Figure 1. Preoperative design and template preparation.

(A) DICOM data were imported into Mimics software for 3D reconstruction. (B) The bone cutting plane and needle insertion channel were simulated; the navigation template was designed with reverse modeling. A Boolean operation was used to acquire femoral surface morphology, and the 3D navigation template model was set up with the insertion channel for the Kirschner wire. (C,D) The navigation template includes all the operation parameters and steps for proximal femoral varus rotation and shortening osteotomy: (a) is the shortening length of bone cutting, (b) is the needle insertion angle on the femoral neck (b = LCP-PHP angle + varus angle), and (c) is the rotation angle of bone cutting. (E) The osteotomy process was simulated using the navigation template in Mimics software using the Kirschner wire as a lever.