He Jinyue, Deng Jiezhong, Xiang Yu, Yang Yusheng, Liao Sheng, Chen Hui, Luo Fei, Xu Jianzhong, Zhang Zhongrong, Zhang Zehua
Department of Orthopedics, Southwest Hospital, Army Medical University, Chongqing, 400038, Chongqing, China.
Department of Orthopedics, 958 Hospital, Army Medical University, Chongqing, 400038, Chongqing, China.
BMC Musculoskelet Disord. 2025 Aug 7;26(1):763. doi: 10.1186/s12891-025-09008-w.
Typical oblique lumbar interbody fusion (OLIF) generally employed either the single lateral screw (SLS) or dual pedicle screws (DPS) for instrumentation, each with their own limitations.
The study aimed to investigate the biomechanical properties of two additional fixation strategies including single reverse pedicle screw (SRS) and dual overlapped screws (DOS) compared with SLS and DPS.
A finite element (FE) analysis study.
A L2-5 finite element model was established and validated with L4/5 as the experimental segment. Four fixations including SLS, SRS, DPS and DOS were established on the segment respectively. The L5's inferior surface was set immobilized. Follower-loaded bending moments were imposed on the superior surface of L2 to record the segment's range of motion (ROM) and maximum stress (MS) on the screws, cage and cortical bone under F-E (flexion and extension), bending (left and right) and rotation (left and right).
The model was validated feasible through comparison with previous studies. Regarding the immediate stability: (i) the ROM was significantly lower in DPS and DOS compared to SLS and SRS during F-E and rotations; (ii) compared to DPS, DOS illustrated mildly increased ROM during F-E motions, and left rotation; (iii) compared to SLS, SRS showed an increase of ROM during flexion but a reduction in extension, without obvious distinctions during other motions. Regarding the mechanical response: (i) DPS and DOS illustrated lower MS on the screws, cortical bone and cage than SLS and SRS during most motions; (ii) Compared to DPS, DOS exhibited increased MS during most motions on the screws, cortical bone and cage; (iii) Compared to SLS, SRS demonstrated an increase of MS on the screws during flexion but an reduction during extension, along with decreased MS on cortical bone and cage during most motions.
Dual-screw systems (DPS and DOS) demonstrated enhanced immediate stability for the segment and mitigated mechanical loading for the instrument compared to single-screw systems (SLS and SRS); For the former, DOS exhibited comparable immediate stability to typical DPS, indicating the potential as a viable alternative; For the later, SRS manifested similar stability to traditional SLS, with less stress loading on the cage and cortical bone, indicating less risk of instrument failure in the long term.
The study provides biomechanical references to achieve differentiated and individualized instrumentation for patients undergoing OLIF surgery.
典型的斜外侧腰椎椎间融合术（OLIF）通常采用单枚外侧螺钉（SLS）或双枚椎弓根螺钉（DPS）进行内固定，二者均有各自的局限性。
本研究旨在探究两种额外的固定策略，即单枚反向椎弓根螺钉（SRS）和双枚重叠螺钉（DOS），并与SLS和DPS进行生物力学性能比较。
有限元（FE）分析研究。
建立L2-5有限元模型，并以L4/5作为实验节段进行验证。在该节段上分别建立包括SLS、SRS、DPS和DOS在内的四种固定方式。将L5的下表面设置为固定不动。在L2的上表面施加随动加载弯矩，以记录该节段在屈伸（F-E）、侧弯（左右）和旋转（左右）时的活动范围（ROM）以及螺钉、椎间融合器和皮质骨上的最大应力（MS）。
通过与既往研究比较，验证了该模型的可行性。关于即刻稳定性：（i）在F-E和旋转过程中，DPS和DOS的ROM显著低于SLS和SRS；（ii）与DPS相比，DOS在F-E运动和左旋时的ROM略有增加；（iii）与SLS相比，SRS在屈曲时ROM增加，但在伸展时ROM降低，在其他运动过程中无明显差异。关于力学响应：（i）在大多数运动中，DPS和DOS在螺钉、皮质骨和椎间融合器上的MS低于SLS和SRS；（ii）与DPS相比，DOS在大多数运动中螺钉、皮质骨和椎间融合器上的MS增加；（iii）与SLS相比，SRS在屈曲时螺钉上的MS增加，但在伸展时降低，在大多数运动中皮质骨和椎间融合器上的MS也降低。
与单螺钉系统（SLS和SRS）相比，双螺钉系统（DPS和DOS）对节段具有更强的即刻稳定性，并减轻了器械的机械负荷；对于前者，DOS表现出与典型DPS相当的即刻稳定性，表明其有作为可行替代方案的潜力；对于后者，SRS表现出与传统SLS相似的稳定性，椎间融合器和皮质骨上的应力负荷较小，表明长期器械失效风险较低。
本研究为接受OLIF手术的患者实现差异化和个体化内固定提供了生物力学参考。
