Sexual dimorphism of the pelvic girdle from 3D images of a living Spanish sample from Castilla-La Mancha.

The aim of our study is to provide data regarding the morphology of the pelvic girdle from a living Spanish sample. The material used comprises radiographic images (CT scans) from 74 adult individuals (39 ♂ and 35 ♀) in DICOM format. The variables recorded were the bi-iliac width and the antero-posterior and transverse diameters of the three anatomical planes of the birth canal, with the exception of the transverse diameter of the outlet. Indices of the inlet and mid-plane were also calculated. Statistical analysis of the data (Student's t-test and principal component analysis) revealed that the variables which display sexual differences are the transverse diameter of the inlet, the antero-posterior and transverse diameters of the mid-plane and the mid-plane index. In particular, Spanish women have significantly higher values in the transverse diameter of the inlet and the antero-posterior and transverse diameter of the mid-plane than men; and Spanish men have significantly higher values in the mid-plane index than women. The results of this study are in accordance with those obtained in previous studies based on dry bone, which suggest considerable populational variability in pelvic and birth canal geometry. This kind of CT-based study of living populations may significantly enhance our understanding of population variation of pelvic morphology. This information can be useful to better understand the birth mechanism in Homo sapiens and the appearance of rotative birth in the Homo lineage through comparison with the other primates, living or fossil.

Ilium growth study: applicability in sex and age diagnosis.

The use of coxal elements for age and sex diagnosis from the skeleton is the primary and most widespread way of bringing us closer to the identity of dead individuals in archaeological and certain forensic scenarios. Diagnosis in sub-adults, especially in fetus and infant age, is not clear; and further studies are needed. This work presents the analysis of the growth of six variables in the ilium, from birth to 97 years of age, in order to evaluate its significance and its capacity for age and sex determination during and after growth. The materials used were 327 specimens from four documented Western European collections. Growth curves were calculated for the three classical variables of the ilium (width, length and index) and three new variables of the acetabulum area (horizontal and vertical diameter of the ilium acetabular surface and the ilium acetabular index). None of the curves showed a lineal growth, except those of the horizontal diameter of the ilium acetabular surface for the male series. The ilium width has the most complicated growth and it is explained by a four-degree polynomial. All the variables studied can be useful for adult sex discrimination with the exception of the ilium width and ilium acetabular index. Furthermore, the most useful variables for subadult and adult age estimation in archaeological samples, as well as in forensic samples, are the absolute measurements (ilium length and width, horizontal and vertical diameter of the ilium acetabular surface); however, the ilium width is the best variable, as this can be applied to all growth ages using both sexual series together up to 20 years of age.

Sex and age diagnosis by ischium morphometric analysis.

The growth of four variables of the ischium was analysed by polynomial regression in order to evaluate its significance and its capacity for age and sex determination during and after growth. The material used was 327 specimens ranging from birth to 97 years of age from four documented west European collections. The growth curves were calculated for ischium length and three new variables of the acetabular surface (horizontal diameter of ischium acetabular surface, vertical diameter of ischium acetabular surface and ischium acetabular index). All curves, except those of the female series of vertical diameter of ischium acetabular surface and its index, showed a lineal growth corresponding to vertical variables. All variables studied, except the ischium acetabular index, can be used variables for adult sexual discrimination. Furthermore, ischium length and the horizontal and vertical diameters of the acetabular surface can be useful for sub-adult age determination in archaeological samples, as well as in forensic samples. However, the ischium length is the best variable, as it can be applied to all the growth ages.

The acetabular point: a morphological and ontogenetic study.

The acetabular point was analysed by studying human pelvic bones from 326 individuals ranging from newborns to age 97 y. The bones were categorised into 3 groups according to the degree of fusion for the 3 elements of the pelvis: nonfused (59), semifused (5) and fused (262). The acetabular point in immature pelvic bones is clearly represented by the point of the fusion lines for each bony element at the level of the acetabular fossa. In adult pelvic bones the acetabular fossa has an irregular clover-leaf shape, the superior lobe being smaller than the anterior and posterior lobes. Cross-sectional analysis of acetabular morphology suggested that the acetabular point in adult pelvic bones is always represented by the indentation between the superior and the anterior lobes of the acetabular fossa.