Bone age assessment

Bone age assessment is used to radiologically assess the biological and structural maturity of immature patients from their hand and wrist x-ray appearances. It forms an important part of the diagnostic and management pathway in children with growth and endocrine disorders. It is helpful in the diagnosis of various growth disorders and can provide a prediction of final height for patients presenting with short stature.

Bone age can also be used to monitor children on growth hormone therapy or those presenting in delayed or advanced stages of puberty that may need treatment.

Methods

Assessment is performed with a radiograph of the non-dominant hand with a single DP view that includes the distal radius and ulna and all the fingers. Appearances of the carpal bones, metacarpal, phalanges, radius, and ulna are compared to standardised versions in one of two main atlases:

• Greulich and Pyle atlas presents a single standardised image for a range of ages of each gender ²
• Tanner-Whitehouse (TW) method involves the scoring of each carpal bone, the radius and ulna leading to a total score, from which age can be estimated ³

In addition, software tools are available to automate the task of bone age assessment. In 2017, the RSNA held a machine learning challenge to automate bone age assessment. The winning model achieved a mean absolute difference from the gold-standard (the average of a panel of paediatric radiologists) of 4.265 months ⁴. Here is a link (works properly perhaps only on Internet Explorer) to one free online tool for bone age assessment based on TW2 method: