Test of stability as an aid to decide the need for osteotomy in association with open reduction in developmental dysplasia of the hip - A long-term review

After open reduction for developmental dysplasia of the hip (DDH), a pelvic or femoral osteotomy may be required to maintain a stable concentric reduc tion. We report the clinical and radiological outcome in 82 children (95 hi ps) with DDH treated by open reduction through an anterior approach in whic h a test of stability was used to assess the need for a concomitant osteoto my, The mean age at the time of surgery was 28 months (9 to 79) and at the latest follow-up, 17 years (12 to 25), All patients have been followed up u ntil closure of the triradiate cartilage with a mean period of 15 years (8 to 23), At the time of open reduction before closure of the joint capsule, the posi tion of maximum stability was assessed. A hip which required flexion with a bduction for stability was considered to need an innominate osteotomy. If o nly internal rotation and abduction were required, an upper femoral derotat ional and varus osteotomy was carried out. For a 'double-diameter' acetabul um with anterolateral deficiency, a Pemberton-type osteotomy was used. A hi p which was stable in the neutral position required no concomitant osteotom y, Overall, 86% of the patients have had a satisfactory radiological outcome ( Severin groups I and II) with an incidence of 7% of secondary procedures fo r persistent dysplasia including one hip which redislocated, The results we re better (p = 0.04) in children under the age of two years. Increased leg length on the affected side was associated with poor acetabular development and recurrence of joint dysplasia (p = 0.01), The incidence of postoperati ve avascular necrosis was 7%, In a further 18%, premature physeal arrest wa s noted during the adolescent growth spurt (Kalamchi-MacEwen types II and I II). Both of these complications were also associated with recurrence of jo int dysplasia (p = 0.01). Studies with a shorter follow-up are therefore li kely to underestimate the proportion of poor radiological results.