TW2 Skeletal Maturation and Growth in Japanese Girls

From 1969, 65 healthy girls living in Tokyo were surveyed once a year, for more than ten years, as to their stature, chest circumference, body weight, and skeletal maturation. 1) Comparing the mean growth curves of the subjects with contemporary standards of the Ministry of Education, the subject girls closely approximate the general population of Tokyo girls. 2) The skeletal maturation of their hands and wrists was estimated by the TW2 method. Between ages 5 and 7, chronological age and skeletal age coincide approximately with each other for RUS, Carpal, and 20-Bone maturity scores. After age 8, RUS and 20-Bone maturities accelerate and attain adult scores of 1,000, at age 15, one year ahead of the British standard. However, Carpal maturation of the Tokyo girls coincides more closely with the British standard. Forty-two girls among these 65 recorded their date of menarche. For this group, we analyzed the adolescent growth fitting spline smoothing function curve on to individual growth and skeletal maturity curves, and their annual velocity curves. The results are summarized as follows: 1) Mean menarcheal age was 12.36. 2) The mean peak height velocity (PHV) appeared at age 11.1, at 141.6cm of stature with a magnitude of 7.8cm, 1.3years before the menarche. 3) Mean stature, weight and chest circumference at menarche were 150.3cm, 41.8kg, and 76.3cm respectively. 4) Mean velocity peaks of growth and maturation are followed by in order of age 9.0 Carpal maturity score, age 9.5 20-Bone maturity score, age 11.1 stature, age 11.1 weight and chest circumference, age 11.9 RUS maturity score, and age 12.4 menarche. 5) Girls experiencing an earlier menarcheal age show earlier ages of PHV, peak weight velocity (PWV), peak chest circumference velocity (PCV), and peak RUS maturity score velocity. And they show larger PHV magnitude. They also show less RUS maturity score and stature at menarche. 6) Girls experiencing an earlier age of PHV are of a lower stature at PHV, but a larger magnitude.