Abstract-3D assessment of scoliotic deformities relies on an accurate 3D reconstruction of bone structures from biplanar Xrays, which requires a precise detection and matching of anatomical structures in both views. In this paper, we propose a novel semi-automated technique for detecting complete scoliotic rib borders from PA-0º and PA-20º chest radiographs, by using an edge-following approach with multiple-path branching and oriented filtering. Edge-following processes are initiated from user starting points along upper and lower rib edges and the final rib border is obtained by finding the most parallel pair among detected edges. The method is based on a perceptual analysis leading to the assumption that no matter how bent a scoliotic rib is, it will always present relatively parallel upper and lower edges. The proposed method was tested on 44 chest radiographs of scoliotic patients and was validated by comparing pixels from all detected rib borders against their reference locations taken from the associated manually delineated rib borders. The overall 2D detection accuracy was 2.64  1.21 pixels. Comparing this accuracy level to reported results in the literature shows that the proposed method is very well suited for precisely detecting borders of scoliotic ribs from PA-0º and PA-20º chest radiographs.