Is there a correlation between pelvic incidence and orientation of the acetabulum? : An analysis based on a three-dimensional statistical model of the pelvic ring
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Abstract
The pelvic ring is a complex anatomical structure building up the connection between
the trunk and the legs. Whilst there is a broad discussion in the literature about the
dynamic interaction between spine, pelvis and the hip joints, there is still little infor mation about the relation and interaction of the constant pelvic parameters. Based
on a three-dimensional (3D) statistical model consisting of 150 uninjured and bony
healthy pelves (100 Europeans, 50 Japanese; 81 males, 69 females; average age
74.3 years ± 17.5 years) an evaluation of pelvic incidence (PI) and acetabular orienta tion in anteversion and inclination was performed and potential correlations of these
intraindividual constant parameters were investigated. Pelvic incidence is defined as
the angle between the perpendicular to the sacral plate at its midpoint and the line
connecting this point to the middle axis of the femoral heads. Acetabular anteversion
is defined as the angle between the perpendicular to the best-fit plane on the acetab ular rim and the coronal plane measured in strict lateral view. Acetabular inclination is
defined as the angle between the perpendicular to the best-fit plane on the acetabular
rim and the sagittal plane in strict frontal view. Data were further analysed with re gard to different subgroup's age, sex and ethnicity. A positive correlation between PI
and acetabular anteversion could be demonstrated. Further, PI and also the acetabu lar parameters anteversion and inclination were found to be significantly higher in the
European individuals than in the Asian. The results of the present study demonstrate
a relation between the anatomical configuration of the constant pelvic parameters
building up the connection points to the next proximal respectively caudal skeleton
section. The findings might lead to more comprehensive treatment strategies in case
of trauma or degenerative pathologies of the pelvis in the future.