Understanding the lower back
The lower back is also called the lumbosacral area of the back. It is the part of the back between the bottom of the ribs and the top of the legs.
Most of the lower back is made up from muscles that attach to, and surround, the spine. The spine is made up of many bones called vertebrae. The vertebrae are roughly cylindrical and between each vertebra is a disc. The discs between the vertebrae are a combination of a strong fibrous outer layer and a softer, gel-like centre. The discs act as shock absorbers and allow the spine to be flexible.
Strong ligaments also attach to nearby (adjacent) vertebrae to give extra support and strength to the spine. The various muscles that are attached to the spine enable the spine to bend and move in various ways.
The spinal cord, which contains the nerve pathways to and from the brain, is protected by the spine. Nerves from the spinal cord come out from between the vertebrae to take and receive messages to various parts of the body.
Causes of lower back pain
Common causes of lower back pain include:
- Nonspecific lower back pain.
- Nerve root pain (sciatica).
- Cauda equina syndrome.
Nonspecific lower back pain
This is the most common type of back pain. The majority of cases of sudden-onset (acute) lower back pain are classed as nonspecific. This is the type of back pain that most people will have at some point in their lives.
Nonspecific lower back pain means that the pain is not due to any specific or underlying disease that can be found. It is thought that in some cases the cause may be:
- An over-stretch (sprain) of a ligament or muscle.
- A minor problem with a disc between two spinal bones (vertebrae).
- A minor problem with a small facet joint between two vertebrae.
There may be other minor problems in the structures and tissues of the lower back that result in pain. However, these causes of the pain are impossible to prove by tests. Therefore, it is usually impossible for a clinician to say exactly where the pain is coming from or exactly what is causing the pain - it is usually attributed to the muscles.
To some people, not knowing the exact cause of the pain is unsettling. However, it can be reassuring to know that the diagnosis is nonspecific back pain which means there is no serious problem or disease of the back or spine.
Nerve root pain (sciatica)
This occurs in less than one case in 20 of acute lower back pain. Nerve root pain means that a nerve coming out from the spinal cord (the root of the nerve) is irritated or pressed on. (Many people call this a trapped nerve.)
Pain is felt along the course of the nerve. Therefore, pain is typically felt down a leg, sometimes as far as to the calf or foot. The pain in the leg or foot is often worse than the pain in the back. The irritation or pressure on the nerve may also cause pins and needles, numbness or weakness in part of a buttock, leg or foot.
About nine in ten cases of nerve root back pain are due to a prolapsed disc - often called a slipped disc. (A disc does not actually slip. What happens is that part of the inner softer part of the disc bulges out (prolapses) through a weakness in the outer harder part of the disc). The prolapsed part of the disc can press on a nerve nearby.
See the separate leaflet called Prolapsed Disc (Slipped Disc) for details.) Other less common conditions can cause pressure on a nerve to cause nerve root pain.
Cauda equina syndrome
Cauda equina syndrome is a particularly serious type of nerve root problem. This is a rare disorder where the nerves at the very bottom of the spinal cord are pressed on. This syndrome can cause lower back pain plus problems with bowel and bladder function (usually inability to pass urine), numbness in the saddle area (around the back passage (anus)) and weakness in one or both legs.
This syndrome needs urgent treatment to prevent the nerves to the bladder and bowel from becoming permanently damaged. Medical advice should be sought immediately if cauda equina syndrome is suspected - this should usually be in an emergency department as urgent scans would be required.
Less common causes of lower back pain
- Osteoarthritis is the most common form of arthritis and usually occurs in older people.
- Ankylosing spondylitis is another form of arthritis that can occur in young adults and which causes pain and stiffness in the lower back.
- Rheumatoid arthritis may affect the spine but other joints are usually affected too.
- Various uncommon bone disorders.
- Narrowing of part of the lumbar spine, causing a condition called "spinal stenosis" where the nerve is trapped in the narrower section.
- Pressure from structures near to the spine (fewer than one in 100 cases of lower back pain).
The rest of this leaflet is mainly about nonspecific lower back pain - the common type of lower back pain.
Symptoms of lower back pain
- Pain immediately after lifting something heavy.
- Pain after an awkward twisting movement.
- Pain that spreads from the lower back area to one or both buttocks or thighs.
- Pain that is usually eased by lying down flat.
- Pain when on moving the back, coughing, or sneezing.
Sometimes it can develop for no apparent reason. Some people just wake up one day with lower back pain.
