椎体成形术的实验研究

Percutaneous Vertebroplasty: An Experimental Study in Osteoporotic Goats

目的 通过对骨质疏松的山羊椎体成形探讨椎体成形术的安全性和临床应用依据。材料与方法 将 5只复制成功的骨质疏松的山羊每只取 3个椎体 (L1～L5)共 15个椎体作为手术组 ,2个椎体 (L1～L5)共 10个椎体作对照组。手术解剖出椎弓根直视下椎体穿刺 ,注入聚甲基丙烯酸甲酯 (PMMA ,骨水泥 )。测量椎体中心、椎体前缘和椎体后缘的温度变化。CT检查椎体骨水泥充填情况。 3天后处死动物每只取 1个注射椎体共 5个椎体行病理检查。将另 10个注射椎体和 10个未手术对照组椎体游离成单个椎体 ,去掉椎间盘和椎体附件 ,双盲法测量其纵向最大负载、极限强度、弹性模量。结果 注射后椎体的最大负载、极限强度、弹性模量比对照组明显提高 (P <0 .0 5 )。注射骨水泥后椎体内中心温度为 5 1.12℃ ,椎体前缘 37.31℃ ,后缘 37.6 1℃。大体病理和显微病理显示骨水泥弥散在椎体内骨小梁间呈不均匀分布 ,同CT检查结果一致。结论 掌握适宜的粉液比例和注射时机是椎体成形术的关键因素 ,椎体内注入骨水泥可显著增强其纵向最大负载、极限强度。

Objective To investigate the safety and theoretical basis of percutaneous vetebroplasty (PVP) by observing the effect of PVP in experimental osteoporotic goats.Materials and Methods Fifteen vertebral bodies (study group), selected from L 1～L 5 in 5 osteoporotic goats, were used for PVP and the other 5 vertebral bodies were used as control group. Pedicle of vertebral arch was dissected. Under direct vision, the needle was punctured into the vertebral body, than, polymethylmethacrylate (PMMA), the bone cement, was injected into the body. The temperature at the center, anterior border and posterior border of the vertebral body were separately measured. CT scanning was carried out to check the filling condition of PMMA. The goats were sacrificed three days after the surgery. Five injected vertebrae were selected from the five goats (one from each) for pathologic exam. The remaining 10 injected and 5 controlled vertebrae were isolated, the intervertebral discs and appendages were removed. Using double blind method, the maximum longitudinal load, ultimate strength and modulus of elasticity were estimated.Results The maximum longitudinal load, ultimate strength and modulus of elasticity in the study group after the injection of PMMA were significantly higher than that in the control group (P<0.05). The average temperature at the center, anterior border and posterior border of the vertebral body was 51.12℃, 37.31℃ and 37.61℃, respectively. The macro- and micro-pathologic exam showed that the PMMA was diffusely and unevenly distributed between bone trabeculae, being in agreement with CT findings. Conclusion Using proper powder/liquid ratio and injecting PMMA at proper moment are the key point for PVP. Injection of PMMA into the vertebral body can significantly increase the maximum longitudinal load, ultimate strength and modulus of elasticity of the vertebral body.