Geschlechtsdiskriminierung und Körperhöhenschätzung anhand des Jochbeins

Definitions of frontal bone inclination: Applicability and quantification

In sex determination from crania, a "vertical" forehead is considered a female feature, while a "sloping" forehead is considered a male feature. Precise description of frontal inclination with a quantitative measure like an angle is considerably more difficult as it requires accurate identification of clearly defined craniometric points. In the literature, the morphognostic terms "frontal bone inclination," or "frontal profile," are defined in numerous ways. The aim of this study was to determine which of these frontal inclination definitions is best suited for sex estimation. In a study in the context of the digital forensic osteology project, 10 of the frontal angle definitions described in the literature were assessed for their usefulness in sex determination on 211 virtual crania, reconstructed from postmortem CT-data. Custom-developed software was used for the automated measurement of frontal bone inclination angles from lateral-profile, volume-rendered 3D cranial images in which 10 anthropometric landmarks had been manually marked. Discriminant function analysis was performed to determine if satisfactory accuracy rates for the classification of sex could be achieved with defined variables. Four of the ten examined definitions were found to be highly significant for sex determination; three of these, also provided satisfactory intra- and inter-observer reliability. The frontal angle according to Schwalbe provided the best accuracy rate of 75.4% and a critical discriminatory value (separation value) of 88.6°: angles greater than this, suggest female sex; angles smaller than this, suggest male sex. Further, the open-source, custom-developed software introduced here proved compatible with commonly used image-processing and statistical programs and allowed quick, automated, valid measurement of numerous cranial angles. Other craniometric angles can, thus, also be quickly and easily determined with this software.

Procedure for the systematic orientation of digitised cranial models. Design and validation

Comparison of bony pieces requires that they are oriented systematically to ensure that homologous regions are compared. Few orientation methods are highly accurate; this is particularly true for methods applied to three-dimensional models obtained by surface scanning, a technique whose special features make it a powerful tool in forensic contexts. The aim of this study was to develop and evaluate a systematic, assisted orientation method for aligning three-dimensional cranial models relative to the Frankfurt Plane, which would be produce accurate orientations independent of operator and anthropological expertise. The study sample comprised four crania of known age and sex. All the crania were scanned and reconstructed using an Eva Artec™ portable 3D surface scanner and subsequently, the position of certain characteristic landmarks were determined by three different operators using the Rhinoceros 3D surface modelling software. Intra-observer analysis showed a tendency for orientation to be more accurate when using the assisted method than when using conventional manual orientation. Inter-observer analysis showed that experienced evaluators achieve results at least as accurate if not more accurate using the assisted method than those obtained using manual orientation; while inexperienced evaluators achieved more accurate orientation using the assisted method. The method tested is a an innovative system capable of providing very precise, systematic and automatised spatial orientations of virtual cranial models relative to standardised anatomical planes independent of the operator and operator experience.

Possible application of CT morphometry of the calcaneus and talus in forensic anthropological identification

Computed tomography (CT) data provide information for volumetric and radiographic density analysis. The present study investigated the application of virtual CT volumetry of the tarsal bones to estimation of the sex, stature, and body weight using postmortem CT (PMCT) data of forensic autopsy cases. Three-dimensional (3D) images of the bilateral foot bones of intact Japanese subjects after adolescence (age ≥ 15 years, n = 179, 100 males and 79 females) were reconstructed on an automated CT image analyzer system. Measured parameters were mass volume, mean CT value (HU), and total CT value of the talus and calcaneus. Mean CT values of these bones showed age-dependent decreases in elderly subjects over 60 years of age for both sexes, with significant sex-related differences especially in the elderly. The mass volumes and total CT values of the talus and calcaneus showed significant sex-related differences, and also moderate correlations with body height and weight for bilateral bones in all cases (r = 0.58-0.78, p < 0.0001); however, the correlations of these parameters of the female talus with body weight were insufficient (r = 0.41-0.61, p < 0.0001). These observations indicate the applicability of virtual CT morphometry of the talus and calcaneus using an automated analyzer to estimate the sex and stature in forensic identification; however, greater variations should be considered in body weight estimations of females.