Cai Ping, Xu Chen, Zhang Zifan, Fang Zhongxin, Deng Chao, Chen Gang, Wang Guoyou, Li Jingchi
Department of Orthopedics, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu, P.R. China.
Department of Spine Surgery, Changzheng Hospital Affiliated to the Naval Medical University, Shanghai, P.R. China.
Ann Biomed Eng. 2025 Mar;53(3):683-698. doi: 10.1007/s10439-024-03643-5. Epub 2024 Dec 5.
Stand-alone oblique lumbar interbody fusion (OLIF) cannot provide credible postoperative stability; additional fixation devices (AFDs) have been used to optimize surgical segment stability. Anterior lateral single rod (ALSR) screw fixation can be performed without intraoperative body position changes and additional surgical incisions, but its biomechanical defect may trigger complications. Inspired by the cross screw in other fixation devices, we designed an OLIF cage integrated with a low-profile plate and cross screw (LPCS).
This study was designed to investigate whether the biomechanical performance of the LPCS OLIF cage is better than that of OLIF with ALSR fixation. The pullout and bending strength of the newly designed conical screw were tested by comparing it with a clinically used cylindrical screw. Different directional fixation strengths of the LPCS OLIF cage were tested by comparing the failure moment and stiffness with the ALSR fixation model. To test the fixation stability and potential risk for screw loosening in models with LPCS OLIF, we also compared the surgical segment's range of motions (ROMs) and stress distributions on OLIF models without and with different AFD fixation under physiological loading conditions.
The bending and pullout strength of the conical screw was better than that of the clinically used screw, and the failure moment and stiffness of the LPCS OLIF model were higher than those of the ALSR model, especially under the extension loading conditions. In which, the maximum failure moment of ALSR fixed OLIF model was 0.88 Nm and 0.76 Nm, while that of the LPCS OLIF model was 9.79 Nm and 7.48 Nm in models with normal and osteoporotic BMD, respectively. Compared to the ALSR fixed OLIF model, failure moment of LPCS models increased by 1012.5% and 884.21% in normal and osteoporotic models, respectively. Moreover, under most physiological loading conditions, the ROM and stress values of the LPCS OLIF model were lower than those of the ALSR model and even slightly lower than those of the OLIF model with bilateral pedicle screw fixation under limited loading conditions.
Compared to OLIF with ALSR fixation, the newly developed LPCS OLIF cage demonstrates inherent biomechanical advantages in establishing immediate postoperative stability and reducing complications related to stress concentration. However, the conclusions of current research should still be validated through in vitro mechanical tests and clinical trials.
单纯斜外侧腰椎椎间融合术（OLIF）无法提供可靠的术后稳定性；已使用额外的固定装置（AFD）来优化手术节段的稳定性。前外侧单棒（ALSR）螺钉固定可在不改变术中体位和增加手术切口的情况下进行，但其生物力学缺陷可能引发并发症。受其他固定装置中交叉螺钉的启发，我们设计了一种集成了低轮廓钢板和交叉螺钉（LPCS）的OLIF椎间融合器。
本研究旨在调查LPCS OLIF椎间融合器的生物力学性能是否优于采用ALSR固定的OLIF。通过将新设计的锥形螺钉与临床使用的圆柱形螺钉进行比较，测试其拔出力和弯曲强度。通过将LPCS OLIF椎间融合器的破坏力矩和刚度与ALSR固定模型进行比较，测试其不同方向的固定强度。为了测试LPCS OLIF模型中螺钉松动的固定稳定性和潜在风险，我们还比较了在生理负荷条件下，有无不同AFD固定的OLIF模型中手术节段的活动范围（ROM）和应力分布。
锥形螺钉的弯曲和拔出强度优于临床使用的螺钉，LPCS OLIF模型的破坏力矩和刚度高于ALSR模型，尤其是在伸展负荷条件下。其中，正常骨密度和骨质疏松骨密度模型中，ALSR固定的OLIF模型的最大破坏力矩分别为0.88 Nm和0.76 Nm，而LPCS OLIF模型分别为9.79 Nm和7.48 Nm。与ALSR固定的OLIF模型相比，正常和骨质疏松模型中LPCS模型的破坏力矩分别增加了1012.5%和884.21%。此外，在大多数生理负荷条件下，LPCS OLIF模型的ROM和应力值低于ALSR模型，甚至在有限负荷条件下略低于双侧椎弓根螺钉固定的OLIF模型。
与采用ALSR固定的OLIF相比，新开发的LPCS OLIF椎间融合器在建立术后即刻稳定性和减少与应力集中相关的并发症方面具有固有的生物力学优势。然而，当前研究的结论仍应通过体外力学测试和临床试验进行验证。
