Kaigle A, Ekström L, Holm S, Rostedt M, Hansson T
Department of Orthopaedics, Göteborg University, Sahlgrenska University Hospital, Sweden.
J Spinal Disord. 1998 Feb;11(1):65-70.
The dynamic axial stiffness of the L2-3 motion segment subjected to vibratory loading under intact and injured states of the intervertebral disc was studied using an in vivo porcine model. Three groups of animals with the following states of the intervertebral discs were studied: intact disc, acutely injured disc, and degenerated disc. A miniaturized servo-hydraulic exciter was used to sinusoidally vibrate the motion segment from 0.05 to 25 Hz under a compressive load with a peak value of either 100 or 200 N. The dynamic axial stiffness of the intervertebral disc was calculated at 1-Hz intervals over the frequency range. The results showed that the dynamic axial stiffness was frequency dependent. A positive relationship was found between an increase in mean dynamic stiffness and load magnitude. An increase in mean stiffness with successive exposures at the same load magnitude was observed, despite the allowance of a recovery period between loading. The greatest difference was noted between the first and second load sets. No significant change in stiffness was found due to an acute disc injury, whereas a significant increase in mean stiffness was found for the degenerated disc group as compared with the intact group. The form of the frequency response curve, however, remained relatively unaltered regardless of the degenerated state of the disc. With heavier loads, repeated loading, and/or disc degeneration, the stiffness of the intervertebral disc increases. An increase in stiffness can mean a reduction in the amount of allowable motion within the motion segment or a potentially harmful increase in force to obtain the desired motion. This may locally result in greater stresses due to an altered ability of the disc to distribute loads.
使用体内猪模型研究了在椎间盘完整和损伤状态下，L2 - 3运动节段在振动载荷作用下的动态轴向刚度。研究了三组具有以下椎间盘状态的动物：完整椎间盘、急性损伤椎间盘和退变椎间盘。使用小型伺服液压激励器在峰值为100或200 N的压缩载荷下，以0.05至25 Hz的频率对运动节段进行正弦振动。在整个频率范围内，每隔1 Hz计算椎间盘的动态轴向刚度。结果表明，动态轴向刚度与频率有关。发现平均动态刚度的增加与载荷大小呈正相关。尽管在加载之间留出了恢复期，但在相同载荷大小下连续暴露时，仍观察到平均刚度有所增加。在第一组和第二组载荷之间观察到最大差异。急性椎间盘损伤未导致刚度有显著变化，而与完整组相比，退变椎间盘组的平均刚度显著增加。然而，无论椎间盘的退变状态如何，频率响应曲线的形式相对保持不变。随着载荷增加、重复加载和/或椎间盘退变，椎间盘的刚度会增加。刚度增加可能意味着运动节段内允许的运动量减少，或者为获得所需运动而产生的力潜在有害增加。由于椎间盘分散载荷的能力改变，这可能会局部导致更大的应力。
