Time of identification of lung metastasis is an important prognostic factor. In terms of clinical behavior, groups 2 and 3 are completely different than group 4. These data ensure the need to stratify stage III osteosarcomas into subgroups according to the time of diagnosis of lung metastases. To improve the survival of osteosarcoma patients, new treatment modalities should be introduced into the treatment armamentarium for lung metastasis from osteosarcoma, especially in groups 1, 2, and 3.

Acute spinal column shortening can be characterized into 3 phases. Phase 1, safe range: occurred during shortening within one-third of the vertebral segment and is characterized by no deformity of the dural sac or the spinal cord. Phase 2, warning range: occurred during spinal shortening between one-third and two-thirds of the vertebral segment and is characterized by shrinking and buckling of the dural sac and no deformity of the spinal cord. Phase 3, dangerous range: occurred after shortening in excess of two-thirds of the vertebral segment and is characterized by spinal cord deformity and compression by the buckled dura. Spinal shortening within the safe range increases spinal cord blood flow.