BackgroundThe aim of the study was to assess the functional and oncological outcomes of patients with distal femoral osteosarcoma managed by limb salvage using modular endoprosthesis as well as to assess related complications.Patients and MethodsA total of 82 patients were included in our study. Functional outcome was assessed using MSTS score and knee range of motion. Oncological outcome was assessed regarding local recurrence, chest metastasis, and patient survivorship. Complications were classified according to Henderson et al.ResultsThe mean MSTS score was 26.21 (87.4%) (range 8–30 points) with 70.7% of patients having more than 90° of flexion. The incidence of local recurrence was 3.7% (3 patients), while the incidence of chest metastasis was 14.6% (12 patients). Aseptic loosening (type 2 failure) was the commonest complication (19.5%), followed by infection (15.9%). The 5- and 10-year survivorships of the limb were 98.8%, while the 5- and 10-year survivorships of the prosthesis were 67.7% and 52.4%, respectively.ConclusionThis study showed that patients with osteosarcoma distal femur who are treated by chemotherapy and limb salvage have an excellent long-term prognosis in terms of patient as well as limb survivorship. The use of modular endoprosthesis in these patients offer an acceptable function, with two-thirds of the patients retaining their prosthesis after 5 years and more than half retaining them after 10 years.