Methods for improving the efficiency of estimating total osteon density in the human anterior mid-diaphyseal femur.

In order to preserve whole bone integrity and minimize destruction, paleohistologists often rely on histomorphometric data obtained from small areas (1.5-50 mm2) sampled within the anterior mid-diaphyseal femur. Because bone exhibits significant histological variation, the validity of results based on such sampling is questionable. The accuracy of various subareas (columns, rows, squares approximating dimensions and locations assessed by paleohistologists) in predicting total osteon density in the anterior mid-diaphyseal femur is assessed in the present study. Thirty-five specimens (12.7 mm wide, 100 microm thick, average area 56.7 mm2) were chosen at random from a skeletal population of 94 Inuits and Pueblo agriculturists. The specimens were photographed and enlarged; an acetate grid (12 columns, 10 rows, 120 squares, square = 1 mm2 of bone surface) was superimposed over the photograph; and secondary osteons and fragments were identified. Alternate columns (50% total area, T.Ar) predicted over 98% of entire section total osteon density. Two column combinations (15% T.Ar), separated by at least one column, predicted 91 to 95% of total osteon density. Individual column (8% T.Ar) predictability ranged from 48 to 86%. Two row combination (32 to 40% T.Ar) predictability values ranged from 86 to 95%. Individual rows (<1 to 20% T.Ar) predicted from 45 to 92% of total variation. Combinations of squares approximating areas and locations assessed by other paleohistologists ranged in predictability values from 80 to 94%. The results demonstrate that subareas of as little as 15% predict 95% of variation in total osteon density in the entire anterior mid-diaphyseal femoral section. A minimization of histological area evaluated without the loss of accuracy allows for a minimization of time invested in data collection and the utilization of partially damaged specimens.

Histologic examination of age of the First African Baptist Church adults.

This study applies a recently formulated method of histologic estimation of age at death to samples of anterior femoral cortex taken from adult skeletons from the First African Baptist Church cemetery and compares the results with macroscopic age estimates made by J.L. Angel and J.O. Kelley. Of the 65 samples taken, 44 were sufficiently well preserved to produce readable thin sections, although most were so fragile that they had to be embedded before sectioning. In most cases the histologic ages agreed with the macroscopic age estimations within the standard error of the estimate of the histologic method. Most cases of disagreement could be attributed to poor preservation. Despite differences between individual gross and microscopic age estimates, the two methods proved to be significantly correlated and produced the same overall demographic picture of a population whose female members were likely to die at earlier ages than the males.

Histologic estimation of age at death using the anterior cortex of the femur.

This report describes a new histologic method for determination of age at death, the latest in a series of studies that began with Kerley's pioneer presentation in 1965. The study population was collected from 328 documented individuals from an anatomy dissecting room in the United States, from two modern cemeteries in the Dominican Republic, and from autopsies performed in a Chilean hospital. Undecalcified thin sections 1.0 cm wide were made from specimens taken from the femoral midshaft directly opposite the linea aspera. Five 0.886 mm2 fields were located at the periosteal edge and photographed, mainly for purposes of defining the fields and providing a permanent record. Secondary osteons, type II osteons, osteon fragments, resorption spaces, and non-Haversian canals were recorded as number/mm2, and a 100-space grid was used to measure average percent of unremodeled, osteonal, and fragmental bone. Stepwise regression analysis of the measurements produced a series of regression equations for age estimation for females, males, and sexes combined. Most equations have a standard error of estimate of about 10 years, but the coefficients of determination (r2) range from 0.48 to 0.72. In practice, sex-specific equations gave better results than opposite-sex or nonspecific equations, mainly because males and females differed in the pattern of relations between osteons and osteon fragments with advancing age.

How "representative" is the Terry collection? evidence from the proximal femur.

The work reported here is the beginning of an attempt to determine whether data on skeletal aging changes derived from the Terry collection (Smithsonian Institution) can safely be applied to present-day clinical and forensic problems. Measurements made on radiographs of the proximal third of the right femur below the greater trochanter were compared in three groups of American white females: Terry collection "regulars," Terry collection willed, and GW (George Washington University Medical Center) willed. Mean birth year for the Terry regulars was 1883, whereas the mean birth year for Terry and GW willed was 1910. Terry willed femora are longer than those of Terry regulars, but not more robust. The two groups show opposing secular trends in femoral length, and in this respect the Terry regulars appear closer to the general U.S. population. In two indices of relative medullary cavity size (which reflect changes in cortical thickness as well as internal and external diameters) all three groups agree in showing age-related increase of medullary diameters, greater increase in the anterior-posterior dimension, and greatest amount of increase at diaphyseal levels. The major difference between groups is in timing, with medullary cavity expansion becoming evident at least a decade earlier and leading to greater eventual loss of cortical thickness in the willed groups.

