Labeled long bones on skeleton: which feature is commonly used to estimate age?

• A. Number of fused bones
• B. Length of the bones
• C. Thickness of cortical bone
• D. Color of bone

Answer: (A)

The feature being tested is skeletal maturity through epiphyseal fusion in long bones. Growth plates at the ends of long bones (epiphyses) ossify and fuse to the shaft (diaphysis as a person matures). The number of epiphyses that have fused provides an age range, because fusion follows a relatively consistent sequence during development. This makes counting fused versus unfused epiphyses a reliable way to estimate age in subadults. Other options—bone length, cortical thickness, or bone color—vary with individual factors like nutrition, activity, or condition and are less precise for age estimation.