Geographic Differences Of The Second Metacarpal Cortical Thickness In Chinese Children And Adolescent

One of the methods used for X-ray radiographs quantification of bone mass was the bone cortical measurement,manually measure bone cortical thickness and bone cortical index at the midpoint of long bone on plain radiographs.This method is inexpensively and swiftly, can be measured on old plain radiographs,thus enabling estimation of cortical bone loss from the time of earlier recordings,gaining wider acceptance among vertical study children bone growth.Objective:The paper is to study the relationship between the second metacarpal cortical thickness(MCT),the second metacarpal cortical index(MCI) and height,weight of children and adolescents,to find out the growth regular pattern of MCT and MCI,geographic differences between northern and southern population in MCT and MCI.In order provide reference to better assessment of bone mass change,and prevention osteoporosis of children and adolescent.Methods:From the standardization sample of "The Skeletal Development Standards of Hand and Wrist for Chinese Children—China 05",chose 11258 healthy children of Han nationality(5580 boys,5670 girls),aged 3-19 years,from cities of Shanghai,Guangzhou, Wenzhou,Dalian and Shijiazhuang were served as the study sample.Stand anteroposterior radiographs of the left hand and wrist were made within 15 days of every sample birthday used X-ray mearsurement,and body height and weight were measured on the same days. Using digital caliper measurements of the second metacarpal performed on X-ray film viewer, outer(subperiosteal) and inner(medullary) diameters of bone midpoint were recorded directly,the second metacarpal thickness(MCT) was obtained by subtract inner diameters from outer diameters,the second metacarpal index(MCI) was the cortical thickness divided by the outer diameter.Rresults:In most age groups,that northern boys have more thicker cortical bone than southern boys,northern girls have less thicker cortical bone than southern girls;MCI of northern boys and girls have greater than southern groups.The thickness of second metacarpai cortical had significantly difference between northern and southern group were: 11,13,15year old boys(p＜0.01);3-5 and 9-13year old girls(p＜0.05).The second metacarpal cortical index had significantly difference between northern and southern group were: 11-16year old boys(p＜0.05);8-13year old girls(p＜0.05).The increase of thickness of cortical bone was respectively 3.22mm and 2.97mm for southern and northern boys,2.64mm and 2.77mm for southern and northern girls from 3 to 19 year of age.The increase amplitude of the second metacarpal cortical thickness was more rapid during puberty,increased was respectively 55.90%for 11-16 year of age of southern boy more than nouther boy 51.85%; 47.81%for 13-15 year of age of northern boys;43.64%for 10-13 year of age of southern girls;45.13%for 11-14 year of age of northern girls;however MCT of northern boys (47.81%) increased bigger than southern boys(34.16%) at 13-15 year of age.The development of MCT and MCI not only an age-related changes,but also a function of growth in body height and weight.Ages that MCT is significant associated with height and weight(P＜0.05):boys aged 8-15 years,girls aged 7-14 years.Ages that MCI is significant associated with height(P＜0.05):southern boys aged 11-13 years,northern boys aged 12-14 years,southern girls at 5-,11-and 15-year old,northern girls at 7-,11-and 14-year old.Ages that MCI is significant associated with weight(P＜0.05):southern boys aged 12-15 years, southern girls at 5-and 12-year old,northern girls at 7-and 11-year old;there have no significant correlation between MCI and weight of northern boys.It is show with multiple regression analysis that the variance significant between height, weight and MCT;the regression coefficient of height(P＜0.05):southern and northern boys aged 12-14 years,southern girls at 5-7,9-and 11-year old,northern girls at 8-14 year old.the regression coefficient of weight(P＜0.05):southern boys aged 8-,9-and 14-18 years and northern boys aged 4-,16-and18-years old,southern girls at 11-17 year old,northern girls at 4-8 and 13-14 year old.Multiple regression analysis the relationship between height,weight and MCI show that:the regression coefficient of height(P＜0.05):southern boys aged 11-13 years old,northern boys aged 12-14 years old,southern girls at 5-15,and 17-year old, northern girls at 11-14 year old;the regression coefficient of weight(P＜0.05):southern boys aged 13-16 years old,northern boys aged 13-and18-years old,northern girls at 16 years old; the regression coefficient of weight of southern girls is not statistical significant.Conclusion:①During the growth and development of children and adolescent(3-19 years),MCT and MCI increased with age similar to body height,weight,the increased velocity was more rapid during puberty.MCT geographic differences significant:boys aged 11,13,15years old,girls at 3-5,and 9-13year old.MCI geographic differences significant: boys aged 11-16 years old,girls at 8-13year old.②The development of MCT and MCI not only an age-related changes,but also a function of growth in body height and weight.After eliminate the influence of age,before puberty MCT is primary influenced by height to a certain degree,the impact of body weight after puberty enhanced.Grouped by age,MCI is influenced by height relatively small,is independently influenced by body weight.