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Objective: To observe the changes of PMMA injection force during Kyphoplasty for the treatment of osteoporotic vertebral compression fracture in the ambient temperature of 20℃and 22℃respectively.Methods: First, the dynamic viscosity of PMMA was measured by a rotational rheometer in the ambient temperature of 20℃and 22℃respectively. Second, a cadaveric osteoporotic spinal column (T10-L4) was chosen to make the osteoporotic vertebral compression fracture models by a home-made clapping apparatus on biomechanical testing machine. Third, seven osteoporotic vertebral compression fracture models were randomly divided into two groups: NO1 (T10, L1, L3, L4)、NO2 (T11, T12, L2) . Then the changes of PMMA injection force were recorded by a pressure transducer in the room temperature of 20℃and 22℃during Kyphoplasty in the NO1 and NO2 osteoporotic vertebral compression fracture groups respectively.Results: The injection force of PMMA increased during cement augmentation in Kyphoplasty. The average, maximum force of the first and second canula injection were 0.068±0.046MPa, 0.179MPa and 0.247±0.159MPa, 0.543MPa respectively in the ambient temperature of 20℃。In ambient temperature of 22℃, the average, maximum force of the first and second canula injection were 0.046±0.042MPa, 0.138MPa and 0.251±0.20MPa, 0.833MPa. The average injection flow rates of PMMA were 0.021ml/s and 0.024ml/s in the room temperature of 20℃and 22℃respectively.Conclusion: 1. The ambient temperature was the most important influencing factor on the viscosity of PMMA. 2. The injection force during Kyphoplasty was mainly affected by the viscosity of PMMA. 3. The PMMA injection force testing can be used as an effective method for safety Kyphoplasty.
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