MR-based Parameters as a Supplement to Radiographs in Managing Developmental Hip Dysplasia

BACKGROUND: Some dysplastic hips with favorable radiographic parameters fail to develop normally, suggesting that we should consider cartilaginous or soft tissue structures for further information regarding the condition of the hip. The purpose of this study was to provide a clear definition of concentric reduction in developmental dysplasia of the hip (DDH) based on magnetic resonance imaging (MRI), and to determine how radiographic and MR-based parameters could be used together to treat dysplastic hips. METHODS: We studied range of motion (ROM)-MRI of 25 patients with unilateral hip dysplasia (mean age at the time of MR imaging, 44.1 months). Each ROM-MRI consisted of a set of bilateral hip scans in the following positions: neutral; abduction; abduction- internal rotation; abduction-internal rotation-flexion; and adduction. Before MR scanning, the 25 patients received the following primary treatments: closed reduction (n = 15; at a mean age of 14.5 months); and open reduction (n = 10; at a mean age of 10.0 months). The following new parameters appear to be useful in treating DDH: 1) the labral angle, the angle the labrum makes with the acetabulum; 2) the uncorrected labral deformity (ULD), the "residual deformity" (deflection of the labrum) when the affected labrum is freed from pressure in abduction; and 3) the zone of compressive force (ZCF), the region of the acetabulum through which the body weight acts on the femoral head. RESULTS: A concentrically-reduced hip is one in which the labrum points downward in the neutral position, at the same angle as that of the normal side; and in which the ZCF is zone 3, the inner acetabular zone as defined herein. The ULD and the ZCF may be determined precisely as we have done, or the physician may simply observe the changes in the orientation of the labrum and compare the changes qualitatively to the unaffected side, and likewise for the medial joint space. CONCLUSIONS: Detailed analysis of the labrum as permitted by ROM-MRI, together with acetabular index and other parameters measured from radiographs, provides important information for physicians treating childhood hip dysplasia.

Measurement and Meaning of the Change of Acetabular Angle and Femoral Anteversion in Congenital Dislocation of the Hip / 대한정형외과학회잡지

Recently, the treatment principles of congenital dislocation of the hip has been altered markedly. The importance of concentric reduction and its maintenance during growth period in CDH has been stressed by many authors. Acetabular remodelling capacity has been argued between many authors, because it was critical criteria about the determination of operating period and methods. Authors selected 25 cases of congenital dislocation of the hip, which was treated by closed reduction, open reduction and femoral osteotomy to obtain concentric reduction of the hip. And we analyzed the change of acetabular angle and femoral anteversion in two group: Group 1-below 2 years and Group 2-from 2 years to 4 years old. The results were as follows: 1. The change of acetabular angle was improved markedly: average 15° in the Group I and average 13° in the Group 2 in 2 years. 2. The change of femoral anteversion in the Group I was markedly improved: average 15°, but, the in the Group 2 was not significant: average 6°. 3. It was thought that the perfomance of femoral osteotomy without innominate osteotomy in the Group 2, could achieve the satisfactory acetabular remodelling.