title: Relationship between sacral pelvic incidence and acetabular orientation.
abstract: The importance of the sacral pelvic incidence (SPI) in relation to individual variations of sagittal spinal curvature has become well-recognised. We attempted to determine the relationship between SPI and acetabular orientation. The three-dimensional coordinates of 47 homologous points were observed on 51 adult anatomical pelvises (26 female and 25 male). The reference vertical plane was Lewinnek's anterior pelvic plane. 10 angular parameters and 11 linear parameters were defined and calculated. These were expressed both in absolute value (in millimetres) and in "acetabular unit" (relative to the mean value of the right and left acetabular rays). Mean values of the parameters were calculated for all pelvises and according to gender. There were two dominant parameters: the "sacral slope" and the "V pubic angle". "Acetabular tilting" was primarily dependent on the "sacral slope" and its intermediary on the "SPI", while "acetabular anteversion" dependent on the "V pubic angle" via the "angle of prow". It is recommended that positioning of the acetabular cup in total hip arthroplasty relates to anatomical parameters, and to the global sagittal balance of the pelvi-spinal unit.
authors.affiliation: Unity INSERM 215, Spinal Bio-mechanic, Garches, France. jean.legaye@uclouvain.be
authors.forename: Jean
authors.initials: J
authors.lastname: Legaye
authors.forename: Ginette
authors.initials: G
authors.lastname: Duval-Beaupere
authors.forename: Andre
authors.initials: A
authors.lastname: Barrau
authors.forename: Christophe
authors.initials: C
authors.lastname: Boulay
authors.forename: Jerome
authors.initials: J
authors.lastname: Hecquet
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Montigny
authors.forename: Christine
authors.initials: C
authors.lastname: Tardieu
mesh_terms: D000077:Acetabulum / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D010384:Pelvic Bones; D010388:Pelvis / Q000033:anatomy & histology*; D012447:Sacrum / Q000033:anatomy & histology*