Long-term survival in osteosarcoma patient: A 21-year follow-up after limb-salvage surgery and custom prosthesis reconstruction

This case report underscores the critical role of early diagnosis and systematic, multidisciplinary management in the treatment of distal femoral osteosarcoma in a 13-year-old female patient. Osteosarcoma is a rare and highly aggressive primary bone malignancy that predominantly affects adolescents and young adults. The uniqueness of this case lies not only in the successful long-term outcome but also in the prompt diagnosis, timely intervention, and use of a custom total knee prosthesis for limb salvage. Although osteosarcoma has been widely reported, this case provides a distinctive contribution by illustrating an evidence-based, structured approach that resulted in 21 years of disease-free survival. It offers valuable guidance for orthopedic oncologists and surgical teams managing similarly complex pediatric musculoskeletal tumors, particularly in resource-intensive reconstructive settings. A 13-year-old female presented in 2004 with a 1 year history of pain and swelling in the right knee. Imaging and biopsy confirmed a diagnosis of high-grade osteosarcoma of the distal femur, with no evidence of metastasis. The patient received neoadjuvant chemotherapy to optimize surgical conditions, followed by en bloc resection and reconstruction using a custom-made STRYKER HOWMEDICA OSTEONICS (HMRS) total knee prosthesis. At 21-year follow-up, she remains completely disease-free and demonstrates excellent functional outcomes, without any activity limitations or complaints. This case report highlights the importance of a comprehensive, multidisciplinary approach in the management of distal femur osteosarcoma. The use of multiple diagnostic modalities, tumor markers, and histopathological evaluation enabled early and accurate diagnosis, facilitating timely and appropriate treatment. Furthermore, the case underscores the long-term durability and effectiveness of limb salvage surgery using a custom-made prosthesis in pediatric osteosarcoma. It also emphasizes the critical role of consistent long-term follow-up in ensuring sustained oncologic control and functional success.