The assessment of low back pain in primary care
Dr Gordon Cameron
Elaine is a forty one year old secretary. She has had back pain several times previously and presents again with a similar episode. The pain is to the left of her lumbar spine and radiates into her buttock and outer thigh. She denies numbness or pins and needles and her bowel and bladder control is normal. She wonders about attending an osteopath. You are unsure how to advise her and give her a prescription for diclofenac. This gives her dyspepsia and she stops taking it after ten days. A month later she still has grumbling discomfort but has not returned to consult you. She eventually attends a local private physiotherapist who manipulates her spine to great effect and her pain fully settles.
Back pain - except in the rarest of circumstances - is not life threatening. But it is common and many patients suffer greatly because of it.A busy GP won't think so but most people with back pain deal with it themselves. Thirty seven percent of adults in the UK experience back pain in any one-year period but only fourteen percent will seek medical help. Of those who don't trouble their GP, many will self medicate, some will attend a physiotherapist and an increasingly large number will have spinal manipulation performed.Many general practitioners feel inadequately trained to assess back pain. This causes uncertainty and leads to over-prescribing, unnecessary use of X-rays and needless referral to hospital specialists. Back pain patients are often best served by remaining at work but only a GP's confident in their assessment skills can push in that direction.
This article will describe:
- A simple back pain assessment routine for the busy GPHow to make better use of X-rays and other imagingWhen to request blood tests
- The role of the MRI scan
A good assessment can be obtained in the space of a ten-minute consultation – all you need is a reliable examination routine – I suggest something like the following:
Observe your patient
You can learn by watching your patient walk through the waiting room. Take note of their posture, their facial gestures and the way they walk. Assess their demeanour.The tendency to "somatize" inner unhappiness can lead to inconsistent or bizarre examination findings but be careful how you interpret them. Chronic back pain can be associated with psychosocial difficulties and many patients use it as a means of communicating distress. True malingering is extremely rare. Almost all patients have an underlying physical problem but, for some, their inner belief systems lead them to magnify the intensity and importance of their pain.
Some back pain sufferers respond to counselling or antidepressant medication. Learn to use your own feelings as a barometer for their psychological state! Patients who make their doctor feel depressed are probably depressed themselves!
Take a good history
- What age are you Mr Smith?
Most patients consulting their GP with back pain are between the ages of twenty five and sixty. Back pain is rare in teenagers and not common as a new presentation in the elderly. If you meet a patient in either of these two categories then lower your threshold for investigation.
Occupation is important. It gives a pointer towards prognosis but not in the way many would expect. Job satisfaction is crucial! Patients in heavy manual jobs do get more back pain than others but those who hate their jobs – whether senior executive or toilet cleaner - are much more likely to take time off.
Next, try to place this episode of back pain in its proper context. I often find it useful to review the patients past medical history and current use of medication before obtaining any other details. Ask the following (or review the case notes):
- "Tell me about your general health and any previous health problems"
Have they had cancer? Tumours of the breast, lung, prostate, kidney and thyroid are particularly likely to metastasise to bone. Might they be HIV positive or could they have had TB? Always ask about symptoms of systemic ill health such as weight loss, night sweats or fatigue and remember that osteoporosis places the patient at risk of vertebral collapse
- "Have you had previous surgery?"
- "Have you had back pain before? How was it treated?"
Back pain is often a recurrent symptom and most patients first experience it in their twenties or thirties. Be wary of the elderly patient who presents with back pain for the first time ever (or the first time for a long time) – they may have serious underlying pathology! Previous experience of treatment will colour the patients expectation of what you, the GP, can or should provide. Many patients get very hung up on the labels applied to their condition by previous therapists and this can sometimes cause problems in communication. Take time to clarify what they mean by the words or phrases they use.
- "Do any other joints give you trouble?"
Most back pain is not related to underlying disease but remember that it may be a manifestation of ankylosing spondylitis or rheumatoid arthritis.
- "What medication are you taking?"
Is your patient being treated with anti-mitotic drugs such as tamoxifen? Steroid therapy – now or in the past – leaves them at risk of osteoporosis and vertebral collapse.
- "Are you taking anything for the pain?"
The answer to this question sheds light on the patient's belief about the significance of the pain. Beware the patient who sees it as your job to "fix them." This abdication of responsibility for their own health puts them at risk of long term illness behaviour. Fear of what the pain might mean and subsequent avoidance of pain provoking activities are also bad prognostic factors.
