人工颈椎复合关节系统假体的研制及生物力学评价

Design and preliminary biomechanical analysis of artificial cervical joint complex

目的探讨自行研制的人工颈椎复合关节系统假体的生物力学稳定性、保留节段活动度及其对邻近椎间活动度的影响。方法人工颈椎复合关节系统假体由两端的关节头假体和中间的人工椎体假体三部分组成，通过杵臼关节模拟正常椎体间多轴运动模式，由钴铬钼合金及聚乙烯塑料材料制成。将经甲醛处理后的21具人体下颈椎标本，通过对颈椎进行三维运动分析，比较假体植入、钉板固定和正常状态下手术节段稳定性和活动度及邻近椎间活动度。结果生物力学测试表明，假体植入组下颈椎整体稳定性与正常对照组在前屈、后伸、左右侧弯、左右扭转方面比较差异无统计学意义。节段活动度与正常对照组相比，除在后伸方面有所增大外，在前屈和左右侧弯方面差异无统计学意义，而在前屈、后伸、左右侧弯方面均明显大于钉板固定组。假体植入组邻近上下位椎间活动度与正常颈椎组在前屈、后伸及左右侧弯方面比较差异无统计学意义。结论颈椎椎体次全切除后，应用人工颈椎复合关节假体进行重建不仅能够即刻获得稳定，而且可有效保留节段活动度，同时不会引起邻近节段椎间活动度异常增大。

Objective To design a new prosthesis called as Artificial Cervical Joint Complex（ACJC） used for non-fusion reconstruction following cervical subtotal corpectomy, to evaluate its biomechanical stability, reservation of segment motion and influence on adjacent intervertebral motions. Methods The pros- thesis was composed of the upper and lower joint-head prosthesis and the middle artificial vertebrae made of Co-Cr-Mo alloy and polyethylene with a ball-and-socket joint design which could simulate intervertebral multiaxial motions in normal conditions. Biomechanical tests of intact spine, ACJC prosthesis and Orion locking plate system were performed in cervical spine specimens marinated in formalin from 21 healthy cadavers to compare all three groups in stability and ROM of the surgical segment and ROM of adjacent invertebral spaces. Results Biomechanical testing revealed that, as for stability of the whole lower cervical spine, there was no significant difference between the intact spine control group and the prosthesis-implantation group in flexion, extension, lateral bending and torsion. As for segment motions, prosthesis-implantation group was no statistically different from the intact spine control group in flexion, lateral bending and torsion except statistically larger in extension, but statistically larger than （P〈 0.05） the plate group in flexion, ex- tension and lateral bending. Adjacent intervertebral ROM of the prosthesis group was not statistically different from the intact spine control group. Conclusion After subtotal corpectomy, reconstruction with ACJC prosthesis can not only obtain stability promptly but also reserve segment motions effectively, and without abnormally highly intervertebral mobility at the adjacent levels.