Do we need femoral derotation osteotomy in DDH of early walking age group? A clinico-radiological correlation study

Abstract

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. 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. 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 degrees 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. 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.