Guyer Richard D, Voronov Leonard I, Havey Robert M, Khayatzadeh Saeed, Carandang Gerard, Blank Kenneth R, Werner Stephanie, Rubin Josh, Padovani Nick, Patwardhan Avinash G
Texas Back Institute Plano Texas.
Loyola University Chicago Maywood Illinois.
JOR Spine. 2018 Dec 17;1(4):e1040. doi: 10.1002/jsp2.1040. eCollection 2018 Dec.
Anterior cervical discectomy and fusion has been associated with the development of adjacent segment degeneration (ASD), with clinical incidence of approximately 3% per year. Cervical total disc arthroplasty (TDA) has been proposed as an alternative to prevent ASD.
TDA in optimal placement using an elastic-core cervical disc (RHINE, K2M Inc., Leesburg, Virginia) will replicate natural kinematics and will improve with optimal vs anterior placement.
Seven C3-T1 cervical cadaver spines were tested intact first, then after one-level TDA at C5-C6 anterior placement, after TDA at C5-C6 optimal placement, after two-level TDA at C5-C6 and C6-C7 optimal placement, and finally after two-level TDA at C5-C6 lateral placement and C6-C7 optimal placement. The specimens were subjected to: Flexion-Extension moments (+1.5 Nm) with compressive preloads of 0 N and 150 N, lateral bending (LB) and axial rotation (AR) (+1.5 Nm) without preload.
optimal placement resulted in a non-significant increase in flexion-extension ROM compared to intact under 0 N and 150 N preload ( > 0.05). Both LB and AR ROM decreased with arthroplasty ( < 0.01). ptimal placement of resulted in an increase in flexion-extension ROM with preload compared to intact ( < 0.05) while LB and AR ROM decreased with arthroplasty ( < 0.01).
This six degree of freedom elastic-core disc arthroplasty effectively restored flexion-extension motion to intact levels. In LB the TDA maintained 42% ROM at C5-C6 and 60% at C6-C7. In AR 57% of the ROM was maintained at C5-C6 and 70% at C6-C7. These findings are supported by literature which shows cervical TDA results in restoration of approximately 50% ROM in LB and AR, which is a multifactorial phenomenon encompassing TDA design parameters and anatomical constraints. Anterior placement of this viscoelastic TDA device shows motion restoration similar to optimal placement suggesting its design may be less sensitive to suboptimal placement.
颈椎前路椎间盘切除融合术与相邻节段退变（ASD）的发生有关，临床发病率约为每年3%。颈椎全椎间盘置换术（TDA）已被提议作为预防ASD的一种替代方法。
使用弹性核颈椎间盘（RHINE，K2M公司，弗吉尼亚州利斯堡）进行最佳位置的TDA将复制自然运动学，并且与前路放置相比，最佳放置会有更好的效果。
首先对7个C3-T1颈椎尸体脊柱进行完整测试，然后在C5-C6前路放置单节段TDA后、C5-C6最佳位置放置TDA后、C5-C6和C6-C7最佳位置放置双节段TDA后，以及最后在C5-C6外侧放置和C6-C7最佳位置放置双节段TDA后进行测试。对标本施加：在0 N和150 N压缩预载荷下的屈伸力矩（+1.5 Nm），以及无预载荷的侧弯（LB）和轴向旋转（AR）（+1.5 Nm）。
与在0 N和150 N预载荷下的完整状态相比，最佳位置放置导致屈伸活动度（ROM）无显著增加（P>0.05）。随着人工椎间盘置换术，侧弯和轴向旋转的ROM均降低（P<0.01）。与完整状态相比，在预载荷下，该弹性核的最佳位置放置导致屈伸ROM增加（P<0.05），而侧弯和轴向旋转的ROM随着人工椎间盘置换术而降低（P<0.01）。
这种六自由度弹性核椎间盘置换术有效地将屈伸运动恢复到完整水平。在侧弯方面，TDA在C5-C6维持了42%的ROM，在C6-C7维持了60%的ROM。在轴向旋转方面，C5-C6维持了57%的ROM，C6-C7维持了70%的ROM。这些发现得到了文献的支持，文献表明颈椎TDA在侧弯和轴向旋转中可恢复约50%的ROM，这是一个多因素现象，包括TDA设计参数和解剖学限制。这种粘弹性TDA装置的前路放置显示出与最佳位置放置相似的运动恢复，表明其设计对次优放置可能不太敏感。
