I. The official name of bone age (bone age, skeletal age) is: skeletal age.
1, what is the bone age: human growth and development can be expressed in two “age”, that is, the age of life (calendar age) and biological age (bone age). Bone age is short for skeletal age and is determined with the help of a specific image of the bone in an X-ray camera. In order to find out the age of a person’s bones, an X-ray of the wrist of the left hand is usually taken, through which the doctor observes the degree of development of the metacarpal phalanges, carpal bones and the ossification centers of the lower radius and ulna of the left hand. It is a biological age that reflects the degree of physical development by measuring the changes in size, form, structure and interrelationship of bones, and expresses it in the form of age in years through statistical processing.
2, standard bone age film shooting method: standard bone age film, only need to take a left hand orthopantomograph. When taking the film, the five fingers of the left hand are opened naturally, the palm is down, the middle finger and forearm are kept in a straight line (try not to deviate from the left and right, and the arm is placed flat and not lifted up), the X-ray bulb is aligned with the third metacarpal bone, and the distance between the bulb and the X-ray film is about 80CM.
3, factors affecting bone development: many diseases affect bone development, making it into advance or backward, such as adrenal cortical hyperplasia or tumor, precocious puberty, hyperthyroidism, simple obesity with excessive growth in stature, ovarian granulosa cell tumor, etc. will lead to early bone age; while ovarian hypoplasia (Turner syndrome), chondrodysplasia, pituitary dwarf (growth hormone deficiency), and low A will lead to significant lag in bone age. The most important factor is the hypothalamic-pituitary-gonadal axis system. Hormones secreted by endocrine glands such as growth hormone, thyroid and adrenocorticotropic hormone also play a regulatory and controlling role in skeletal development, among which sex hormones play a leading role in pubertal skeletal development.
II. Clinical significance of bone age assessment
The changes of human skeletal development are basically similar, and the development process of each bone has continuity and stages, and the bones at different stages have different morphological characteristics. At present, the following aspects of growth and development are often required: ① Bone age assessment can reflect more accurately the level of growth and maturity of individuals (to determine what stage of growth and development they are in, and also help to distinguish “early growth” or “late growth”, etc.); ② It can not only determine the biological age of the child, but also provide an early understanding of the growth potential of the child and the trend of sexual maturity through bone age (determination of the remaining growth space and sexual maturity); (3) bone age can also predict the adult height of the child (determination of whether a child with short or early growth needs treatment); (4) bone age determination is also very helpful for the diagnosis of some endocrine diseases in children (e.g. growth hormone (e.g., children with growth hormone deficiency often lag behind in bone age, while children with precocious puberty often advance in bone age); (5) to guide the clinical use of endocrine drugs and the judgment of treatment effects (e.g., children with precocious puberty need regular assessment of bone age to guide the adjustment of drug dosage); (6) bone age is also used in forensic medicine to determine the age of a specific individual as a basis for conviction; (7) for the selection of athletic, artistic and other special talents with different height requirements. It is also used in the selection of athletes with different height requirements, artistic talents and other special talents, and in the grouping of athletes in competitions, etc.
The difference between biological age (bone age) and life age within ±1 year is called normal development.
The difference of biological age (bone age) – life age > 1 year is called early development.
If the difference between biological age (bone age) and life age is <1 year, it is called developmentally delayed. < p="">
Bone age determination plays an important role in the x-ray diagnosis of certain endocrine disorders, metabolic disorders, and growth disorders. Abnormalities in bone age are often an aspect of the presentation of certain endocrine disorders in pediatrics.
Bone age and growth potential
BA
(years)
% of completed adult height
Average growth potential for girls
Female (160.2cm)
Male (172.1cm)
Remaining growth space (cm)
Growth rate (cm/year)
11
91.5
84.4
13-14
7
12
95.1
88.3
7-8
4
13
97.6
92.7
4
2-3
14
99.0
96.4
1-2
1-2
Male: +5~12cm
According to the latest TW3 assessment method, when the bone age reaches 16.5 years for boys and 15.0 years for girls, the epiphysis basically closes, the skeleton reaches adulthood, and height basically stops growing. However, the age at which the epiphysis is completely closed is different for different bone age assessment methods. For example, for the TW2 method released in 1975, the epiphysis is completely closed at 18.3 years old for boys, reaching adulthood, a difference of 1.8 years from TW3, and at 17.2 years old for girls, reaching adulthood, a difference of 2.2 years from TW3. In June 2014, the table was modified according to the 2005 national normal height table for male and female children and adolescents of all age groups in nine cities because there were still some differences with the TW3 method).
