Virtual implant model generated from CAD data (a) and aligned and fitted to the contour of the real prosthetic stem postoperatively. The virtual model was aligned in the same position with a preoperative CT image (b). The contact pattern images were three-dimensionally visualized using a color map based on the CT values around the stem (c). The stem was defined as being in contact with the cortical bone if the CT value around the stem was ≥600 HU. Red color indicates 600 HU and yellow color indicates 1200 HU. (A) Anteromedial view. (B) Anterolateral view. (C) Modified Gruen zone classification; for example, zone 2A/zone 2P indicates the anterior/posterior portion of zone 2.