Neutral zone (NZ) is an important biomechanical parameter when evaluating spinal instability following destabilizing and restabilizing events, with particular relevance for implant efficacy testing. It remains unclear what NZ calculation methods are most sensitive at capturing NZ changes across treatment conditions and a direct comparison is needed. The purpose of this study was to determine the most sensitive method at quantifying instability in human spines. Six cadaveric lumbar motion segments were subjected to a repeated measures implant testing schema of four sequential conditions: (1) Intact, (2) injury by herniation, (3) device implantation, (4) long-term cyclic fatigue loading. NZ was expected to increase after destabilization (steps 2 & 4) and decrease after restabilization (step 3). NZ methods compared in this study were: trilinear (TL), double sigmoid (DS), zero load (ZL), stiffness threshold (ST), and extrapolated elastic zone (EEZ). TL, ZL, and EEZ identified statistically significant NZ differences after each condition in flexion/extension and lateral bending. The ZL method also captured differences in axial rotation. All methods identified expected NZ changes after destabilization and restabilization, except DS in axial rotation. The TL, ZL, and EEZ methods were the most sensitive methods with this human cadaveric dataset. Future investigations comparing methods with additional datasets will clarify outcome generalizability and determine what curve profiles are most suitable for DS and ST methods. Understanding the applicability of NZ methods can enhance rigor and reliability of spinal instability measurements when quantifying the efficacy of novel implants and permits insight into clinically relevant biomechanical changes.

在评估不稳定和再稳定事件后的脊柱不稳定性时，中性区 (NZ) 是一个重要的生物力学参数，与植入物功效测试特别相关。目前尚不清楚哪种 NZ 计算方法在捕获处理条件下的 NZ 变化时最敏感，需要进行直接比较。本研究的目的是确定量化人体脊柱不稳定性的最灵敏方法。对六个尸体腰椎运动节段进行了四种连续条件的重复测量植入物测试方案：（1）完整，（2）疝出损伤，（3）装置植入，（4）长期循环疲劳负荷。预计新西兰将在不稳定后增加（步骤 2 和 4），并在重新稳定后减少（步骤 3）。本研究中比较的 NZ 方法是：三线性 (TL)、双 sigmoid (DS)、零负载 (ZL)、刚度阈值 (ST) 和外推弹性区 (EEZ)。TL、ZL 和 EEZ 在屈曲/伸展和横向弯曲的每种情况下确定了统计学上显着的 NZ 差异。ZL 方法还捕获了轴向旋转的差异。除轴向旋转中的 DS 外，所有方法都确定了去稳定和再稳定后预期的 NZ 变化。TL、ZL 和 EEZ 方法是此人类尸体数据集最敏感的方法。将方法与其他数据集进行比较的未来调查将阐明结果的普遍性，并确定哪些曲线配置文件最适合 DS 和 ST 方法。