Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois;
J Neurosurg Spine. 2014 May;20(5):485-91. doi: 10.3171/2014.1.SPINE13837. Epub 2014 Feb 21.
OBJECT The clinical success rates of anterior cervical discectomy and fusion (ACDF) procedures are substantially reduced as more cervical levels are included in the fusion procedure. One method that has been proposed as an adjunctive technique for multilevel ACDF is the placement of screws across the facet joints ("transfacet screws"). However, the biomechanical stability imparted by transfacet screw placement (either unilaterally or bilaterally) has not been reported. Therefore, the purpose of this study was to determine the acute stability conferred by implementation of unilateral and bilateral transfacet screws to an ACDF construct. METHODS Eight C2-T1 fresh-frozen human cadaveric spines (3 female and 5 male; mean age 50 years) were tested. Three different instrumentation variants were performed on cadaveric cervical spines across C4-7: 1) ACDF with an intervertebral spacer and standard plate/screw instrumentation; 2) ACDF with an intervertebral spacer and standard plate/screw instrumentation with unilateral facet screw placement; and 3) ACDF with an intervertebral spacer and standard plate/screw instrumentation with bilateral facet screw placement. Kinetic ranges of motion in flexion-extension, lateral bending, and axial rotation at 1.5 Nm were captured after each of these procedures and were statistically analyzed for significance. RESULTS All 3 fixation scenarios produced statistically significant reductions (p < 0.05) in all 3 bending planes compared with the intact condition. The addition of a unilateral facet screw to the ACDF construct produced significant reductions at the C4-5 and C6-7 levels in lateral bending and axial rotation but not in flexion-extension motion. Bilateral facet screw fixation did not produce any statistically significant decreases in flexion-extension motion compared with unilateral facet screw fixation. However, in lateral bending, significant reductions at the C4-5 and C5-6 levels were observed with the addition of a second facet screw. The untreated, adjacent levels (C2-3, C3-4, and C7-1) did not demonstrate significant differences in range of motion. CONCLUSIONS The data demonstrated that adjunctive unilateral facet screw fixation to an ACDF construct provides significant gains in stability and should be considered a potential option for increasing the likelihood for obtaining a successful arthrodesis for multilevel ACDF procedures.
随着融合手术中包含的颈椎节段增多，前路颈椎间盘切除融合术（ACDF）的临床成功率显著降低。作为多节段 ACDF 的辅助技术之一，已提出在关节突关节间放置螺钉（“跨关节突螺钉”）的方法。然而，跨关节突螺钉放置（单侧或双侧）所带来的生物力学稳定性尚未报道。因此，本研究旨在确定单侧和双侧跨关节突螺钉置入对 ACDF 结构的急性稳定性的影响。
对 8 具 C2-T1 新鲜冷冻的人体尸体脊柱（3 名女性和 5 名男性；平均年龄 50 岁）进行了测试。在 C4-7 处对尸体颈椎进行了三种不同的器械处理：1）ACDF 融合术伴椎间间隔器和标准板/螺钉器械；2）ACDF 融合术伴椎间间隔器和标准板/螺钉器械伴单侧关节突螺钉置入；3）ACDF 融合术伴椎间间隔器和标准板/螺钉器械伴双侧关节突螺钉置入。在完成这些手术的每个阶段后，以 1.5Nm 的扭矩测量屈伸、侧屈和轴向旋转的运动范围，并对其进行统计学分析。
与完整状态相比，所有 3 种固定方案在所有 3 个弯曲平面都产生了统计学上显著的减少（p < 0.05）。在 ACDF 结构中增加单侧关节突螺钉固定，在侧屈和轴向旋转时，在 C4-5 和 C6-7 水平显著减少，但在屈伸运动时没有显著减少。与单侧关节突螺钉固定相比，双侧关节突螺钉固定在屈伸运动时没有产生任何统计学上的显著减少。然而，在侧屈时，在增加第二枚关节突螺钉后，在 C4-5 和 C5-6 水平观察到显著减少。未治疗的相邻节段（C2-3、C3-4 和 C7-1）在运动范围上没有显著差异。
数据表明，ACDF 结构中附加的单侧关节突螺钉固定提供了显著的稳定性增益，应被视为增加多节段 ACDF 手术获得成功融合的潜在选择。
