Introduction
The occurrence of exaggerated femoral anteversion and the role of femoral derotation osteotomy in developmental dysplasia
of hip, especially early walking age group are controversial.
Method
We evaluated femoral anteversion, acetabular anteversion, acetabular index in 15 dislocated hips and 11 normal hips in cases
of unilateral dislocation of hip in DDH of age group 12–48 months. We correlated this femoral anteversion with the intra operative
“test of stability” which is described by Zadeh et al. We found that there was no statistically significant difference in
femoral anteversion between dislocated and normal hips. In all the 15 cases we did open reduction by anterior approach (Somerville
approach) and evaluated the position for maximum stability. In 3 cases we were unable to perform test of stability as they
needed femoral shortening for reduction of joint.
Results
In the rest 12 hips, 10 were stable in flexion and abduction while 2 were stable in flexion. None of the hips required internal
rotation for stability. Hence we did salters osteotomy in all the hips and femoral shortening through lateral approach in
3 cases. At a minimum follow up of 18 months all the hips were clinically stable and none of them dislocated till final follow
up. The mean correction of acetabular index was 15.4° and the outcome was excellent in 8 hips and good in 7 hips as per modified
McKay’s criteria. Hence we recommend that femoral derotation osteotomy is not needed in DDH of early walking age group.
Conclusion
As the surgical treatment of DDH involves complex osteotomies around the hip and these surgeries have effect on long term
outcome, MRI evaluation of femoral anteversion as a part of pre operative evaluation is advised. Also, as the intra operative
evaluation needs enough clinical experience and it can not be performed in cases requiring femoral shortening for reduction,
we consider pre operative evaluation of femoral anteversion by MRI as essential rather than adjunctive.
Keywords DDH - MRI evaluation - Femoral anteversion - Femoral derotation osteotomy - Test of stability