轴向载荷对双节段颈椎人工椎间盘置换邻下位关节突关节压力的影响

背景:国内外尚未见双节段Bryan颈人工椎间盘置换后邻近节段关节突关节内压力的测量研究.目的:观察轴向载荷对双节段颈椎人工椎间盘置换和前路椎间融合内固定对邻下位节段关节突关节内压力的影响,以期为双节段人工颈椎间盘置换的临床应用提供生物力学依据.设计、时间及地点:体外对比观察,生物力学测定实验,于2006-01/02在中南大学材料科学与工程学院国家重点实验室完成.材料:取新鲜人体尸体颈椎标本11具,节段包括C_3T_1),剔除肌肉组织保留椎间盘、韧带和关节囊结构的完整.方法:取11具新鲜完整的成人下颈段标本,分别制成C_(4～5),C_(5～6)椎间盘完整、椎间盘置换、椎间融合3个模型组,在标本上施加轴向分级载荷,将微型阻电式压力传感器置入C_(5～6),C_(6～7)关节突关节内.主要观察指标:测量各组于25,50,75,100,125和150 N载荷下C_(5～6),C_(6～7)关节突关节内的压力.结果:在轴向加载下,下位节段关节突关节内的压力随着施加载荷的增大而增大.C_(4～5),C_(5～6)双节段人工椎间盘置换组与椎间盘完整组相比,下位置换节段和邻近下位节段关节突关节内的压力变化相近,差异无显著性意义(P>0.05).C_(4～5),C_(5～6)椎间融合组与人工椎间盘置换组、椎间盘完整组相比邻近下位节段关节突关节内的压力显著增高(P<0.05).结论:颈椎双节段人工椎间盘置换后置换下位节段和邻近下位节段关节突关节内压力与完整标本相近,提示颈椎双节段人工椎间盘置换能够重建颈椎生物力学性能.颈椎双节段椎间盘摘除融合内固定后邻近下位关节突关节压力增加,可能是多节段颈椎融合后邻近节段发生退行性变或退行性变加速的原因之一.

Stress distribution in zygapophyseal joint following two level artificial disc replacement under axial loading

BACKGROUND:There is no study about adjacent zygapophyseal joint stress distribution following two level artificial disc replacement (ADR) in China.OBJECTIVE:To explore cervical adjacent zygapophyseal joint stress distribution following two level ADR and anterior cervical discectomy and fusion (ACDF),so as to provide biomechanical reference for clinical application of two level ADR.DESIGN,TIME AND SETTING:In vitro contrast observation and biomechanical detection were performed at the National Key Laboratory of College of Material Science and Engineering,Central South University from January to February 2006.MATERIALS:A total of 11 fresh adult corpse cervical samples with intact cervical disc and ligament and the facet joint capsule ranged from C_3 to T_1 segment.METHODS:A total of 11 intact adult fresh-frozen multi-segmental cervical spine segments were utilized and biomechanically evaluated under the following C_(4～5),C_(5～6) cervical disc conditions:intact spine (intact group),Bryan disc prosthesis implantation (ACDR group) and intervertebral fusion (ACDF group).The testing was performed under axial load (25 N-150 N) on each group.The stress changes of the caudad (C_(5～6),C_(6～7)) zygapophyseal joint was tested.MAIN OUTCOME MEASURES:The pressure of the caudad (C_(5～6),C_(6～7)) zygapophyseal joint.RESULTS:Under axial loading,stress of the caudad (C_(5～6),C_(6～7)) zygapophyseal joint increased with the load and showed no difference between the intact group and ACDR group (P>0.05).Under axial loading,the ACDF group resulted in significant increase of the stress of the caudad (C_(5～6),C_(6～7)) zygapophyseal joint compared with intact group and ACDR group (P<0.05).CONCLUSION:Two level artificial cervical disc replacement can maintain stress in the caudad (C_(5～6),C_(6～7)) zygapophyseal joint,thus reconstruct biomechanical property of cervical spine.Two level cervical discectomy and fusion can increase stress in the caudad (C_(5～6),C_(6～7)) zygapophyseal joint,which may be one of the causes for adjacent cervical spondyiosis postoperatively.