Multilevel Measurement of Acetabular Version Using 3-D CT-generated Models: Implications for Hip Preservation Surgery

Abstract

BackgroundNumerous structural deformities of the acetabulum are associated with hip osteoarthritis (OA). Acetabular retroversion has been implicated in the development of femoroacetabular impingement. However, it is unknown if retroversion occurs from isolated excessive bone in the superior acetabulum or a torsional phenomenon of the entire pelvic segment.Questions/purposesA method was developed to measure acetabular version (AV) using 3-D models thus eliminating positional factors. This method was used to determine if acetabular retroversion is an isolated entity or an effect involving the entire pelvic segment containing the acetabulum.MethodFifty pelvic CT scans were selected from a large database. Measurements were performed for abduction, ischial spine position, and AV at multiple levels. The relationships between anteversion at multiple levels and between midacetabular anteversion and ischial spine position were analyzed.ResultsThe mean upper and midlevel acetabular anteversion values were 14.4° ± 10.5° and 21.3° ± 5.8°, respectively. The mean abduction was 39.7° ± 4.3°. The prevalence of acetabular retroversion was 7%. Females had greater anteversion than males at all levels. Correlations were found between Levels 1 and 4 version (r = 0.74) and the ischial spine index and Level 4 version (r = 0.67).ConclusionsThese data suggest retroversion involves the acetabulum at all levels and includes the entire pelvic segment containing the acetabulum and the ischial spine.Clinical RelevanceThese data are relevant for surgeons in providing targets for normal positioning of the acetabulum during periacetabular osteotomies and acetabular recontouring procedures.

The Acetabular Wall Index for Assessing Anteroposterior Femoral Head Coverage in Symptomatic Patients

“…There is increasing concern that failure to recognize abnormalities of acetabular morphology leads to inadequate or inappropriate treatment of hip disease [7,[11][12][13][14]16]. Consequently, the question arises whether normal coverage of the femoral head can be defined on an AP pelvis radiograph.…”

New Radiographic Index for Evaluating Acetabular Version

“…Acetabular anteversion generally became smaller cranially [9,12,21,22]. Reynolds et al [22] described the acetabular mouth opening as spiraling gradually into increasing anteversion distal to the roof edge in normal hips.…”

“…To quantify acetabular version, CT with an axial plane is commonly used [1,8,9,21,30]. However, as with conventional radiographs, CT is not used repetitively because of higher doses of radiation and higher cost.…”

Computed Tomography: Role in Femoroacetabular Impingement

“…Since the pelvis has a spatial arrangement in three dimensions and considering the deviations by the position of the pelvis in relation to the table of the tomographer, the axial reconstructions and in the three dimensions were corrected in three planes [20,21], that is to say corrected the rotation, the lateral inclination and the tilting of the pelvis. For the later, diferences between genders were considered, seting a distance of 3 cm between the sacrococcygeal junction and upper border of the pubis in men and 6 cm in women [22].…”