Hsieh Ming-Kai, Li Yun-Da, Chen Weng-Pin, Lee De-Mei, Tai Ching-Lung
Department of Orthopaedic Surgery, Spine Section, Bone and Joint Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
Department of Biomedical Engineering, Chang Gung University, Taoyuan, Taiwan.
J Orthop Surg Res. 2025 Jan 10;20(1):31. doi: 10.1186/s13018-025-05452-5.
Combining oblique lumbar interbody fusion (OLIF) with posterior pedicle screw fixation (PPSF) has been proposed to reduce cage subsidence, especially in osteoporotic spines. Recently, anterolateral screw-rod fixation has gained interest as it allows direct pathology observation and avoids a posterior approach. However, controversies exist between anterolateral screw fixation systems and traditional PPSF due to variations in osteoporotic vertebral mineral density, screw fixation positions, and fixation methods (bicortical vs. unicortical). This study aimed to investigate the biomechanical impact of fixation position and method in osteoporotic spine.
Seventy-two fresh‑frozen porcine vertebrae (L1-6) were decalcified using 0.5 M EDTA and divided into two groups based on fixation method: bicortical or unicortical. Six groups for each method were created according to the screw position in the lateral vertebral body, with six specimens in each group: anterior, central, and posterior in the middle body and para-endplate regions. Correlations among screw position, fixation method and axial pullout strength were analyzed.
A 4-week decalcification process, bone mineral density in the porcine vertebrae decreased to approximately 48% (p < 0.05) of the original value, categorizing them as osteoporotic. Bicortical fixation showed significantly greater pullout forces than unicortical fixation, with differences ranging from 82 to 273%. Notably, central or posterior screws outperformed anterior screws in pullout strength.
Bicortical fixation exhibited significantly greater pullout forces than unicortical fixation. We suggest positioning screws in the central or posterior region of the middle body with bicortical fixation in osteoporotic vertebrae.
有人提出将斜外侧腰椎椎间融合术（OLIF）与后路椎弓根螺钉固定术（PPSF）相结合，以减少椎间融合器下沉，尤其是在骨质疏松性脊柱中。近来，由于前外侧螺钉-棒固定术能够直接观察病变情况并避免后路入路，因而受到关注。然而，由于骨质疏松性椎体骨密度、螺钉固定位置及固定方法（双皮质与单皮质）的差异，前外侧螺钉固定系统与传统的PPSF之间存在争议。本研究旨在探讨固定位置和方法对骨质疏松性脊柱的生物力学影响。
使用0.5M乙二胺四乙酸（EDTA）对72个新鲜冷冻猪椎体（L1-6）进行脱钙处理，并根据固定方法分为两组：双皮质或单皮质。根据椎体外侧的螺钉位置，每种方法创建六组，每组六个标本：椎体中部及终板旁区域的前部、中部和后部。分析螺钉位置、固定方法与轴向拔出力之间的相关性。
经过4周的脱钙过程，猪椎体的骨密度降至原始值的约48%（p<0.05），将其归类为骨质疏松。双皮质固定的拔出力明显大于单皮质固定，差异范围为82%至273%。值得注意的是，中部或后部螺钉的拔出强度优于前部螺钉。
双皮质固定的拔出力明显大于单皮质固定。我们建议在骨质疏松性椎体中采用双皮质固定，将螺钉置于椎体中部的中央或后部区域。
