scholarly journals Biomechanical Comparison of a Notched Head Locking T-Plate and a Straight Locking Compression Plate in a Juxta-Articular Fracture Model

2020 ◽  
Author(s):  
Guy Bird ◽  
Mark Glyde ◽  
Giselle Hosgood ◽  
Alex Hayes ◽  
Robert Day
Keyword(s):  
Three Dimensional ◽  
Locking Compression Plate ◽  
Surface Strain ◽  
Image Correlation ◽  
Fracture Model ◽  
Articular Fracture ◽  
Short Fragment ◽  
Working Length ◽  
Compression Plate ◽  
Short Working

Abstract Objective This investigation compared the biomechanical properties of a 2.0 mm locking compression notched head T-plate (NHTP) and 2.0 mm straight locking compression plate (LCP), in a simple transverse juxta-articular fracture model. Study Design Two different screw configurations were compared for the NHTP and LCP, modelling short (configuration 1) and long working length (configuration 2). Constructs were tested in compression, perpendicular and tension non-destructive four point bending and torsion. Plate surface strain was measured at 12 regions of interest (ROI) using three-dimensional digital image correlation. Stiffness and strain were compared between screw configurations within and between each plate. Results The LCP was stiffer than the NHTP in all three planes of bending and torsion (p < 0.05). The NHTP had greater strain than the LCP during compression bending and torsion at all ROI (p < 0.0005). The short working length was stiffer in all three planes of bending and in torsion (p < 0.05) than the longer working length for both plates. The long working length showed greater strain than the short working length at most ROI. Conclusion In this experimental model, a 2.0 mm LCP with two screws in the short fragment was significantly stiffer and had lower plate strain than a 2.0 mm NHTP with three screws in the short fragment. Extending the working length significantly reduced construct stiffness and increased plate strain. These findings may guide construct selection.

scholarly journals Effect of Plate Type and Working Length on a Synthetic Compressed Juxta-Articular Fracture Model

VCOT Open ◽  
2020 ◽  
Vol 03 (02) ◽  
pp. e119-e128
Author(s):  
Guy Bird ◽  
Mark Glyde ◽  
Giselle Hosgood ◽  
Alex Hayes ◽  
Rob Day
Keyword(s):  
Three Dimensional ◽  
Biomechanical Properties ◽  
Regions Of Interest ◽  
Surface Strain ◽  
Image Correlation ◽  
Fracture Model ◽  
Short Fragment ◽  
Working Length ◽  
Multiple Regions ◽  
Short Working

Abstract Objective This investigation compared the biomechanical properties of a 2.0 mm locking compression notched head T-plate (NHTP) and 2.0 mm straight locking compression plate (LCP), in a compressed, short, juxta-articular fragment fracture model. Methods Two different screw configurations were compared for the NHTP and LCP, modelling short (configuration 1) and long working length (configuration 2). Constructs were tested in compression, perpendicular and tension four-point bending and torsion. Plate surface strain was measured at 12 regions of interest using three-dimensional digital image correlation. Stiffness and strain were compared. Results The LCP was stiffer than the NHTP in all three planes of bending (p < 0.05). The NHTP was stiffer than the LCP in torsion (p < 0.05). The NHTP had greater strain than the LCP during compression bending and torsion (p < 0.0005). The short working length NHTP was stiffer in all three planes of bending and in torsion (p < 0.05) than the longer working length. The short working length LCP was stiffer in compression bending and in torsion (p < 0.05) than the longer working length. The long working length showed greater strain than the short working length at multiple regions of interest. Conclusion In this experimental model of a compressed transverse fracture with a juxta-articular 9 mm fragment, a 2.0 mm LCP with two hybrid screws in the short fragment was stiffer than a 2.0 mm NHTP with three locking screws in the short fragment in three planes of bending but not torsion. Extending the working length of each construct reduced construct stiffness and increased plate strain.

The effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs under axial load

2016 ◽  
Vol 29 (06) ◽  
pp. 451-458 ◽  
Author(s):  
Mark Glyde ◽  
Robert Day ◽  
Giselle Hosgood ◽  
Tim Pearson
Keyword(s):  
Large Diameter ◽  
Three Dimensional ◽  
Fracture Site ◽  
Locking Compression Plate ◽  
Image Correlation ◽  
Lower Strain ◽  
Working Length ◽  
Significant Difference ◽  
Compression Plate ◽  
Short Working

SummaryObjective: To investigate the effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs.Methods: A synthetic bone model with a 40 mm fracture gap was used. Locking compression plates with monocortical locking screws were tested with no pin (LCP-Mono) and intramedullary pins of 20% (LCPR-20), 30% (LCPR-30) and 40% (LCPR-40) of intramedullary diameter. Two screws per fragment modelled a long (8-hole) and short (4-hole) plate working length. Strain responses to axial compression were recorded at six regions of the plate via three-dimensional digital image correlation.Results: The addition of a pin of any size provided a significant decrease in plate strain. For the long working length, LCPR-30 and LCPR-40 had significantly lower strain than the LCPR-20, and plate strain was significantly higher adjacent to the screw closest to the fracture site. For the short working length, there was no significant difference in strain across any LCPR constructs or at any region of the plate. Plate strain was significantly lower for the short working length compared to the long working length for the LCP-Mono and LCPR-20 constructs, but not for the LCPR-30 and LCPR-40 constructs.Clinical significance: The increase in plate strain encountered with a long working length can be overcome by the use of a pin of 30–40% intramedullary diameter. Where placement of a large diameter pin is not possible, screws should be placed as close to the fracture gap as possible to minimize plate strain and distribute it more evenly over the plate.

