Effects of cervical total disc replacement versus anterior cervical discectomy and fusion on biomechanics of the segments adjacent to the operation level / 中国组织工程研究

ABSTRACT

BACKGROUND: Long-term follow-up of the patients undergoing anterior cervical discectomy and fusion (ACDF) shows some incidence of degeneration at the segments adjacent to the fusion level. Cervical total disc replacement may resolve this problem. OBJECTIVE: To compare the effects of cervical total disc replacement versus ACDF on the biomechanics of the segment adjacent to the operation level. DESIGN, TIME AND SETTING: The randomized controlled trial was performed at biomechanical laboratory in Beijng Trauma and Orthopaedic Institute from August 2007 to February 2008. MATERIALS: Eighteen samples of fresh goat cervical spine; Bryan artificial cervical disk (Medtronic); CSLP-VA cervical plate (Synthes); coral bone (Beijing Yihuajian Science And Trade Co., Ltd.). METHODS: The goat spines were divided into 3 groups: control group with no specific treatment; total disc replacement group, in which C5/6 segment underwent Bryan artificial cervical disk replacement and fusion; internal fixation group, in which the C5/6 segment underwent cervical discectomy, coral bone implantation and internal fixation with CSLP-VA cervical plate. MAIN OUTCOME MEASURES: The adjacent intervertebral disk pressure (IDP) was measured in flexion, extension, rotation and lateral bending under certain loading, and the pressure changes were compared among three groups. RESULTS: At level C4/5, the IDP between total disk replacement group and the control group had no statistical significances in flexion (P 0.05) but internal fixation group was significantly higher than control group (P=0.014). There were no significant differences among the three groups in IDP in extension, rotation and lateral bending. CONCLUSION: Compared with ACDF, the total disk replacement can reduce the adjacent segment IDP and may avoid the degeneration in adjacent cervical segment.