Abstract:Cage plus plate (CP) and zero-profile (Zero-P) devices are widely used in anterior cervical discectomy and fusion (ACDF). This study aimed to compare adjacent segment biomechanical changes after ACDF when using Zero-P device and CP in different segments. First, complete C1—C7 cervical segments were constructed and validated. Meanwhile, four surgery models were developed by implanting the Zero-P device or CP into C4—C5 or C5—C6 segments based on the intact model. The segmental range of motion (ROM) and maximum value of the intradiscal pressure of the surgery models were compared with those of the intact model. The implantation of CP and Zero-P devices in C4—C5 segments decreased ROM by about 91.6% and 84.3%, respectively, and increased adjacent segment ROM by about 8.3% and 6.82%, respectively. The implantation of CP and Zero-P devices in C5—C6 segments decreased ROM by about 93.3% and 89.9%, respectively, while increasing adjacent segment ROM by about 4.9% and 4%, respectively. Furthermore, the implantation of CP and Zero-P devices increased the intradiscal pressure in the adjacent segments of C4—C5 segments by about 4.5% and 6.7%, respectively. The implantation of CP and Zero-P devices significantly increased the intradiscal pressure in the adjacent segments of C5—C6 by about 54.1% and 15.4%, respectively. In conclusion, CP and Zero-P fusion systems can significantly reduce the ROM of the fusion implant segment in ACDF while increasing the ROM and intradiscal pressure of adjacent segments. Results showed that Zero-P fusion system is the best choice for C5—C6 segmental ACDF. However, further studies are needed to select the most suitable cervical fusion system for C4—C5 segmental ACDF. Therefore, this study provides biomechanical recommendations for clinical surgery.

Key words:biomechanics, finite element analysis, adjacent segment degeneration, range of motion (ROM), intradiscal pressure

摘要：Cage-Plate融合器（CP）系统和零切迹融合器（Zero-P）系统广泛用于颈椎前路椎间盘切除和融合术中（ACDF）。本研究对比分析了不同节段ACDF植入CP或Zero-P融合器系统后相邻节段生物力学特性。首先，建立了完整C1—C7颈椎节段的模型，并对其有效性进行了验证。同时，通过在完整模型的基础上将Zero-P或CP植入C4—C5或C5—C6节段，建立了四种手术模型。将手术模型的节段活动度（ROM)和椎间盘内压最大值与完整模型进行比较。C4—C5植入CP、Zero-P使其ROM平均减少了91.6%，84.3%；临近节段ROM平均增大了8.3%，6.82%。C5—C6植入CP、Zero-P使其ROM平均减少了93.3%，89.9%；临近节段ROM平均增大了4.9%，4%。此外，C4—C5植入CP、Zero-P使临近节段椎间盘内压平均增大了4.5%，6.7%。C5—C6植入CP、Zero-P使临近节段椎间盘内压平均增大了54.1%，15.4%。总之，植入CP和Zero-P融合器系统均会显著降低ACDF中植入节段的ROM，同时增加相邻节段的ROM和椎间盘内压力。结果表明，Zero-P融合器系统是C5—C6节段ACDF的最佳选择。然而，需要进一步的研究来选择最适合C4—C5节段ACDF的颈椎融合器系统。同时，本研究为临床手术提供生物力学建议。

关键词:生物力学，有限元分析，邻近节段退变，活动度，椎间盘内压