Flexural Behavior of a Layer-to-Layer Orthogonal Interlocked Three-Dimensional Textile Composite

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
D. Zhang ◽  
A. M. Waas ◽  
M. Pankow ◽  
C. F. Yen ◽  
S. Ghiorse
Keyword(s):  
Mechanical Response ◽  
Peak Load ◽  
Three Dimensional ◽  
Peak Stress ◽  
Surface Strain ◽  
Image Correlation ◽  
Flexural Behavior ◽  
Fe Model ◽  
Textile Composite ◽  
The Matrix

The flexural response of a three-dimensional (3D) layer-to-layer orthogonal interlocked textile composite has been investigated under quasi-static three-point bending. Fiber tow kinking on the compressive side of the flexed specimens has been found to be a strength limiting mechanism for both warp and weft panels. The digital image correlation (DIC) technique has been utilized to map the deformation and identify the matrix microcracking on the tensile side prior to the peak load in the warp direction loaded panels. It has been shown that the geometrical characteristics of textile reinforcement play a key role in the mechanical response of this class of material. A 3D local–global finite element (FE) model that reflects the textile architectures has been proposed to successfully capture the surface strain localizations in the predamage region. To analyze the kink banding event, the fiber tow is modeled as an inelastic degrading homogenized orthotropic solid in a state of plane stress based on Schapery Theory (ST). The predicted peak stress is in agreement with the tow kinking stress obtained from the 3D FE model.

scholarly journals The effect of intramedullary pin size and monocortical screw configuration on locking compression plate-rod constructs in an in vitro fracture gap model

2015 ◽  
Vol 28 (02) ◽  
pp. 95-103 ◽  
Author(s):  
M. Glyde ◽  
G. Hosgood ◽  
R. Day ◽  
T. Pearson
Keyword(s):  
Locking Compression Plate ◽  
Axial Stiffness ◽  
Four Point Bending ◽  
Maximum Stiffness ◽  
Locking Compression Plates ◽  
Working Length ◽  
Compression Plate ◽  
Load To Failure ◽  
Short Plate

SummaryObjective: To investigate the effect of intramedullary pin size in combination with various monocortical screw configurations on locking compression plate-rod constructs.Methods: A synthetic bone model with a 40 mm fracture gap was used. Locking compression plates with monocortical locking screws were tested with no pin (LCP-Mono) and intramedullary pins of 20% (LCPR-20), 30% (LCPR-30) and 40% (LCPR-40) of intramedullary diameter. Locking compression plates with bicortical screws (LCP-Bi) were also tested. Screw configurations with two or three screws per fragment modelled long (8-hole), intermediate (6-hole), and short (4-hole) plate working lengths. Responses to axial compression, biplanar four-point bending and axial load-to-failure were recorded.Results: LCP-Bi were not significantly different from LCP-Mono control for any of the outcome variables. In bending, LCPR-20 were not significantly different from LCP-Bi and LCP-Mono. The LCPR-30 were stiffer than LCPR-20 and the controls. The LCPR-40 constructs were stiffer than all other constructs. The addition of an intramedullary pin of any size provided a significant increase in axial stiffness and load to failure. This effect was incremental with increasing intramedullary pin diameter. As plate working length decreased there was a significant increase in stiffness across all constructs.Clinical significance: A pin of any size increases resistance to axial loads whereas a pin of at least 30% intramedullary diameter is required to increase bending stiffness. Short plate working lengths provide maximum stiffness. However, the overwhelming effect of intramedullary pin size obviates the effect of changing working length on construct stiffness.

scholarly journals A method for predicting the blasting pressure of balloons using the surface strain in low pressure

2019 ◽  
Vol 11 (10) ◽  
pp. 168781401988155
Author(s):  
Yong-Zheng Shen ◽  
Guo-Chang Lin ◽  
Hui-Feng Tan
Keyword(s):  
Internal Pressure ◽  
Correction Factor ◽  
Three Dimensional ◽  
Reference Value ◽  
Surface Strain ◽  
Test Strain ◽  
Image Correlation ◽  
Correlation Technique ◽  
Maximum Test ◽  
Novel Method

Balloons made by cut fabric pieces are widely used in space research. To predict the blasting pressure of a balloon, we propose a novel method based on the non-contact test strain at a low internal pressure. The three-dimensional digital image correlation technique is introduced to measure the surface strain of the balloon. Representative regions of the balloon are selected as the test regions. A correction factor is proposed that accounts for the relationship between the internal pressure and the surface strain for the actual and the ideal balloon. By combining the maximum surface strain at a given internal pressure and the correction factor, we can predict the blasting pressure of the balloon. A blasting test is carried out to verify the feasibility of the predictive method. When the value of the ratio of the maximum test strain to the limiting strain reaches about a reference value, the absolute value of the deviation percentage between the predicted blasting pressure and the actual blasting pressure is less than 10%. The blasting pressure for balloon can be predicted accurately. This method does not require the balloon to be inflated to a high internal pressure, which improves the practicality of the prediction.

