| Objective: Percutaneous vertebroplasty(PVP), as a minimally invasive technique, can relieve the low back pain effectively and rebuild the stability of the spine. PVP has been widely used in the treatment of osteoporotic vertebral compression fracture(OVCF) and achieved good therapeutic effect, but due to the potential channel of fracture fissure and venous plexus, its related complications can not be ignored, such as bone cement leakage, pulmonary embolism, can cause fatal consequences.Therefore, the PVP in the injection of polymethylmethacrylate(PMMA) must be carefully carried out. To evaluate the prevention of bone cement leakage by sequential PMMA application in percutaneous vertebroplasty(PVP),with exsomatize vertebral bodyies as experimental subjects?Methods: 70 vertebrae(T8- L5) were harvested from each of seven elderly embalmed samples,which from the same area with the same race and age(65±3years).The fractures,tumors and congenital malformation were ruled out by X-ray.Bone mineral density was measured by bone mineral density instrument to remove non osteoporotic vertebral body. The whole vertebral bodies were placed between two nickelclads. Preloading 100 N pressure, with the time of 5 min, eliminated corrosion vertebral relaxation and creep effects and then loaded vertically with 5mm/min until the vertebral bodies were yielded. 70 vertebrae(T8- L5),of which 10 did pre-test,were made into compression fracture models and randomly divided into three groups.Three injection techniques of 3 ml PMMA were assessed:injection in one single step(group A); injection of 0.5 ml at the first and 2.5 ml at the second step with 1 min latency in-between(group B);sequential injection of 0.5 ml with 1 min latency between the sequences(group C),which with time 6.5 min.The cement leakage rate, injection force and distribution of cement were assessed with the reference of postoperative CT scan; Simultaneously leakage volume of each group were measured quantitatively.Statistical software were employed to analyze the data. Leakage rate were compared by ?~2 test among the three groups, and the Fisher's exact probability test were used in between-group differences; the volume of the leakage were compared by multiple analysis of variance in three groups, while SNK test using between group differences.The differences were regarded as statistically significant when P< 0.05?Results: 1 The leakage rate was lower in Group C(15%) than Group A(75%) and Group B(55%), there was statistical significant differences(?~2=14.95,P<0.05); Group C cement leakage volume(0.2000±0.1000)ml was lower than in group A(0.7667±0.3331)ml and group B(0.5818±0.3250)ml,with statistically significant difference(F=4.24,P<0.05); 2 The predilection site of cement leakage :paraspinal soft tissue leakage(56.76%),disc leakage(24.32%),paravertebral vascular leakage(13.51%),intravertebral leakage(5.41%), while CT scan displayed: In group C the cement distribution was more uniform, regular than group A and B;3 In group C,the maximum injection pressure of the first pipe cement(after mixing 300-465s) was about 0.8400 MPa,the maximum injection p-ressure of the second tube(525-690s) was about 1.2700MPa?Conclusion: The sequential cement injection is a simple and easy approach to distribute cement uniformly and reduce significantly the risk for leakage. Sequential injection of small amounts allows making use of the time-dependent of cement polymerization,without increasing the waiting time or working time.Using sequential injection of small cement volumes possible leakage paths can be blocked before further injection of the low-viscous cement?... |
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