Impairment, disability and handicap are not synonymous terms. These are distinct and separate terms. A child might have a physical impairment and be disabled, but may not feel handicapped at all.
Another child, who has no physical impairment is not disabled and is tremendously handicapped. Not every impairment result in disability and not every disability result in handicap. Impairment refers to biological forces, the disability to how a culture deals with impairment and the handicap to how the individual deals with physical impairment.