Ultrasound Imaging-Based Methods for Assessing Biological Maturity during Adolescence and Possible Application in Youth Sport: A Scoping Review

Abstract

Bone maturity is an indicator for estimating the biological maturity of an individual. During adolescence, individuals show heterogeneous growth rates, and thus, differences in biological maturity should be considered in talent identification and development. Radiography of the left hand and wrist is considered the gold standard of biological maturity estimation. The use of ultrasound imaging (US) may be advantageous; however, its validity and reliability are under discussion. The aims of this scoping review are (1) to summarize the different methods for estimating biological maturity by US imaging in adolescents, (2) to obtain an overview of the level of validity and reliability of the methods, and (3) to point out the practicability and usefulness of ultrasound imaging in the field of youth sports. The search included articles published up to November 2022. The inclusion criteria stipulated that participants had to fall within the age range of 8 to 23 years and be free of bone disease and fractures in the region of interest. Nine body regions were investigated, while the hand and wrist were most commonly analyzed. US assessment methods were usually based on the estimation of a bone maturity stage, rather than a decimal bone age. Furthermore, 70% of the assessments were evaluated as applicable, 10% expressed restraint about implementation, and 20% were evaluated as not applicable. When tested, inter- and intra-rater reliability was high to excellent. Despite the absence of ionization, low costs, fast assessment, and accessibility, none of the US assessments could be referred to as a gold standard. If further development succeeds, its application has the potential to incorporate biological age into selection processes. This would allow for more equal opportunities in talent selection and thus make talent development fairer and more efficient.

Reliability of Two Recently Developed Procedures Assessing Biological Maturity by Ultrasound Imaging—A Pilot Study

“…With adequate training and sufficient time to mature physically, these talented late-developers have the chance to become more successful athletes, compared to less talented early-developers [ 14 ]. In order to actively involve late-developers in sports participation and to create fair conditions in training, competition and development, it is important to take the biological age into account in selection processes [ 15 , 16 ]. Knowledge of the biological age and its relation to an athlete’s chronological age helps to define the status (e.g., early-developer if biological age—chronological age ≥ 1).…”

“…Bone age can either be estimated in the comparative collective by comparing US images of the left hand and wrist with images of an atlas or it can be derived by calculating a maturity score. Bone maturity can be derived by staging of the ossification process or by a measurement of distances and/or calculation of a ratio [ 16 ].…”

“…To adjust training loads and to organize adapted competition categories, the athlete’s biological maturity should be assessed. Therefore, there is a need for a reasonable, cost-effective and practicable US-based standard method for estimation of bone maturity in youth sports [ 16 ]. In the existing literature on US-based assessment of bone maturity, there is wide diversity in the domains of application, in the methods used and in the body regions examined [ 16 ].…”

“…Therefore, there is a need for a reasonable, cost-effective and practicable US-based standard method for estimation of bone maturity in youth sports [ 16 ]. In the existing literature on US-based assessment of bone maturity, there is wide diversity in the domains of application, in the methods used and in the body regions examined [ 16 ]. Despite several studies concluding good accuracy of US assessments compared to MRI or X-ray [ 16 , 25 , 26 , 27 , 28 , 29 ], the validity of US and its clinical utility is still under discussion [ 30 , 31 ].…”

“…In the existing literature on US-based assessment of bone maturity, there is wide diversity in the domains of application, in the methods used and in the body regions examined [ 16 ]. Despite several studies concluding good accuracy of US assessments compared to MRI or X-ray [ 16 , 25 , 26 , 27 , 28 , 29 ], the validity of US and its clinical utility is still under discussion [ 30 , 31 ]. To date, there is no literature on US-based assessment of bone maturity that considers the differences in the expertise level of the examiners [ 16 ].…”