目的  分析单侧椎弓根钉棒固定对单节段腰椎的生物力学稳定性及其对邻近节段活动度的影响。 方法  新鲜成人尸体腰椎标本6具，测定L4~5不稳固定节段及其上下邻近节段屈伸、左右侧弯、左右旋转6个方向ROM，按4组顺序依次测试：A组（完整组）；B组（模拟L4~5不稳组）；C组（单侧椎弓根钉棒固定＋椎间单枚cage）；D组（双侧椎弓根钉棒固定＋椎间单枚cage）。 结果  L4~5节段除左侧弯外，C组与D组相比各运动方向ROM差异无统计学意义(P>0.05)；L3~4、L5~S1节段除左、右侧弯外，C组与D组相比各运动方向ROM差异无统计学意义(P>0.05)。 结论  单侧椎弓根钉棒固定对单节段腰椎在大部分运动方向上具有与双侧固定相似的即刻稳定性，邻近节段侧弯活动度较双侧固定后更少。

        Objective   To evaluate the biomechanical efficiency of single-level unilateral pedicle screw fixation on the instrumented lumbar segment and adjacent segments. Methods  Six fresh-frozen human cadaveric lumbar spines of simulated instability at L4~5 were conducted to a serial of biomechanical tests including flexion, extension, lateral bending and axial rotation. The range of motion in each specimen was tested in sequence according to such four groups: intact in group A, L4-5 segmental instability in group B, unilateral pedicle screw fixation combined with single cage in group C and bilateral pedicle screw fixation combined with single cage in group D.  Results  Apart from the ROM of left lateral bending, there was no significant difference of ROM at L4-5 between group C and group D (P>0.05). Apart from the ROM of left and right lateral bending, there was no significant difference of ROM at L3-4 and L5-S1 between group C and group D (P>0.05). Conclusions  All tested single-level unilateral pedicle screw fixation can achieve similar initial biomechanical stability and cause less lateral bending motion at adjacent segments in comparison with bilateral pedicle screw fixation.