ACETABULAR ANTEVERSION IN CDH

Material and method Acetabular anteversion angle (AAA) and orientation angle of the iliac bone (AOOI) determined by use of a CT scan were st udied in CDH. 55 childrens with CDH were selected on hip arthrography for this study. Subluxated hips were excluded (i.e opposite hip of a u nilateral CDH is normal). 10 boys and 45 girls with a mean of age of 2 years 1 month (extremes from 1 to 4 years 3 months) were studied. CT scan was performed before any orthopaedic treatment in 3 cases of bila teral luxation and 14 cases of unilateral. In the other cases, time be etwen the end of orthopaedic treatment and CT scan varied between 4 an d 18 months. A group of 23 normal childrens, 10 boys and 13 girls, (me an age of 2 years 10 months) served as reference group. On the selecte d CT slide we measured AAA, AOOI, IAA and IAP (anterior acetabular ind ex and posterior acetabular index as proposed by Guggenheim). Results We noted that the orientation of the iliac bone was variable in the tw o groups. This orientation angle could have higher or lower values. AA A : in bilateral luxation, this angle was higher (16-degrees +/- 5-deg rees) than in reference group (13-degrees +/- 4-degrees), p<0.005. In unilateral luxation there was no statistical difference (14-degrees +/ - 4-degrees) with reference group, between normal and pathological sid e and when CT scan was performed before or after orthopaedic reduction . AOOI : there was no significant difference between bilateral, unilat eral or reference group. Correlation analysis showed that AAA and AOOI moved in the same direction. IAA : in bilateral luxation this index w as higher (p<0.001); in unilateral luxation only right luxation showed an higher index (p=0.002). IAP : no significant difference between th e different groups. Discussion This study shows that there is any typi cal CT scan aspects of morphologic abnormality in CDH. The lesions of the anterior or posterior acetabular wedge are variable. The orientati on of the iliac bone is also variable; we concluded that acetabular an teversion must be analysed depending on the morphologic aspects of the anterior and posterior extremities of the acetabulum and iliac bone o rientation.