经皮置入式腰椎棘突间撑开器的生物力学测试

Biomechanical analysis of a novel percutaneously placed low profile interspinous device

中文关键词:  腰椎  置入式棘突间撑开器  经皮  生物力学

英文关键词:Lumbar spine  Interspious implant  Percutaneous  Biomechanicas

中文摘要:

  【摘要】　目的：评价经皮置入式腰椎棘突间撑开器对置入节段及其邻近节段活动度的影响。方法：选取6具新鲜人体腰椎标本（L1~L5），剔除附着肌肉，保留各韧带及骨骼，将标本的头尾端固定在MTS生物力学试验测试机上，对标本施加400N的轴向压力，然后以0.5°/s速度施加六个方向（前屈/后伸、左右侧屈、左右轴向旋转）±7.5Nm的力矩，测量L2/3、L3/4节段各个运动方向的运动范围（ROM，完整状态组）；于L3/4节段置入Bullet棘突间撑开器，按照同样方法测试标本各个方向的活动度（置入撑开器组）。测试后以2Hz频率循环加载，屈伸20 000次、侧屈15 000次、旋转5 000次，摄X线片观察内置物位置及棘突有无骨折，肉眼观察内置物有无变形和破损。结果：L3/4节段完整状态下前屈和后伸的平均ROM值分别为4.62°±2.26°和4.07°±1.92°，置入撑开器后前屈和后伸的平均ROM值分别为3.87°±2.06°和2.57°±2.06°，两组比较差异有统计学意义（P<0.05）；两组侧方屈曲和旋转的平均ROM值差异均无统计学意义。在完整状态和置入撑开器后L2/3节段各个运动方向的平均ROM值差异均无统计学意义。循环加载至预定加载次数后X线片示撑开器无移位，棘突无骨折；未发现棘突撑开装置变形或出现裂缝。结论：经皮置入式棘突间撑开器能够使置入节段前屈和后伸的活动度明显减少，但轴向旋转和侧向弯曲不受影响，且对邻近上位节段的活动度无影响。

英文摘要:

  【Abstract】　Objective：To investigate the influence of the interspinous spacer implant on the kinematics of the lumbar spine.Method：Six cadaver spine functional units（L1-L5） were observed.The muscles were removed while the discs，ligaments and joint capsules were intact.The cranial portion of L1 and caudal portion of L5 vertebrae were secured in polymethylmethacrylate（PMMA）.Specimens were initially tested by applying a 400N axial compression，followed by a ±7.5Nm bending moment in six directions（lexion and extension，left and right axial rotation，and left and right lateral bending） with a speed of 0.5°/s.The range of motion（ROM） at L2/3 and L3/4 of the intact group was measured，while the ROM at the L3/4 was measured after the Bullet interspinous device was placed.After the measurement，force was imposed with a frequency of 2Hz.Flexsion and extension were done 20000 time，lateral flexion was done 15000 times，and rotation was done 5000 times.X-ray was taken to see the positions of the implants，whether there was fracture of the spinous processes，whether the implants were deformed or broken.Result：The ROM in flexion-extension of L3/4 at intact state was 4.62°±2.26° and 4.07°±1.92° respectively.The ROM in flexion-extension at the instrumented level was 3.87°±2.06° and 2.57°±2.06°，the ROM of both groups in flexion-extension were significantly different（P<0.05），whereas there was no significant effect on the other directions.The novel device had the ability to resist fatigue.Conclusion：Similar to other interspinous implants，the novel percutaneously placed low profile inter-spinous device has an effect on the control of flexibility of the treated segments.It can provide spine stabilization while in extension，but has little effect on the range of motion in flexion，lateral bending and axial rotation.