Campanacci Grade III Giant Cell Tumor of the Distal Femur Treated With Wide En Bloc Resection and Cemented Modular Megaprosthetic Reconstruction: A Case Report.

Giant cell tumor of bone (GCTB) is a benign but locally aggressive primary bone neoplasm that accounts for approximately 5% of all primary bone tumors and 20% of benign skeletal neoplasms. It most commonly presents between the second and fourth decades of life and typically involves the epimetaphyseal region of long bones in skeletally mature patients. Campanacci grade III tumors exhibit extensive cortical destruction and soft-tissue extension, which may preclude joint-preserving intralesional treatment. We report the case of a 26-year-old woman with a two-year history of progressive left knee pain, distal thigh swelling, and functional limitation. Radiographs and computed tomography revealed an expansile osteolytic lesion of the distal femur with extensive cortical destruction. Histopathological examination following an open biopsy confirmed GCTB, radiographically classified as Campanacci grade III. Given the extent of cortical and articular involvement, limb-salvage surgery was performed through wide en bloc resection of the distal femur, followed by reconstruction with a cemented modular distal femoral megaprosthesis. Rehabilitation was initiated on the third postoperative day, and no immediate postoperative complications occurred. At 12 months, the patient had a Musculoskeletal Tumor Society (MSTS) score of 26/30 (87%), substantial pain relief, and return to daily activities. Serial radiographs demonstrated stable prosthetic alignment and fixation without mechanical failure or aseptic loosening. No local recurrence or distant metastasis was identified. Wide resection followed by megaprosthetic reconstruction can provide satisfactory short-term oncologic and functional outcomes in selected patients with Campanacci grade III GCTB of the distal femur when extensive bone and joint destruction makes joint preservation unsuitable. Longer follow-up remains necessary to assess disease recurrence and implant survival.