Preoperative imaging, intraoperative steps, and postoperative outcome of proximal femoral replacement using a MUTARS^® modular megaprosthesis (Implantcast GmbH) in a patient with recurrent Grade 2 chondrosarcoma of the right proximal femur. (A) Preoperative anteroposterior radiograph demonstrating a lytic lesion of the proximal right femur with pathological fracture and prior internal fixation using a dynamic hip screw. (B) Intraoperative image showing surgical exposure and mobilization of the tumor-bearing segment with removal of the previously implanted plate. (C) Gross specimen after wide en bloc resection of the proximal femur, including the tumor mass and attached hardware. (D) Intraoperative photograph showing implantation and alignment using the MUTARS^® modular megaprosthesis. (E) Reconstruction of periarticular soft tissues using a Trevira^® tube (Implantcast GmbH) for tendon reattachment and capsular stabilization. (F) Immediate postoperative anteroposterior radiograph showing the final position of the MUTARS^® proximal femoral replacement with appropriate alignment and fixation.