Fusion of most bones' epiphyses occurs between which ages?

• A. 5-10
• B. 10-25
• C. 25-40
• D. 40-60

Answer: (B)

Epiphyseal fusion marks the end of longitudinal bone growth. The ends of long bones (epiphyses) start as separate centers of ossification and gradually fuse to the main shaft (diaphysis) as maturation occurs. This process happens at different rates for different bones, and it is influenced by sex, nutrition, and health, but the general pattern is that fusion occurs during late childhood into early adulthood. Because most bones fuse within a broad window, the range that best encompasses the timing for the majority of epiphyses is 10 to 25 years. By late teens to early twenties, most epiphyses have fused, with a few bones (such as the clavicle) occasionally fusing a bit later. Therefore, the 10–25 year range is the most representative for when fusion of most bones’ epiphyses occurs.