scholarly journals Comparative Pull-Out Performances of Cephalomedullary Nail with Screw and Helical Blade According to Femur Bone Densities

2021 ◽  
Vol 11 (2) ◽  
pp. 496
Author(s):  
Young-Chang Park ◽  
Dong-Sik Chae ◽  
Kyung-Yil Kang ◽  
Yao Ding ◽  
Sung-Jun Park ◽  
...  
Keyword(s):  
Bone Density ◽  
Elderly Person ◽  
Normal Person ◽  
Foam Density ◽  
Compression Tests ◽  
Cephalomedullary Nail ◽  
Pull Out ◽  
Helical Blade ◽  
Biomedical Polyurethane ◽  
Method Analysis

This paper mainly examines the fixation performances of the cephalomedullary nail for the incidence of intertrochanteric (IT) fracture to guide the appropriate fixations with respect to the bone density in terms of a biomechanical perspective. It is substantially important to guide which types of fixation are applied during the operation since it tends to induce the backout or migration of the helical blade and screw according to weight and bone density. Biomedical polyurethane (PUR) foam blocks for simulating human bone are adopted with two grades of densities to simulate a normal person and an elderly person who has osteoporosis. Tensile and compression tests are conducted to analyze the tensile-compression anisotropy of PUR foams. Pull-out performances of screw and helical blades are evaluated from experimental perspectives, which are supported by comparison with the results of finite element method analysis. The clamping force of the screw is higher than the helical blade, about 177% in normal foam density and 198% in low foam density. After physical evaluation of the critical pull-out fixation force of screw and helical blade, we have suggested that stable fixation is guaranteed when the pull-out force is larger than projected force.

scholarly journals Estimation of compressive strength based on Pull-Out bond test results for on-site concrete quality control

2011 ◽  
Vol 4 (4) ◽  
pp. 582-591 ◽  
Author(s):  
M. S. Lorrain ◽  
M. P. Barbosa ◽  
L. C. P. Silva Fº
Keyword(s):  
Quality Control ◽  
Compressive Strength ◽  
Concrete Strength ◽  
Test Results ◽  
Compression Tests ◽  
Pull Out ◽  
Underlying Principle ◽  
Strength Based ◽  
Concrete Quality ◽  
Definition Of

Quality control of structural concrete has been conducted for several decades based mainly on the results of axial compression tests. This kind of test, although widely used, is not exempt from errors and has some considerable drawbacks that may affect its reliability, such as the need for appropriate and careful specimen conditioning and adoption of adequate capping techniques. For these reasons, it would be useful to have complementary or alternative ways to check compressive strength, in order to improve concrete quality control. The use of a bond test to monitor concrete strength is being proposed by an international group of researchers from France, Tunisia and Brazil as a potential means to this end. Given the fact that the link between bond resistance and concrete strength is already well established, this type of test seems to be a viable alternative to traditional methods. Nonetheless, to check if the underlying principle is sound when used in different circumstances, the group has been gathering data from several studies conducted by different researchers in various countries, with distinct concretes and rebar types. An analysis of the data collected shows that there is a clear and strong correlation between bond resistance and compressive strength, no matter the influence of other variables. This result validates the basic idea of using an Appropriate Pull-Out (APULOT) bond test to assess concrete strength. If the general principle is valid for random data obtained from different studies, the definition of a clear and appropriate test will probably lead to the reduction of experimental noise and increase the precision of the strength estimates obtained using this method.

Pull-Out and Push-Out Tests for Rubber-to Metal Adhesion

1989 ◽  
Vol 62 (4) ◽  
pp. 757-766 ◽  
Author(s):  
A. N. Gent ◽  
S. Y. Kaang
Keyword(s):  
Large Fraction ◽  
Theoretical Treatment ◽  
Total Force ◽  
Compression Tests ◽  
Cross Sectional ◽  
Pull Out ◽  
Good Accord ◽  
Compressive Loads ◽  
And Control ◽  
Push Out

Abstract A study has been carried out of adhesive failure forces for a steel rod embedded in and bonded to a rubber block. Emphasis has been placed on comparing tension (pull-out) and compression (push-out) forces. A fractional contribution to the pull-out force appeared to be significant for rods having a diameter greater than about 0.5 mm in the present experiments. Indeed, it became a large fraction of the total force when the rod diameter was 1 mm or more. On the other hand, it was negligibly small in push-out experiments. They would therefore be preferred on this basis for measuring the strength of adhesion. But experimental difficulties in carrying out compression tests are considerable. Tall blocks become unstable under large compressive loads, and short ones are markedly stiffer than long ones, due to restraints on their lateral expansion, which are difficult to specify and control. Thus, although measurements of push-out force for a wide variety of samples have been shown to be in good accord with a simple theoretical treatment of debonding, ignoring friction, it is recommended that pull-out tests be retained for assessing the strength of adhesive bonds. Caution is necessary to minimize the effect of friction. The theoretical treatment indicates that the product aL of the rod radius a and the embedded length L should be held smaller than the cross-sectional area of the block in which the rod is embedded.

