What are the causes of child back pain?
Back pain in childhood can sometimes point to serious disorders – Dr George Bennet explains how to recognise specific conditions
lThere is no evidence implicating heavy school bags
lPsychological causes are more frequent than mechanical
lDiscitis is probably most common cause in under-fives
Traditionally back pain in children has been taken seriously and assumed to be a significant problem until proved otherwise. This perception may be changing as it appears, certainly in older children, that they are developing a pattern of backache akin to that found in adults.
Back pain in childhood is more common than might be thought; the incidence in adolescents now approaches that of adults. A recent study of almost 1,500 British schoolchildren aged 11-14 found an overall one-month prevalence of 24 per cent, rising to 34 per cent in girls over 14. Half of all boys have had low back pain by the age of 15 and almost 70 per cent of girls. Other studies confirm these very high figures. Medical attention, however, is seldom sought.
In the majority of older children no cause can be found; it seems that non-specific backache has a psychological rather than a mechanical basis. It has been found to be more common in those children who disliked going to school, who suffered from headaches, sore throats, abdominal pain or daytime tiredness and those who had a part-time job.
There does seem to be some relationship between time spent watching television and backache, although it is not as strong as many parents would imagine – or hope! Playing video games for more than two hours per day does seem to have an effect. Surprisingly, there is little evidence linking obesity and backache.
Physical activity does appear to have a protective effect, but if this is excessive then the opposite is true. Of those competing in sports at a high level, 75 per cent may have or have had the complaint.
What of the vexed question of school satchels? There have been several studies, but scientifically they are of a poor standard.
The consensus seems to be that satchels have little effect; there is no evidence whatever that they produce spinal deformity. Of children with back pain, few say that carrying a school bag makes it worse. There is no evidence of safe weights for backpacks.
This has not prevented calls for sets of books and musical instruments to be duplicated to save children carrying them. While this may be justifiable in the case of a child who plays the piano, there is little evidence upon which to base these views!
The facts then suggest the condition is a very common one, not dissimilar to that in the adult population, more often than not having a psychological rather than mechanical basis. Pain is a universal experience but not a disease. We should avoid medicalising the condition.
Within the group of children with this complaint, however, are a number with more specific and serious complaints. How do we pick them out from the larger group? The initial screening is of course a history and examination.
Who brings the child to the surgery may be significant. The presence of the father may signify that he has high hopes for the child in sporting spheres. The child may be being over-trained or may be looking for a way out of father's sporting ambitions. Tread warily The age of the child is of paramount importance – the younger the child the more seriously the complaint should be taken. Certainly those aged under four should be investigated to exclude tumours or infection.
In all age groups the characteristics of the pain are important: how long has it been there, is there radiation into the buttocks or legs, does it waken the child at night, is it constant or merely brought on by activity?
Constitutional symptoms such as fever or weight loss may suggest infection, tumour or leukaemia.
Check the gait The child may have a short stride due to hamstring spasm. Assess posture in the spine, looking particularly for lateral curvature (scoliosis) or a hump (kyphosis). A hairy patch may indicate underlying structural abnormalities.
Palpate for tenderness. Have them move to assess stiffness. A young child may not co-operate; instead, have them pick something off the floor – watch if they bend their knees rather than their spine.
Finally, check the straight leg raise for tight hamstrings
The younger child (under 10)
The shape of the spine in childhood changes with maturation. A baby's spine is a long C shape and has no curves. As the child develops, a thoracic kyphosis and lumbar lordosis appear. There is then a slow and gradual increase in both curves until skeletal maturity. Take complaints of back pain seriously, often a cause can be found. Do an X-ray and, if there are any constitutional symptoms, a full blood count and CRP.
The older child (over 10) The majority in this age group will have either indeterminate shortlived pain, which needs no treatment, mechanical pain, usually post-traumatic in more active children or, in the same group, spondylosis.
The basis of a sensible management plan is to pick out those who do not show any signs of being at risk of a serious disorder. In an older child, if there is a short history, minor trauma and no hamstring tightness then adopt a wait-and-see policy. Review a couple of weeks later.
If the pain persists, or has been there for longer than a month, and examination is normal then an X-ray is indicated. If it is normal, reassure. If the pain persists, get a bone scan.
As in the younger child, if there are systemic symptoms, blood tests should be done. Children who have constant or night pain or have constitutional symptoms in the presence of an abnormal examination should be investigated with the above and an MRI.
Discitis Uncommon, but probably the most common cause of backache below the age of five. The intervertebral disc in the child has a blood supply. This allows haematogenous spread of infection; staphylococcus is the most common bacterium implicated. Failure to walk, a stiff spine and hamstring tightness are characteristic. Half will be pyrexial. Radiographs may initially be normal but later will show disc space narrowing. Antibiotics are usually effective.
Tumours These are rare but should be considered, particularly in the younger child. Most are benign. They characteristically present with constant or night pain. Of the malignancies, probably leukaemia is the one that most commonly presents in this way.
Scheuermann's disease Typically found in children over 10, aetiology is unknown. It results in anterior wedging of vertebrae producing a roundback deformity.
One-third will have a mild scoliosis. Postural exercises are usually prescribed although there is little evidence of their efficacy.
Spondylosis This is a defect in the pars interarticularis, that is a posterior structure of the vertebra, usually L5/S1. It is common in Eskimos. It probably reflects a stress fracture, possibly due to repeated hyperextension. Many remain asymptomatic. Back pain on extension is the common presenting feature and hamstring tightness is characteristic. Reduction of activities usually allows the pain to settle.
Spondylolithesis This is the end result of spondylosis: the upper vertebra slips on the lower. Flattening of the lumbar lordosis may be seen and a palpable step felt. If the slip is moderate (25-50 per cent) then observation is indicated. If the pain persists fusion may be required.
Prolapsed intervertebral disc
This is rare, being most commonly found in gymnasts. Sciatica is unusual. Neurological signs are not commonly found. If it is considered a possibility, MRI should be performed. Conservative treatment is attempted
as the long-term results of surgery
Causes of child back pain
Age <10 age="">10
When to suspect a serious problem
lAge under four years
lAge over 10 if symptoms >four weeks
lLimitation of trunk movement or straight leg raising
Hollingworth P. Back pain in children. Br J. Rheumatology 1996:35,1022-1028.
Sassmanshausen G, Smith B. Back pain in the young athlete. Clinics in Sports Medicine 2002:21,121-132.
Watson D et al. Low back pain in children: occurrence and characteristics. Pain 2002;97,87-92.
Watson D et al. Low back pain in schoolchildren: the role of mechanical and psychosocial factors. Arch Dis Child 2003:88,12-17.
George Bennet is consultant in orthopaedics, Royal Hospital for Sick Children, Glasgow10>