Which feature is NOT typical of an old sternal rib end?

• A. Shallow pit with a thick rim
• B. Deep pit with a porous rim
• C. Pit deep and rim thin and fragile
• D. Irregular rim

Answer: (A)

The feature being tested is how the sternal (costal) end of the rib changes with age. As bone remodels over time, the pit at the costal end becomes deeper and the rim loses thickness, becoming porous and fragile due to resorption of cortical bone. Irregularities in the rim appear from ongoing remodeling. A shallow pit with a thick rim is not typical of an old rib end; it reflects a younger stage where remodeling is minimal and the surface remains broad and intact. Therefore, that shallow pit with a thick rim best fits a younger presentation, while the other described features—deep pits with a porous rim, a pit deep with a thin and fragile rim, and an irregular rim—are more consistent with aging.