Age estimation from the rib by phase analysis: white females.

Metamorphosis at the sternal extremity of the rib has already been established as a reliable indicator of age at death. Using a sample of white males, it was shown that an accurate estimation of age can be made by direct examination of the bone itself. However, because of sexual differences in hormonal production and dimorphism in the skeleton, the present study was carried out to develop an appropriate standard for age determination from the sternal rib in white females. The sample consisted of 86 ribs of known age, sex, and race. Observations were made at the costochondral junction with special attention to pit formation (its shape and depth), changes in the walls and rim surrounding it, and overall bone density and texture. Based on changes in these areas, the ribs were separated into nine phases (0 through 8). The most rapid metamorphosis occurred in Phases 1 through 4 (mean ages 14-28) with changes noticeable at 3 to 4 year intervals. After mean age 28, this process slowed, considerably expanding the interval between phases to 10 to 15 years. The female ribs showed both earlier initial pit formation and a different morphologic pattern of aging as compared with males. Statistical analysis revealed that the features chosen to delineate the phases are valid predictors of age. This study has shown that the sternal rib can provide an accurate estimation of age in females spanning a mean age of 14 to 76 years.