slipped disc refers to a disc protrusion through the annulus. Strong ligaments support the spine by attaching from one bone to another up and down the whole spinal column.

A large number of strong muscles attach to the spine and acts as movers or stabilisers when we want to complete activities. At the back of the spine is the spinal canal, a bony tube where the spinal cord sits as it runs down from the brain to allow the nerves to reach all parts of the body.


Types of Low Back Pain

Back pain can be caused by a large number of different conditions, some related to the structure of the low back and some related to other diseases and illnesses.


Non-specific Low Back Pain

This is the name given to the commonest type of lower back pain and around 80% of all episodes are diagnosed as “non-specific” which means that no structure can be identified as the cause with any certainty. This type of back pain can be mild or extremely severe and troublesome but is not serious from a medical point of view, i.e. there is no serious condition underlying it.


Nerve Root Pain – Sciatica

Much less common than back pain, it occurs in around five percent of cases and is distinguished from back pain by being very severe, surging pain down the leg, often worse in the foot than further up. The pain is usually in a typical pattern related to which nerve is involved. In some cases there may be no back pain at all.

Sciatica is mostly caused by nerve compression and irritation caused by a disc prolapse, as the nucleus of the disc protrudes through the outer wall and hits what is called the nerve root, the part of the nerve which has just come off the spinal cord and is on its way down to the leg. This is often referred to as a trapped nerve.

Irritation and compression of the nerve root gives the severe pain in the leg and also can give loss of reflexes on testing, loss of muscle power in the muscles it supplies, pins and needles and numbness.

Most leg pain is not sciatica but referred pain from the structures in the spine, where the brain interprets the messages coming in from the spine as being in the buttock, hips or legs. This kind of pain rarely goes below the knee and is more achey and hard to pin down, rather than the sharp, very unpleasant and clearly defined pain of sciatica.


Cauda Equina Syndrome CES – A Rare but Serious Condition

Cauda equina syndrome a very serious type of nerve compression where the nerve in the lowest part of the spinal canal are compressed severely, either by a huge disc prolapse, trauma such as a fracture, or a tumour.

Symptoms of CES include severe and disabling back pain, variable leg weakness or pain, interference in bladder or bowel function and loss of feeling between the legs around the genitals and anus. This is an extremely serious condition if it occurs and you should consult a doctor at once if you have this combination of symptoms, or you may risk long term problems.


Other Causes of Low Back Pain

Osteoarthritis, the commonest degenerative joint condition in the world, can affect the posterior spinal joints and become painful. This is more common in older people.

Ankylosing spondylitis is an arthritic disease most commonly presenting in young men, where the inflammation and pain leads to increasing joint stiffness over time. AS needs management by a rheumatologist.

Rheumatoid arthritis, another arthritic disease, can also have serious spinal effects along with the more obvious effects on the limb joints. Rheumatological management is important here too.

Tumours, infections, trauma, osteoporosis and other conditions may also cause low back pain and are referred to as non-mechanical low back pain. These problems all need specialist assessment and treatment. These occur in less than 1% of cases of low back pain and are more common again in older people.


The Cause of Non-specific Low Back Pain

Most lower back pain is classified by doctors and physiotherapists as being non-specific lower back pain. This is really a non-diagnosis or diagnosis of exclusion, which means that all medically serious diagnoses have been ruled out, and back pain due to a strain or sprain of one of the tissues in the back is the most likely cause.

The likely candidates for this kind of mechanical back pain are a strain or sprain of a muscle or a ligament, damage to the capsule (fibrous bag) surrounding one of the small facet joints or damage to the back wall of the disc. In almost all of these cases it is not possible to determine which structure is responsible for the back pain.

While it can be frustrating not to have a specific diagnosis for back pain, this at least means that the pain is not serious from a medical point of view as there is no underlying condition responsible for it.


The Symptoms of Non-specific Lower Back Pain

Acute back pain may come on suddenly such as on bending over, lifting something or pulling something in the garden, while in other cases it just appears for no obvious reason. Sometimes it comes on insidiously (slow and sneaky) and builds up over time. In other cases a person might wake up and suddenly be aware they have significant low back pain.

Non-specific low back pain, also referred to as simple back pain, may be very mild and of no importance or very severe and disabling. There is always some back pain, either higher or lower, along with buttock and thigh pain at times. Mechanical lower back pain is related to the stresses and strains on the tissues of the low back so is usually worse with movement, maintained postures, leaning forward, sneezing, coughing or laughing and better lying down.

Back pain may also be referred round to the side, giving hip pain such as lateral hip pain which could be mistaken for bursitis, particularly hip bursitis, a common cause of hip pain running. A physio will be able to examine the areas and distinguish between back and hip pain, treating the back or the hip locally for hip pain relief. Buttock and lateral hip pain can be hip related and if examination shows very limited movement and pain then the joint might be a candidate for hip replacement.

