1. A non-transitory computer-readable medium embodying a program of instructions executable by machine to perform steps for segmenting articulated structures, the steps comprising: (i) generating statistical shape models and local appearance models based on a reference image and training images; (ii) receiving a target image; (iii) determining a non-rigid transformation function that registers first centerline landmarks along centerlines of articulated structures in the reference image with second centerline landmarks along centerlines of articulated structures in the target image; (iv) deforming mean shapes of the statistical shape models to the target image space by applying the non-rigid transformation function on the mean shapes; (v) decoupling any overlapping segments of articulated structures in the mean shapes; (vi) searching for candidate points in the mean shapes using the local appearance models; and (vii) fitting the mean shapes to the candidate points to generate a segmentation mask.