No abstract

Recent roentgenographic studies suggest that periosteal apposition adds femoral cortical bone faster than it is lost by endosteal involution, so that cortical bone area increases with age. A comparison was made of direct and roentgenographic measurements of femoral cortical bone using femora from 23 females and 20 males of a prehistoric Mississippian population dated at A.D. . The comparison revealed that significant errors existed in the technique of radiographic measurement (p < O.OOOOOl), in estimating male and female cortical thickness ( p < O.OOOOOl), and the changes in thickness with age ( p < 0.000001). There was no significant interaction of the variables: age, sex, and method.The errors arose partly from the inability of the roentgenograph to reveal clearly endosteal porosity, and partly in the assumption that the medial and lateral cortical wall thickness would be representative of the mean cortical thickness.The reduction in cortical thickness (11.3% males and 29.3% females) with age as measured directly is comparable with loss in modern populations.Osteoporosis, which has been defined as a decrease in skeletal mass, has become a major problem in our aging population. It occurs in contemporary western (Frost, '61a,b; Urist et al., '63; and Bartley et al., '66) as well as in peasant populations (Garn and Rohmann, '66), and although Jarcho ('64) stated there was no evidence in prehistoric archaeological populations, recent investigations (Dewey, '68; Dewey, Armelagos and Bartley, '68; Dewey, Bartley and Armelagos, '68) of prehistoric Nubian populations indicate that this process does occur in such population and so has historical depth.Although autopsy and biopsy material has been used in the study of involution (Bartley et al., '66; Frost, '61a), roentgenographic analysis has been the most widely used tool in quantifying bone loss. For example, Smith and Walker ('64), utilizing antero-posterior radiographs, measured femoral cortical thickness and periosteal diameter of the mid third of the left femur from 2,030 women aged 45-90 years and computed estimates of cortical area based on the assumption that the geometry of the cortical-endosteal and periosteal cir-AM. J. PHYS. ANTHROP., 311 23-38.cumferences were regularly circular so that their diameters were reliable indices of the circular areas within them. They reported cortical area increased with age, and although cortical thickness decreased, the outer diameter of the mid-shaft increased enough to cause a net increase of cortical area. This implies periosteal apposition exceeded endosteal resorption.The findings of Garn and his colleagues ('67), in a study of the second metacarpal, seem to correspond to Smith and Walkers's results. Since the second metacarpal is essentially tubular, these results were not unexpected.On the other hand, Epker and Frost ('66) ('65) found a 40% decrease in femoral cortical tissue in ninth decade females while that of the males decreased 12%. Dewey ('68) and Dewey et al. ('68), utilizing direct measure...