Craniocaudal toggling increases the risk of screw loosening in osteoporotic vertebrae

Song, Fei; Fu, Ruisen; Gao, Xing; Iqbal, Kamran; Yang, Dongyue; Liu, Y.; Yang, Haisheng

doi:10.1016/j.cmpb.2023.107625

Cited by 2 publications

(1 citation statement)

References 50 publications

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“… 34 , 43 Though the displacements in the three groups are not large, they are generally similar to those biomechanical studies having tension‐compression‐bending load, which also shows the validity of the model to some extent. 44 , 45 Also, tension‐compression‐bending load used in osteoporotic vertebra has been proven a risk factor for pedicle screw loosening, 46 which indicates that usage of 5 pcf SRPF replacing osteoporotic bone not only conforms to common disease clinically, but also makes the results easier to observe. The normalized SHV in the removal group was even lower than that in all direction groups, suggesting that the effect of removing the pedicle screw on the SHV was negligible.…”

Section: Discussionmentioning

confidence: 99%

Effect of Insertional Direction of Pedicle Screw on Screw Loosening: A Biomechanical Study on Synthetic Bone Vertebra under a Physiology‐like Load

Zhan,

Gao,

Yang

et al. 2024

Orthopaedic Surgery

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ObjectivesIt is now understood that pedicle screw loosening at the implant‐bone interface can lead to poor screw–bone interface purchase and decreased fixation stability. Previous biomechanical tests used cadaveric vertebrae and pull‐out or torque loads to assess the effect of the insertional direction of pedicle screws on screw loosening. However, these tests faced challenges in matching biomechanical differences among specimens and simulating in vivo loads applied on pedicle screws. This study aimed to evaluate the effect of the insertional direction of pedicle screws on screw loosening using tension‐compression‐bending loads and synthetic bone vertebrae.MethodsPolyaxial pedicle screws were inserted into nine synthetic bone vertebrae in three directions (three samples per group): cranial, parallel, and caudad (−10°, 0°, +10° of the pedicle screw rod to the upper plane of the vertebra, respectively). Pedicle screws in the vertebrae were loaded using a polyethylene block connected to a material testing machine. Tension‐compression‐bending loads (100N–250N) with 30,000 cycles were applied to the pedicle screws, and displacements were recorded and then cycle‐displacement curve was drawn based on cycle number. Micro‐CT scans were performed on the vertebrae after removing the pedicle screws to obtain images of the screw hole, and the screw hole volume was measured using imaging analysis software. Direct comparison of displacements was conducted via cycle‐displacement curve. Screw hole volume was analyzed using analysis of variance. The correlation between the displacement, screw hole volume and the direction of pedicle screw was assessed by Spearman correlation analysis.ResultsThe smallest displacements were observed in the caudad group, followed by the parallel and cranial groups. The caudad group had the smallest screw hole volume (p < 0.001 and p = 0.009 compared to the cranial and parallel groups, respectively), while the volume in the parallel group was greater than that in the cranial group (p = 0.003). Correlation analysis revealed that the insertional direction of the pedicle screw was associated with the displacement (p = −0.949, p < 0.001) and screw hole volume (p = −0.944, p < 0.001).ConclusionStrong correlations were found between the insertional direction of the pedicle screw and relevant parameters, including displacement and screw hole volume. Pedicle screw insertion in the caudad direction resulted in the least pedicle screw loosening.

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Section: Discussionmentioning

confidence: 99%

Effect of Insertional Direction of Pedicle Screw on Screw Loosening: A Biomechanical Study on Synthetic Bone Vertebra under a Physiology‐like Load

Zhan,

Gao,

Yang

et al. 2024

Orthopaedic Surgery

View full text Add to dashboard Cite

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Craniocaudal cyclic load improve risk assessment of lumbar pedicle screw loosening：finite element analysis based on computer tomography

Jiang,

ouyang,

et al. 2024

Preprint

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Background: Screw loosening remains a prominent complication for osteoporotic patients with pedicle screw fixation surgeries, yet with limited risk assessment approach. The aim of this study was to investigate influence of craniocaudal cyclic load on pedicle screw fixation strength by computed tomography (CT) based finite element analysis (FEA) and we examined predict ability in pedicle screw loosening (PSL). Methods: 12 clinical PSL cases (7 men, 5 women) and 12 age- and sex-matched controls were enrolled for CT based FEA. Simple axial pullout load and axial pullout load with preset craniocaudal cyclic load were applied to each model respectively, and the ultimate pullout force under both conditions is calculated as the fixed strength and compared. Besides, HU values of the vertebral body trabeculae and screw trajectory were measured as an assessment of osteoporosis. The ultimate pullout force and HU value were compared between PSL and controls cases. Results The cyclic load remarkably reduce the pullout force of pedicle screws (906.2 ± 180.2 N vs. 729.3 ± 172.3 N, p<0.0001) by CT based FEA. No significant difference between the PSL and the control group in the simple axial pull-out force and HU values of the vertebral body. But the pullout force with preset cyclic load (639.2 ± 169.4 N vs. 819.4 ± 125.1 N, p = 0.072) and the HU value of the screw trajectory (177.5 ± 43.8 vs. 217.2 ± 29.6, p = 0.016) in the PSL group is significantly lower than that in the control group. Area under receiver operating characteristic curve (ROC) revealed pullout force with preset cyclic load slightly better predicted PSL than HU value of the screw trajectory (AUC = 0.798 vs. 0.750). Conclusions The craniocaudal cyclic load significantly reduces the screw fixation strength. HU value of screw trajectory and pullout force with preset cyclic load by CT based FEA are helpful for the clinical prediction of PSL.

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Craniocaudal toggling increases the risk of screw loosening in osteoporotic vertebrae

Cited by 2 publications

References 50 publications

Effect of Insertional Direction of Pedicle Screw on Screw Loosening: A Biomechanical Study on Synthetic Bone Vertebra under a Physiology‐like Load

Effect of Insertional Direction of Pedicle Screw on Screw Loosening: A Biomechanical Study on Synthetic Bone Vertebra under a Physiology‐like Load

Craniocaudal cyclic load improve risk assessment of lumbar pedicle screw loosening：finite element analysis based on computer tomography

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