Kozaki Takuhei, Shimizu Takachika, Murata Akimasa, Nakanishi Ryuichiro, Kozaki Takahiro, Yamamoto Ei, Tsutsui Shunji, Kawakami Mamoru, Yamada Hiroshi
Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan.
Department of Orthopaedic Surgery, Gunma Spine Center (Harunaso Hospital), Takasaki, Japan.
Spine Surg Relat Res. 2024 Aug 30;9(2):202-210. doi: 10.22603/ssrr.2024-0169. eCollection 2025 Mar 27.
This study aimed to compare the biomechanical stress at the proximal junctional aspect between the conventional pedicle screw (PS) fixation (PSF) and the low PS density fixation (LPF) method.
This study involved 10 patients, half of whom have non-osteoporosis and the other half have osteoporosis. We made two types of intact models (one is from the upper thoracic-to-pelvis model, and the other is from the lower thoracic-to-pelvis model). From the intact models, we constructed two kinds of fusion models: (1) PSF and (2) LPF. The LPF method was as follows: The claw hooks (the combination of the down-going transverse process hooks and facet hooks) were set at the upper instrumented vertebra (UIV) and sublaminar wires at the thoracic spine and PSs at the lumbo-pelvis.
In non-osteoporosis, no significant difference between the PSF and LPF is found. In osteoporosis, the von Mises stresses of the vertebra body at UIV, UIV+1, and disc were significantly lower in LPF than in PSF. In non-osteoporosis, the average von Mises stress of the vertebral body at UIV+1 and the maximum stress at UIV were lower in LPF than in PSF; however, no significant difference was found in the others. In osteoporosis, the von Mises stress was significantly lower in LPF than in PSF.
The claw hooks stabilized the vertebra body at UIV firmly, and sublaminar wires reduced load translation from the fixed spine.
本研究旨在比较传统椎弓根螺钉（PS）固定（PSF）与低PS密度固定（LPF）方法在近端交界部位的生物力学应力。
本研究纳入10例患者，其中一半为非骨质疏松患者，另一半为骨质疏松患者。我们制作了两种完整模型（一种是从胸上段到骨盆的模型，另一种是从胸下段到骨盆的模型）。从完整模型中，我们构建了两种融合模型：（1）PSF和（2）LPF。LPF方法如下：在上端固定椎体（UIV）设置爪形钩（下行横突钩和关节突钩的组合），在胸椎设置椎板下钢丝，在腰骶骨盆设置PS。
在非骨质疏松患者中，PSF和LPF之间未发现显著差异。在骨质疏松患者中，LPF组UIV、UIV + 1椎体及椎间盘的von Mises应力显著低于PSF组。在非骨质疏松患者中，LPF组UIV + 1椎体的平均von Mises应力和UIV处的最大应力低于PSF组；然而，其他部位未发现显著差异。在骨质疏松患者中，LPF组的von Mises应力显著低于PSF组。
爪形钩可牢固稳定UIV椎体，椎板下钢丝可减少固定脊柱的负荷转移。
