Hybrid Prosthetic and Biological Reconstruction Using Extracorporeal Radiotherapy for Long-Segment Humeral...

Osteosarcoma, the most prevalent malignant primary bone tumor in children and adolescents, can present formidable challenges when involving long segments of the humerus. Reconstruction options must balance oncological clearance with long-term limb function, particularly in skeletally immature patients.

We report a case of a 15-year-old female diagnosed with high-grade osteosarcoma involving the proximal epiphysis and most of the diaphysis of the right humerus, sparing only the distal 3 cm. Following neoadjuvant chemotherapy, the patient underwent wide tumor excision and a novel hybrid limb-salvage reconstruction using a custom proximal prosthesis combined with biological reconstruction of the diaphysis via extracorporeal radiotherapy (ECRT). The tumor-bearing bone was irradiated with 50 Gy ex vivo and reimplanted, fixed to the preserved distal humerus with a locking plate. At 18-month follow-up, the patient remained disease-free, with radiographic evidence of graft incorporation and preserved elbow function.

This case highlights the viability of combining prosthetic and biological methods in complex pediatric osteosarcoma, especially when distal joint preservation is possible. ECRT provides a cost-effective, anatomically compatible solution that maintains structural integrity, especially when used with proximal prosthetic support. This hybrid method represents an optimal limb-salvage strategy in selected pediatric cases involving long bone tumors.