The history proper
Onset and duration
Try to discover how long the pain has been present and how it started. Most patients can recall an event that triggered the problem and an approximate time of onset. Be wary of the pain that just seemed to creep up from nowhere – it may indicate serious pathology.
Site and spread of the pain
Is the pain mainly in the back or mainly in the leg? Mainly in the leg and associated with numbness or pins and needles points towards nerve root involvement. Nerve root pain is typically shooting, lancinating, or like an "electric shock" and may be felt all the way to the foot. Most simple back pain does not spread far beyond the buttock, is dull in nature, and patients say it feels like toothache. Take care over descriptions of the site of pain – many people say "hip" when they mean "buttock."
Behaviour of the pain
Beware the patient who can never get comfortable! No matter what is wrong with their back, your patient will always find a position that gives them some relief. The only exception is when serious pathology is present. Chronic, unremitting pain – particularly if sleep is disturbed – is in my view the most immediately alarming "red flag" in any pain history.
Most cases of back pain get better with rest and worse with activity. The exception is in ankylosing spondylitis when the opposite is true!
Other important questions
A patient with cauda equina compression will describe loss of sphincter control and may have bilateral neurogenic type leg pain. Test for impaired sensation in the saddle area and assess anal sphincter tone by digital examination while the patient tries to "squeeze" your examining finger. A compressed nerve root recovers in time but a compressed cauda equina never does and the patient risks being left permanently incontinent of urine and faeces. The condition is rare but all GP's should be alert to the possibility. If in any doubt – admit the patient to hospital immediately.
The physical examination of the patient with back pain should follow a logical thought process and with practice takes no more than a few minutes. The bad news for GP's is – you need to undress the patient! This is often the most time consuming part of the process but the extra information gained makes the exercise well worthwhile.
With the patient standing:
- Inspect for obvious spinal asymmetryAssess the lumbar lordosis – a very flat lordosis may point towards ankylosing spondylitisLook for muscle wasting in the gluteal region, the calf or the thighCheck for discrepancy in leg lengths by comparing the levels of knee and buttock creases and the relative levels of the posterior superior iliac spines.
- Ask the patient to extend their spine, to flex forward and then to side flex by sliding their palms down their outer thigh. This assesses quality and range of spinal movement. Most patients with simple back ache will be slightly stiff in extension, be painful on flexion and show asymmetric limitation and pain on side flexion of the spine.
Lie your patient flat and supine:
Rule out other joint involvement
- check the hip joints for range of movement and for pain or limitation. Hip joint pathology can present with predominant back and buttock pain although more typically a "hip patient" will feel pain in the groin. A loss of range on internal rotation of the hip is often the earliest sign of hip disease.
- Perform stress tests on the sacroiliac joints – especially in younger or female patients. Mechanical dysfunction or inflammatory processes in these joints produces buttock and groin pain which may radiate down the leg.
Test the nerve roots
- Straight leg raise test. This stretches nerve roots L5, S1 and S2. Pick up the leg at the ankle and keep the knee fully extended. Take the leg up towards ninety degrees or beyond. If the patient has significant nerve root entrapment then you will reproduce their shooting leg pain before you get much beyond thirty degrees of elevation. Back pain produced by straight leg raising is common and does not indicate nerve root involvement.
- Assess muscle power and tone – see box
Assessing the power of lumbar nerve roots
L2 and L3 – resisted flexion of the hipL4 – resisted dorsiflexion of the ankleL5 – resisted extension of the big toeS1 – resisted eversion of the foot or resisted plantar flexion of the ankleS2 – resisted hamstring contraction (resisted knee flexion)
- Check the reflexes. The knee jerk is innervated from the L3 and L4 nerve roots, the ankle jerk from L5 and S1Assess the babinski plantar response
- Check for skin sensory loss
Turn your patient over into prone lying
- Femoral nerve stretch test (nerve roots L2, L3 and L4). Keep the patients anterior thigh fixed on the couch and flex the knee towards ninety degrees. If they have femoral nerve irritation or entrapment then this manoeuvre will produce burning discomfort in the groin and anterior thigh.
- Palpate the spine for tenderness and for muscle spasm
With practice you can perform the above examination in no more time than it took you to read about it. By the end of the process you will have differentiated between patients with simple backache (the vast majority), with nerve root pain (a few) and with possible serious spinal pathology (as rare as "hens teeth!") and can now plan a course of treatment.
