Computerized Tomography and Magnetic Resonance Imaging in Treatment of Congenital Luxation of the Hip

Abstract

In treatment of congenital dislocation of the hip, a main aim is to achieve concentricity of reduction. Control by plain x-ray lacks accuracy in determining anteroposterior position. Arthrography and sonography cannot be used when a spica cast is in place. After April 1988, therefore, as an alternative in 16 hips, we have used computed tomography to determine femoral head position, acetabular angle, and extent and integrity of posterior rim. However, the presence of any metallic artefacts, unossified cartilage and the general poor-quality imaging of soft tissue associated with the technique reduce its usefulness. Since January 1990, we have instead used magnetic resonance imaging to control treatment. This technique, in 34 hips, proved accurate in determinating the femoral head position. MRI also gave better images than computed tomography of osseous and cartilaginous structures of the acetabulum and the surrounding soft tissue. Spica casting does not affect the quality of imaging. The effect of metal artefacts can be minimized by using, where necessary, implants of titanium alloy.