Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, CH-8008, Zurich, Switzerland; University Spine Center Zurich, Balgrist University Hospital, University of Zurich, Forchstrasse 340, CH-8008, Zurich, Switzerland.
Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, CH-8008, Zurich, Switzerland.
Spine J. 2023 Jul;23(7):1088-1095. doi: 10.1016/j.spinee.2023.02.005. Epub 2023 Feb 15.
Transforaminal endoscopic decompression is an emerging minimally invasive surgical technique in spine surgery. The biomechanical effects and limitations of resections associated with this technique are scarce.
The objective of this study was to analyze the effects of three different extents of reduction at the craniomedial pedicle (10%, 25%, and 50%) and to compare them with the intact native side. In addition, the influence of bone quality on the resistance of the pedicle after reduction was investigated.
Biomechanical cadaveric study.
Thirty lumbar vertebrae originating from six fresh frozen cadavers were tested under uniaxial compression load in a ramp-to-failure test: (1) the reduced pedicle on one side, and (2) the native pedicle on the other side. Of the 30 lumbar vertebrae, ten were assigned to each reduction group (10%, 25%, and 50%).
On the intact side, the median axial compression force to failure was 593 N (442.4-785.8). A reduction of the pedicle by 10% of the cross-sectional area resulted in a decrease of the axial load resistance by 4% to 66% compared to the intact opposite side (p=.046). The median compression force to failure was 381.89 N (range: 336-662.1). A reduction by 25% resulted in a decrease of 7% to 71% (p=.001). The median compression force to failure was 333 N (265.1-397.3). A reduction by 50% resulted in a decrease of 39% to 90% (p<.001). The median compression force to failure was 200.9 N (192.3-283.9). At 10% pedicle reduction, the Hounsfield units (HU) value and the absolute force required to generate a pedicle fracture showed significant correlations (ρ=.872; p=.001). At 25%, a positive correlation between the two variables could still be identified (ρ=.603; p=.065). At 50%, no correlation was found (ρ=-.122; p=.738).
Resection of the inner, upper part of the pedicle significantly reduces the axial resistance force of the pedicle until a fracture occurs.
The extent of pedicle reduction itself plays only a limited role: once the cortical bone in the pedicle region is compromised, significant loss of resistance to loading must be anticipated.
经椎间孔内窥镜减压术是脊柱外科领域新兴的微创技术。与该技术相关的切除的生物力学效应和局限性知之甚少。
本研究旨在分析在颅内侧骨（10%、25%和 50%）上进行三种不同程度减压的效果，并将其与完整的天然侧进行比较。此外，还研究了骨质量对减压后椎弓根阻力的影响。
生物力学尸体研究。
在 ramp-to-failure 试验中，对来自六个新鲜冷冻尸体的 30 个腰椎进行了单轴压缩载荷测试：（1）一侧减压的椎弓根，（2）另一侧天然椎弓根。30 个腰椎中，10 个被分配到每个减压组（10%、25%和 50%）。
在完整侧，轴向破坏的中位压缩力为 593N（442.4-785.8）。与对侧完整的天然椎弓根相比，椎弓根横截面积减少 10%会导致轴向载荷阻力降低 4%至 66%（p=.046）。中位压缩破坏力为 381.89N（范围：336-662.1）。减少 25%会导致 7%至 71%的降低（p=.001）。中位压缩破坏力为 333N（265.1-397.3）。减少 50%会导致 39%至 90%的降低（p<.001）。中位压缩破坏力为 200.9N（192.3-283.9）。在 10%的椎弓根减压时，HU 值和产生椎弓根骨折所需的绝对力之间存在显著相关性（ρ=.872；p=.001）。在 25%时，仍能识别到两个变量之间的正相关性（ρ=.603；p=.065）。在 50%时，未发现相关性（ρ=-.122；p=.738）。
椎弓根内、上部分的切除显著降低了椎弓根的轴向阻力，直至发生骨折。
椎弓根减压的程度本身仅起有限作用：一旦椎弓根区域的皮质骨受到损害，预计会出现明显的负荷阻力丧失。
