颈后路脊髓前外侧减压术对颈椎稳定性影响的生物力学评价

Biomechanical evaluation on stability of cervical spine following anteri-or-lateral decompression of spinal cord through posterior cervical approach

采用8具新鲜颈段脊柱标本,定量地研究了正常颈椎和脊髓前外侧减压术中下部颈椎(C_3～C_7)各节段的前屈、后伸、左/右侧弯、左/右轴向旋转运动。所施加的最大纯力矩为2.34N·m,用摄影记录各节段颈椎的运动,计算得到中性区 NZ(Neutral Zone)和运动范围 ROM(Range of motion)。将正常颈椎作为自身对照,然后摹拟临床手术分别切除 C_5～C_6(右)→C_4～C_5→(右)C_(5～6)→(左)→C_(4～5)(左)的内侧50%小关节及其相连的部分椎板。结果表明:同一节段单侧手术对颈椎的稳定性无显著影响,同一节段双侧手术则该节段的稳定性遭到破坏,提示临床需附加植骨融合。

The movements of the middle/lower cervical spine(C_3～C_7)both in normal structure and thepostoperative state were measured in flexion/extension,right/left lateral bending and right/leftaxial rotation.Eight fresh cervical spine specimens of young cadavers were used.Pure momentsof a maximum of 2.34N.m were loaded incrementally.Parameters of neutral zone(NZ)andrange of motion(ROM)were calculated.Intact specimens were taken as normal self-controlgroup,then the clinical operation was performed.The part of 50% inter-facet and connectingvertebral lamina were resected on right C_5～C_6→right C_4～C_5→left C_5～C_6→left C_4～C_5.It showsthat unilaterally opening one or two intervertebral foramen have less influence on spinal stability,but if two irrtervertebral foramens are opened bilateral at the same level will greatly decrease thestability of the cervical spine.So in that case an interspinal process fusion must be pberformed.