Department of Orthopedic Surgery, Suite 4D-4, UHC Detroit Receiving Hospital, Detroit, MI 42801, USA.
Spine J. 2011 Sep;11(9):863-9. doi: 10.1016/j.spinee.2011.06.015. Epub 2011 Jul 29.
Spinal fusion is a commonly performed surgical procedure. It is used to treat a variety of spinal pathologies, including degenerative disease, trauma, spondylolisthesis, and deformities. A mechanically stable spine provides an ideal environment for the formation of a fusion mass. Instrumented spinal fusion allows early ambulation with minimal need for a postoperative external immobilizer. Several biomechanical and clinical studies have evaluated the stability offered by different posterior instrumentation techniques and the effects of reduced instrumentation.
The aim of the study was to compare the biomechanics of a novel pedicle and translaminar facet screw (TLFS) construct. Also, in this study, comparisons were made with the more common pedicle screw/TLFS constructs for posterior fixation.
Human cadaveric lumbar spines were tested in an in vitro flexibility experiment to investigate the biomechanical stability provided by a novel pedicle and TLFS construct after transforaminal lumbar interbody fusion (TLIF).
Seven fresh human lumbar spines (L2-L5) were tested by applying pure moments of ±8 Nm. After intact specimen testing, a left-sided TLIF with a radiolucent interbody spacer was performed at L3-L4. Each specimen was then tested for the following constructs: bilateral pedicle screws (BPS) and rods at L3-L4; unilateral pedicle screws (UPS) and rods at L3-L4; UPS and rods and TLFS at L3-L4 (UPS+TLFS); and unilateral single pedicle screw and TLFS and rod at L3-L4 (V construct). The L3-L4 range of motion (ROM) and stiffness for each construct were obtained by applying pure moments in flexion, extension, lateral bending, and axial rotation.
All instrumented constructs significantly reduced ROM in flexion-extension and lateral bending compared with the intact specimen. In axial rotation, only BPS constructs significantly reduced ROM compared with intact specimen. The V construct was able to achieve more reduction in ROM compared with UPS construct and was comparable to UPS+TLFS construct. Unilateral pedicle screws construct was the least stable in all loading modes and was significantly different than BPS construct in lateral bending.
The V construct exhibited enhanced stability compared with UPS construct in all loading modes. It provides bilateral fixation and preserves the anatomic integrity of the superior facet joint. The novel construct may offer advantages of less invasiveness, significant reduction in operation time, duration of hospitalization, and costs of implants, which would require further clinical evaluation.
脊柱融合是一种常见的手术。它用于治疗多种脊柱疾病，包括退行性疾病、创伤、脊椎滑脱和畸形。机械稳定的脊柱为融合质量的形成提供了理想的环境。器械性脊柱融合允许术后早期活动，对外固定器的需求最小。几项生物力学和临床研究已经评估了不同后路器械技术提供的稳定性以及减少器械的影响。
本研究的目的是比较新型椎弓根和经椎板关节突螺钉（TLFS）结构的生物力学。此外，还与更常见的椎弓根螺钉/TLFS 结构进行了比较，用于后路固定。
在体外柔韧性试验中，对人尸体腰椎进行测试，以研究经椎间孔腰椎体间融合（TLIF）后路固定后新型椎弓根和 TLFS 结构提供的生物力学稳定性。
对 7 个人体腰椎（L2-L5）进行了测试，施加了±8Nm 的纯力矩。在完整标本测试后，在 L3-L4 进行左侧 TLIF 并使用透明椎间融合器。然后，对每个标本进行以下结构的测试：双侧椎弓根螺钉（BPS）和 L3-L4 棒；单侧椎弓根螺钉（UPS）和 L3-L4 棒；L3-L4 的 UPS 和棒和 TLFS（UPS+TLFS）；以及单侧单椎弓根螺钉和 TLFS 和 L3-L4 棒（V 结构）。通过在屈伸、侧屈和轴向旋转中施加纯力矩，获得每个结构的 L3-L4 活动范围（ROM）和刚度。
所有器械化结构在屈伸和侧屈方面均显著降低了 ROM，与完整标本相比。在轴向旋转中，只有 BPS 结构与完整标本相比显著降低了 ROM。与 UPS 结构相比，V 结构能够实现更大的 ROM 减少，与 UPS+TLFS 结构相当。单侧椎弓根螺钉结构在所有加载模式下均最不稳定，在侧屈方面与 BPS 结构有显著差异。
V 结构在所有加载模式下与 UPS 结构相比表现出增强的稳定性。它提供双侧固定，并保留上关节突关节的解剖完整性。新型结构可能具有微创、显著减少手术时间、住院时间和植入物成本的优势，这需要进一步的临床评估。