III. Commonly used bone age assessment methods at home and abroad
1.Bone age assessment methods
The traditional bone age assessment usually involves taking X-ray pictures of the subject’s hands and wrists, which are then interpreted by a doctor according to the X-ray pictures taken. The most commonly used methods are the G-P atlas method and the TW2 (TW3) scoring method; the prediction of adult height based on bone age includes the B-P method, the CHN method, and the TW3 method. In recent years, a new technique of bone age assessment by ultrasound called BoneAge has also been developed in Israel.
1.1 Counting method
In the early 20th century, ossification center counting was dominant, with the following contents: (1) observation of the number of ossification centers appearing at a certain age, mainly in carpal bones; (2) measurement of the area of ossification centers and the ratio between bone and bone; and (3) observation of the fusion time of epiphysis. That is, the bone age counting method, such as Vogt and Vickers’ method published in 1938. Because of the early appearance of ossification centers in the wrist and the increase in the number of sites that would result in excessive X-ray exposure, there were no significant developments in this type of study later.
1.2 Atlas method
After the discovery of X-rays in 1895, scholars began to use them in the study of skeletal development, and the earliest atlas of skeletal development was proposed by John Poland in 1898. ), which was revised in 1959. The G-P Atlas is a longitudinal study based on children from middle and upper class families in the United States, from birth to adulthood. The method is based on the order of appearance and disappearance of the ossification center and epiphysis of the wrist at different ages of children and adolescents, and establishes a standard bone age chart for both sexes. This method is simple, intuitive and easy to use, and countries or regions have established their own standard atlas, including Gu’s atlas in China.
1.3 Scoring method
The atlas method is subjective, deviates greatly, and the bone maturation rate is not clear, so Tanner and Whitehouse et al. (1962) proposed the TW1 bone age scoring method through their study, which was modified to TW2 method in 1975. In this method, 20 wrist bones were taken from left wrist orthopantomographs, and each bone was divided into 8-9 stages according to different developmental grades and assigned different scores, and the total bone development score (SMS) was from 0-1000. The bone development score of each bone was accumulated from wrist x-rays, and then the bone age score table or SMS an age curve was checked to obtain the bone age. The scoring system has three series: (1) R (radius, ulna and short finger bones, RUS) series, which contains 13 distal ulnar radius, 1st, III and V metacarpal bones; (2) C (carpals) series, which contains 7 carpal bones, except pea bones; (3) T (TW20 a bones) series, which is a combination of R and C series. In 2001 has been modified to TW3 method, which is currently the latest international standard for judging, mainly to cancel the T series, that the T series is only the synthesis of R, C series, no special use; as well as the reformulation of the R series standard, that the standard is affected by the times, the population and other factors. China introduced the Li Guozhen percentage counting method (1979), the Chinese wrist bone development standard CHN method (1992) and the direct reference to TW2’s Ye’s scorekeeping method (1991).
1.4 Other bone age assessment methods that have emerged in recent years
Bone age is mainly assessed with the help of higher modern technology.
① Computer-aided bone age assessment: mainly used for TW3 method, CHN method and other bone age scoring methods that require complex calculations. However, because it requires scanning of bone age films or can only be uploaded through the imaging department of our hospital, it increases the assessment procedure or is inconvenient to assess patients’ own films; at the same time, due to the current imperfections in the procedure, the score is fixed for each period, and it is inconvenient to make appropriate adjustment of the score for those in between two periods, and only the same method can be used when predicting adult height, the application is currently subject to some limitations.
