Megaprosthesis Reconstruction Following Failed Knee Arthrodesis after Wide Resection of Proximal Tibial Chondroblastoma: A Case Report

Abstract

Aims: To describe the surgical management and early outcome of megaprosthesis reconstruction following failed knee arthrodesis after wide resection of a proximal tibial chondroblastoma. Presentation of Case: A 19-year-old female with a proximal tibial tumour suspicious for chondroblastoma underwent tumour resection and knee arthrodesis with intramedullary nailing and bone spacer placement in 2022. Histopathological confirmation from the 2022 procedure was not available in the referral records reviewed by our team; therefore, the diagnosis in this report is based on the referral diagnosis and imaging findings. Persistent pain and functional limitation led to conversion to megaprosthesis reconstruction in January 2026. The previous nail and bone spacer were removed, the femur and tibia were prepared, and a cemented rotating-hinge megaprosthesis was implanted. Postoperative rehabilitation included partial weight-bearing ambulation and range-of-motion exercises. At the two-month follow-up, limb alignment improved, implant fixation remained stable, tenderness was absent, and the limb-length discrepancy had resolved. Knee and ankle motion remained limited because of postoperative stiffness. Discussion: Megaprosthesis reconstruction may offer a limb-salvage option after failed arthrodesis by restoring alignment, joint mobility, and functional capacity. Careful surgical planning and structured rehabilitation are important because prior surgery, altered anatomy, soft-tissue scarring, and stiffness make conversion technically demanding. Conclusion: Megaprosthesis reconstruction showed promising short-term clinical and functional results after failed knee arthrodesis in this young patient with a proximal tibial benign bone tumour suspicious for chondroblastoma. Because the follow-up was limited to two months, longer surveillance is necessary to evaluate implant survival, durable functional recovery, and local disease status.