Anterior Inferior Iliac Spine Morphology Correlates with Hip Range of Motion: A CT-based Classification System and Dynamic Hip Model

Abstract

The AIIS can be reproducibly classified into 3 morphological types (i.e. I, II, III) based on 3D CT reconstructions. When hips in patients with signs of FAI are matched for version and alpha angle, AIIS types II and III are associated with decrease in hip flexion and internal rotation, supporting the rationale to consider AIIS decompression for types that extends to and below the acetabular rim.