| This study was designed to evaluate the applied value of MRI in the infantile congenital dislocation of the hip (CDH) and to provide a reasonable basis of the examination for clinic by analyzing MRI find-ings of the infantile CDH.Materials and methodsForty - seven untreated patients ( 12 boys and 35 girls; age range, from 6 months to 3 years; mean age, 21. 5 months) diagnosed CDH were examined using MRI. These patients include unilateral hip dislocation 34, bilateral hip dislocation 13, in total normal hip 34, dislocated hip 60.MRI studies were performed using a super conductive MR system operating at a field of 2.0 T and in a body coil. Axial and coronal im-ages were obtained with a Tl - weithted spin - echo ( SE) pulse se-juence, a repetition time (TR) of msec, and echo time (TE) ofmsec (TR/TE = 500 /15ms) , a T2 - weighted fast spin - echo (FSE) pulse sequence (TR/TE = 2500 -3000/96ms) , and 1 -2 excitations.All dislocated hips were classified three types according to the standard of Ogden and Dunn based on the position of femoral head on coronal layer, the femoral head removed lateral and located in acetab-ulum in Type I ; the head center situated acetabular lateral rim in type II ; the head removed out completely from acetabulum and form a false acetabulum in type III. All patients except for type HI hips were measured with BAI ( Bony Acetabular Index) , CAI ( Cartilaginous Acetabular index) , BAQ ( Bony Acetabular Quotient) and CAQ (Cartilaginous Acetabular Quotient) on the coronal view passing fem-oral head center according to the method described by Fisher etc.Results1) The average value of CAI, BAI, CAQ, and BAQ of the nor-mal hips were respectively 25.24, 8.49, 0.199, and 0.195; those of the dislocated hips were 38. 13,17.25, 0. 126, and 0. 120, respec-tively. The AI of the dislocated hips was bigger than that of normal hips, but the AQ was smaller than that of normal hips. The dislocated hip was presented when CAI ≥13. 85, BAI ≥32. 73 corresponding CAQ≤0. 154, BAl≤O. 147. We performed the statistical analysis a-bout the measurement results of all normal and dislocated hips. It shows there is a linear correlation between bone parameters and carti-laginous parameters.2) The average value of CAI, BAI, CAQ, and BAQ of type I hips were respectively 35. 59, 15. 85 ,.0. 131, and 0. 120; those ofthe type II hips were 39.64, 18.08, 0.124, and 0.121, respective-ly. Tlie AI of type I hips was smaller than that of type II hips, but the AQ was bigger than that of type II hips. It shows BAI and CAI have an increase, and BAQ and CAQ have a decrease with the aggra-vation of dislocation. There is a linear correlation both between BAI and CAI, and between BAQ and CAQ respectively.3) The MRI manifestations of CDH include: A) Bony changes; In all dislocated hips, the femoral head became thin and flat, the e-piphysis were smaller than that in normal hips. In one dislocated hip the epiphysis was irregular and uneven, presenting one wirelike low signal. The bony portion of the acetabulum of dislocated hips became even, lost normal sphericity contour in coronal view, and there was an angulation between the anterior and posterior portions of the acetabu-lum in the axial view. B) Cartilaginous changes: The femoral head cartilage lacked smooth in most of dislocated hips. The changes of ac-etabular cartilage were various with different types, the acetabular car-tilage was moved outward and proliferated unobviously in type I . The cartilage was displaced outward and thickened more visibly, most la-brum were exerted in type II , it was proliferated gibbously and its sig-nal was uneven while labrum was inverted in type III. C) Other chan-ges : a few effusion of articular cavity were presented in 11 dislocated hips, the extrasynovial fibrofatty fat pad of acetabular fossa was hyper-trophied in 39 hips, soft tissue was filled in articular space in 15 hips, transverse acetabular ligament appeared to be pulled up in 2 hips.ConclusionMRI can be used for diagnosing CDH accurate... |
PDF Full Text Request