Density of os calcis and limb dominance.

The absolute density of the right and left os calcis has been measured in a group of healthy, sedentary volunteers. There was a significant difference between the density of the right and left os calcis in 90% of the subjects. Statistically, when all of the subjects were considered, the side on which the os calcis was denser was also the side of hand preference. Since there was no evidence, in the present study, of the environment having encouraged the use of one foot rather than the other, it is concluded that the concordance between upper limb dominance and greater density of the ipsilateral os calcis must have been determined before birth.