Dr. Timothy Neuschwander of University of California, San Diego, used magnetic resonance imaging (MRI), to study the spines of eight children, with a mean age of 11 years. They scanned the youngsters first with an empty backpack, then with increasing weights of 9, 18, and 26 lb. These weights represented about 10%, 20%, and 30% of the children’s body weight.

Heavier weights caused intervertebral discs depression and decreased disc height. Heavier loads were also associated with increased curvature of the lumbar spine, either to the right or the left. Half of the children had a significant spinal curve even with the 18 lb weight, with Cobb angles greater than 10°. 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.

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.

“Low back pain in children may be worsened by discogenic 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.

Source: Spine – January 1, 2010;35:83-88.
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