## Why option B is correct The capitate and hamate are the **first carpal bones to ossify**, appearing by 6 months of age. They serve as the earliest and most reliable carpal landmarks for bone age assessment in infants, particularly in the first year of life. The "COUNT YOUR AGE" mnemonic (the number of visible carpal ossification centers approximates age in years) begins with capitate and hamate as the foundational pair. Their presence in a 10-month-old is expected and normal, confirming bone age is appropriate for chronologic age. This is a key shortcut used in Greulich-Pyle and Tanner-Whitehouse methods for rapid bone age estimation in pediatric growth disorder workups. ## Why each distractor is wrong - **Option A**: Skeletal maturity is not achieved until late adolescence (typically 16–18 years in females, 18–20 years in males), with complete fusion of epiphyses. Presence of capitate and hamate alone does not indicate skeletal maturity; they are among the earliest ossification centers to appear. - **Option C**: This is factually incorrect. Capitate and hamate are the **first** carpal bones to ossify (by 6 months), not the last. The pisiform is the last carpal bone to ossify (9–12 years). This is a common distractor testing whether students confuse the ossification sequence. - **Option D**: The distal radial epiphysis appears around 1 year of age, so its absence at 10 months is normal and expected. This does not suggest advanced skeletal maturation; rather, it is consistent with normal development. Advanced bone age would be indicated by premature appearance of epiphyses relative to chronologic age. **High-Yield:** Capitate + hamate by 6 months = first carpal ossification centers; use "COUNT YOUR AGE" rule for rapid bone age screening in infants and growth disorder evaluation. [cite: Nelson 21e; Maheshwari Orthopedics 10e]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.