Development of body proportions in achondroplasia: Sitting height, leg length, arm span, and foot length.

The aims of this study was to construct references for sitting height, leg length, arm span, relative sitting height (sitting height/height), and foot length and to discuss the development for these anthropometric variables in achondroplasia. Sex-specific references covering ±2 SD are presented for ages 2-20 years. Legs and arms in achondroplasia are already at 2 years of age considerably shorter than in the general population and this deviation increases with age. At adult ages, legs are almost 50% shorter than in the general population and arm span roughly 35% shorter. As sitting height is only mildly affected, relative sitting height position develops far beyond normal ranges. Foot length is also not as affected as limbs.