BACKGROUND: A great amount of red bone marrow in the cancellous bone losses during orthopedic surgery.OBJECTIVE: To explore the feasibility to isolate bone marrow mesenchymal stem cells (BMSCs) during spinal surgery bleeding and to investigate the relationship of the number of BMMSCs with age and time.METHODS: Three cases of degenerative lumbar instability and 16 cases of lumbar burst fractures were selected to undergo posterior pedicle screw fixation,including 4 cases of 20-30 years,5 of 30-40 years,5 of 4...