Back pain is a common complaint among adolescents. But there are several misconceptions about back pain that lead to excessive referrals and unnecessary imaging.
One of the most common of these misconceptions is that back pain in adolescents is caused by their carrying a heavy backpack. When this was researched, carrying a heavy backpack had a weak association with back pain,1,2 but because so many relate the two, the American Academy of Pediatrics came out with recommendations limiting the weight to 20% of the child’s body weight.3
Dr. Francine Pearce
Another misconception regarding back pain in children is that the cause is likely serious and needs a prompt work-up. A study followed 560 children who were diagnosed with low back pain and idiopathic scoliosis. In only 9% of cases was an underlying pathologic condition found: 29 patients had spondylolysis or spondylolisthesis, 9 had Scheuermann’s kyphosis, 5 had a syrinx, 2 had a herniated disk, 1 had hydromyelia, 1 had a tethered cord, and 1 had an intraspinal tumor.4
As with all diagnoses, a detailed history is very important. Is the pain acute or chronic? Does the pain radiate? Is there nighttime pain? Where exactly is the pain? Commonly, with acute onset there is an association of new activity or trauma. A good social history is also important because complaints of back pain are high on the list with psychosomatic issues as well.
The physical exam should include inspection of the back with the patient standing, bent forward, and in a hyperextended position. Identifying curvatures of the spine and pinpointing what increases the pain are helpful in getting the correct diagnosis. Middle back pain associated with an excessively rounded back, or kyphosis of the thoracic spine, is known as Scheuermann’s kyphosis. This is due to the vertebrae becoming wedged.5
Body habitus also is important to note. Adolescents with large breasts may complain of upper back pain especially, if they are not wearing a supportive bra. Weak abdominal muscles can also give rise to back pain, most commonly in the lower back. Tight hamstrings can cause posterior rotation of the pelvis, which can result in lumbosacral pain.
More worrisome causes of back pain are spondylosis or stress fractures; these are usually caused by a sports trauma such as gymnastics or diving, but also can be caused by a rapid growth spurt.1 Pain is usually mild initially. Spondylolisthesis is the forward movement of one vertebra on another. This causes pain in the lumbosacral area, with radiation into the lower extremities and weakness.4
Infection and tumor are rare causes of low back pain. Both can cause nighttime pain. Infection in the intervertebral disk space, or diskitis, is more common in younger children. Pain can be described in the back or the abdominal area.1 Limping or refusal to walk are also noted.
Tumors, although rare, are what parents worry the most about. Osteoid osteoma is the most common form, and should be considered whenever a scoliosis is of new onset or advances quickly.6
A work-up for acute low back pain associated with minor trauma and no radiation or limitation to movement can be done conservatively. If the physical exam reveals muscle imbalances or tightness and abdominal weakness, referral to physical therapy is warranted.
If low back pain is associated with abnormal findings, then an x-ray should be done. Anteroposterior and lateral views are usually sufficient. Oblique views should be added if there is suspicion of a stress fracture.
Referral to an orthopedist is warranted if there are any bowel or bladder changes, significant weakness, and/or sensory changes. A bone scan, CT scan and MRI are more definitive tests. The bone scan is not very sensitive (61%) but has a high specificity (80%). CT scans show soft tissue, but no marrow elements are seen, so it is not as helpful with a herniated disk.7
In this ever-changing medical arena, taking a detailed history and doing a good exam will not only save a lot of time but also decrease the number of unnecessary referrals, which is the name of the game!
References
1. J Pediatr Orthop. 2006 May-Jun;26(3):358-63.
2. Pediatrics. 2003 Apr;111(4 Pt 1):822-8.
3. American Academy of Pediatrics. Backpack safety.
4. J Bone Joint Surg Am. 1997 Mar;79(3):364-8.
6. J Paediatr Child Health. 2000 Jun;36(3):208-12.
7. Skeletal Radiol. 2005 Feb;34(2):63-73.
Dr. Pearce is a pediatrician in Frankfort, Ill.