Biomechanics of growth and development in the healthy human infant: a pilot study.

Detailed measurements were acquired from 168 healthy subjects who were brought to the West Virginia School of Osteopathic Medicine's Robert C. Byrd Clinic in Lewisburg, WVa, during 1998 and 1999 by their parents for routine well-baby visits. Measurements of body-segment length, diameter, circumference, and skinfold thickness were taken at several segment locations. The center of volume was calculated for each body segment and was used as an approximation of center of mass. Findings from this study are strikingly similar to those found in the preceding long-term study by Turnquist and Wells of body-segment morphology, locomotion, and posture in the rhesus monkey (Macaca mulata). In human growth and development, the center of mass of each limb body segment migrates proximally, and more so in the more proximal segments. This trend is more pronounced in the lower extremities. Limb length and circumference increase with age in a linear pattern. These ontogenic changes are the consequence of the development of a propulsive hindlimb. This report is part of an ongoing study that will conclude in 2005 and that is intended to provide clinicians with detailed ontogenic information about changes in limb proportions in normal healthy children.