Pullout strength of monocortical and bicortical screws in meta -physeal and diaphyseal regions of the canine humerus

2016 ◽  
Vol 29 (06) ◽  
pp. 466-474 ◽  
Author(s):  
Jason Alan Syrcle ◽  
John Ball ◽  
Steven Elder ◽  
Jennifer Michele Gambino ◽  
Russell Griffin ◽  
...  
Keyword(s):  
Bone Density ◽  
Cortical Thickness ◽  
Locking Plate ◽  
Plate Fixation ◽  
Humeral Fractures ◽  
Pullout Strength ◽  
Locking Plate Fixation ◽  
Pull Out ◽  
Screw Length ◽  
Monocortical Screws

Summary Objective: Monocortical screws are commonly employed in locking plate fixation, but specific recommendations for their placement are lacking and use of short monocortical screws in metaphyseal bone may be contra indicated. Objectives of this study were to evaluate axial pullout strength of two different lengths of monocortical screws placed in various regions of the canine humerus compared to bicortical screws, and to derive cortical thickness and bone density values for those regions using quantitative computed tomography analysis (QCT). Methods: The QCT analysis was performed on 36 cadaveric canine humeri for six regions of interest (ROI). A bicortical, short monocortical, or 50% transcortical 3.5 mm screw was implanted in each ROI and axial pullout testing was performed. Results: Bicortical screws were stronger than monocortical screws in all ROI except the lateral epicondylar crest. Short monocortical metaphyseal screws were weaker than those placed in other regions. The 50% transcortical screws were stronger than the short monocortical screws in the condyle. A linear relationship between screw length and pull-out strength was observed. Clinical significance: Cortical thickness and bone density measurements were obtained from multiple regions of the canine humerus using QCT. Use of short monocortical screws may contribute to failure of locking plate fixation of humeral fractures, especially when placed in the condyle. When bicortical screw placement is not possible, maximizing monocortical screw length may optimize fixation stability for distal humeral fractures.

Deflection of Cancellous Bone Screws Under a Cantilever Bending Load

2013 ◽  
Author(s):  
Carolina Vega ◽  
Maria Arshanskiy ◽  
Amrit Sagar ◽  
Anil Saigal ◽  
Thomas P. James ◽  
...  
Keyword(s):  
Bone Density ◽  
Cancellous Bone ◽  
Testing Machine ◽  
Bone Screws ◽  
Pull Out ◽  
Screw Length ◽  
Significant Difference ◽  
Bending Load ◽  
Bending Loads ◽  
Cantilever Bending

Surgical bone screws can be subjected to cyclic bending loads when plating constructs are used in the fixation of weight bearing members. While extensive research has been conducted on axial loading that leads to screw pull-out, there is a gap in our understanding of how asymmetric bending loads contribute to screw fracture. The focus of this research was to examine the effect of screw length (20 mm and 40 mm) and cancellous bone density (0.48 g/cm3 and 0.24 g/cm3) on the relative stiffness of 6.5 mm cancellous bone screws subjected to a cantilever bending load. It was hypothesized that longer screws in higher density cancellous bone would result in less screw deflection, supporting clinical practice. For testing, synthetic composite bone was used to simulate the characteristics of natural bone while subjecting screws to quasi-static loading with a universal testing machine. Contrary to the hypothesis, neither screw length nor cancellous bone density resulted in a statistically significant difference (p > 0.05) in deflection for loading up 450 N. The cortical shelf appeared to support the majority of the bending load through compression, rather than acting as a fulcrum. When the 3.0 mm cortex was removed, there was a significant difference in deflection due to both screw length and cancellous bone density.

Experimental investigation of pull-out performance of pedicle screws at different polyurethane (PU) foam densities

2021 ◽  
pp. 095441192110025
Author(s):  
Ahmet Çetin ◽  
Durmuş Ali Bircan
Keyword(s):  
Pedicle Screws ◽  
Poor Quality ◽  
Osteoporotic Bone ◽  
Foam Density ◽  
Pull Out ◽  
Pu Foam ◽  
Screw Diameter ◽  
Critical Materials ◽  
Materials Used ◽  
Force Displacement

Pedicle bone screws are one of the most critical materials used in spinal orthopaedic operations. Screw loosening and pull-out (PO) are basic complications encountered during or after surgery. Pull-out Strength (POS) of the bone is one of the significant parameters to understand the mechanical behaviour of a screw fixed to poor quality or osteoporotic bone. This study investigates how the POS of a pedicle screw is affected by the factors of the screw diameter and the polyurethane (PU) foam density by experimental analysis. In the experiments, two different diameter (5.5 and 6.5 mm) of conical pedicle screws and five different density (0.08, 0.16, 0.24, 0.32 and 0.48 g·cm−3) PU foams were used. According to the force-displacement curves obtained from experimental results, the POS increased with the increases in screw diameter and PU foam density.

