"There's a window," predicts orthopedic specialist Michael Zuscik of the University of Rochester.

If he's right, it could dramatically change orthopedic practice for the nation's 48 million smokers.

Bone damage is arguably the least publicized of tobacco's harms.

The first time many smokers ever hear of the problem is if they need spinal fusion, a back operation that surgeons often won't perform unless patients kick the habit _ with a urine test to prove they quit. That's because the surgery is far more likely to fail in smokers than nonsmokers.