Dr. Joshua Hyman, director of orthopedic surgery at Morgan Stanley Children's Hospital of NewYork-Presbyterian advises parents to inspect their child's backpack to take out shoes, toys and other unnecessary items. If textbooks are making the bag too heavy, he advises parents to speak with the teacher about leaving some books at school. Hyman also recommends:

-- A backpack shouldn't weigh more than 15 percent of the child's weight or about seven pounds for a child who weighs 50 pounds.

-- Wear the pack over both shoulders to spread the weight evenly. Consider a wheeled backpack.

-- If the child experiences persistent pain, parents should consult with their pediatrician, who may recommend physical therapy to strengthen the back muscles. Some indicators of trouble include a change in the child's posture while wearing the backpack, struggling to put it on, pain, tingling or red marks.

The American Occupational Therapy Association has named Sept. 19 as National School Backpack Awareness Day and has scheduled community events on proper backpack ergonomics.