This video demonstrates radical resection of a proximal tibia osteosarcoma. The video discusses the case presentation of a 21-year old man with right leg pain. He had no relevant medical history. Radiographs and MRIs revealed a heterogenous lesion extending from the epiphysis to the diaphysis of the tibia. Intraoperative biopsy was performed and confirmed the diagnosis of a high-grade osteosarcoma. This is a rare tumor that predominantly arises in the long bones. The patient underwent preoperative chemotherapy. He then underwent radical resection of the proximal tibia and reconstruction with the use of a proximal tibia tumor prosthesis.