Confirming reduction of a developmental dislocation of the hip (DDH) through a spica cast is an imaging challenge. Computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound have been advocated.1-11 Each of these modalities has its benefits and drawbacks. Ultrasound allows the hip to be visualized in the operating room but is operator-dependent and requires cutting a window in the osterolateral aspect of the cast—thereby weakening an area that is crucial in holding the reduction. MRI is useful for visualizing the hip, acetabulum, and soft-tissue structures through a spica cast, but MRI availability and cost, and the prolonged sedation required, make this modality prohibitive for routine use at many centers. CT provides excellent visualization of bony details and anatomical relationships but subjects patients to ionizing radiation. In addition, both MRI and CT require waiting for the patient to recover from general anesthesia before moving him or her from the operating room to the scanner. When the reduction is suboptimal, the patient must be returned to the operating room for repeat anesthesia and corrective action.
This article first appeared in American Journal of Orthopedics 37(9):E159-62 2008 Sep.