What is the difference between Greulich-Pyle and Tanner-Whitehouse?

Greulich-Pyle matches the X-ray with the atlas holistically (fast); Tanner-Whitehouse scores each bone separately and adds them up (more analytical). Both produce a bone age and are widely used.

Does the bone-age reading vary from person to person?

Small differences can occur; the assessment depends somewhat on experience. So bone age is interpreted not on its own but together with growth data.

At what ages is Greulich-Pyle used?

The Greulich-Pyle atlas can be used across a wide age range, from infancy to the end of adolescence; it contains standard images covering roughly ages 0–19 in boys and 0–18 in girls. Once the growth plates have closed (when the skeleton has matured), the method no longer provides additional information, because there is no growth left to assess.

Does artificial intelligence read bone age more accurately than a human?

AI-assisted systems can give fast and consistent results by reducing assessor-dependent differences; in some studies they show accuracy similar to experienced readers. But rather than saying “more accurate”, it is more appropriate to say “a consistent and fast assistant”. In every case the result should be interpreted by a doctor in the clinical context, together with growth data.

The Greulich-Pyle Atlas

Greulich-Pyle is the classic method that determines bone age by comparing a hand-wrist X-ray with standard atlas images. It is one of the fundamental references for bone-age assessment.

What is the Greulich-Pyle method?

Greulich-Pyle is the most common classic method used to determine bone age. The child’s left hand-wrist X-ray is compared with standard images in a reference atlas arranged by age and sex; the standard that most closely resembles the X-ray is taken as the child’s bone age. The method works on the basis of the appearance of the ossification centres and the maturity of the growth plates.

This “visual matching” approach is fast and practical; in the hands of an experienced assessor it gives reliable results. The alternative, the Tanner-Whitehouse method, scores each bone individually and offers a more analytical but more time-consuming assessment.

What is it used for?

The bone age obtained with Greulich-Pyle serves two main purposes. The first is to measure maturation: whether bone age is ahead of or behind calendar age shows where the child is on their growth journey. The second is height prediction: bone age is combined with the Bayley-Pinneau method to produce an adult-height estimate.

It is also used in assessing early/delayed puberty, in investigating certain growth disorders and in maturity-based planning in sport. AI-assisted systems can automate this atlas comparison; but the result should always be interpreted in the clinical context.

Accuracy and limits

Greulich-Pyle is a reliable method, but it can show small assessor-dependent differences; the same X-ray may be read slightly differently by two different specialists. Also, differences between the population in which the atlas was developed and the child’s population can lead to small deviations.

For this reason, bone age is treated not as a stand-alone result but as a piece of data interpreted together with growth velocity, height and the clinical picture. Because it requires an X-ray, it is used only when there is a clinical reason.

Modern methods and artificial intelligence

Although Greulich-Pyle has been in use for more than half a century, bone-age assessment can today also be done with digital and AI-assisted tools. These systems can produce a fast and consistent bone-age estimate by comparing the hand-wrist X-ray with large datasets; they carry the potential to reduce assessor-dependent differences. The bone-age support tool on the Çocuk Gelişim platform also draws on this approach.

But whatever the technology, bone age is not a result on its own. The value obtained by AI or the atlas method must always be interpreted by a doctor, together with the child’s growth velocity, height, pubertal findings and overall health. Automated tools speed up and standardise the assessment; but they do not replace the clinical decision. An X-ray is requested only when there is a medical reason.

This glossary entry is for information only and is not medical advice. Consult your paediatrician or the relevant specialist for diagnosis and treatment.