Abstract: BACKGROUND: With the increasing number of osteoporosis vertebrae compression fracture patients, it is difficult to reach a consensus on how much bone cement is given in percutaneous kyphoplasty surgery. 
OBJECTIVE: To investigate the relationship of different doses of bone cement with clinical efficacy and bone cement leakage using Mimics software, and to explore the safe and effective bone cement injection threshold in percutaneous kyphoplasty for cases with osteoporosis vertebrae compression fracture.  
METHODS: Forty-three patients with osteoporosis vertebrae compression fracture undergoing percutaneous kyphoplasty were included and randomly divided into two groups. The amount of bone cement injected into the vertebral body and the volume of vertebral body were designed by Mimics software. The volume ratio of bone cement was calculated according to the average volume of upper and lower vertebrae. In groups A and B, 24% and 15% of bone cement were injected according to the bone cement volume ratio (bone cement volume/vertebral volume ratio) recognized by most documents. The differences of pain, leakage rate, Cobb’s angle and refracture rate between the two groups were evaluated by follow-up.
RESULTS AND CONCLUSION: (1) All patients were followed up for 6-24 months. (2) There were significant differences in visual analogue scale score between the two groups between preoperation and at each time point after operation, the first day after operation and the fifth day (before discharge), three months and 12 months after operation (P < 0.05). There was no significant difference in pain degree between the two groups at each time point after surgery (P > 0.05). (3) There were 5 cases (24%) with leakage in group A and 2 cases (10%) in group B; there was no significant difference in the leakage rate of bone cement between the two groups (P > 0.05). (4) There were significant differences in Cobb’s angle between the two groups between different time points after operation and preoperation (P < 0.05). There was no significant difference between the two groups at 5 days, 3 months and 12 months after operation (P > 0.05). (5) There were 3 cases of refracture in group A (14%) and 2 cases in group B (10%). There was no significant difference between the two groups (P > 0.05). (6) Above results confirm that it was accurate for us to evaluate bone cement volume according to the fracture vertebral body volume by 15% and 24% injection of bone cement using Mimics software, which showed less complications and short-term satisfactory clinical efficacy.

Key words: thoracic spine, lumbar spine, osteoporosis, vertebral body, kyphoplasty, bone cement, leakage