Roller Blades: Whiz! Zoom! Crash! Ouch!

^ Here they come, whizzing along city streets and suburban roadways by the thousands. Then, watch out, there they go, down on the pavement, writhing in pain. This year about 1 million people -- twice as many as last year -- are dashing around on "in-line" blades, the ice skates on wheels, and casualties are mounting. Health officials, roller buffs and the $150 million industry are growing concerned at the rising number of fractures, sprains and contusions as throngs of wobbly tyros fasten on the high-speed, tricky devices.

On one recent weekend, New York City's Lenox Hill Hospital treated 17 bladers...