Radiographic age estimation of sub-adults: Epiphyseal union for upper limb joints in South African females

Age estimation is an integral component of sub-adult skeletal assessment. Epiphyseal union timing is a common age estimation method; however, popular standards are of international origin and inaccurate in South Africans. Of the limited data available, females are underrepresented. This study used radiographs to create a population-specific dataset of epiphyseal union timings for upper limb joints in South African females. Nine upper limb epiphyses (shoulder: humeral head, greater tubercle; elbow: medial epicondyle, trochlea, capitulum, lateral epicondyle, radial head; wrist: distal ulna, distal radius) were assessed in 2444 pre-existing, full-body radiographs of females aged 5 – 24 years (Radiographs obtained from three medical institutions in Cape Town, South Africa). Epiphyseal union was assessed using a five-stage scoring system (from Stage 0 - ‘epiphysis absent’ to Stage 4 - ‘total union’). Union progression analyses, descriptive statistics and posterior probability tables were generated for each epiphysis. Epiphyses reached maturity in the predicted sequence; however union timing differed from literature: Elbow (Capitulum: 12 years, trochlea: ±13 years, lateral epicondyle: ±15 years, radial head: ±17 years, medial epicondyle: ±18 years), wrist (Distal ulna: ±20 years, distal radius: 21 years), shoulder (Greater tubercle, humeral head: ±21 years). Union occurred earlier than South African males but was delayed compared to females of other populations. These results represent the nuanced South African female skeletal development and provides comprehensive epiphyseal union data for the upper limb, previously unavailable for this population. The scoring system and probability tables have forensic applications and multi-site epiphyseal data are useful for cases containing incomplete remains. • South African female epiphyseal union timings differ from international standards • Epiphyseal union timing delayed in South African females compared internationally • Upper limb maturity: Elbow = ±15 yrs, wrist ±19 yrs, shoulder ±21 yrs • First comprehensive dataset for upper limb epiphyseal union in South African females • First account of South African females showing prolonged union before maturity