目的　通过生物力学分析经颈椎双节段融合术后下相邻节段的运动补偿特点。　方法　采用新鲜人体颈椎离体标本试验，以无损方式模拟理想状态下的颈椎 C _3~5、C _4~6、C _5~7 三种双节段融合手术，从前屈运动、后伸运动、左右侧弯运动四种运动角度研究融合手术对相邻下位节段的运动影响。　结果　三种模式的双节段融合手术对下位相邻节段的运动具有显著影响（P<0.05）或较为显著的影响（P>0.05）。大多数情况下下相邻节段对融合节段的运动补偿均超过 20%。　结论　颈椎双节段融合术后，下位相邻节段运动普遍受到影响，融合术后邻近节段代偿性的活动度增加是导致邻近节段退变的可能原因。

Objective　To explore the motion compensation features of the lower adjacent segments after the procedure of double cervical segment fusion through biomechanic test.　Methods　Fresh specimens of human cervical spine were used in this study. Double segment fusion surgery of cervical 3-5, 4-6 or 5-7 vertebrae were simulated under the ideal non-destructive state. The effects of fusion procedure on the motion of the lower segments were analyzed under the movement conditions of flexion, extension and lateral bend. 　Results　Every kind of fusion method would effect on the motion range of the lower adjacent vertebrae at the different degree, with about 20% motion compensation between the fused and adjacent segments.　Conclusions　The motion of the lower segments will be disturbed after the double cervical segments fusion, which will increase the incorrect compensation and cause the degeneration of adjacent segment after the fusion.