Spinal fusion with pedicle-screw-rod is being used widely for treating spinal deformities diseases. Several biomechanical studies on screw rod based implant failure through screw pullout, bending, screw breakage have been performed. But few studies are available regarding the effect of strain for breakage of rod. So, the purpose of the present study is to observe strain at the rod connected with the pedicle screw for different loading condition. The strain in stainless steel (SS) connecting rods for pedicle screw fixation were measured using strain gauge. In order to investigate the bio-mechanical response of lumbar spine with reference to strain in the rod, a simple experimental setup was developed using a specimen of L1-S spine segment. SS rods were used for pedicle screw implant on prototyped lumbar Spine. Prior to testing with pedicle screw, the lumbar spine specimen was also compared with FE results. The strain measured using strain gauges at L3-L4 level on SS rod were within a range of 85 to 310 microstrain under 6, 8, 10 Nm flexion and extension, and for L4-L5 level, these values were within a range of 95 to 440 microstrain. It was found that FE result was higher than the strain gauge result and the error varied between 10.5% to 33% with average error of 22.8%. However similar stain behavior was observed by the FE analysis. The proposed method, as well as the qualitative data, might be helpful for the researchers to understand biomechanical behavior of pedicle-screw implanted spine.

椎弓根螺钉杆脊柱融合术被广泛用于治疗脊柱畸形疾病。已经进行了几项关于螺钉拔出、弯曲、螺钉断裂导致的基于螺钉的植入物失效的生物力学研究。但是很少有关于应变对杆断裂的影响的研究。因此，本研究的目的是观察与椎弓根螺钉连接的杆在不同负载条件下的应变。使用应变仪测量用于椎弓根螺钉固定的不锈钢 (SS) 连杆的应变。为了研究腰椎对杆中应变的生物力学响应，使用 L1-S 脊柱节段的样本开发了一个简单的实验装置。SS 棒用于在原型腰椎上植入椎弓根螺钉。在使用椎弓根螺钉进行测试之前，腰椎标本也与FE结果进行了比较。在 6、8、10 Nm 的弯曲和伸展下，使用应变仪在 SS 杆上的 L3-L4 水平测量的应变在 85 到 310 微应变的范围内，对于 L4-L5 水平，这些值在 95 到440 微应变。发现有限元结果高于应变片结果，误差在 10.5% 到 33% 之间变化，平均误差为 22.8%。然而，通过有限元分析观察到类似的染色行为。所提出的方法以及定性数据可能有助于研究人员了解椎弓根螺钉植入脊柱的生物力学行为。10 Nm 弯曲和伸展，对于 L4-L5 水平，这些值在 95 到 440 微应变的范围内。发现有限元结果高于应变片结果，误差在 10.5% 到 33% 之间变化，平均误差为 22.8%。然而，通过有限元分析观察到类似的染色行为。所提出的方法以及定性数据可能有助于研究人员了解椎弓根螺钉植入脊柱的生物力学行为。10 Nm 弯曲和伸展，对于 L4-L5 水平，这些值在 95 到 440 微应变的范围内。发现有限元结果高于应变片结果，误差在 10.5% 到 33% 之间变化，平均误差为 22.8%。然而，通过有限元分析观察到类似的染色行为。所提出的方法以及定性数据可能有助于研究人员了解椎弓根螺钉植入脊柱的生物力学行为。