Revision surgery for developmental dysplasia of the hip.

Revision surgery following failed open reduction for developmental dysplasia of the hip (DDH) is technically demanding. We reviewed 12 patients in our institution that required a revision surgery between January 1994 and December 2003. The aims of this study are to identify the causes of redislocation after the primary open reduction and to determine the clinical and radiological outcome after the revision surgery. The mean age at presentation for DDH was 31 months (range 1-84) and the mean age at primary open reduction surgery was 38 months (range 15-84) and the mean age at revision surgery was 69 months (range 21-180). The mean follow-up period after revision surgery was 20 months (range 3-84). All the revision surgery was performed via an anterior Smith Peterson approach. The most common cause for redislocation was inadequate exposure and failure to release the obstructing soft tissues around the hip. The bony factors for redislocation included failure to perform a femoral shortening and excessive derotation of an anteverted femoral head combined with a Salter osteotomy. Three cases with posterior acetabular wall deficiency needed immobilization of the hip in extension as the hip tended to dislocate in flexion. Six patients had limb length discrepancy ranging from 1 cm to 4 cm and 50% developed avascular necrosis. Only 2 patients were asymptomatic and the majority had a limp and limitation of motion. All were pain free except one. In view of the technically demanding surgery and poor results after revision, the surgeon should recognize the pathology and ensure that the primary procedure achieves a stable and concentric reduction.