scholarly journals Bone density optimized pedicle screw instrumentation improves screw pull-out force in lumbar vertebrae

2021 ◽  
pp. 1-11
Author(s):  
Sebastiano Caprara ◽  
Marie-Rosa Fasser ◽  
José Miguel Spirig ◽  
Jonas Widmer ◽  
Jess G. Snedeker ◽  
...  
Keyword(s):  
Bone Density ◽  
Pedicle Screw ◽  
Lumbar Vertebrae ◽  
Pedicle Screw Instrumentation ◽  
Pull Out

scholarly journals Treatment With Helical Blade Cephalomedullary Nail for Two-Part Basicervical Proximal Femoral Fracture in Elderly Patients: A Retrospective Observational Study

2017 ◽  
Vol 8 (4) ◽  
pp. 244-251 ◽  
Author(s):  
Ichiro Okano ◽  
Takatoshi Sawada ◽  
Nobumasa Kushima ◽  
Tetsuya Tachibana ◽  
Katsunori Inagaki
Keyword(s):  
Elderly Patients ◽  
Femoral Fracture ◽  
Proximal Femoral Fracture ◽  
Rotational Stability ◽  
Cephalomedullary Nail ◽  
Related Complication ◽  
Fracture Group ◽  
Helical Blade ◽  
Extracapsular Fracture

Background: Basicervical proximal femoral fracture is a known subtype of extracapsular fracture and is mechanically unstable, especially for the rotational direction, which may lead to implant failure. A cephalomedullary nail (CMN) is widely used for the fixation of unstable extracapsular fracture; however, its application for basicervical fracture remains controversial. Helical blade CMN is proven to have more rotational stability than traditional lag screw implants and potentially advantageous in the treatment of basicervical fracture. The aim of this study is to assess the effectiveness of helical blade CMN for basicervical fracture in elderly patients. Methods: We conducted a retrospective review of 500 consecutive extracapsular fracture patients treated surgically between January 2005 and February 2015. Patients who had trochanteric extension or multifragment fracture were excluded. Sixteen cases of 2-part basicervical proximal femoral fracture were identified. All patients were treated with the same single helical blade CMN system (DePuy Synthes PFNA-II). Implant-related complications were recorded. Results: Two patients dropped out during follow-up and 14 patients were included in the analysis. The average follow-up period was 21.9 months. No major complication was observed. The patients were subcategorized into 2 groups: nondisplaced (displacement <2 mm at any point of the fracture line) or displaced. Excessive telescoping was observed in 2 patients, both of whom were in the displaced fracture group. The overall implant-related complication rate was 14.2% (2/16). Conclusion: Internal fixation with the helical blade CMN system can be considered as a treatment option for 2-part basicervical proximal femoral fracture in elderly patients.

scholarly journals Comparative analysis of the lateral and posterolateral trajectories for fixation of the sacroiliac joint—a cadaveric study

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Christopher Payne ◽  
Stephen Jaffee ◽  
Isaac Swink ◽  
Daniel Cook ◽  
Matthew Yeager ◽  
...  
Keyword(s):  
Bone Density ◽  
Minimally Invasive ◽  
Cortical Bone ◽  
Volume Fraction ◽  
Bone Volume ◽  
Pull Out ◽  
Joint Fusion ◽  
Joint Gap ◽  
Cortical Density ◽  
Si Joint

Abstract Background A number of minimally invasive sacroiliac (SI) joint fusion solutions for placing implants exist, with reduced post-operative pain and improved outcomes compared to open procedures. The objective of this study was to compare two MIS SI joint fusion approaches that place implants directly across the joint by comparing the ilium and sacrum bone characteristics and SI joint separation along the implant trajectories. Methods Nine cadaveric specimens (n = 9) were CT scanned and the left and right ilium and sacrum were segmented. The bone density, bone volume fraction, and SI joint gap distance were calculated along lateral and posterolateral trajectories and compared using analysis of variance between the two orientations. Results Iliac bone density, indicated by the mean Hounsfield Unit, was significantly greater for each lateral trajectory compared to posterolateral. The volume of cortical bone in the ilium was greater for the middle lateral trajectory compared to all others and for the top and bottom lateral trajectories compared to both posterolateral trajectories. Cortical density was greater in the ilium for all lateral trajectories compared to posterolateral. The bone fraction was significantly greater in all lateral trajectories compared to posterolateral in the ilium. No differences in cortical volume, cortical density, or cancellous density were found between trajectories in the sacrum. The ilium was significantly greater in density compared with the sacrum when compared irrespective of trajectory (p < 0.001). The posterolateral trajectories had a significantly larger SI joint gap than the lateral trajectories (p < 0.001). Conclusion Use of the lateral approach for minimally invasive SI fusion allows the implant to interact with bone across a significantly smaller joint space. This interaction with increased cortical bone volume and density may afford better fixation with a lower risk of pull-out or implant loosening when compared to the posterolateral approach.

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