Most people with a bout of nonspecific lower back pain improve quickly, usually within a week or two. However, once the pain has eased or gone it is common to have further bouts (recurrences) of pain from time to time in the future.
Also, it is common to have minor pains on and off for quite some time after an initial bad bout of pain. In a small number of cases the pain persists for several months or longer. This is called chronic back pain (discussed in more detail later).
See the separate article called When to worry about back pain.
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Diagnosing lower back pain
Most people who develop lower back pain that comes on suddenly (acutely) have nonspecific lower back pain. If there are no other associated symptoms and the pain is not too bad, many people are confident to just 'get on with it' and treat it themselves, and indeed most get better quickly. However, if the pain is not settling or if there are other concerning features, medical advice should be sought.
A clinician will usually want to ask questions about the symptoms and to perform an examination.
As a general guide, if any of the following occur then there may be a more serious underlying cause. But note: the vast majority of people with lower back pain do not have any of the following symptoms or features. They are included here for completeness and as an aid to what to look out for.
- Pain that develops gradually and slowly gets worse and worse over days or weeks.
- Constant back pain that is not eased by lying down or resting.
- Pain that travels to the chest, or is higher in the back behind the chest.
- Weakness of any muscles in a leg or foot.
- Lack of feeling (numbness) in any part of the bottom or leg.
- Having taken steroid tablets without bone protection for more than a few months.
- Symptoms that may indicate an inflammatory (arthritic) cause such as ankylosing spondylitis. The main ones are:
- Pain which is worse in the second half of the night or after waking.
- Stiffness, in addition to pain, of the back muscles in the morning after getting up from bed that lasts for more than 30 minutes.
- The pain is eased (and not made worse) by activity.
- Symptoms that may indicate cauda equina syndrome. The main ones are, in addition to back pain:
- Numbness around the back passage (anus) - the saddle area.
- Bladder symptoms such as loss of bladder sensation; loss of bladder control, incontinence, loss of sensation when passing urine.
- Incontinence of stools (faeces).
- Symptoms that may indicate a fracture in the spine The main ones are:
- Back pain following major trauma such as a road accident or fall from a height.
- Back pain following minor trauma in people with 'thinning' of the bones (osteoporosis).
- Symptoms that may indicate infection or spread of cancer affecting the spine. The main ones are:
- Onset of pain in a person aged over 50 years, or under 20 years.
- Pain that remains when lying down; night-time pain disturbing sleep.
- Symptoms or problems in addition to pain such as:
- Having or having had a cancer of any part of the body.
- General symptoms, such as high temperature (fever), unexplained weight loss, etc.
- Injecting street drugs.
- Having a poor immune system, for example, being on chemotherapy.
Are tests needed for lower back pain?
Usually not. A clinician will usually be able to diagnose nonspecific lower back pain from the description of the pain and by an examination. Therefore, in most cases, no tests are needed.
Current UK guidelines are clear that routine tests such as X-rays and scans should not be done if the diagnosis is made of nonspecific lower back pain.
Tests such as X-rays, MRI scans or blood tests may be advised in certain situations. This is mainly if there are symptoms, or signs during an examination, to suggest that there may be a serious underlying cause for the back pain.
Treatment for lower back pain
The following advice and treatment are commonly given for a sudden-onset (acute) bout of nonspecific lower back pain.
It is best to continue with normal activities as much as possible. This may not be possible at first if the pain is very bad. However, it is important to move around as soon as possible, and get back into normal activities.
As a rule, it is best to avoid activities that cause a lot of pain. However, some discomfort when trying to keep active is usual. Avoiding exercise and activities tends to mean the back pain takes longer to resolve and leads to weakening of muscles which makes future bouts of back pain more likely.
Physiotherapist-designed exercises at home can help faster recovery; keeping them up regularly can strengthen the muscles of the lower back, reducing the chance of back pain returning.
In the past, the advice had been to rest until the pain eases. It is now known that this was incorrect advice. The evidence from research trials is that faster recovery is more likely to be achieved by getting moving again and by getting back to work as soon as possible. Persistent (chronic) back pain is less likely to develop by keeping active during back pain rather than resting.
If painkillers are needed, it is best to take them regularly. The pain is then more likely to be eased for more of the time, enabling exercise and normal activity.