② Ultrasound bone age assessment: In 1995, Castriota et al. used ultrasound to measure the thickness of femoral head articular cartilage (FHC) in children, showing a strong correlation between FHC thickness and bone age and life age, suggesting that ultrasound measurement is a meaningful method for assessing skeletal development in children and adolescents. It has also been reported that there is a significant correlation between the heel bone broadband ultrasound attenuation values and age in children and adolescents aged 6 to 15 years. Ultrasonic bone age measurement instrument has been introduced, which is based on the structural changes in the process of cartilage ossification in the wrist, and the bone age is calculated by measuring the ultrasound velocity through the wrist, and the results are highly correlated with those obtained by the G-P method, suggesting that ultrasound technology has good application prospects in bone age assessment.
The application of dual-energy X-ray absorptiometry (DXA): In 2002, some foreign scholars used a low-radiation measuring instrument DXA to image the wrist and explore bone density to assess bone age. Pludowski et al. reported that the DXA test and X-ray test had high consistency in bone age assessment, and among 60 individuals, 40 cases had the same bone age, and the difference in bone age was less than 0.5 years in another 16 cases, and The image quality and resolution of DXM meet the requirements, but DXA is not yet able to achieve the accuracy of bone age within 0.5 years, and its application is limited by its high cost and relatively complicated operation.
2.The history of bone age assessment in China
①, Liang Duo (1937), Liu Huifang (1959), Gu Guangning (1962), and Zhang Naiju (1963) had successively proposed the standard of bone age calculation method for children in China. Liu Baolin (1983) and Xu Jida (1985) had proposed a bone age atlas for children in China, but none of them was widely used.
In the 1960s, Li Guozhen proposed the “Chinese Bone Age Percentage Counting Method”, which was widely used for a certain period of time.
In 1992, the National Sports Commission organized relevant professionals to revise the TW2 bone age according to the characteristics of Chinese children, removing the ulna and adding the cephalic bone and hook bone. And scored by similar method, called CHN method. In recent years, it was revised by Hebei Sports Institute.
④, In 1991, Yeyin Ye et al. made the adult height prediction method of TW2 bone age by first converting Chinese height to British height, and then converting back to Chinese height after making annual height prediction by TW2 method. Because of its high accuracy, it has been widely used in the field of pediatric endocrinology and is referred to as “TW2 Ye’s method”.
Currently, the clinical method of hand and wrist bone age (BA) assessment is commonly used.
Assessment methods
TW1
TW2
TW2 (leaf)
TW3
CHN
G-P
Published
1962
1975
1991
2001
1995
1950 (Revised 1959)
Target audience
British
Middle
British
Lower middle
Changsha
Middle
Europe North America
Middle
China
6 provinces and cities
United States
Upper Tier
Number of people
2600 people
2702
2122
3300
22160
6879BA tablets
Method
horizontal
vertical+horizontal
horizontal
vertical+horizontal
horizontal
vertical
Special Points
20 bones
Same as before
Same as before
Same as before
14 bones
29 bones
Score
C,R,T lineage
Same as before
Different scores for male and female
Same as before
BA age same as TW2
C,R series scores Criteria unchanged BA age changed
Score modified TW2 bone development grade criteria
Chart
BA age visualized not refined
IV. Advantages and disadvantages of various bone age assessments
1.GP atlas method: The advantages are concise, intuitive and easy to assess; different data of advanced bone age, normal bone age and lagging bone age are available for adult height prediction, which is helpful for predicting the height of people with endocrine diseases. The main disadvantages are the lack of accuracy; it is easier to distinguish the morphology of the carpal bones by the atlas method, while it is more difficult to distinguish the long bones, but the adult height prediction is mainly based on the bone age of the long bones, so the accuracy is often felt to be insufficient in clinical practice. And the original data from the 50’s U.S. middle and upper class family children, but after all, after 1959 has not been updated, the age is older.
