Most of the time, back pain in children is due to muscle strain from sports, and goes away with rest for one or two weeks. Back pain that persists beyond 4 weeks should be evaluated more thoroughly, because there is often a significant cause for the back pain.

The following factors places the child at a higher risk of having back pain that has a significant underlying cause.

1. Duration of back pain. Pain that persists beyond 4 weeks should be worked up.
2. Character of back pain. If the pain is persistent, and bad enough to interfere with the child's activities, it should be looked into.
3. Any systemic symptoms like fever, cough, urinary or bowel disturbance, menstrual disturbance etc. should be considered.
4. If the pain radiates down either or both legs, it should be taken more seriously.
5. Age of the child. In preschool children, back pain should be viewed seriously.
6. History of significant trauma will need X-rays to rule out fractures or dislocations.
7. Night pain if constantly present should be investigated.

In children where further workup is needed, the following tests are often done.

1. Blood tests including complete blood count checking the red and white cell count, the differential white cell count, and platelet count. Sedimentation rate is an indicator of any systemic inflammatory process in the body. C-reactive protein also increases with inflammation, but gets back down to normal sooner than the sedimentation rate.
2. X-rays of the spine, including the pelvis rules out any fractures or dislocations, any infection or tumors.
3. Triple phase (Technetium) bone scan is more sensitive than a plain X-ray in showing any active infection or tumor. The test involves injecting a minute dose of radioactive material (Technetium) intravenously. If there is a area of active pathology in any part of the skeleton, the Technetium will be concentrated in that area, giving rise to a "hot" scan in that region. While it does not define the actual pathology, e.g., trauma or infection or tumor, it localizes the area of pathology.
4. MRI or magnetic resonance imaging utilizes electromagnetic waves (or radio waves) to create an image of the part of the body being studied. This is an expensive, but accurate test to define the lesion being studied. The part of the body being studied is placed in a big machine with a large electromagnet that produces these radio waves. If the head or neck or back is being studied, very often the whole body has to be placed within the machine. This is not well-tolerated by people who are claustrophobic, and Valium may have to be prescribed to allow these patients to undergo the test. More recently, some MRI machines have been developed that have a more open architecture, that allows for "open" MRI studies; however, the images obtained are usually not as sharp as those obtained with the "closed" system. In any case, the MRI test is accurate, safe, and usually painless.
5. CT scan (or computerized axial tomography) is a specialized X-ray test which a allows for 3D imaging of the skeleton. This is especially useful in studying spine problems.

Causes of back pain in children include the following.

1. Trauma. Trivial trauma like muscle strain is very common, and usually resolves with rest for 1 or 2 weeks. In cases of severe trauma, X-rays are important to rule out fractures or dislocations of the spine or pelvis.
2. Infection. Discitis occurs in preschool children, who may refuse to sit up or stand, of acute onset associated with fever. The infection starts in the disc space of the spine, and is often due to the bacteria Staphylococcus aureus. If untreated, it leads to osteomyelitis of the vertebral body. X-rays and Bone scan or MRI will confirm the diagnosis. Treatment is intravenous antibiotics.
3. Spondylolysis and spondylolisthesis.
4. Scheuermann's disease.
5. Juvenile rheumatoid arthritis and Ankylosing spondylitis
6. Bone tumors, particularly Osteoid osteoma, Osteoblastoma, Eosinophilic granuloma, aneurysmal bone cyst, and malignant tumors, including leukemia. X-rays, bone scan and or CT and MRI studies will delineate these lesions.