1. A reconstruction system for generating a patient-specific bone shell representative of at least a portion of a patient's bone in its current state, the reconstruction system comprising: a recognition module configured to receive a plurality of 2D images of a portion of a patient's anatomy, the recognition module configured to recognize from the plurality of 2D image slices at least a cartilage segment comprising an enclosed boundary corresponding to an exterior of a portion of the patient's cartilage; a construction module configured to produce and output a 3D image cartilage shell of at least the portion of the patient's cartilage by associating the plurality of 2D images of the portion of the patient's anatomy based on the recognition of the enclosed boundary of each cartilage segment, where the 3D image cartilage shell depicts a current state of the patient's cartilage.