Estimation of Sex Using Demarking Points from Diameters of Lumbar Pedicles in Adult Nigerians

Aim: To estimate sex using demarking points and index of sexual dimorphism of horizontal and vertical diameters of lumbar pedicles in male and female Nigerians.
Study Design: Retrospective study.
Place and Duration of Study: Department of Human Anatomy and Department of Radiology (University of Maiduguri Teaching Hospital), University of Maiduguri, Borno State Nigeria between February 2007 and June 2008.
Methodology: Four hundred (400) radiographs of adult Nigerians (200 males and 200 females) were measured.Age range for the individuals was 18-76 years. Radiographs used for this study were obtained from the collection of record unit of the Radiology Department, University of Maiduguri Teaching Hospital (UMTH) in Borno state, Nigeria.Radiographic viewing box, temporary maker, pencil and a meter rule were used for the measurements.The radiographs for males and females were classified separately into six (6) age groups with ten (10) years interval. Vertical and Horizontal diameters of lumbar pedicle were represented on the radiographs by “h” (taken as the maximum dimension of the pedicle between the upper and lower margins of the pedicles) and by “t” (maximum diameter between the medial and lateral aspect of each pedicle). Distance between upper and lower extremities, as well as that between medial and lateral extremities of each pedicle were marked and measured as vertical and horizontal diameters respectively.
Results: The result of the present study showed that, the vertical and horizontal diameters of the lumbar pedicles in adult Nigerians were all greater in male than in female counterpart. It was also observed that sexual differences in the two parameters were found to be statistically significant (P<0.001) in both sexes. Index of sexual dimorphism (ISD) was also calculated and it was observed that all parameters were found to be greater than 100; this showed that male had higher values over female counterpart. Demarking points were also calculated for each parameter, the result also showed similar pattern of increase in male parameters over female counterpart. The result also showed age-related significant (P<0.001) variations for the lumbar pedicle diameters, from 18-27 through 38-47 years age groups with a decrease in diameters at the 48-57 through 68-77 years age groups in both sexes.
Conclusion: It was observed that the vertical and horizontal diameters were sexually dimorphic; the demarking points of male diameter were all higher than those of the female counterpart. Index of sexual dimorphism also showed that male vertical and horizontal diameters were all greater than female vertical diameter as the index of sexual dimorphism were all greater than 100 from L1 through L5. This study reconfirms the fact that osteometric assessment is highly population- specific. It may be added that more studies are required in the southern part of Nigerian population to give a better picture of the racial variation that exists there and to offer more osteometric standards for assessing sex for the entire country.