Imaging Studies In The Pelvic Morphologic Deformity Of Developmental Dislocation Of The Hip

Objective:To analysis the pelvic morphologic deformity of the unilateral DDH by using 3D-CT technology,then measure the pelvic rotation deformity according to the grade of dislocation,and to explore its clinical significance.Methods:From 2007 to 2014,72 patients with unilateral DDH and 28 patients of normal control were recruited in this study.12 cases were male and 60 cases were female.These patients aged from 7 to 60 months(average age,18 months).38 cases with left hip dislocation,34 cases with right hip dislocation.23 cases were grade I dislocation,28 as grade II and 21 as grade III.All patients were accepted the computed tomography with bilateral hip,then the images of three-dimensional computed tomography(3D-CT)were retrospectively reconstructed to compare the acetabular anteversion angle(AA),the rotational angle of the upper pelvis(URA),and the rotational angle of the lower pelvis(LRA).The correlation of the AA with LRA was analyzed.Results:All of 28 cases the difference of URA?LRA and AA had no statistical significance in normal control group(P > 0.05).72 cases with unilateral DDH,the URA ? LRA and AA of the dislocated side were greater than normal side,the difference has obvious statistical significance(P < 0.05).In the group of grade I and III,the LRA in the dislocated side were greater than the normal hips,and there was obvious statistical significance(P < 0.05),but the URA did not differ between the two sides(P > 0.05).In the group of grade II,the URA and LRA in the dislocated side were greater than the normal side(P < 0.05).There was positive correlation between AA and LRA on the dislocated side in the group of grade I,II,III.Conclusion : The pelvic rotation deformity on the dislocated side was not universally presented in unilateral DDH,and with different grade of femoral head dislocation,the mechanism of pelvic rotation deformity may not be consistent.Correction in the excessived acetabular anteversion,not only to measure the acetabular anteversion angle,but also to measure the rotational angle of the upper pelvis,and observed the development situation of the acetabulum anterior wall andposterior wall.we could give appropriate correction when we found the clear reason of excessived acetabular anteversion,and it was important to prevent acetabular retroversion happening.