We evaluated the medium and long-term outcomes on the basis of patients' function and general quality of life after three different surgical procedures for osteosarcoma around the knee joints, that is, amputation, prosthetic reconstruction and rotationplasty. Twenty-six procedures in 22 patients who survived for at least 1 year after surgery were assessed for functional analysis (scores of the Musculoskeletal Tumor Society), and health-related quality of life assessment (SF-36) was applied to 17 patients who are alive without the disease. The patients treated with rotationplasty showed significantly high functional scores in two of six categories as compared with those undergoing the other two procedures. The scores of SF-36 also showed higher values for seven of eight subscales, however, no significant differences were observed for any subscale. We demonstrated that despite no statistical difference in patient self-assessment of outcome between the treatment modalities, there were functional benefits of rotationplasty over prosthetic reconstruction and amputation.