Can Pre-operative MRI Predict the Need for Salter's Osteotomy in DDH Children Undergoing Open Reduction?

MRI having the multiplanar capability is a good choice for pre-operative planning in developmental dysplasia of hip (DDH). Although few previous studies utilised MRI to quantify dysplasia, predict outcomes, and the procedure required, there are no defined pre-operative conclusive criteria on when to do Salter's osteotomy?

A prospective cohort study was conducted in unilateral idiopathic DDH cases those who underwent an open reduction in the age group of one to four years. Pre- and post-operative MRI was done to assess various acetabular and femoral parameters. Intra-operatively, osteotomy was planned. Based on stability assessment given by Zadeh et al Clinical follow-up assessment was done at three- and six-month post-op. Functional assessment using Modified McKay's criteria was done at six months follow-up.

Out of 15 cases, seven children underwent only open reduction (OR), whereas eight underwent OR with Salter's osteotomy. Based on pre-op acetabular index and anteversion, Salter's osteotomy should be done in 14 out of 15 cases, but intra-operative stability test precluded Salter's in 6 cases. Post-operative anterior sectoral angle and femoral head coverage percentage were better in OR with Salter's group than OR-only group, but not statistically significant. Functional assessment at final follow-up showed all OR with Salter's group cases were Grade I, whereas in OR-only group, 4 were Grade I and 3 were Grade II.

Three-dimensional dynamic assessment using intra-operative stability test predicts the best possible interrelation between the articular surface of the femoral head and acetabulum and the need for osteotomy rather than preoperative MRI.