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A Novel Approach for Determining Three-Dimensional Acetabular Orientation: Results from Two Hundred Subjects

Higgins, Sean W. MS; Spratley, E. Meade PhD; Boe, Richard A. BS; Hayes, Curtis W. MD; Jiranek, William A. MD; Wayne, Jennifer S. PhD

Journal of Bone & Joint Surgery - American Volume: 5 November 2014 - Volume 96 - Issue 21 - p 1776–1784
doi: 10.2106/JBJS.L.01141
Scientific Articles

Background: The inherently complex three-dimensional morphology of both the pelvis and acetabulum create difficulties in accurately determining acetabular orientation. Our objectives were to develop a reliable and accurate methodology for determining three-dimensional acetabular orientation and to utilize it to describe relevant characteristics of a large population of subjects without apparent hip pathology.

Methods: High-resolution computed tomography studies of 200 patients previously receiving pelvic scans for indications not related to orthopaedic conditions were selected from our institution’s database. Three-dimensional models of each osseous pelvis were generated to extract specific anatomical data sets. A novel computational method was developed to determine standard measures of three-dimensional acetabular orientation within an automatically identified anterior pelvic plane reference frame. Automatically selected points on the osseous ridge of the acetabulum were used to generate a best-fit plane for describing acetabular orientation.

Results: Our method showed excellent interobserver and intraobserver agreement (an intraclass correlation coefficient [ICC] of >0.999) and achieved high levels of accuracy. A significant difference between males and females in both anteversion (average, 3.5°; 95% confidence interval [CI], 1.9° to 5.1° across all angular definitions; p < 0.0001) and inclination (1.4°; 95% CI, 0.6° to 2.3° for anatomic angular definition; p < 0.002) was observed. Intrapatient asymmetry in anatomic measures showed bilateral differences in anteversion (maximum, 12.1°) and in inclination (maximum, 10.9°).

Conclusions: Significant differences in acetabular orientation between the sexes can be detected only with accurate measurements that account for the entire acetabulum. While a wide range of interpatient acetabular orientations was observed, the majority of subjects had acetabula that were relatively symmetrical in both inclination and anteversion.

Clinical Relevance: A highly accurate and reproducible method for determining the orientation of the acetabulum’s aperture will benefit both surgeons and patients, by further refining the distinctions between normal and abnormal hip characteristics. Enhanced understanding of the acetabulum could be useful in the diagnostic, planning, and execution stages for surgical procedures of the hip or in advancing the design of new implant systems.

13071 Montfort Loop, Richmond, VA 23294. E-mail address: sehiggin@vt.edu

2Virginia Commonwealth University, P.O. Box 843067, Richmond, VA 23284-3067. E-mail address: spratleyem@vcu.edu. E-mail address for J.S. Wayne: jwayne@vcu.edu

3615 North 23rd Street, Richmond, VA 23223. E-mail address: boera@vcu.edu

4VCU Medical Center, Main Hospital, 1101 East Marshall Street, Room 3-444, Richmond, VA 23298. E-mail address: cwhayes@vcu.edu

5VCU Medical Center, West Hospital, 1200 East Broad Street, 9th Floor, East Wing, P.O. Box 980153, Richmond, VA 23298-0153. E-mail address: wjiranek@gmail.com

Copyright 2014 by The Journal of Bone and Joint Surgery, Incorporated
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