Determination of hip reduction in spica cast treatment for DDH: a comparison of radiography and ultrasound.

Purpose: In this retrospective study we compared the efficacy of ultrasound and radiography for determining the position of the femoral head after closed or open reduction in DDH.

Materials and methods: The ultrasound was performed using the van Douveren technique by a transinguinal approach through a perineal window of the spica cast. Sixty-eight a.p. radiographs of the pelvis were correlated to 68 ultrasound images.

Results: Thirty-two radiographs were not useful for precisely determining the femoral head position, whereas the criteria described by van Douveren et al. could be identified in all ultrasound images. All ultrasound images in the study were useful and gave reliable information about the position of the femoral head.

Conclusion: Consequently, standard radiographic documentation is no longer used as a standard in our clinic. MRI and CT are reserved for special cases. We recommend transinguinal ultrasound as a standard diagnostic method to determine the position of the femoral head in hip spica casts safely and reliably.