Families are shattered when children are maimed or killed by accidents. This newspaper often reports the worst occurrences, but many smaller injuries also occur. A certain hazard always lurks when exuberant kids fling themselves into energetic sports.

The American Academy of Pediatrics regularly issues warnings about perils of bicycling, swimming, diving, etc. Last week, it raised a special alarm about trampoline-bouncing.

In the 1990s, the number of U.S. children hurt on trampolines more than doubled, from 39,000 to 83,000, the AAP said. By 2004, casualties rose to 112,000, and have hovered around 100,000 per year since.

Many injuries are mere sprains, but some are horrible neck fractures and the like. Most happen when several kids bounce together -- and tiny tots are more likely to be flipped out of control by larger bouncers.

"Approximately three-quarters of injuries occur when multiple people were using the trampoline at the same time," the AAP report said. "The smallest participants were up to 14 times more likely to sustain injury, relative to their heavier playmates."

Safety nets around trampolines do little to remove the danger, the report added.

The childhood physician group issued this caution list for backyard play:

* Make sure the trampoline is level, with no dangerous objects nearby.

* Never let more than one child on the springy mat at a time, and discourage somersaults and flips.

* Adult supervision should be constant -- and strict.

It's difficult to protect children from all the menaces they eagerly pursue, but every family should try. Consequences can be too horrible to think about.