Skeletal Age Evaluation with BAUSportTM Ultrasound in Young Slovak Female Athletes and Non-Athletes—A Cross-Sectional Study

Background: Biological maturity assessment is increasingly discussed in youth sport because chronological age alone does not reflect inter-individual variation in growth and pubertal timing. Ultrasound-based systems such as BAUSport™ provide a radiation-free alternative to radiographic skeletal age assessment. This exploratory cross-sectional study examined skeletal age (SA) in Slovak female volleyball players, track-and-field athletes, and non-athletes using BAUSport™, while acknowledging substantial age differences between groups. Methods: Eighty girls (55 non-athletes, 13 volleyball players, 12 track-and-field athletes; aged 6.85–14.41 years) underwent anthropometric measurement and skeletal age (SA) assessment with BAUSport™. Chronological age (CA) was calculated as decimal age from birth date to measurement date. Groups were not age-matched; volleyball players were on average markedly older than the other groups. Skeletal maturity was categorized as early, on-time, or late using a ±1.0-year SA–CA threshold. Menarche status was recorded as an indicator of pubertal development. Group differences were evaluated using chi-square or Fisher’s exact tests as appropriate, while differences in SA and SA–CA according to menarche status were assessed using Welch’s t-test. Results: Volleyball players were older (12.90 ± 0.95 years) than non-athletes (10.22 ± 2.40 years) and track-and-field athletes (8.47 ± 1.51 years). They also demonstrated the largest mean SA–CA difference (+1.98 ± 0.73 years). The distribution of maturity categories differed across groups (χ2(4) = 14.32, p = 0.006, Cramer’s V = 0.30). Post-menarcheal girls exhibited significantly higher skeletal age and SA–CA values compared to pre-menarcheal girls. However, the substantial age disparity between groups represents a primary confounding factor and limits interpretation of sport-specific effects. Conclusions: This study demonstrates the practical application of BAUSport™ for rapid, radiation-free skeletal age assessment in youth. Differences according to menarche status support the biological relevance of skeletal maturity assessment. However, no valid between-group sport-specific inferences can be made because the groups were not age-matched and puberty is the dominant driver of skeletal maturation. Larger, age-matched studies are required before drawing conclusions regarding sport-specific selection patterns.