Bipositional MR imaging vs. arthrography for the evaluation of femoral head sphericity and containment in Legg–Calvé–Perthes disease

Eleven hips of 10 patients with Legg–Calvé–Perthes disease (LCPD) were examined by arthrography and magnetic resonance (MR) imaging. Arthrogram and MR images were obtained with the hips in neutral position and in 20° flexion–abduction and internal rotation. Modified arthrographic index (AI) was used for the evaluation of sphericity and acetabulum head index (AHI) was used for the assessment of containment. According to AI, there is no significant difference between the arthrograms and coronal MR imaging, but the difference between the coronal and sagittal MR imaging was significant. There was no statistical difference between the arthrograms and MR measurements in terms of AHI. Anterior flattening of the femoral head and the effect of hip flexion in the containment at the sagittal plane could be demonstrated clearly in sagittal MR imaging. Even if there was significant flattening in coronal plane, the sphericity of the head was preserved in the sagittal plane. Bipositional MR imaging is comparable to arthrography for the demonstration of sphericity and containment of the femoral head in both coronal and sagittal planes in LCPD.