A hierarchical strategy for reconstruction of 3D acetabular surface models from 2D calibrated X-ray images

Abstract

Recent studies have shown the advantage of performing range of motion experiments based on three-dimensional (3D) bone models to diagnose femoro-acetabular impingement (FAI). The relative motion of pelvic and femoral surface models is assessed dynamically in order to analyze potential bony conflicts. 3D surface models are normally retrieved by 3D imaging modalities like computed tomography (CT) or magnetic resonance imaging (MRI). Despite the obvious advantage of using these modalities, surgeons still rely on the acquisition of planar X-ray radiographs to diagnose orthopedic impairments like FAI. Although X-ray imaging has advantages such as accessibility, inexpensiveness and low radiation exposure, it only provides two-dimensional information. Therefore, a 3D reconstruction of the hip joint based on planar X-ray radiographs would bring an enormous benefit for diagnosis and planning of FAI-related problems. In this paper we present a new approach to calibrate conventional X-ray images and to reconstruct a 3D surface model of the acetabulum. Starting from the registration of a statistical shape model (SSM) of the hemi-pelvis, a localized patch-SSM is matched to the calibrated X-ray scene in order to recover the acetabular shape. We validated the proposed approach with X-ray radiographs acquired from 6 different cadaveric hips. © 2012 Springer-Verlag.