Hedman Thomas P, Ohnmeiss Donna D, Leasure Jeremi, Raji Oluwatodimu R, Hochschuler Stephen H
Biomedical Engineering, University of Kentucky, Lexington, USA.
Research Foundation, Texas Back Institute, Plano, USA.
Cureus. 2023 Jul 15;15(7):e41918. doi: 10.7759/cureus.41918. eCollection 2023 Jul.
Objective Lumbar fusion performed through lateral approaches is becoming more common. The interbody devices are generally supported by supplemental posterior fixation implanted through a posterior approach, potentially requiring a second incision and intraoperative repositioning of the patient. A minimally invasive lateral interspinous fixation device may eliminate the need for intraoperative repositioning and avoid disruption of the supraspinous ligament. The objective of this in vitrobiomechanical study was to investigate segmental multidirectional stability and maintenance of foraminal distraction of a lateral interspinous fixation device compared to commonly used pedicle screw and facet screw posterior fixation constructs when combined with lumbar interbody cages. Methods Six human cadaver lumbar spine specimens were subjected to nondestructive quasistatic loading in the following states: (1) intact; (2) interspinous fixation device alone and (3) with lateral interbody cage; (4) lateral lumbar interbody cage with bilateral pedicle screws; (5) lateral lumbar interbody cage with unilateral pedicle screws; and (6) lateral lumbar interbody cage with facet screws. Multidirectional pure bending in 1.5 Nm increments to 7.5 Nm, and 7.5 Nm flexion-extension bending with a 700 N compressive follower load were performed separately with optoelectronic segmental motion measurement. Relative angular motions of L2-L3, L3-L4, and L4-L5 functional spinal units were evaluated, and the mean instantaneous axis of rotation in the sagittal plane was calculated for the index level. Foraminal height was assessed during combined flexion-extension and compression loading for each test construct. Results All implant configurations significantly restricted flexion-extension motion compared with intact (p < 0.05). No significant differences were found in flexion-extension when comparing the different posterior implants combined with lateral lumbar interbody cages. All posterior fixation devices provided comparable neuroforaminal distraction and maintained distraction during flexion and extension. Conclusions When combinedwith lateral lumbar interbody cages, the minimally invasive lateral interspinous fixation device effectively stabilized the spine and maintained neuroforaminal distraction comparable to pedicle screw constructs or facet screws. These results suggest the lateral interspinous fixation device may provide a favorable alternative to other posterior systems that require patient repositioning during surgery and involve a greater disruption of native tissues.
目的 通过外侧入路进行腰椎融合术正变得越来越普遍。椎间融合器通常由通过后入路植入的辅助后路固定装置支撑，这可能需要第二个切口并在术中重新安置患者体位。一种微创外侧椎弓根间固定装置可能无需术中重新安置体位，并避免棘上韧带的破坏。本体外生物力学研究的目的是，将一种外侧椎弓根间固定装置与常用的椎弓根螺钉和小关节螺钉后路固定结构相结合，并与腰椎椎间融合器联合使用时，研究其节段多向稳定性和椎间孔撑开的维持情况。方法 对6个新鲜冰冻的人体腰椎标本在以下状态下进行无损准静态加载：(1) 完整状态；(2) 单独使用椎弓根间固定装置；(3) 与外侧椎间融合器联合使用；(4) 外侧腰椎椎间融合器联合双侧椎弓根螺钉；(5) 外侧腰椎椎间融合器联合单侧椎弓根螺钉；(6) 外侧腰椎椎间融合器联合小关节螺钉。使用光电节段运动测量仪分别进行以1.5 Nm递增至7.5 Nm的多向纯弯曲，以及在700 N的压缩跟随载荷下进行7.5 Nm的屈伸弯曲。评估L2-L3、L3-L4和L4-L5功能脊柱单元的相对角运动，并计算索引节段矢状面的平均瞬时旋转轴。在每个测试结构的屈伸和压缩加载过程中评估椎间孔高度。结果 与完整状态相比，所有植入物配置均显著限制了屈伸运动（p < 0.05）。比较与外侧腰椎椎间融合器联合使用的不同后路植入物时，屈伸方面未发现显著差异。所有后路固定装置均提供了相当的神经孔撑开效果，并在屈伸过程中维持撑开。结论 当与外侧腰椎椎间融合器联合使用时，微创外侧椎弓根间固定装置能有效稳定脊柱，并维持与椎弓根螺钉结构或小关节螺钉相当的神经孔撑开效果。这些结果表明，外侧椎弓根间固定装置可能为其他需要在手术过程中重新安置患者体位且对原生组织破坏更大的后路系统提供一个良好的替代方案。