Most patients with back pain need no investigations performed before starting treatment. X- rays are over used and rarely help plan management. The royal college of radiologists state that one set of lumbar films uses the same amount of radiation as a hundred and fifty chest X-rays. False positive findings abound and often only confuse the issue. The RCGP guidelines suggest X-raying if the pain has been present for more than six weeks but I find in practice that even at that stage the result rarely contributes much to the management decision process.X-rays are of benefit in the younger patient with back pain when spondylolysis or spondylolisthesis are possible diagnoses. They may also help in detecting osteoporotic collapse in the elderly and you may wish to use them if the patient has had recent trauma, whatever their age.
Do not use plain X-ray if you suspect serious pathology. Even advanced tumour may not show on the films. If you suspect underlying disease then check bloods for a full blood count, an ESR and an alkaline phosphatase level (with isoenzymes for bone if the basic level is elevated). Arrange an isotope bone scan - many areas of the UK now allow GP's direct access to radioisotope imaging in these circumstances.
The role of MRI scanning
Magnetic resonance imaging is an amazing technology and has advanced our understanding of back pain. But it is not the gold standard some see it to be and shares many draw backs with simple X-ray.False positive results are common and the scan picture does not always correspond to the patient's clinical presentation. MRI can be entirely normal in people with severe back pain and patients who have never had back pain in their lives can show marked changes on scanning.In my view it is best to make a diagnosis based on a good history and clinical examination. MRI is not usually appropriate for patients with predominant back pain and is best reserved for the investigation of neurogenic leg pain or as an alternative to isotope bone scan in cases of possible serious pathology. In some senses it is best seen as a "route map" for the surgeon.
Many specialists in the field now acknowledge that society and the medical profession have colluded to produce an epidemic of back pain. But at last the focus is moving away from highly technical and hugely expensive procedures towards the sort of simple interventions that may transform the lives of most that are afflicted. Back pain rarely kills patients but, if mishandled, can lead to loss of earnings, the break up of marriages and a lifetime of misery. The assessment of back pain is not difficult to learn but for now our report card reads "trying hard …. but must do better!"
Idea for audit – X-ray use in back pain
- How many lumbar X-rays has your practice requested in the last year?What were the indications for the requests?Did the request comply with the Royal College of Radiologists guidelines?
- Was the significance of the reported result easy to understand?
How many of the X-rays resulted in a change of management for the patient
Practice point – which patients should be admitted to hospital
The following patients should be admitted
- Any patient in whom cauda equina compression is suspected – as a GP you should always err on the side of caution. It's better to look foolish later than to leave your patient permanently disabled. Any patient with evidence of a root palsy that is rapidly progressive – especially if the L5 root is involved, since the patient can be left with a foot drop
- Patients who have intractable pain despite appropriate analgesia and good compliance with the prescribed regimen
Practice point – what is "mechanical back pain?"
The use of the term mechanical back pain can cause confusion. It is often used loosely to imply back pain where no specific pathology has been identified. A better term for this is "simple backache."
Mechanical pain is simply back ache which alters in relation to the patients posture or activity. For example a pain that is eased by bending backwards but eased by walking could be said to be "mechanical."
This website is brought to you by Doctor Gordon Cameron - a specialist in sports medicine and in Joint Injections
Page Links for other lower back pain pages on this site
Lower back pain overview page
How the back works - an overview of back pain anatomy
How the spine nerves work
The joints of the spine and the sacroiliac joint
Back pain, disc pain and disc degeneration
Lumbar facet joint pain - lower back pain and the lumbar facet joints
What is Lower Back Pain - Why does your back hurt?
The Pain Gate and why your lower back pain hurts so much
Lower Back Pain and Referred Pain
First aid treatment measures for a low back pain attack
Spinal Manipulation - some truths and myths about spinal manipulation treatment
Acupuncture treatment for lower back pain
The Cameron Medical Website has a huge amount of content on issues related to joint pain, arthritis, back pain and other orthopaedic or joint problems. Most of it is written by Dr Cameron specially for this website. Click here to see what's available.
Other pages on the site contain details of:
frozen shoulder heel pain heel pain treatment lower back pain
back pain treatment spine manipulation synvisc treatment
carpal tunnel syndrome whiplash injury treatment whiplash injury
neck pains tennis elbow gout pain relief gout pain treatment
sporting injury manuka honey