Evaluation of translation in the normal and XXXX hip using three-dimensional magnetic resonance imaging and voxel-based registration.

@entity572 @entity2738 @entity6349 @entity7195
OBJECTIVE: To elucidate in vivo hip instability by comparing normal hips to hips with @entity7195 by evaluating three-dimensional (3D) translations of the @entity2738 ( @entity2738 ) at different hip positions using magnetic resonance imaging (MRI). DESIGN: Forty normal hips and 22 @entity6349 female hips were examined. MRI was performed at four different positions bilaterally: neutral, 45   of flexion, 15   of extension, and the Patrick position. Femoral and pelvic bones were separately extracted at the neutral position and superimposed over the images of each different position using voxel-based registration. The distance between the acetabular center and @entity2738 at neutral position was defined as 3D-migration. The distance between @entity2738 at neutral position and that at each different position was defined as 3D-translation. Two-way repeated measures analysis of variance was performed to consider the dependency between right and left-side data, and multiple linear regression analyses were performed to assess independent relationships. RESULTS: The center-edge (CE) angle was the determinant for 3D-migration (b=-0.415, P=0.001), and there was a statistical significant difference in 3D-migration between normal female hips and @entity572 (P=0.047). From neutral to the Patrick position, the @entity2738 of normal and @entity572 translated postero-infero-medially by 1.12  0.39mm (0.45-1.85mm) and 1.97  0.84mm (0.95-4.34mm), respectively, and the difference between the groups was statistically significant (P=0.005). CE angle was the determinant for 3D-translation from neutral to the Patrick position (b=-0.730, P<0.001). The average root mean square error in 3D-translation was 0.172mm and 0.193mm for intra- and interobserver reproducibility, respectively. CONCLUSIONS: Hip instability was increased in proportion to the severity of @entity7195 . A 3D MRI voxel-based registration technique can show in vivo morphology and kinematics of the native hip without exposure to radioactivity.
