Measurement of acetabular anteversion in developmental dysplasia of the hip in children by two- and three-dimensional computed tomography.

ABSTRACT

This study assessed the angle of acetabular anteversion (AA) in 66 children with developmental dysplasia of the hip (132 hips 24 left, 25 right, 17 bilateral and 49 unaffected hips as controls). The AA was measured by two- and three-dimensional computed tomography (2D-CT and 3D-CT). Measurements were taken by three observers and repeated 2 weeks later by one of these observers. Intra- and inter-observer agreement was analysed using the intra-class correlation coefficient. For all hips, the mean AA (+/-SD) measured by 2D-CT versus 3D-CT was statistically significantly different (15.76 +/- 5.23 degrees versus 16.76 +/- 4.43 degrees , respectively). The mean (+/-SD) AA by 3D-CT in unaffected and affected hips was also statistically significantly different (13.92 +/- 3.95 degrees versus 18.44 +/- 3.82 degrees , respectively). A significant positive correlation between age at presentation and AA was found in affected, but not unaffected, hips. The 3D-CT showed better intra- and inter-observer agreement than 2D-CT for assessing AA hence is a more reliable measurement of AA. An increased AA is one component of anatomical abnormalities in developmental dysplasia of the hip and the abnormality appears to worsen with age.