Aging changes in thickness of the proximal femoral cortex.

This study explores age-related thinning of cortical bone in an area of the femur that is becoming of increasing clinical interest. It is based on measurements of medial-lateral and posterior-anterior radiographs of the proximal one-third of the right femur, below the greater trochanter. The study population consisted of 458 skeletons from the Terry collection and included approximately equal numbers of blacks and whites, males and females, age 20 to 98 years. Cortical thicknesses were measured at 11 levels, beginning with a line drawn perpendicular to the linea aspera at the level of the inferior border of the greater trochanter. The four quandrants (medial, lateral, anterior, posterior) differed in amount of change with age. In general, except for the relatively thick medial cortex, intertrochanteric levels showed less change than subtroachanteric levels. It is postulated that this is because the greatest remodeling activity takes place in trabecular rather than cortical bone in the intertrochanteric region. The anterior and posterior cortex showed the most regular and greatest amount of thinning with age. In males at lower levels, there was little or no loss in either medial or lateral cortex, but females showed considerable loss after the sixth decade. It is suggested that a stress-related "maintenance" factor retards cortical thinning in these quadrants. A review of the literature suggests that age-related cortical loss in the femur may have been accelerated in archaeological population, compared with modern groups.

Aging in the lumbar spine. II. L1 and L2.

The bodies of the first and second lumbar vertebrae, like those of L3 and L4, show a significant trend toward lowering and broadening with age. Superior, inferior, and midbody transverse breadths increase, but there is little or no increase in endplate "flaring" with age. There is essentially no change in the relationship between anterior and posterior heights, but as reported for L3 and L4, there is a sexual difference in the amount and type of wedging of the bodies of L1 and L2. Posterior wedging (posterior height less than anterior height) of these vertebrae is about twice as common in females as in males. Whites of both sexes show a statistically significant relationship between age and increased biconcavity of the endplates. Black females, but not the males, show a similar trend, especially in L1.

Aging in the lumber spine. III. L5.

The fifth lumbar vertebra, like the other units of the lumbar spine, shows a significant trend toward lowering and broadening of the body with age. In most individuals the pedicales of L5 arise from the lateral surface of the body, rather than posteriorly as in the other lumbar vertebrae, and the increase in body breadth is very often associated with the formation of reinforcing columns of bone between the bases of the pedicles and osteophytes bordering the inferior endplate. In L5 midbody breadth shows a greater gain than endplate breadths, so "flaring" is decreased with age, a change that is statistically significant in Black males and White females. This vertebra shows no significant change in endplate biconcavity or posterior wedging with age.

Some aspects of aging in the lumbar spine.

I measured the bodies of vertebrae L3 and L4 of 338 skeletons from the Terry collection in the Smithsonian Institution, including Blacks and Whites, males and females, aged from 20 to 90 years. Transverse breadths of the upper and lower endplates (excluding osteophytes) and minimum transverse breadths all increase with age. In general, the greater broadening occurs in the endplates, but the middle of the body also broadens to such a degree that there is no demonstrable increase in vertebral "flaring" with age. In males, posterior body height decreases relative to anterior height, so that the lumbar bodies become more wedge-shaped with age but females show essentially no change. Anterior height decreases in proportion to minimum breadth, so that the lumbar bodies become relatively lower and broader, and this change is significantly correlated with age in all groups. Midbody height decreases relative to anterior height, so that Nordin's biconcavity index is reduced with age. The increase in biconcavity remains evident even when average anterior-posterior height is used to calculate the index. At all age levels a high percentage of individuals have biconcavity indices of 80% or less, indicating that Nordin's standard of normality for this index, established from measurement on radiographs of the living, should be revised downward for use in evaluating osteoporosis in skeletal populations.

Cortical bone loss with age in three native American populations.

Age-related thinning of cortical bone was investigated in archaeological populations of Eskimos, Pueblos, and Arikaras. Medial-lateral cortical thickness was measured on radiographs of humerus and femur, and thickness of the anterior femoral cortex was measured directly on samples taken for histologic study. Maximum length of the bones was used to calculate indices of relative cortical thickness, in order to minimize differences due to body size and build. Bone loss in the humerus begins before middle age in all three populations and, except for Eskimo males, the same is true of the anterior femoral cortex. In general, overall female loss of cortical bone amounts to two or three times that of the males, and in the case of the humerus and the anterior cortex of the femur, this difference is evident by middle age. The weight-bearing femoral medial-lateral cortex shows less sexual difference but has the greatest number of statistically significant differences between populations and the greatest contrast between populations in pattern of loss with age. It appears that of the cortical regions studied this is the area upon which environmental factors have the greatest effect, whereas areas more subject to tensile stress, the humerus and anterior femoral cortex, are less affected by these factors.