Surgical treatment for spinal disorders, such as cervical disc herniation and spondylosis, includes the removal of the intervertebral disc and replacement of biological or artificial materials. In the former case, bone graft is used to fill the space, and this conventional procedure is termed anterior cervical discectomy and fusion (ACDF). The latter surgery is termed as artificial disc replacement ADR) or cervical disc arthroplasty (CDA). Surgeries are most commonly performed at one or two levels. The present study was designed to determine the external (range of motion, ROM) and internal (anterior and posterior load sharing) responses of the spines with one-level and two-level surgeries in both models (ACDF and CDA) using a previously validated finite element model (FEM) of the subaxial cervical spinal column. The FEM simulated the vertebra (cancellous core and cortical shell of the body, posterior elements – laminae, pedicles and spinous processes), discs (anulus fibers, ground substance, and nucleus pulposus), anterior and posterior ligaments of the disc and facet joints, and interspinous and supraspinous ligaments. Appropriate material properties were assigned to the spinal components. The United States Food Drug Administration-approved Mobi-C was used for the CDA option. The FEM was exercised under pure flexion and extension moment loading of 2 Nm in the intact state. The overall ROM of the column was obtained. The hybrid loading protocol applied moments that matched the ROM in the intact spine for both one-level (C5–C6) and two-level (C5–C7) ACDF and CDA surgeries. ROM at the level(s) of surgery, termed the index level was obtained. These data along with anterior column load (ACL) and posterior column load (PCL) sharing were obtained for all surgical options at superior and inferior segments (termed adjacent segment outputs). Results for both one-level and two-level surgeries showed that ACDFs decreases ROM at the index level, while CDAs increase motions compared to the intact normal spine. The ROM, ACL, and PCL increased at both adjacent levels for the ACDF while CDA showed a decrease. Although two-level surgeries resulted in increased these biomechanical variables, greater changes to adjacent segment biomechanics in ACDF may accelerate adjacent segment disease. Decreased ROM and lower load sharing in CDAs may limit adjacent segment effects such as accelerated degeneration. Their increased posterior load sharing, however, may need additional attention for patients with suspected facet joint disease.

脊柱疾病（例如颈椎间盘突出症和脊椎病）的外科手术治疗包括去除椎间盘并更换生物或人工材料。在前一种情况下，使用骨移植物填充该空间，这种常规手术称为前颈椎间盘摘除术和融合术（ACDF）。后一种手术称为人工椎间盘置换术（ADR）或颈椎间盘置换术（CDA）。外科手术最通常在一两个级别上进行。本研究旨在使用先前验证的方法确定两种模型（ACDF和CDA）中采用一级和二级手术的脊柱的外部（运动范围，ROM）和内部（前部和后部负荷分担）响应颈椎下轴脊柱的有限元模型（FEM）。FEM模拟了椎骨（身体的松质核心和皮质外壳，后部元素-椎板，椎弓根和棘突），椎间盘（无纤维，基底物质和髓核），椎间盘和小关节的前韧带和后韧带，棘突间和棘突上韧带。将适当的材料属性分配给脊柱组件。CDA选项使用了美国食品药品管理局批准的Mobi-C。在完整状态下，在2 Nm的纯屈曲和伸展力矩载荷下进行有限元分析。获得该柱的总ROM。混合加载协议在一级（C5–C6）和二级（C5–C7）ACDF和CDA手术中应用与完整脊柱中的ROM匹配的力矩。获得了手术水平的ROM，称为索引水平。这些数据连同前柱负荷（ACL）和后柱负荷（PCL）共享是针对上，下节段（称为相邻节段输出）的所有手术选择获得的。一级和二级手术的结果均显示，与完整的正常脊柱相比，ACDFs在指数级减少ROM，而CDA则增加运动。ACDF的ROM，ACL和PCL在两个相邻级别上都增加了，而CDA却减少了。尽管二级手术导致这些生物力学变量的增加，但是ACDF中相邻节段生物力学的更大变化可能会加速相邻节段疾病。ROM的减少和CDA中较低的负载分担可能会限制相邻段的影响，例如加速退化。但是，它们增加了后部负荷分担，