Parents may not notice when their child's shoe catches on the side of the slide for a second or two, but that, combined with the speed at which the parent and child are zipping down the slide, can create enough friction to break the child's shin bone (tibia). Instead, what parents do notice is that at the bottom of the slide, instead of laughing with joy, the child is whimpering or screaming in pain.
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"My wife was just trying to keep Hannah extra safe and make sure she didn’t fall,” Jed Dickman told the New York Times. His 18-month-old daughter's sneaker snagged on the slide, and by the time his wife freed it the child's tibia had fractured. "She felt very guilty about it."
Amy Canterella had a similar experience in 2009, when her daughter was 18 months old. "I was horrified,” she told MSNBC. "I thought I was making her safer. I’d never heard this sort of thing could happen."
Dr. John Gaffney, a pediatric orthopedist at Winthrop University Hospital in Mineola, N.Y., saw so many toddlers with broken legs that he decided to try to figure out what was causing the problem. He studied the medical records of all of the kids with fractured tibias whom he had treated over the course of 11 months and found that, out of the 58 cases, 13 of the kids had broken their tibias on playground slides -- and every one of them had been riding on an adult's or older sibling's lap at the time.
"If a toddler is riding by himself and gets his leg stuck against the side of the slide, he can stop himself pretty easily," Dr. Gaffney explained to MSNBC. "But with the parent's weight added in, you've got greater velocity and momentum and it's harder to stop."
It can happen even if you've carefully tucked your toddler's legs between yours, too: if the edge of the shoe sticks on the surface of the slide on the way down, the child's leg can twist, snapping the tibia.
Dr. Ed Holt, an orthopedic surgeon at Anne Arundel Medical enter in Annapolis, Maryland, told the New York Times that he's treated several children with what he describes as a "sliding board fracture," which he calls "entirely preventable."
"The parent, the adult, is devastated for having caused a fracture when they were trying to keep the child safe," he said in a video he created to tell parents about the risk.
According to information from Childrens Hospital in Boston, the tibia is the most often-broken leg bone in kids, "especially if they're very active, play contact sports or run competitively." Stress (hairline) fractures to these bones are common among young athletes. More than half of all stress fractures occur in the lower leg bones." The break is typically treated by putting the child in a cast from the foot to above the knee for four to six weeks.
Instead of riding the slide with your child on your lap, you're better off letting your toddler slide down by herself while you monitor her (or hold her hand) from the ground. "If the child can't use the slide independently," Dr. Gaffney says, "then the parent should divert him to something more appropriate for his age."