Avascular necrosis and the Aberdeen splint in developmental dysplasia of the hip

Between January 1987 and December 1988 there were 7575 births in the Swanse a maternity unit. Of these 823 (10.9%) were considered to be at 'high risk' for developmental dysplasia of the hip (DDH). Static ultrasound examinatio n was performed in each case and the results classified on the basis of the method of Graf. A total of 117 type III-IV hips in 83 infants was splinted using the Aberdeen splint. Radiographs of these hips were taken at six and 12 months. Hilgenreiner's m easurements of the acetabular angle were made in all cases and the developm ent of the femoral capital epiphysis was assessed by measuring the epiphyse al area. The effect of splintage on the acetabular angle and the epiphyseal area between the normal and abnormal splinted hips was compared. Radiograp hs of 16 normal infants (32 normal unsplinted hips) were used as a control group. This cohort has now been followed up for a minimum of nine years. There hav e been no complications as a result of splintage. The failure rate was 1.7% or 0.25 per 1000 live births. No statistical difference was found when com paring the effect of splintage on the acetabular angle and epiphyseal area between normal and abnormal splinted hips and normal unsplinted hips. Our study has shown that while the Aberdeen splint had a definite but small failure rate, it was safe in that it did not produce avascular necrosis. T he current conventional view that a low rate of splintage is always best is therefore brought into question if the Aberdeen splint is chosen for the m anagement of neonatal DDH.