Do orthotics work? That's the question explored in this less than definitive piece by Gina Kolata of the New York Times. The first answer, from professors of biomechanics at two different universities, is "If they do work, we don't don't know how they work." The second, and perhaps more meaningful answer, is "The vast majority of patients are happier having them than not." Kolata consults Dr. Benno Nigg, a professor of biomechanics and co-director of the Human Performance Lab at the University of Calgary in Alberta, who says orthotics have little effect on kinematics — the actual movement of the skeleton, but they can have large effects on muscles and joints, often making muscles work as much as 50 percent harder for the same movement and increasing stress on joints by a similar amount. As for “corrective” orthotics, he says, they do not correct so much as lead to a reduction in muscle strength. Nigg, who dismisses most studies of the benefits of orthodics as lacking scientific rigor, did his own study of 240 soldiiers, half of whom wore orthoditcs. What did he find? Those who used orthodics had half as many injuries, but there was no obvious relation between the insert a soldier chose and his biomechanics without it. Yes. It's confusing.