Bone and body segment lengthening and widening: a 7-year follow-up study in pubertal girls.

During growth bone increases in length and width as does the body size. The aim of this paper was to examine the growth pattern of body height and weight, and the width and length of various body segments, and to establish the timing of peak growth velocity (PV) in relation to time of menarche in a cohort of Finnish girls followed from age 10 until 18. The study was a 7-year longitudinal cohort study. Widths and lengths of body segments and bones were measured from DXA scan images using bone landmarks in 396 girls aged 10 to 13 years at baseline, and in 255 mothers and 159 grandmothers. The girls' growth velocities (rate of change with time) peaked at 13.5 months prior to menarche for height, 14.4 months for weight, and 15.4 months for BMI. Shoulder width peaked at 18.2 months, lesser pelvis width at 13.5 months and greater pelvis width at 11.6 months prior to menarche. The PV of various body segment lengths showed that the femur peaked earliest at 20.7 months prior to menarche, followed by the humerus (at 18.0 months), radius (at 17.4 months), tibia (at 17.5 months), and trunk (at 11.8 months), respectively. All the long bones were linearly correlated with height while the flat and irregular bones had a nonlinear growth relationship with height (r(2)=0.73-0.88). By the age of 18 years the girls had reached their mothers' height (101%) and humerus, radius, femur and tibia lengths (100-101%), but not their mothers' shoulder, great pelvis and lesser pelvis widths (98%, 95% and 93%, respectively). Our data confirmed that, after bone elongation had ceased, segment width continued to increase, although at a slower speed, into early adulthood. The wide variations in growth velocity of these anthropomorphic measurements underscore the need to optimize nutrition and physical activity from early puberty onward in order to maximize bone development.