1. A method of generating a patient-specific bone shell representative of at least a portion of a patient's bone in its current state by a reconstruction system, the method comprising: imaging at least a portion of a patient's anatomy to create a plurality of 2D image slices of the patient's anatomy taken orthogonal to an axis extending through the patient's anatomy, where each of the plurality of 2D image slices includes a bone segment comprising an enclosed boundary corresponding to an exterior of the patient's bone; recognizing the enclosed boundary of each bone segment on the 2D image slices by using a template 3D image bone shell that is not patient specific; and constructing and outputting a 3D image bone shell of at least the portion of the patient's bone by associating the plurality of 2D image slices of the patient's bone based on the recognition of the enclosed boundary of each bone segment, where the 3D image bone shell depicts a current state of the patient's bone.