Pronation in childhood is an expression of deficiency in the function of the intrinsic osteo-articular structures of the foot. By application of the principles of Wolff's law. pronation may be greatly improved or entirely eliminated by the time the child is sixteen. In both children and adults, the preservation of function of the intrinsic and extrinsic structures essential to normal stance and locomotion is required for maximum efficiency and greatest freedom from discomfort. The shoes in which feet must work constitute the major cause of these problems common to successive generations. Excellence in quality of footwear cannot assure that the feet will be free from functional impairment. The structural and functional relationship between foot and shoe is determined by the last over which the shoe is made. The design of lasts has been determined by a combination of empirical influences, without benefit of measurements necessary for the preservation of function of the intrinsic and extrinsic structures essential to efficiency and comfort in stance and locomotion.

Full understanding of the needs of the human foot in action awaits the further application of measurement to the study of foot dynamics. Proved principles can then replace opinion in the design of shoe lasts and in the application of therapeutic measures.