Three-dimensional computed tomography analysis and anteversion study after periacetabular osteotomy of pelvis in children.
OBJECTIVE
Three-dimensional computed tomography (CT) is the method of choice in understanding the morphological changes after periacetabular osteotomy in children. We studied different parameters and compared aspects of operated hip (OH) with non-operated hip (NOH) to define the maneuver that promotes normalization of the hip during repositioning of the acetabulum.


METHODS
A total of 22 patients with 25 OHs underwent CT control scans an average of 4 years after surgery. The patients, with a mean age of 6.8 years, had either Legg-Calvé-Perthes disease (12 cases) or dysplasia (10 cases).The measurements included the anterior and posterior coverage angles of the hip and version of the acetabulum on axial CT views. The 3D reconstructed images measured the inclination of the antero- and postero-lateral lips, the external rotation and the anterior inclination of the acetabulum.


RESULTS
The mean anterior coverage angle was 27 degrees for OHs, 31 degrees for NOHs, and 12 degrees versus 10.3 degrees for the posterior coverage angle. Acetabular anteversion was 2 degrees for OHs (6.3 degrees in the dysplastic OHs) and 6 degrees for NOHs. The mean angle of inclination of the antero-lateral lip was 37 degrees for OHs, 47 degrees for NOHs, and the postero-lateral lip inclination was 56 degrees for OHs and 67 degrees for NOHs. Inferior 3D views showed a mean internal acetabular rotation of 1.5 degrees (4.8 degrees in the dysplastic OH), 3 degrees for NOH. The anterior acetabular inclination angle measured with lateral 3D views was 6 degrees for OHs, 11 degrees for NOHs.


CONCLUSIONS
Our analysis demonstrated a mean anteversion of the acetabulum despite normalization of the anterior coverage of the hip, particularly in the dysplastic group, in which the osteotomized fragments had anteversion superior to NOH. The unexpected external rotation used to improve anterior coverage of a coax magna in Legg-Calvé-Perthes disease was responsible for the retroversion and the decrease of the posterior coverage.
Jawish
Roger
R
Medical School, Sacre Coeur Hospital, St Joseph University, Beirut, Lebanon, rjawish@cyberia.net.lb.
Khalife
Rami
R
Ghorayeb
Jacques
J