Pull-out strength of patient-specific template-guided vs. free-hand fluoroscopically controlled thoracolumbar pedicle screws: a biomechanical analysis of a randomized cadaveric study

Aichmair, Alexander; Moser, Manuel; Bauer, Michael R.; Bachmann, Elias; Snedeker, Jess G.; Betz, Michael; Farshad, Mazda

doi:10.1007/s00586-017-5025-7

Cited by 11 publications

(7 citation statements)

References 45 publications

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“…31 In 2017, Farshad et al 32 compared time of instrumentation, accuracy, and radiation exposure between patient-specific template-guided and freehand fluoroscopically controlled pedicle screw placement in the thoracic and lumbar spine, assessing the superiority of template-guided positioning. A significantly higher pullout strength of thoracic-lumbar pedicle screws when inserted via a patient-specific tubular guide was found by Aichmair et al, 33 and this potentially was associated with better screw trajectory. Moreover, Putzier et al 30 conducted a pilot study proving that custom-made positioning guides are a feasible navigational tool that permit a safe and accurate implantation of pedicle screws in patients with severe scoliosis.…”

Section: Discussionmentioning

confidence: 74%

Cortical Bone Trajectory Screw Placement Accuracy with a Patient-Matched 3-Dimensional Printed Guide in Lumbar Spinal Surgery: A Clinical Study

et al. 2019

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Section: Discussionmentioning

confidence: 74%

Cortical Bone Trajectory Screw Placement Accuracy with a Patient-Matched 3-Dimensional Printed Guide in Lumbar Spinal Surgery: A Clinical Study

et al. 2019

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“…The CT data was also used to quantify the bone density of the vertebral bodies [ 13 ]. Alternating between TT and CBT to generate equivalent groups, the trajectories were planned by an experienced spine surgeon using the MySpine software based on the CT-data (Medacta International, Castel San Peitro, Switzerland) [ 14 ]. Screw diameter and length were maximized as recommended [ 15 ].…”

Section: Methodsmentioning

confidence: 99%

Is a cross-connector beneficial for single level traditional or cortical bone trajectory pedicle screw instrumentation?

et al. 2021

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The cortical bone trajectory (CBT) has been introduced with the aim of better screw hold, however, screw-rod constructs with this trajectory might provide less rigidity in lateral bending (LB) and axial rotation (AR) compared to the constructs with the traditional trajectory (TT). Therefore, the addition of a horizontal cross-connector could be beneficial in counteracting this possible inferiority. The aim of this study was to compare the primary rigidity of TT with CBT screw-rod constructs and to quantify the effect of cross-connector-augmentation in both. Spines of four human cadavers (T9 –L5) were cropped into 15 functional spine units (FSU). Eight FSUs were instrumented with TT and seven FSUs with CBT pedicle screws. The segments were tested in six loading directions in three configurations: uninstrumented, instrumented with and without cross-connector. The motion between the cranial and caudal vertebra was recorded. The range of motion (ROM) between the CBT and the TT group did not differ significantly in either configuration. Cross-connector -augmentation did reduce the ROM in AR (16.3%, 0.27°, p = 0.02), LB (2.9%, 0.07°, p = 0.03) and flexion-extension FE (2.3%, 0.04°, p = 0.02) for the TT group and in AR (20.6%, 0.31°, p = 0.01) for the CBT-group. The primary rigidity of TT and CBT single level screw-rod constructs did not show significant difference. The minimal reduction of ROM due to cross-connector-augmentation seems clinically not relevant. Based on the findings of these study there is no increased necessity to use a cross-connector in a CBT-construct.

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“…In orthopedic surgery, Aichmair et al [19] demonstrated a trend towards a greater pullout strength with a greater vertebral BMD measured using CT values. However, their research had two drawbacks: BMD was evaluated in the ellipsoidal regions of the vertebral body (not the screw path), and the pullout strength was compared among only three subgroups divided according to CT values [19]. Therefore, to further clarify the effect of CT values on pullout strength, we investigated the correlation between the CT values of the screw path and the pullout strength of the pedicle screw.…”

Section: Discussionmentioning

confidence: 99%

“…In dentistry, the correlation between CT values and implant stability has been shown in vitro and in vivo, and normal CT values have been reported for specific regions of the mandible and maxilla [17,18]. In orthopedic surgery, Aichmair et al [19] demonstrated a trend towards a greater pullout strength with a greater vertebral BMD measured using CT values. However, their research had two drawbacks: BMD was evaluated in the ellipsoidal regions of the vertebral body (not the screw path), and the pullout strength was compared among only three subgroups divided according to CT values [19].…”

Section: Discussionmentioning

confidence: 99%

Correlation between the Computed Tomography Values of the Screw Path and Pedicle Screw Pullout Strength: An Experimental Study in Porcine Vertebrae

Ikeura

Kushida

et al. 2020

Asian Spine J

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Study Design: Biomechanical study.Purpose: To assess the correlation between the computed tomography (CT) values of the pedicle screw path and screw pull-out strength.Overview of Literature: The correlation between pedicle screw pull-out strength and bone mineral density has been well established. In addition, several reports have demonstrated a correlation between bone mineral density and CT values. However, no previous biomechanical studies investigated the correlation between CT values and pedicle screw pull-out strength.Methods: Sixty fresh-frozen lumbar vertebrae from 6-month-old pigs were used. Before screw insertion, the CT values of the screw path were obtained for each sample. Specimens were then randomly divided into three equal groups. Each group had one of three pedicle screws inserted: 4.0-mm LEGACY (4.0-LEG), 4.5-mm LEGACY (4.5-LEG), or 4.5-mm SOLERA (4.5-SOL) (all from Medtronic Sofamor Danek Inc., Memphis, TN, USA). Each screw had a consistent 30-mm thread length. Axial pull-out testing was performed at a rate of 1.0 mm/min. Correlations between the CT values and pedicle screw pull-out strength were evaluated using Pearson’s correlation coefficient analysis.Results: The correlation coefficients between the CT values of the screw path and pedicle screw pull-out strength for the 4.0-LEG, 4.5-LEG, and 4.5-SOL groups were 0.836 (p <0.001), 0.780 (p <0.001), and 0.873 (p <0.001), respectively. Greater CT values were associated with greater screw pull-out strength.Conclusions: The CT values of the screw path were strongly positively correlated with pedicle screw pull-out strength, regardless of the screw type and diameter, suggesting that the CT values could be clinically useful for predicting pedicle screw pull-out strength.

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Pull-out strength of patient-specific template-guided vs. free-hand fluoroscopically controlled thoracolumbar pedicle screws: a biomechanical analysis of a randomized cadaveric study

Abstract: There was a significantly higher pull-out strength of thoracolumbar pedicle screws when inserted via a patient-specific template-guided versus conventional free-hand fluoroscopically controlled technique, potentially associated with screw trajectory.

Cited by 11 publications

References 45 publications

Cortical Bone Trajectory Screw Placement Accuracy with a Patient-Matched 3-Dimensional Printed Guide in Lumbar Spinal Surgery: A Clinical Study

Cortical Bone Trajectory Screw Placement Accuracy with a Patient-Matched 3-Dimensional Printed Guide in Lumbar Spinal Surgery: A Clinical Study

Is a cross-connector beneficial for single level traditional or cortical bone trajectory pedicle screw instrumentation?

Correlation between the Computed Tomography Values of the Screw Path and Pedicle Screw Pullout Strength: An Experimental Study in Porcine Vertebrae

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