Nonlinear Membrane Direct and Inverse FEM Analysis

2014 ◽  
Author(s):  
Mattia Alioli ◽  
Pierangelo Masarati ◽  
Marco Morandini ◽  
Trenton Carpenter ◽  
Roberto Albertani
Keyword(s):  
Three Dimensional ◽  
Fem Analysis ◽  
Solution Procedure ◽  
General Purpose ◽  
Inverse Solution ◽  
Surface Strain ◽  
Image Correlation ◽  
Direct Solution ◽  
Strain Measurements ◽  
Solution Approach

The analysis of thin structural components integrated within a general-purpose multibody system dynamics formulation is presented. An original inverse finite element solution procedure is developed to reconstruct the deformed shape of a membrane from in-plane membrane strain measurements, and eventually indirectly estimate the distributed loads. A direct solution approach is used in co-simulation with fluid-dynamics solvers to predict the configuration of the system under static and unsteady loads. Numerical validation of the inverse solution is performed considering the results of direct solution analysis. The direct and inverse solutions are validated considering experimental displacement and strain measurements obtained using digital image correlation. Moving Least Squares are used to smooth and remap measurements as needed by the inverse solution meshing. Utilizing surface strain measurements from strain sensors, the methodology enables the accurate computation of the three-dimensional displacement field.

Deformation Measurements and Material Property Estimation of Mouse Carotid Artery Using a Microstructure-Based Constitutive Model

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Jinfeng Ning ◽  
Shaowen Xu ◽  
Ying Wang ◽  
Susan M. Lessner ◽  
Michael A. Sutton ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Constitutive Model ◽  
Vascular Tissue ◽  
Three Dimensional ◽  
Tensile Loading ◽  
Surface Strain ◽  
Image Correlation ◽  
Element Analysis ◽  
Constitutive Parameters ◽  
Deformation Measurements

A series of pressurization and tensile loading experiments on mouse carotid arteries is performed with deformation measurements acquired during each experiment using three-dimensional digital image correlation. Using a combination of finite element analysis and a microstructure-based constitutive model to describe the response of biological tissue, the measured surface strains during pressurization, and the average axial strains during tensile loading, an inverse procedure is used to identify the optimal constitutive parameters for the mouse carotid artery. The results demonstrate that surface strain measurements can be combined with computational methods to identify material properties in a vascular tissue. Additional computational studies using the optimal material parameters for the mouse carotid artery are discussed with emphasis on the significance of the qualitative trends observed.

scholarly journals The effects of locking inserts and overtorque on the mechanical properties of a large fragment locking compression plate

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Kathleen N. Meyers ◽  
Timothy S. Achor ◽  
Mark L. Prasarn ◽  
Jaimo Ahn ◽  
Kevin Khalsa ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Locking Compression Plate ◽  
Control Group ◽  
Insertion Torque ◽  
Large Fragment ◽  
Defect Groups ◽  
Working Length ◽  
Compression Plate ◽  
Cycles To Failure

Abstract Purpose The study was to determine the effect of locking hole inserts and their insertion torque on the fatigue life of a large fragment Locking Compression Plate (LCP) under bending forces. Methods Fatigue strength of the LCP was examined using cyclic three-point bend testing at 80% yield strength of the construct. Locking hole inserts were used in 2, 4, and 6-hole of a 12-hole plate to simulate three different working lengths. Within each working length, plates were tested without locking inserts serving as the control group. In the experimental groups, inserts were tightened to manufacturer recommendations (4 Nm) and using overtorque (8 Nm). Results Significantly fewer cycles to failure were observed in control groups versus the locking hole insert groups for all working lengths (2-hole: 4 Nm p = 0.003, 8 Nm p = 0.003; 4-hole: 4 Nm p = 0.02, 8 Nm p < 0.001; 6-hole: 4 Nm p = 0.004, 8 Nm p < 0.001). There was a statistically significant increase in fatigue strength when using overtorque in the 4-hole (p = 0.04) and 6-hole (p = 0.01) defect groups. This was not shown in the 2-hole defect group (p = 0.99). Conclusions By placing locking inserts in the empty locking regions of Combi holes along the working length, the number of cycles to failure was increased. Tightening inserts to twice the recommended insertion torque further increased cycles to failure in longer working length models. A longer fatigue life has the potential to decease the incidence of plate failure especially in the setting of delayed union due to poor intrinsic healing capacity, fractures in the geriatric population, osteoporosis and periprosthetic fractures.

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