2, CHN method: Since the 80s, according to the current development of children, China has improved the TW2 method and developed a unified bone age standard in China – CHN standard, which is more suitable for the evaluation of bone age of children in China and is common in China, but not common internationally, causing inconvenience in communication. And it is as complicated as the TW method. At the same time, because it comes from the results of cross-sectional studies (the same period, the collection of different age groups of normal children and adolescents bone age data), its reliability is lower than that of longitudinal studies (the same group of normal children, from birth to adulthood, regular bone age films).
3. TW3 bone age: In 2001, the TW2 bone age scoring method, updated to the TW3 method, and the RUS score was adjusted to correspond to the bone age of male and female children according to the changing times. Adult height prediction is no longer predicted by bone age, which is more obviously influenced by race, era and region, but by direct prediction of bone development score, and after 9 years of longitudinal observation of 3300 children in North America and Europe, it is found that this method is more accurate than other methods in adult height prediction, and it is not restricted by race and region, so it is worth to promote vigorously.
Currently, the National Endocrinology Group’s “Guidelines for the Management of Children with Short Stature” recommends either the BP method or the TW3 method. However, the TW3 method is definitely more accurate and more up-to-date.
V. Adult height prediction
1.The significance of adult height prediction
At present, most hospitals assess the bone age based on the radiology bone age report or the bone age assessed by the pediatric endocrinologist against the chart, and very few hospitals make the adult height prediction for the patients. However, adult height prediction is very important for the diagnosis, treatment and efficacy observation of pediatric endocrine diseases.
(1) Adult height prediction is an important basis for clinical intervention
(2) Adult height prediction is the main indicator of whether to continue intervention
(3) Adult height prediction is one of the bases for the effectiveness of treatment.
(4) Adult height prediction is an important basis for differentiating pathological shortening from pubertal growth retardation.
⑤ The adult height prediction is the most important indicator for parents.
2. Methods of adult height prediction
B-P (Bayley-Pinneau) method: The proportion (%) of children reaching adult height at that bone age is closely related to the proportion of children reaching adult height at that bone age. Calculation method: Adult predicted height = height at that time / P x 100
By bone age (BA) developmental rate.
Normal BA – CA = < 1y
Fast BA – CA = > 1y
Slow BA – CA = < - 1y
Bone age was measured by the G-P method, and PH was performed using the B-P table.
(ii), CHN method to predict height with the same principle as B-P method, with different reference tables (Chinese children, divided into northern, central and southern, but without values when there is a difference between bone age and age).
③, HtSDs (BA) trajectory extension method (curve method): The height shown is extended at the trajectory of the HtSD locus comparable to the present BA indicated by the growth curve.
(iv) TW3 method for adult height prediction is the latest method available (bone age from European children in Belgium, Spain, and Texas, USA, and adult height prediction from children born in the late 1970s and early 1980s in Zurich, Switzerland), calculated based on the RUS bone age score, current height, current age, and height gain in the previous year. Calculations ± 2 standard deviations included 95% of the population range. Since the bone development score is not affected by race, region and era, it can be used for different ethnic groups in theory.
3. Prediction of timing of menarche in girls.
TW3 girl menarche method: age at menarche = 12.6-0.68*(years of bone age – years of age) ± 0.625 years.
3.The discussion of adult height prediction problem
①, each kind of adult height prediction has its advantages and disadvantages, TW3 method into the original data of annual height prediction, after all, from the Western countries, although the appointment of height by bone development score (response to the degree of bone growth) can be independent of the era, region, race, but after all, the era is different, the average height of normal people still have differences, and again, there is a lack of a large sample size of validation data. ②, growth curve method to predict height for bone age and age similar or slightly older children are relatively accurate, bone age is significantly less than the age of accuracy.
③, TW2 Ye’s adult height prediction method has been widely accepted in the past.
(iv) The BP method predicts height with data on bone age matching age, bone age greater than age 1 year or more and bone age less than age 1 year or more. It is relatively more meaningful in the presence of childhood endocrine diseases when bone age does not match age. However, the GP chart method is less accurate in assessing bone age, and the proficiency of the assessing physicians varies greatly, which obviously affects the accuracy of the prediction results, and after all, the age is long ago, and the average height of normal people has changed a lot.
It is best to evaluate all bone age assessment methods for each child when available, and to make adult height predictions for all methods for them.
