Tsitsopoulos Parmenion P, Serhan Hassan, Voronov Leonard I, Carandang Gerard, Havey Robert M, Ghanayem Alexander J, Patwardhan Avinash G
Musculoskeletal Biomechanics Laboratory, Department of Veterans Affairs, Edward Hines Jr. VA Hospital, Hines, IL, USA.
J Spinal Disord Tech. 2012 Dec;25(8):E240-4. doi: 10.1097/BSD.0b013e31824c820c.
A biomechanical cadaveric study of lumbar spine segments.
To compare the immediate stability provided by parallel-shaped and anatomically shaped carbon fiber interbody fusion I/F cages in posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) constructs with posterior pedicle screw instrumentation.
Few biomechanical data are available on the anatomically shaped cages in PLIF and TLIF constructs.
Twenty human lumbar segments were tested in flexion-extension (FE) (8 N m flexion, 6 N m extension), lateral bending (LB) (± 6 N m), and torsional loading (± 5 N m). Each segment was tested in the intact state and after insertion of interbody cages in one of 3 constructs: PLIF with 2 parallel-shaped or anatomically shaped cages and TLIF with 1 anatomically shaped cage. All cages received supplementary pedicle screw fixation. The range-of-motion (ROM) values after cage insertion and posterior fixation were compared with the intact specimen values using analysis of variance and multiple comparisons with Bonferroni correction.
All constructs significantly reduced segmental motion relative to intact (P < 0.001). The motion reductions in FE, LB, and axial rotation were 85 ± 15%, 83 ± 18%, and 67 ± 6.8% for the PLIF construct using parallel cages, 79 ± 5.5%, 87 ± 10%, and 66 ± 20% for PLIF using anatomically shaped cages, and 90 ± 6.8%, 87 ± 12%, and 77 ± 22% for TLIF with an anatomically shaped cage. In FE and LB, the reductions in the ROM caused between the 3 constructs were equivalent (P > 0.05). In axial rotation, the TLIF cage provided significantly greater limitation in the ROM compared with the parallel-shaped PLIF cage (P = 0.01).
The parallel-shaped and anatomically shaped I/F cages provided similar stability in a PLIF construct. The greater stability of the TLIF construct was likely due to a more anterior placement of the TLIF cage and preservation of the contralateral facet joint.
腰椎节段的生物力学尸体研究。
比较平行形状和解剖形状的碳纤维椎间融合（I/F）融合器在后路腰椎椎间融合术（PLIF）和经椎间孔腰椎椎间融合术（TLIF）中联合后路椎弓根螺钉内固定时提供的即时稳定性。
关于PLIF和TLIF结构中解剖形状融合器的生物力学数据很少。
对20个腰椎节段进行屈伸（FE）（8 N·m前屈，6 N·m后伸）、侧方弯曲（LB）（±6 N·m）和扭转加载（±5 N·m）测试。每个节段在完整状态下以及在以下3种结构之一中植入椎间融合器后进行测试：PLIF使用2个平行形状或解剖形状的融合器，TLIF使用1个解剖形状的融合器。所有融合器均接受辅助椎弓根螺钉固定。使用方差分析和Bonferroni校正的多重比较，将植入融合器并进行后路固定后的活动范围（ROM）值与完整标本值进行比较。
相对于完整状态，所有结构均显著降低了节段运动（P < 0.001）。使用平行融合器的PLIF结构在FE、LB和轴向旋转中的运动减少分别为85±15%、83±18%和67±6.8%，使用解剖形状融合器的PLIF分别为79±5.5%、87±10%和66±20%，使用解剖形状融合器的TLIF分别为90±6.8%、87±12%和77±22%。在FE和LB中，3种结构之间导致的ROM减少相当（P > 0.05）。在轴向旋转中，与平行形状的PLIF融合器相比，TLIF融合器在ROM方面提供了显著更大的限制（P = 0.01）。
平行形状和解剖形状的I/F融合器在PLIF结构中提供了相似的稳定性。TLIF结构更大的稳定性可能归因于TLIF融合器更靠前的放置以及对侧小关节的保留。
