Is your kid's backpack causing a backache?

A new backpack is likely high on the back to school shopping list. They're not just functional, but fashionable and a critical piece to your child's success at school. Sometimes the large, colorful, trendy bags can set your young student up for failure creating long-term problems with their posture and spine.

Dad and neurosurgeon Nimesh Patel, MD, FNP, with the Methodist Brain and Spine Institute, weighs in on choosing the right bag:

How do I choose the right size backpack for my child?

Make sure you buy a child-size backpack, not an adult one. Some parents buy an adult backpack thinking that it doesn't matter, but it does. Pay attention to how the backpack fits when it's worn. As a general rule, the length of the backpack when placed on the child's shoulders should not extend more than two inches past the child's waistline. When the backpack sits too low, it puts more pressure on the spine.

What other features should I look for?

Look for backpacks that have two wide straps with padding. Skinny straps tend to dig into the shoulder blades making it uncomfortable to wear. If you can find a backpack that also has waist belts, that's even better. The waist belts, which are attached to the backpack and strap around the child's waist, help support the load and take pressure off the spine.

What about those trendy messenger bags?

While kids may think they look cool slinging one strap over their shoulder, using only one strap puts all the weight on one side of the body where it's not evenly distributed. This can cause the child to lean to one side which can affect their posture and cause sore joints, and that's not so cool!

How will I know if my child's backpack is too heavy?

Here's one tip: if the backpack is too heavy for you, it's definitely too heavy for your child. Your child's backpack should not weigh more that 10 to 15% of his or her body weight.

Another way to tell if there's a weight issue is if you see the child leaning forward or arching backward to support it, then the backpack is probably too heavy. Or, you may see them dragging it across the floor because it's too heavy to carry.

Other options for lightening the load

Sometimes backpacks are stuffed with a lot of items the child does not need that day. Do they really need that toy or extra book? A better option might be to place items in the locker or leave them at home until needed.

Even better, if your child really needs all those items, get a rolling backpack, which takes the weight off the shoulders completely. Just roll with it! This is especially true for children with scoliosis, an abnormal curvature of the spine.

What are the consequences for the back?

Carrying a backpack that's too heavy causes weight to be unevenly distributed that can cause problems for your child both now and later in life. Short-term effects include muscle strain, shoulder pain and lower back pain.

Long term effects can affect a child's physical development. The growth of muscles can be uneven to compensate for the excess weight. Improper weight distribution can lead to chronic shoulder pain and chronic neck and back.

When your child's backpack is too heavy or worn improperly, it shifts the center of gravity causing unbalance. In addition to hurting muscles, ham strings, and back pain, unbalance affects their posture.

Children do not typically complain of back pain. If they do, or if theycomplain of numbness or weakness in the arms or legs, it could indicate a serious problem that needs to be evaluated by a doctor.

A healthy back and spine will carry your child throughout his or her life. Make sure he or she is packing light!