Radiographic epiphyseal union standards for age estimation of the upper limb in South African males

Accurate skeletal age estimation is crucial in biological anthropology. Epiphyseal union is a common age estimation method; however, popular standards are overwhelmingly of European origin, and inaccurate for South Africans. In this study, we present a population-specific dataset of epiphyseal union timings for the upper limb joints in South African males. Upper limb epiphyses (shoulder - humeral head, greater tubercle; elbow - medial epicondyle, trochlea, capitulum, lateral epicondyle, proximal radius; wrist - distal ulna and radius) were assessed in 1290 pre-existing full-body radiographs of males aged 6 – 24 years. Radiographs were extracted from LODOX® Statscan systems of multiple hospitals in Cape Town and Johannesburg. Each epiphysis’ degree of union was classified into one of four stages, ranging from non-union to complete union (the age where 95% of the sample exhibited total union/stage 4). Based on union data, joint maturity was reached in the predicted sequence: Elbow = ±17 years (medial + lateral epicondyle = 17 years; trochlea, capitulum = 15 years; proximal radius = 16 years), wrist epiphyses at 20 years, and shoulder at 21 years. However, timing-of-union was delayed compared to international study samples. Similar to previous studies, South African males exhibit prolonged union before reaching maturity. These results are a representation of South African male skeletal development, is applicable to both living and deceased, and forms the first comprehensive multi-site epiphyseal union dataset for South African males. The stage-of-union methodology is applicable to both the living and deceased, whilst laying the foundation for clinical and medico-legal applications in South Africans. • South African male epiphyseal union timings differ from international standards. • Epiphyseal union timing delayed in South African males compared internationally. • Upper limb maturity: Elbow = ±17 yrs, wrist ±20 yrs, shoulder ±21 yrs. • First comprehensive dataset for union of the upper limb in South African males. • Stage-of-union method applicable to the living and deceased.