Jiang Chenyu, Ouyang Hanqiang, Li Yali, Lang Ning, Zhang Yan, Jiang Liang, Yuan Huishu
Department of Radiology, Peking University Third Hospital, Beijing, China.
Department of Orthopaedics, Peking University Third Hospital, Beijing, China.
Front Bioeng Biotechnol. 2025 Mar 24;13:1542352. doi: 10.3389/fbioe.2025.1542352. eCollection 2025.
Pedicle screw loosening (PSL) is a frequent complication in osteoporotic patients undergoing spinal fixation, yet effective risk assessment methods are limited. This study explores the impact of craniocaudal cyclic load on pedicle screw fixation strength using computed tomography-based finite element analysis (CT-FEA) and evaluates its predictive value for PSL.
A total of 23 PSL cases (7 men and 16 women) and 29 matched controls were analyzed using CT-FEA. Both a simple axial pullout load and a pullout load with a preset craniocaudal cyclic load were applied to calculate the pullout force. Hounsfield unit (HU) values and volumetric bone mineral density (vBMD) of the screw trajectory were also assessed for osteoporosis evaluation. The pullout force and osteoporotic assessment value were compared between PSL and controls.
Craniocaudal cyclic loading significantly reduced the pullout force (924.3 ± 195.1 N vs. 745.2 ± 188.7 N, p < 0.0001). The PSL group had a lower pullout force under cyclic load (629.6 ± 188.2 N vs. 836.9 ± 131.6 N, p < 0.0001) and lower HU value of screw trajectories (183.7 ± 42.6 vs. 206.7 ± 29.72, p = 0.026) than controls, while simple axial pullout force and vBMD showed no significant differences. Receiver operating characteristic (ROC) analysis indicated that pullout force under cyclic load (AUC = 0.806) was a better predictor of PSL than HU values (AUC = 0.629).
This study demonstrates the critical role of craniocaudal cyclic loading in pedicle screw fixation strength and its predictive value for PSL. Craniocaudal cyclic load reduces screw fixation strength significantly. Pullout force under cyclic load assessed by CT-FEA enhances the predictive accuracy for PSL risk.
椎弓根螺钉松动（PSL）是骨质疏松患者脊柱固定术后常见的并发症，但有效的风险评估方法有限。本研究采用基于计算机断层扫描的有限元分析（CT-FEA）探讨头尾向循环载荷对椎弓根螺钉固定强度的影响，并评估其对PSL的预测价值。
使用CT-FEA分析了23例PSL病例（7例男性和16例女性）和29例匹配的对照。施加简单轴向拔出载荷和预设头尾向循环载荷的拔出载荷以计算拔出力。还评估了螺钉轨迹的亨氏单位（HU）值和体积骨密度（vBMD）以进行骨质疏松评估。比较PSL组和对照组的拔出力和骨质疏松评估值。
头尾向循环载荷显著降低了拔出力（924.3±195.1 N对745.2±188.7 N，p<0.0001）。PSL组在循环载荷下的拔出力较低（629.6±188.2 N对836.9±131.6 N，p<0.0001），螺钉轨迹的HU值低于对照组（183.7±42.6对206.7±29.72，p = 0.026），而简单轴向拔出力和vBMD无显著差异。受试者工作特征（ROC）分析表明，循环载荷下的拔出力（AUC = 0.806）比HU值（AUC = 0.629）更能预测PSL。
本研究证明了头尾向循环载荷在椎弓根螺钉固定强度中的关键作用及其对PSL的预测价值。头尾向循环载荷显著降低螺钉固定强度。通过CT-FEA评估的循环载荷下的拔出力提高了PSL风险的预测准确性。
