Heavy backpacks place a measurable strain on the spines of children, with heavier loads causing greater spinal strain and increased back pain, reports a study in the January 1 issue of Spine. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, and pharmacy.
Magnetic resonance imaging (MRI) scans show compression of the spinal discs and spinal curvature caused by typical school backpack loads in children, according to Dr. Timothy Neuschwander of University of California, San Diego, and colleagues.
Backpacks' Effects on Disc Height and Spinal Curve Linked to Back Pain
The study included eight children, mean age 11 years. A special upright MRI scanner was used to image the children's spines in standing position—first with an empty backpack, then with increasing weights of 9, 18, and 26 lb. These weights represented about 10, 20, and 30 percent of the children's body weight.
Two key spinal measurements changed as the backpack load increased. Heavier weights caused compression of the intervertebral discs, which act as a cushion between the vertebrae (bones of the spine). Especially in the lower spine, the disc height became smaller (reflecting greater disc compression) at heavier backpack weights.
Heavier loads were also associated with increased curvature of the lower spine, either to the right or the left. Half of the children had a significant spinal curve even with the 18 lb weight. Most of the children had to adjust their posture to bear the 26 lb backpack load.
As backpack weight increased, so did the amount of pain reported by the children. At the heaviest load, the average pain score was nearly five (on a ten-point scale).
More than 90 percent of U.S. children carry backpacks, typically with weights equal to 10 to 22 percent of their body weight. Parents are increasingly concerned about the heavy backpacks their children have to carry. The new study is the first to use imaging techniques to see how backpacks affect children's spines.
The results suggest that heavy backpacks cause compression of the spinal disks and increased spinal curvature, both of which are related to back pain reported by the children. Although the children were wearing the backpack straps over both shoulders when the MRI scans were performed, the researchers note that spinal curvature could be even greater if the backpack was carried over one shoulder—as many children do.
"Low back pain in children may be worsened by discogenic [disc-related] or postural changes," Dr. Neuschwander and colleagues write. This could have long-term implications, as children with back pain are at increased risk of having back pain as adults. The researchers call for similar studies to examine the effects of heavy backpacks in children with existing back pain.
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