Orientation of the human sacrum: anthropological perspectives and methodological approaches.
Discovering the nature of sacral orientation is of considerable anthropological importance. Therefore, this study aims at presenting a new anthropologically based definition for sacral anatomical orientation (SAO) angle, establishing standards of SAO for human population; examining the relationship between pelvic incidence (PI) and SAO; and associating SAO with demographic parameters. The study population consisted of 424 adult and 14 sub-adult (13-18 years, for SAO only) pelvises. Sacral orientation was measured using two different definitions: a) SAO is the angle created between the intersection of a line running parallel to the superior surface of the sacrum and a line running between the anterior superior iliac spine (ASIS) and the anterior-superior edge of the symphysis pubis; b) PI is the angle created between the perpendicular to the sacral plate at its midpoint and the line connecting this point to the middle of the axis of the acetabulum. SAO was measured using a specially designed mechanical measurement tool and a 3D digitizer. PI was measured via the 3D digitizer. The methods developed by us for measuring SAO and PI in skeletal material are valid and reliable. SAO and PI measures were highly correlated (r = -0.824, P < 0.001). The average SAO was 49.01 degrees (SD = 10.16), and the average PI 54.08 degrees (SD = 12.64). SAO was independent of ethnicity and sex, yet age dependent. This study establishes a methodology for estimating SAO and PI in skeletal material and furnishes the anthropological milieu with base line data regarding these parameters. Future studies in human evolution can greatly benefit from this study.
Peleg
Smadar
S
Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel. smadarpeleg@yahoo.com
Dar
Gali
G
Medlej
Bahaa
B
Steinberg
Nili
N
Masharawi
Youssef
Y
Latimer
Bruce
B
Jellema
Lyman
L
Peled
Nathan
N
Arensburg
Baruch
B
Hershkovitz
Israel
I
D000293:Adolescent; D000328:Adult; D000885:Anthropology, Physical / Q000379:methods*; D005075:Biological Evolution; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000033:anatomy & histology; D012447:Sacrum / Q000033:anatomy & histology*