Given that osteosarcoma typically presents at an early age and predominantly affects pediatric and adolescent populations, early control of disease progression and the opportunity for complete tumor resection are particularly crucial. Postoperatively, patients can regain functional mobility through prosthetic implantation and artificial joint reconstruction, thereby preventing premature loss of mobility in young patients. This study aims to explore the efficacy and safety of neoadjuvant treatment with the PD-L1 antibody envafolimab in combination with standard chemotherapy in patients with resectable stage IIb osteosarcoma, and to assess whether this combined regimen can increase the proportion of patients achieving complete tumor resection.