Utility of magnetic resonance imaging (MRI) after closed reduction of developmental dysplasia of the hip.

ABSTRACT

PURPOSE: Magnetic resonance imaging (MRI) has been successfully used in the determination of the adequacy of the surgical reduction of congenitally dislocated hips in children. We present the results of a prospective series of patients treated conservatively. MRI was performed in all hips after positioning was deemed adequate on radiographs after spica cast application. The goal of this study was to evaluate the usefulness of MRI in this indication. METHODS: After the study was approved by our local ethics committee, 31 patients for a total of 36 dislocated hips were included. After the traction period, hip testing was performed and a hip spica cast was applied under general anaesthesia. All children had MRI within 1 week of reduction, without the need for contention or general anaesthesia. Hip reduction was assessed on axial and coronal MRI images. RESULTS: The concentric reduction of the hip was confirmed in 30 cases out of 36. In three cases, the dislocation was retrospectively suspected on radiographs and then confirmed. In the three remaining cases, hip dislocation was only diagnosed on MRI. CONCLUSIONS: MRI screening of congenitally dislocated hips after reduction procedures is a safe and reliable procedure to assess the concentric reduction of the hip. Even in doubtful cases, MRI detected persistent hip dislocations and was conducive to iterative reduction and satisfactory outcome and result.