09-07-2025
Skeletal signatures: how bone age shapes medicine, law, and sport
In June 2025, the BCCI (the Board of Control for Cricket in India) announced a crucial update to its Age Verification Programme, now offering a second bone-age test for junior cricketers whose skeletal age initially exceeds the fixed limit. Boys under-16 and girls under-15, as determined by wrist X-rays using the TW3 method, will have another opportunity to validate their bone age before being barred from the same age category. The threshold remains a bone age of 16.4 years for boys and 14.9 years for girls; however, a second test ensures that select players do not lose a season due to narrow margins or biological variability.
Protecting fair play
Age fraud has long been a concern in competitive sports, particularly in India. Chronological age can be manipulated on paper, but skeletal age estimation offers an additional measure. BCCI's use of BoneXpert software for players ensures a level playing field, preventing older adolescents from unfairly dominating younger age brackets. However, it is important to clarify that a mere mismatch between bone age and declared age does not always imply cheating. Some children naturally mature earlier, and others later. For instance, a 13-year-old with early puberty may have the bone age of a 15-year-old without any foul play. Clinical judgment remains essential.
What is bone age?
Bone age, used in paediatric endocrinology, juvenile law, and age-group sports, is an estimate of skeletal maturity, obtained by examining how far the bones have developed. It is not the same as chronological age, which is calculated by the number of years since birth, but rather a biological index of how mature the body is. To measure bone age, doctors typically rely on a radiograph of the non-dominant hand wrist (usually left). This is chosen because it's less likely to have been subjected to injuries, fractures, or overuse, which could alter the growth plate appearance and distort age estimation. Furthermore, the hand and wrist contain many small bones, each at a different stage of ossification. They offer a broad and reliable picture of skeletal development with minimal radiation exposure.
Methods of estimation
While the X-ray provides the image, the interpretation is based on standardised atlases or scoring systems. Two prominent and common methods exist: the Greulich and Pyle (GP) atlas and the Tanner-Whitehouse (TW) method. The GP atlas compares the child's X-ray to a set of reference images developed from American children in the mid-20th century. Though easy to use, it is prone to subjectivity and may not reflect population differences. The TW method, in contrast, evaluates the maturity of each bone—from the radius and ulna to the short carpel bones of the hand—and assigns a score based on its stage, from A to H. The cumulative score is then converted into a bone age. TW3, the latest version (updated in 2001), is considered more systematic and less error-prone.
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Growth variation by gender and time
Bone maturation differs notably by gender, primarily due to hormonal influences. Girls tend to mature faster than boys because oestrogen—present in higher levels (three times higher than boys) even before puberty—accelerates the fusion of growth plates. This results in earlier skeletal maturation in girls, making bone age estimation less reliable for them beyond 14 to 15 years. In boys, growth continues longer, allowing wrist-based assessments up to 16 to 17 years.
Bone maturation follows a known sequence: at birth, carpal bones are absent (knee X-rays are used to assess); the triquetral (carpel bone) appears by 2.5 years, and the pisiform by around 11 years. Wrist X-rays help place children accurately into age brackets like 3–10 or 11–17 years. While such ranges can be reliably identified, predicting exact age remains approximate, as ossification varies with genetics, nutrition, hormones and health. Overlapping developmental patterns in mid-childhood further reduce precision. For newborns, knee X-rays are preferred. Clavicle assessment via CT becomes the standard in late adolescence(14-22 years ). In adults aged 30 to 65, the manubrium sterni—which fuses progressively with adjacent sternal parts—is sometimes used for age estimation, though with considerable individual and population level variability. Thus, bone maturation is influenced by genetics, nutrition, hormones, and health conditions, leading to biological variability even among children of the same chronological age.
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Uses of bone age estimation
Bone age plays a key role in diagnosing growth and hormonal disorders. It helps differentiate between constitutional delays and conditions like hypothyroidism or growth hormone deficiency. In early puberty, bone age is advanced; in delayed puberty it lags. It also guides hormone therapy and predicts adult height. Beyond medicine, bone age aids juvenile justice when birth records are absent, with courts favouring the lower estimate under the Juvenile Justice Act. It is also used in immigration, adoption, and child trafficking or bonded labour—especially for rescued children without documentation—ensuring legal and welfare decisions are based on biological maturity rather than uncertain paperwork.
Need for local tools
Despite being the world's richest cricketing body, the BCCI still relies on age estimation methods like Tanner-Whitehouse staging, rooted in mid-20th-century England. Cricket in India follows British frameworks, even as the sport thrives locally. With deep pockets, the BCCI can lead a nationwide anthropometric survey reflecting India's vast ethnic and genetic diversity. Our country is a mosaic of races, ethnicities, and genetic lineages. Yet, even today, much of Indian medical textbooks continues to rely on Western normative data—whether it's the average stomach volume, anaemia cut-offs, BMI cut-offs, Negele's rule in estimating the delivery date of the foetus, or the medico-legal documentation of custodial torture. An Indianised framework, grounded in data from our people, remains rare even in our Indian textbooks. By investing in indigenous research, India can move from applying borrowed standards to setting our Indian standards for medicine, law, and sports.
(Dr. C. Aravinda is an academic and public health physician. The views expressed are personal. aravindaaiimsjr10@
