Evaluation of two scoring systems assessing the epiphyseal union at shoulder joint as predictors of chronological age among a sample of Egyptians

•Radiography of humerus and acromion is reliable age-assessing tool in Egyptians.•Epiphyseal union of humeral head commenced at age of 16.1–17 and completed by 21 years.•Complete epiphyseal union of acromion was observed by the age of 20.8 years.•Humeral and acromial epiphyseal maturation occurs earlier in females than males.•Chronological age positively correlated with established total shoulder Scores A/B. Age estimation has extensive medicolegal implications in civil and criminal identification. Despite the surge in adopting radiological investigations to assess developmental bony changes, the shoulder joint is understudied. A cross-sectional study was conducted, enrolling 283 shoulder radiographs of Egyptians, investigating the reliability of two previously established scores as predictors of chronological age using the epiphyseal maturation of proximal humerus and acromion process. Epiphyseal union of proximal humerus commenced at age of 16.1–17 and completed around 21, while complete acromial union was observed around the age of 20.8. Females significantly preceded males and showed lower mean total Scores A and B at different maturation stages. There was a significant strong positive correlation between the chronological age and the epiphyseal maturation of humerus, acromion and total shoulder scores with correlation coefficients between 0.84 and 0.9. The receiver operating characteristic curves showed significant discriminating power of the total shoulder Scores A and B as predictors of the ages of 14 and 16, with area under curves above 0.9, minimal accuracy of 96.5 % and p values of 0.001. Six proposed models were established where the model “age = 0.318 + (0.388) total shoulder Score A + (2.842) total shoulder Score B + 1.931 (sex)” showed the best significant prediction power of radiographic evaluation of epiphyseal maturation in the proximal humerus and acromion in estimating the ages between 8 and around 20 years (R2 of 0.812). Applying this model to assess the chronological age, especially if the results from the hand and teeth are inconclusive, is promising.