The thoracic spine presents a challenge for biomechanical testing. With more segments than the lumbar and cervical regions and the integration with the rib cage, experimental approaches to evaluate the mechanical behavior of cadaveric thoracic spines have varied widely. Some researchers are now including the rib cage intact during testing, and some are incorporating follower load techniques in the thoracic spine. Both of these approaches aim to more closely model physiological conditions. To date, no studies have examined the impact of the rib cage on thoracic spine motion and stiffness in conjunction with follower loads. The purpose of this research was to quantify the mechanical effect of the rib cage on cadaveric thoracic spine motion and stiffness with a follower load under dynamic moments. It was hypothesized that the rib cage would increase stiffness and decrease motion of the thoracic spine with a follower load. Eight fresh-frozen human cadaveric thoracic spines with rib cages (T1–T12) were loaded with a 400 N compressive follower load. Dynamic moments of ± 5 N m were applied in lateral bending, flexion/extension, and axial rotation, and the motion and stiffness of the specimens with the rib cage intact have been previously reported. This study evaluated the motion and stiffness of the specimens after rib cage removal, and compared the data to the rib cage intact condition. Range-of-motion and stiffness were calculated for the upper, middle, and lower segments of the thoracic spine. Range-of-motion significantly increased with the removal of the rib cage in lateral bending, flexion/extension, and axial rotation by 63.5%, 63.0%, and 58.8%, respectively (p < 0.05). Neutral and elastic zones increased in flexion/extension and axial rotation, and neutral zone stiffness decreased in axial rotation with rib cage removal. Overall, the removal of the rib cage increases the range-of-motion and decreases the stiffness of cadaveric thoracic spines under compressive follower loads in vitro. This study suggests that the rib cage should be included when testing a cadaveric thoracic spine with a follower load to optimize clinical relevance.

胸椎对生物力学测试提出了挑战。与腰椎和颈椎区域相比，节段更多，并且与肋骨融合在一起，评估尸体胸椎力学行为的实验方法千差万别。现在，一些研究人员在测试过程中保留了完整的肋骨保持架，还有一些研究人员在胸椎中采用了追随者负重技术。这两种方法都旨在更紧密地模拟生理状况。迄今为止，还没有研究检查肋骨笼与跟随者负荷一起对胸椎运动和僵硬的影响。这项研究的目的是量化在动态力矩下，随动载荷下肋骨对尸体胸椎运动和僵硬的机械作用。据推测，在跟随者负荷下，肋骨保持架会增加刚度并降低胸椎的运动。八只带有肋骨笼的新鲜冷冻人尸体胸椎（T1-T12）被加载了400 N的压缩随动载荷。在横向弯曲，屈曲/伸展和轴向旋转中施加了±5 N m的动态力矩，先前已经报道了肋骨保持完整的标本的运动和刚度。这项研究评估了去除肋骨保持架后标本的运动和刚度，并将数据与肋骨保持完好状态进行了比较。计算胸椎上段，中段和下段的运动范围和刚度。随着侧向弯曲，屈曲/伸展和轴向旋转中肋骨的移走，运动范围显着增加，分别为63.5％，63.0％，和58.8％（p <0.05）。中性和弹性区的屈曲/伸展度和轴向旋转增加，而中性区的硬度在轴向旋转中随着肋骨保持架的去除而降低。总的来说，肋骨笼的移除增加了活动范围，并降低了体外受压跟随者负荷下尸体胸椎的刚度。这项研究表明，在对具有一定负荷的尸体胸椎进行测试以优化临床相关性时，应包括肋骨笼。肋骨笼的去除增加了活动范围，并降低了体外受压跟随者负载下尸体胸椎的刚度。这项研究表明，在对具有一定负荷的尸体胸椎进行测试以优化临床相关性时，应包括肋骨笼。肋骨笼的去除增加了活动范围，并降低了体外受压跟随者负载下尸体胸椎的刚度。这项研究表明，在对具有一定负荷的尸体胸椎进行测试以优化临床相关性时，应包括肋骨笼。