Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA.
Spine (Phila Pa 1976). 2011 Apr 20;36(9):721-30. doi: 10.1097/BRS.0b013e3181df10fc.
Prospective, randomized trial.
To assess the in vivo kinematics of the cervical spine after cervical fusion and arthroplasty.
Compared with spinal fusion, disc replacement may impede the development of adjacent segment disease. To achieve this goal, any arthroplasty device should achieve desired spinal alignment while maintaining physiologic spinal motion at both the operated and surrounding motion segments.
As part of a multicenter, prospective, randomized Food and Drug Administration IDE clinical evaluation of the porous coated motion artificial cervical disc, patients underwent either a single-level total disc replacement (TDR; 272 patients) or anterior cervical discectomy and fusion (ACDF; 182 patients) for treatment of cervical radiculopathy or myelopathy. Neutral, flexion, and extension radiographs of the cervical spine obtained before surgery, and at 3, 6, and 12 months after surgery were assessed. Quantitative assessments and comparisons of motion patterns were produced using validated computer-assisted methods. Kinematic parameters, including segmental rotation, translation, center of rotation (COR), disc height, and disc angle were calculated.
Cervical TDR preserved angular motion at the operated level, although the range was reduced from 8.0° before surgery to 6.2° at 12 months after surgery (P < 0.001). Significantly after TDR, adjacent-level angular motion was unchanged. In patients treated with fusion, angular motion at the superior adjacent level increased from 9.6° before surgery to 11.0° (P = 0.003) at 12 months, with a trend toward increased postoperative translation (P = 0.07). For the TDR group, the horizontal COR averaged 0.8 mm posterior to the disc center before surgery and 0.2 mm anterior to the center at 12 months after TDR (P < 0.001), and the vertical COR averaged 2.5 mm below the endplate before surgery and 4.0 mm below at 12 months (P = 0.001). COR at the adjacent levels was unaltered by fusion or TDR. Lordotic alignment and disc height at the index level increased after intervention in both groups.
TDR with the porous coated motion implant is able to restore and maintain lordotic alignment and disc height and maintain angular motion while allowing for similar translation to that seen before surgery. In contrast, after ACDF, the superior adjacent level developed increased angular motion compared with preoperative range of motion. This study provides in vivo data regarding the functioning of TDR and ACDF and their impact on adjacent-level kinematics.
前瞻性、随机试验。
评估颈椎融合和关节置换术后颈椎的体内运动学。
与脊柱融合相比，椎间盘置换可能会阻碍相邻节段疾病的发展。为了实现这一目标，任何关节置换装置都应该在保持手术和周围运动节段的生理运动的同时，达到理想的脊柱排列。
作为多孔涂层运动人工颈椎椎间盘多中心、前瞻性、随机食品和药物管理局 IDE 临床评估的一部分，患者接受了单节段全椎间盘置换术（TDR；272 例）或前路颈椎间盘切除术和融合术（ACDF；182 例）治疗颈椎神经根病或颈椎病。在手术前、手术后 3、6 和 12 个月，对颈椎的中立位、前屈位和伸展位进行放射摄影检查。使用经过验证的计算机辅助方法进行运动模式的定量评估和比较。计算节段旋转、平移、旋转中心（COR）、椎间盘高度和椎间盘角度等运动学参数。
颈椎 TDR 保留了手术水平的角运动，尽管范围从术前的 8.0°减少到术后 12 个月的 6.2°（P <0.001）。TDR 后，相邻节段的角运动无明显变化。在接受融合治疗的患者中，上相邻节段的角运动从术前的 9.6°增加到术后 12 个月的 11.0°（P = 0.003），术后有增加翻译的趋势（P = 0.07）。对于 TDR 组，术前 COR 平均位于椎间盘中心后 0.8 毫米，术后 12 个月时位于椎间盘中心前 0.2 毫米（P <0.001），垂直 COR 术前平均位于终板下 2.5 毫米，术后 12 个月时位于终板下 4.0 毫米（P = 0.001）。融合或 TDR 对相邻节段的 COR 没有影响。两组干预后，指数水平的前凸排列和椎间盘高度均增加。
多孔涂层运动植入物的 TDR 能够恢复和维持前凸排列和椎间盘高度，并保持角运动，同时允许与术前相似的平移。相比之下，ACDF 后，与术前运动范围相比，上相邻节段的角运动增加。本研究提供了关于 TDR 和 ACDF 功能及其对相邻节段运动学影响的体内数据。
