Morphometric sexual dimorphism of human sternum in a north Indian autopsy sample: sexing efficacy of different statistical techniques and a comparison with other sexing methods.

Forensic anthropologists have proposed different sex determination methods based on metric and non-metric skeletal features of various bones. The main objective of the present investigation was to evaluate sexual dimorphism in human sternum and make comparative analysis based on studies by several workers who used different methodologies and techniques. For this study, 343 sternums were collected and examined from 252 male and 91 female cadavers of a north Indian population. Significant differences were noticed between the mean sternal measurements measured directly on bone specimens in present study and those measured indirectly on radiographs or CT scan images reported by previous researchers. Comparative analysis of absolute sternal measurements showed concordance with some earlier Indian studies but discordance with most other population studies conducted worldwide. Limiting points gave much higher sex accuracy levels than the demarking points. The calculated multivariate DFA equation (y=-14.222+0.076MBL+0.137WS_1) and regression equation (y=36.675-0.198MBL-0.405WS_1) correctly estimated sex of 84.8% and 89.8% sternums, respectively. Multivariate analyses gave more striking results than the univariate ones. Though logistic regression analysis gave higher accuracy rates but discriminant function analysis was found to be a more reliable statistical tool for sex determination because of low sex biases. The sexing efficacies of the dry and wet sternums did not differ significantly, so bone specimens are equally reliable as the radiographs or CT scans for sex determination. The sternal area and the combined length were found the best parameters among all the criteria and methods considered. The changes in the body proportions, nutritional, environmental, climatic changes, etc., are attributable to secular changes in sterna measurements when compared to Jit et al. [13]. The osteometric techniques are better representative of biological identity of the deceased because of some inherent defects associated with radiographic methods. Like other sex-predictive bones of the human skeleton, the sternum can also be a valuable adjunct for sex determination of unknown subjects.

Sex and age related non-metric variation of the human sternum in a Northwest Indian postmortem sample: a pilot study.

Nonmetric traits are quasi-continuous skeletal traits that cannot be measured, but are observed as ranks or scores. In the present study, 8 nonmetric traits of sternum were examined from 343 sternums collected from the autopsy cases. More males, particularly older subjects, had a mesosternal foramen. The frequency of mesosternal foramen, arch-shaped prominence on the manubrium and radial strips on mesosternum significantly increased but that of lateral projection of manubrium decreased in the 30+ year age-group (older individuals). The denticulate costal incisures were found mostly in females and younger subjects; however, the crescent incisures and arch shaped prominence of manubrium were noticed mainly in males and older subjects. Majority of subjects had 'deep and narrow' jugular notch and xiphi-sternum was 'bifid' or 'oblong' in males and 'small sized' in females and younger subjects. Xiphi-sternum was generally found absent in females and younger subjects. The different shapes of costal incisures, jugular notch and xiphoid process were found to have significant sex and age differences. The number of cases with fused elements significantly increased with advancing age in both sexes. The sternal elements' fusion showed a variable pattern and hence was not found to be a reliable criterion. Chi-square analysis revealed significant differences between two age-groups of individual sex in the distribution of 3 of the 8 nonmetric traits. Significant sex and age differences were noticed in the frequency of occurrence of mesosternal foramina between the younger and older age groups in both the sexes. The logistic regression analysis of the scores classified 73.8% sternums to their sex category and 70.0% sternums to their age-group. Though present findings may not be enough for absolute personal identification, these traits can still serve as important identification tools if antemortem radiographs/CT or MRI scans are available for comparisons, or help classify an unknown sternum to its sex or age category based on the morphological features discussed in present study.

Age estimation from clavicular epiphyseal union sequencing in a Northwest Indian population of the Chandigarh region.

Medial clavicular epiphysis is the long bone epiphysis to fuse last and therefore, is useful for estimating age in the post-pubertal period. Age estimation was done from clavicles obtained from 343 cadavers (252 males and 91 females) of known age. The data was subjected to statistical analysis to see whether the difference obtained in the various ages was significant or not. Commencement of fusion was seen as early as 18 years of age in both male and female clavicles. No clavicle showed complete fusion until the age of 22 years. Complete fusion of the medial end of the clavicle was seen latest at 32 years in the male clavicles while the same was observed at 31 years in the female bones, i.e., the medial epiphysis of female clavicles fused one year earlier than their male counterparts. Advanced stages of clavicular epiphyseal union were seen in most of the clavicles after 24 years of age in females and 23 years of age in males. No significant difference was noticed in both sexes for the right and left clavicles as regards to the occurrence of various stages of epiphyseal union.

Skeletal height estimation from regression analysis of sternal lengths in a Northwest Indian population of Chandigarh region: a postmortem study.

Skeletal height estimation from regression analysis of eight sternal lengths in the subjects of Chandigarh zone of Northwest India is the topic of discussion in this study. Analysis of eight sternal lengths (length of manubrium, length of mesosternum, combined length of manubrium and mesosternum, total sternal length and first four intercostals lengths of mesosternum) measured from 252 male and 91 female sternums obtained at postmortems revealed that mean cadaver stature and sternal lengths were more in North Indians and males than the South Indians and females. Except intercostal lengths, all the sternal lengths were positively correlated with stature of the deceased in both sexes (P < 0.001). The multiple regression analysis of sternal lengths was found more useful than the linear regression for stature estimation. Using multivariate regression analysis, the combined length of manubrium and mesosternum in both sexes and the length of manubrium along with 2nd and 3rd intercostal lengths of mesosternum in males were selected as best estimators of stature. Nonetheless, the stature of males can be predicted with SEE of 6.66 (R(2) = 0.16, r = 0.318) from combination of MBL+BL_3+LM+BL_2, and in females from MBL only, it can be estimated with SEE of 6.65 (R(2) = 0.10, r = 0.318), whereas from the multiple regression analysis of pooled data, stature can be known with SEE of 6.97 (R(2) = 0.387, r = 575) from the combination of MBL+LM+BL_2+TSL+BL_3. The R(2) and F-ratio were found to be statistically significant for almost all the variables in both the sexes, except 4th intercostal length in males and 2nd to 4th intercostal lengths in females. The 'major' sternal lengths were more useful than the 'minor' ones for stature estimation The universal regression analysis used by Kanchan et al. [39] when applied to sternal lengths, gave satisfactory estimates of stature for males only but female stature was comparatively better estimated from simple linear regressions. But they are not proposed for the subjects of known sex, as they underestimate the male and overestimate female stature. However, intercostal lengths were found to be the poor estimators of stature (P < 0.05). And also sternal lengths exhibit weaker correlation coefficients and higher standard errors of estimate.