VI. Special tips.
①. Except for a very small number of prediction methods for a specific disease, the raw data for the majority of adult height prediction methods are derived from normal individuals. The difference between bone age and age in normal people is generally less than 1 year. When the bone age and age match, the predicted height is relatively accurate; when the bone age and age differ by 1 to 2 years, the predicted height is for reference only; when the bone age and age differ by more than 2 years, the predicted height is not used as a basis, but can be used as a comparison for observing the efficacy before and after treatment.
②, the prediction of height can only be based on the height and bone age at the time of examination and predicted future height according to the normal growth trajectory. For children with short stature, if they did not grow according to the normal growth trajectory in the past and without any treatment, there is little possibility that they can grow according to the normal growth trajectory from the time of prediction, and their actual height without treatment is often lower than the predicted height. The same is true for children with precocious puberty, who cannot grow according to their normal growth trajectory because of their early development. The premature development, bone age often changes quickly, and later on the prediction may decline.
How can I roughly judge the reliability of adult height prediction?
Recently, when answering online inquiries, I often see some adult height prediction results after bone age assessment, but many of them are very unreliable. For example, there is “an 11.5-year-old boy with a current height of 150 cm and a bone age of 13.1 years, but the predicted adult height is over 176 cm. The average height of boys at age 13 is 159.5cm, the average adult height of normal men is only 172.1cm, the average late growth space of 13-year-old boys is less than 13cm, the bone age is already 13.1 years, even if the age is slightly younger, the late growth space may be slightly greater than 13cm, but there is more than 26cm of growth space is impossible, if we consider the rapid progress of bone age, the late growth space Less than 13cm is still possible.
1, for the bone age and age equivalent and normal growth, after excluding precociousness, dwarfism, etc., can be based on the normal height table of each age group (although it is an age table, because normal children and adolescents bone age and age is equivalent, can be compared by bone age), to see the average height of the corresponding bone age and adult average height gap, to compare the late growth space. You can also consider using the growth curve to do a rough comparison.
2, for the bone age in advance of more than 1 year, can also be compared according to the above method, however, the late growth space may be slightly larger than the corresponding bone age segment growth space, because the prediction of adult height also has an age factor. However, the older the bone age, the lower the weight of age in predicting adult height and the smaller the magnitude greater than the average growth space. However, if one considers the possibility of rapid progression of bone age in early growers, there is also the possibility of a later growth space below the normal average growth space. In the case of girls, the above method cannot be used to compare directly after menarche, while if a girl has menarche too early, it will also obviously affect the later growth space.
3, for the bone age behind the age of more than 1 year, especially the bone age behind the normal age of more than 2 years, the presence of diseases affecting growth and development of children, it is best to roughly according to the age to compare the corresponding age of late growth space. Although theoretically the actual growth space should be greater than that of the corresponding age due to the younger bone age, the actual annual growth will be less than that of a normal child due to the presence of growth abnormalities, and the later growth space will be limited. Of course, the comparison is more reliable by calculating the corrected bone age, but it is not possible to calculate the corrected bone age without a very experienced professional.
With the development of our society and the improvement of people’s health, the growth and development of children has received great attention from the society. Bone age, as an important indicator of an individual’s level of development and maturity, should be promoted and applied in clinical practice. And familiarity, mastery, and selection of appropriate methods are required to guide and help the work.
Our hospital has also purchased the software for bone age assessment, but since it is necessary to scan the bone age film into the computer beforehand, then manually compare the chart, select a fixed score, and summarize the RSU points by the computer, the advantage is that the manual calculation process is saved. However, the disadvantage is that the score cannot be added or subtracted between the bone age division and the two stages, and the method of predicting adult height is limited, which we think cannot meet the requirement of clinical guidance. Therefore, we have accumulated rich experience in assessing bone age manually for each patient and predicting adult height by various methods (in the bone age research projects undertaken by our hospital, a double-blind method is required for the selected bone age films, and the same bone age film is evaluated twice, and it is rare that the difference between the two is greater than 0.2 years), which has been widely recognized by the society.