Children and adolescents with an injury or disability may use mobility aids such as crutches, walkers and wheelchairs to help them move around more easily. However, use of these aids has been associated with risk for injury. A new study found that more than 63,000 pediatric mobility aid-related injuries were treated in United States emergency departments from 1991-2008, and the annual number of cases increased 23 percent during the 19-year study period.