The Systematic Isolation of Key Parameters for Estimating Skeletal Maturity on Lateral Elbow Radiographs

Abstract

Background: Skeletal maturity estimation is central in the management of scoliosis and lower-limb deformity. Utilizing demographic characteristics and modern computing, we sought to create a reliable, rapid, and accurate method for measuring skeletal maturity on an elbow radiograph.

Methods: Utilizing the Bolton-Brush Collection, 4 parameters from the modified Sauvegrain method and 7 novel parameters were screened. Ten parameters were evaluated on serial peripubertal elbow radiographs, using Greulich and Pyle (GP) skeletal age from corresponding hand radiographs as a comparison. Stepwise linear regression and generalized estimating equations were used to identify radiographic and demographic parameters for estimating skeletal maturity based on 90% of final height. The elbow system was compared with GP only; olecranon apophysis only; age, sex, and GP; age, sex, and olecranon apophysis; age, sex, and elbow system with anteroposterior and lateral parameters; age, sex, and elbow system with anteroposterior parameters; and age, sex, and elbow system with lateral parameters.

Results: In this study, 367 radiographs from 77 patients (40 girls and 37 boys) were included. Following stepwise linear regression, 4 radiographic parameters were included in the anteroposterior and lateral elbow system; 3 were included in the anteroposterior elbow system; and 4 were included in the lateral elbow system. The lateral elbow system predicted skeletal maturity with a mean discrepancy of 0.41 year and produced similar mean discrepancies to GP with age and sex (0.42; p = 0.93), and it trended toward better performance than the olecranon apophysis system with age and sex (0.43; p = 0.06). The lateral elbow system had the lowest percent of outlier predictions >1 year discrepant from the skeletal maturity reference (4.6%), although it was only significantly better than the GP-only group (29.4%) and the olecranon apophysis-only group (21.0%) (p < 0.001 for both).

Conclusions: We systematically developed a lateral elbow system that performed equivalently to GP using 4 simple parameters and trended toward outperforming the olecranon apophysis systems in skeletal maturity estimation. Future clinical validation will be necessary to understand the utility of this system.

Clinical relevance: The lateral elbow system may be a more accurate prediction of skeletal maturity compared with the previously described olecranon apophysis system and can be used to guide the management of many pediatric orthopaedic conditions.