Abstract: A method provide a patient-specific guidance system developed from 3D bone models, which are generated based on the patient's 2D image data. The surgical guide that is generated from this 3D data has an exterior surface that conforms to the interior surface of the acetabulum of an individual patient. Once this custom guide is placed into the patient's acetabulum, desired 3D implant position data can be transferred from the preoperative image to the acetabulum during an operation. The custom made guide allows surgeons to place guide rods into either the acetabulum itself, or into the sidewall of the pelvis (ileum or ischium) according to a preoperative plan. This guiding system is also coupled with an offset stemmed acetabular component to allow precise implantation and secure fixation of an acetabular component in a predetermined 3-D position relative to the pelvis.