1. A computer implemented method for determining the 3-dimensional shape of an implant to be implanted into a subject, the method comprising: obtaining a computer readable image including a defective portion and a non-defective portion of tissue in the subject; identifying landmarks on the image; superimposing on the image a template to span the defective portion; deforming the template to match the landmarks on the image; and determining the 3-dimensional shape of the implant based on the template that spans the defective portion.