Age Determination at Death from Osteon Counting by Means of Interactive Computer Graphics

The purpose of this study is to show the feasibility of doing osteon counting on the computer. A sample of 11 specimens were prepared by thin section techniques in order to be photographed through a Reichert transmitted-light interface contrast Zetopan research microscope. After the photographs were mosaiced into a single representative picture of the field of vision, the picture was digitized and processed for age by the computer.

Digitizing the specimens is accomplished by the use of interactive computer graphics. Using a tablet with a cursor or pen, the picture is digitized and stored in a file of x and y coordinates on a magnetic disk by the computer. This file of stored data is used in other computer programs to measure dmax, centroid plots, area information on the individual features and calculate age at death for the specimen. Kerley and Ubelaker's (1978) regression formulas were utilized.

The major findings of the research concerned percent of circumferential lamellar bone and individual fields of vision. The regression formula for percent of circumferential lamellar bone as determined by the Kerley technique (1965) was not reliable with measured data of the computer. A new regression formula was calculated based on the measured data of the sample with eight out of eleven cases having the age range score bracketing the known age of the specimen. All three cases which were aged incorrectly were within plus or minus 10 years of the actual age.

Another finding revealed that one field of vision is not superior to another. Some anthropologists had implied that the posterior field of vision, because of muscle attachment to the linea aspera, would yield faulty scores. My results show that the worst field is the medial view and not the posterior. When comparing individual field statistics to the four field total the results demonstrate that one field may be selected. The resulting age range calculated by the computer is as satisfactory as those age ranges produced from the four field total.

Since no special training is required to operate the computer and cost of the equipment is economical, a large group of researchers wanting to do osteon counting could utilize my procedure.