Sex identification and software development using digital femoral head radiographs

Abstract

The determination of sex is considered one of the first essential steps in positive identification. The current study aspires to accomplish a threefold purpose: to develop an easy and rapid sex determination technique using digital radiographs from the proximal epiphysis of the femur, to develop a simplified tool for pathologists that will provide accurate sex identification using radiographs and to compare this method with standard osteometric techniques applied to the same population. A total of 70 (36 males and 34 females) left femora were measured according to standard osteometric techniques. The proximal epiphyses of the same sample were then radiographed using a digital X-ray machine (TCA 4R PLUS). The skeletal remains were selected from the exhumed skeletons of St. Konstantinos and Pateles Cemeteries, Heraklion, Crete. Nine classical measurements were taken from the entire dry femora. Stepwise discriminant function analysis selected only 2 dimensions (maximum head diameter and anterior–posterior midshaft diameter) producing an accuracy rate of 88.6% for both original and cross-validated data. If assuming that only the proximal part of the femur is present, direct procedure results in 87.1% correct group membership. Six landmarks were selected in the radiograph and 15 variables representing all possible combinations of these landmarks were calculated using a specially designed calibrated Java program. Measurements were submitted to discriminant function analysis using SPSS subroutines. Stepwise discriminant function analysis selected only 3 out of 15 dimensions, producing an accuracy rate of 92.9%. The formula generated was then incorporated into the Java application, resulting in the development of a sex identification software (SIS). A sample of 36 (23 left and 13 right) femoral radiographs was used in order to test the software's reliability and sex was correctly identified in 32/36 cases, giving an accuracy rate of 91.7%. The radiographic technique proposed here performed better compared to conventional methods in the same population. From a forensic point of view it is a useful alternative method when semi-decomposed or charred remains are recovered in mass disasters or crime scenes and maceration is not an option. The application of metric methods in radiographs and the development of a highly specific software provides a useful and easy tool for sex identification that can be used in certain forensic cases in which osteometry does not apply.