Pullout Analysis of a Lumbar Plate With Varying Screw Orientations

Ríos, D. Subirá; Patacxil, Wyzscx Merfil; Palmer, Daniel Stephen Vaughan; Williams, Paul A.; Cheng, Wayne K.; İnceoğlu, Serkan

doi:10.1097/brs.0b013e318254155a

Cited by 8 publications

(5 citation statements)

References 15 publications

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“…It has been described in the previous studies that the strain occurred mainly around the screws, and the main reasons were the pressure of the thread on the bone in contact with it destroyed the bone around the screw and the stiffness of the vertebrae was weaker than that of the screw 14 , 17 , 35 ; the results of current study were coincided with these findings (Supplemental Digital Content Figure 8, http://links.lww.com/BRS/B980 ). At the same time, the strain on the vertebrae was mainly in the vicinity of the screw ( i.e.…”

Section: Discussionmentioning

confidence: 99%

Screw Pullout Strength After Pedicle Screw Reposition: A Finite Element Analysis

Huang²,

Hao³

et al. 2022

Spine

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Research design. Finite element analysis based on computed tomography images from the lumbar spine. Objective. Determined the pullout strength of unsatisfactorily placed screws and repositioned screws after unsatisfactory place in lumbar spine surgery. Background. Pedicle screws are widely used to stabilize the spinal vertebral body. Unsatisfactory screws could lead to surgical complications, and may need to be repositioned. Screw removal and reposition, however, may decrease pullout strength. Methods. We conducted a three-dimensional finite element analysis based on high-resolution computed tomography images from a 39-year-old healthy woman. Pullout strength was determined with the screw placed in different orientations at the same entry point (as selected by the Magerl method), as well as after removal and reposition. The material properties of the vertebral body and the screw were simulated by using grayscale values and verified data, respectively. A load along the screw axis was applied to the end of the screw to simulate the pullout. Results. The pullout strength was 1840.0 N with the Magerl method. For unsatisfactorily placed screws, the pullout strength was 1500.8 N at 20% overlap, 1609.6 N at 40% overlap, 1628.9 N at 60% overlap, and 1734.7 N at 80% overlap with the hypothetical screw path of the Magerl method. For repositioned screws, the pullout strength was 1763.6 N, with 20% overlap, 1728.3 N at 40% overlap, 1544.0 N at 60% overlap, and 1491.1 N at 80% overlap, with the original path. Comparison of repositioned screw with unsatisfactorily placed screw showed 14.04% decrease in pullout strength at 80% overlap, 5.21% decrease at 60% overlap, 7.37% increase at 40% overlap, and 17.51% increase at 20% overlap, with the screw path of the Magerl method. Conclusions. Removal and reposition increased the pullout strength at 20% and 40% overlap, but decreased the pullout strength at 60% and 80% overlap. For clinical translation, we recommend removal and reposition of the screw when the overlap is in the range of 20% to 40% or less. In vitro specimen studies are needed to verify these preliminary findings.

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Section: Discussionmentioning

confidence: 99%

Screw Pullout Strength After Pedicle Screw Reposition: A Finite Element Analysis

Huang²,

Hao³

et al. 2022

Spine

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“…Polyurethane blocks are a well‐established bone surrogate and are recommended for interbody fusion device testing. However, they do not include a vertebral cortical shell and endplate, which represents a potential limitation for the clinical extrapolation of results.…”

Section: Discussionmentioning

confidence: 99%

Anterior Lumbar Interbody Fusion Integrated Screw Cages: Intrinsic Load Generation, Subsidence, and Torsional Stability

Assem

Pelletier

Mobbs

et al. 2017

Orthopaedic Surgery

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“…However, the pullout strength of an ALP system that includes four individual screws was complicated. Rios et al [10] evaluated the pullout force of the anterior lumbar interbody fixa tion plate using experimental and finite element analyses. They concluded that the parallel constructs revealed the maximum pullout force in both the foam model and the bovine cancellous bone.…”

Section: Discussionmentioning

confidence: 99%

“…However, patients with spinal decompression treatment using the ALP system still face compli cations such as implant loosening and breakage [7][8][9]. Past studies suggested that locking screws should be inserted with a particular inclined angle to strengthen the biomechanical performances of ALP systems [10], but oppo site conclusion has also been reached [9], Unfortunately, the screw orientations determined in past studies are mainly based on the surgeon's experience without biomechanical evidence. Past studies suggested that locking screws should be inserted with a particular inclined angle to strengthen the biomechanical performances of ALP systems [10], but oppo site conclusion has also been reached [9], Unfortunately, the screw orientations determined in past studies are mainly based on the surgeon's experience without biomechanical evidence.…”

Section: Introductionmentioning

confidence: 99%

An Optimization Study of the Screw Orientation on the Interfacial Strength of the Anterior Lumbar Plate System Using Neurogenetic Algorithms and Experimental Validation

Lee

Hsu

Huy

2014

Journal of Biomechanical Engineering

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Anterior lumbar plate (ALP) systems have been widely used as an effective interbody fusion device for treating spinal cord compression. However, clinical complications, such as implant loosening and breakage, still occur. Past studies have investigated the effects of the screw orientation on the interfacial strength, but these studies were inconsistent. The purpose of this study was to identify an ALP system with excellent interfacial strength by varying the screw orientation. Three-dimensional finite element models of L4-L5 segments with an ALP system were first constructed. A neurogenetic algorithm, which combines artificial neural networks and genetic algorithms, was subsequently developed to discover the optimum plate design. Finally, biomechanical tests were conducted to validate the results of the finite element models and the engineering algorithm. The results indicated that the interfacial strength of the optimum plate design obtained using the neurogenetic algorithm was excellent compared with the other designs and that all of the locking screws should be inserted divergently. Both the numerical and experimental outcomes can provide clinical suggestions to surgeons and help them to understand the interfacial strength of ALP systems in terms of the screw orientation.

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Pullout Analysis of a Lumbar Plate With Varying Screw Orientations

Cited by 8 publications

References 15 publications

Screw Pullout Strength After Pedicle Screw Reposition: A Finite Element Analysis

Screw Pullout Strength After Pedicle Screw Reposition: A Finite Element Analysis

Anterior Lumbar Interbody Fusion Integrated Screw Cages: Intrinsic Load Generation, Subsidence, and Torsional Stability

An Optimization Study of the Screw Orientation on the Interfacial Strength of the Anterior Lumbar Plate System Using Neurogenetic Algorithms and Experimental Validation

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