School of PhD Studies, Semmelweis University, Üllői Str. 26, Budapest, Hungary; In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Királyhágó Str. 1-3, Budapest, Hungary.
School of PhD Studies, Semmelweis University, Üllői Str. 26, Budapest, Hungary; National Center for Spinal Disorders, Királyhágó Str. 1-3, Budapest, Hungary.
Spine J. 2024 Oct;24(10):1981-1992. doi: 10.1016/j.spinee.2024.04.024. Epub 2024 Apr 28.
Following total sacrectomy, lumbopelvic reconstruction is essential to restore continuity between the lumbar spine and pelvis. However, to achieve long-term clinical stability, bony fusion between the lumbar spine and the pelvic ring is crucial. Reduction of the lumbopelvic distance can promote successful bony fusion. Although many lumbopelvic reconstruction techniques (LPRTs) have been previously analyzed, the biomechanical effect of lumbopelvic distance reduction (LPDR) has not been investigated yet.
To evaluate and compare the biomechanical characteristics of four different LPRTs while considering the effect of LPDR.
STUDY DESIGN/SETTING: A comparative finite element (FE) study.
The FE models following total sacrectomy were developed to analyze four different LPRTs, with and without LPDR. The closed-loop reconstruction (CLR), the sacral-rod reconstruction (SRR), the four-rod reconstruction (FRR), and the improved compound reconstruction (ICR) techniques were analyzed in flexion, extension, lateral bending, and axial rotation. Lumbopelvic stability was assessed through the shift-down displacement and the relative sagittal rotation of L5, while implant safety was evaluated based on the stress state at the bone-implant interface and within the rods.
Regardless of LPDR, both the shift-down displacement and relative sagittal rotation of L5 consistently ranked the LPRTs as ICR<SRR<FRR<CLR, with ICR being the stiffest for both parameters. LPDR decreased the shift-down displacement values by 25% in CLR, by 61% in SRR, by 15% in FRR, and by 46% in ICR, as well as reduced the relative sagittal rotation values by 21% in CLR, by 73% in SRR, by 11% in FRR, and by 53% in ICR. Considering the stress at the bone-implant interface, without LPDR, the ICR yielded the smallest stress values for flexion, lateral bending, and axial rotation with 131.4 MPa, 68.2 MPa, and 70.3 MPa, respectively, and the second smallest in extension with 36.1 MPa. Due to LPDR, these stress values were reduced by 31% in flexion, by 17% in extension, by 29% in lateral bending, and by 29% in axial rotation. Within the rods, without LPDR, the ICR yielded the smallest stress values for flexion, extension, lateral bending, and axial rotation with 346.5 MPa, 108.0 MPa, 186.2 MPa, and 199.7 MPa, respectively. With LPDR, these stress values were reduced by 16% in flexion, by 9% in extension, by 11% in lateral bending, and by 12% in axial rotation.
LPDR significantly improved both lumbopelvic stability and implant safety in all reconstruction techniques after total sacrectomy. LPDR reduced the shift-down displacement of L5, the relative sagittal rotation of L5, and the stress values at the bone-implant interface. Furthermore, in the ICR and SRR techniques, LPDR decreased the peak stress values within the rods. All four investigated LPRTs demonstrated suitability for lumbopelvic reconstruction, with the ICR technique exhibiting the highest lumbopelvic stiffness.
LPDR creates a biomechanically advantageous environment following total sacrectomy; therefore, it has the potential to impact the design of custom-made 3D-printed or traditional LPRTs. However, to confirm the findings of the current FE study, long-term clinical trials are recommended.
全骶骨切除术后，进行腰骶重建对于恢复腰椎和骨盆之间的连续性至关重要。然而，为了实现长期临床稳定性，腰椎和骨盆环之间的骨性融合至关重要。减少腰骶距离可以促进成功的骨性融合。虽然已经分析了许多腰骶重建技术（LPRT），但尚未研究腰骶距离减少（LPDR）的生物力学效应。
评估和比较四种不同 LPRT 的生物力学特性，同时考虑 LPDR 的影响。
研究设计/设置：比较有限元（FE）研究。
开发了全骶骨切除术后的 FE 模型，以分析四种不同的 LPRT，包括有无 LPDR。分析了闭合环重建（CLR）、骶棒重建（SRR）、四棒重建（FRR）和改良复合重建（ICR）技术在屈伸、侧屈和轴向旋转中的应用。通过 L5 的向下移位和相对矢状旋转评估腰骶稳定性，通过骨-植入物界面和棒内的应力状态评估植入物安全性。
无论是否进行 LPDR，L5 的向下移位和相对矢状旋转均将 LPRT 排名为 ICR<SRR<FRR<CLR，其中 ICR 对这两个参数的刚度最大。LPDR 将 CLR 中的 L5 向下移位值降低了 25%，将 SRR 中的 L5 向下移位值降低了 61%，将 FRR 中的 L5 向下移位值降低了 15%，将 ICR 中的 L5 向下移位值降低了 46%，将 CLR 中的 L5 相对矢状旋转值降低了 21%，将 SRR 中的 L5 相对矢状旋转值降低了 73%，将 FRR 中的 L5 相对矢状旋转值降低了 11%，将 ICR 中的 L5 相对矢状旋转值降低了 53%。考虑到骨-植入物界面的应力，没有 LPDR，ICR 在屈伸、侧屈和轴向旋转时产生的应力最小，分别为 131.4 MPa、68.2 MPa 和 70.3 MPa，在伸展时产生的应力第二小，为 36.1 MPa。由于 LPDR，这些应力值在屈伸时降低了 31%，在伸展时降低了 17%，在侧屈时降低了 29%，在轴向旋转时降低了 29%。在棒内，没有 LPDR，ICR 在屈伸、伸展、侧屈和轴向旋转时产生的应力最小，分别为 346.5 MPa、108.0 MPa、186.2 MPa 和 199.7 MPa。有 LPDR 时，这些应力值在屈伸时降低了 16%，在伸展时降低了 9%，在侧屈时降低了 11%，在轴向旋转时降低了 12%。
LPDR 显著提高了全骶骨切除术后所有重建技术的腰骶稳定性和植入物安全性。LPDR 降低了 L5 的向下移位、L5 的相对矢状旋转和骨-植入物界面的应力值。此外，在 ICR 和 SRR 技术中，LPDR 降低了棒内的峰值应力值。所有四种研究的 LPRT 都适合腰骶重建，其中 ICR 技术具有最高的腰骶刚度。
LPDR 为全骶骨切除术后创造了有利的生物力学环境；因此，它有可能影响定制 3D 打印或传统 LPRT 的设计。然而，为了证实当前 FE 研究的结果，建议进行长期临床试验。