Once an episode of acute back pain has occurred, it is usually a few days until the pain begins to subside, with a good improvement by a week. It may take many weeks for all the symptoms to disappear and it is common to have repeat episodes. If a significant amount of pain remains over three or six months, then the problem is term chronic back pain and may be persistent over the long term.

The Diagnosis of Non-specific Low Back Pain

Most people manage their episodes of acute back pain themselves as they instinctively realise that there is nothing seriously amiss and just get on with things. If however the pain is extremely severe or there are other worrying symptoms it may be worth getting advice from a doctor.

A typical examination will cover your medical history, your previous back pain history if you have one, as the clearest predictor of having back pain is having had some in the past, and the history of the present episode The area of the pain, its severity and type, what makes it worse and better, all these things will be asked so that a picture can be built up of the type of back pain you have.

Examination will typically show limited movement with pain in the spine but little else of concern, allowing the examiner to be confident that the diagnosis is indeed non-specific low back pain.

There are signs and symptoms (called red flags) which have to be more carefully looked at in case there is a rare chance of a serious condition causing the back pain, these include:

Cancer and infection risks:

  • First onset of back pain over 50 years of age

  • Onset of back pain under 20 years of age

  • Pain not better on lying down, or worse at night

  • Significant unexplained weight loss or a fever

  • A previous history of cancer

  • The use of injected recreational drugs

  • Lowered immunity either due to a medical condition, chemotherapy or HIV.

Fracture risks:

  • Traumatic origin such as a fall from a height

  • A history of osteoporosis with pain from a trivial activity

Cauda Equina Syndrome risks:

  • Very severe back and legs painkiller

  • Problems with bladder and bowel function – loss of bladder control and incontinence of urine or faeces

  • Saddle anaesthesia – loss of feeling between the legs

Arthritic disease risks:

  • Stiffness in the mornings lasting over an hour

  • Pain worse early in the morning after a time of rest

  • Pain made easier by activity and worse by resting

Other cautions:

  • Steadily worsening pain over time

  • Back pain not made better by lying down or resting

  • Pain around the chest

  • Leg or foot weakness, especially if progressive

  • Numbness in the leg or foot

  • Steroid use by mouth over a period of time.

The Need for Investigations and Tests

Most low back pain episodes do not need any investigation as the diagnosis will be clear from the history and examination and your doctor will feel secure that there is nothing serious amiss. Tests may actually be harmful as they may introduce delays and come up with problems in the spine that do not have any relevance.

Treatment guidelines in the UK recommend against x-raying or scanning unless there is a suspicion of some serious condition.


Treatment for Non-specific Lower Back Pain

Keep up activities as normally as you can

If the pain in severe you may need to limit your activity greatly or even rest completely for a day or so, but as soon as you can you should get back to normal day to day tasks, returning to full and normal function. Don't wait until all the pain is gone before going back to work or your normal daily routine. Whilst avoiding a severe worsening of your pain, you should challenge your back gently every day by setting goals for activity such as being up for a number of minutes every hour or walking to the paper shop daily.

Sleep as you can most comfortably. Orthopaedic and firm mattresses are not necessary and there is no evidence which shows they are helpful to back pain sufferers. You will need to know which type of bed suits you.

Go back to work as soon as you can, it will not be damaging to your back and having some pain whilst back at work is not a significant concern. Keeping busy can distract you from the pain and get you back to normality sooner.

Avoid resting for significant periods, which was often advised in the past. However, modern research shows this is a counter-productive strategy and can make the development of chronic low er back pain more likely.

Take painkillers regularly as advised by your doctor, do not take them just when the pain is severe. It's better to take them as full doses for a while as this will allow you to be more active and return to normal more quickly.

Physiotherapy may be of some use if you have problems with joint restriction as well as pain, with physios teaching mobilising exercises and core stability work.

How Back Pain Turns Out

The prognosis (how things are going to go) for low back pain is generally very positive. Whilst many people will have a good easing of their back pain within a week it has been shown that a significant section of people still have some problems after a year. Recurrences of back pain are also common, particularly during the first year after the initial episode, and if they are numerous and lead to more persistent problems, chronic back pain is what results. This is a different matter to acute back pain and needs different management.

Preventing Further Back Pain Episodes

Keeping active and exercising regularly have been indicated as the important things in preventing further episodes of acute back pain. Other exercise regimes may be useful but the evidence is not clear. Pacing activity (spreading jobs out over time) and the avoidance of performing jobs in awkward positions are obvious common sense strategies.


The Back Book: the Best Way to Deal with Back Pain; Get Back Active

Royal College of General Practitioners, The Stationery Office, 2002. Around £1.25 from Amazon.

This 21 page booklet summarises the scientific evidence for the management of acute back pain episodes and is written by a combination of professions including a physiotherapist, osteopath, orthopaedic surgeon, psychologist and GP.

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