- Anti-inflammatory painkillers. They include ibuprofen and naproxen which may be prescribed , but is also available to buy over the counter, without a prescription. Diclofenac is no longer recommended. Some people may not be able to take anti-inflammatories, for example, some people with kidney failure or heart failure. Anti-inflammatory medicine should only be used at the lowest effective dose and for the shortest possible time.
- A stronger painkiller such as codeine is an option if anti-inflammatories do not suit or do not work well. This may be taken as co-codamol, which is codeine with paracetamol. Constipation is a common side-effect from codeine. This may make back pain worse if straining to go to the toilet. To prevent constipation, it is important to have lots to drink and to eat foods with plenty of fibre.
- A muscle relaxant such as diazepam is very occasionally prescribed for a few days if there is muscle spasm which makes the pain worse. Diazepam is one of a group of medicines called benzodiazepines which can be habit-forming and should be taken for as short a period of time as possible. These medicines are not used very much any longer as the evidence of benefit is very poor and the risks of these medications is considered relatively high.
See the separate article called How to relieve sciatica pain.
Heat such as a hot bath may help to ease pain.
It is best to sleep in the most naturally comfortable position on whatever is the most comfortable surface. Advice given in the past used to be to sleep on a firm mattress. However, there is no evidence to say that a firm mattress is better than any other type of mattress for people with lower back pain. Some people find that a small firm pillow between the knees when sleeping on the side helps to ease symptoms at night.
It is important to aim to get back to work as soon as possible. There is no need to wait for complete freedom from pain before returning to work. Returning to work often helps to relieve pain by getting back to a normal pattern of activity and providing a distraction from the pain.
Treatment may vary and the situation should be reviewed by a clinician if the pain becomes worse, or if the pain persists beyond 4-6 weeks, or if symptoms change. Other pain-relieving techniques may be tried if the pain becomes chronic.
Preventing lower back pain
Evidence suggests that the best way to prevent bouts of lower back pain is simply to keep active and to exercise regularly. This means general physical activity such as walking, running, swimming, etc.
There is no firm evidence to say that any particular back strengthening exercises are more useful to prevent back pain than simply keeping fit and active. It is also sensible to be back-aware, for example, not lifting objects when in an awkward twisting posture.
Maintaining a healthy weight is also important to reduce stress on the muscles of the lower back.
How common is lower back pain?
Most people (about six in ten people) will have a bout of nonspecific lower back pain at some point.
Persistent (chronic) lower back pain
Nonspecific lower back pain is classed as chronic if it lasts for longer than six weeks. In some people it lasts for months, or even years. Symptoms may be constant. However, the more usual pattern is one in which symptoms follow an irregular course. That is, reasonably long periods of mild or moderate pain may be interrupted by bouts of more severe pain.
What is the treatment for chronic nonspecific lower back pain
Initial treatment is similar to sudden-onset (acute) attacks, aiming to keep as active as possible. Also, painkillers can help. In addition to the painkillers listed above, a course of an antidepressant medicine in the tricyclic group - for example, amitriptyline - might be suggested. Tricyclic antidepressants have other actions separate to their action on depression. They are used in a variety of painful conditions, including back pain.
Also, a national guideline (from the National Institute for Health and Care Excellence (NICE), referenced below) recommends one or more of the following treatments should be considered. Each of these treatments has some evidence from research trials to suggest that they will help to ease symptoms in some people (but not all):
- Structured exercise programme. This means a programme of exercise supervised by a professional such as a physiotherapist. This is likely to be in a group setting. Exercises may include aerobic activity, movement instruction, muscle strengthening, posture control and stretching. It typically consists of up to eight supervised sessions over 8-12 weeks with encouragement to keep on doing the exercises at home between sessions.
- Manual therapy. Typically this includes several sessions of massage, spinal mobilisation and/or spinal manipulation. With spinal mobilisation the therapist moves the joints of the spine around in their normal movement range. In spinal manipulation, the therapist moves joints beyond the usual range of movement.
- A course of acupuncture. It is not clear how this may work. (Some doctors feel that this is a controversial recommendation as the evidence for effectiveness is weak.)
Cognitive behavioural therapy (CBT) may also be recommended as a treatment option. There is good evidence from research trials that it can help. CBT aims to help change the way that people think, feel and behave. It is used as a treatment for various health problems, including various types of chronic pain.
If the above treatments have not helped much then a referral to a specialist pain clinic might be advised. Sometimes nerve root injections or facet joint injections are suggested, depending on the findings in the pain clinic.