A Biomechanical Comparative Analysis of Two Techniques for Tibiotalar Arthrodesis

1994 ◽  
Vol 15 (6) ◽  
pp. 301-305 ◽  
Author(s):  
Robert L. Friedman ◽  
Richard R. Glisson ◽  
James A. Nunley
Keyword(s):  
Laboratory Testing ◽  
Biomechanical Analysis ◽  
Torsional Motion ◽  
Bending Tests ◽  
Torsional Testing ◽  
Fusion Site ◽  
Fresh Frozen ◽  
Tibiotalar Arthrodesis ◽  
Cancellous Screws ◽  
Cantilever Bending

Two commonly used techniques for tibiotalar fusion were quantitatively compared using instrumented testing of the strength of the construct. The tibiae and tali from 10 pairs of fresh-frozen cadaveric limbs were used. One joint of each pair was fused using two 6.5-mm crossed cancellous screws from proximal to distal while the contralateral joint was fused using two 6.5-mm parallel cancellous screws from distal to proximal. Each specimen was subjected to cantilever bending and torsional testing by servohydraulic actuators. The bending tests included plantarflexion, dorsiflexion, inversion, and eversion, and measured the load during deflection applied 10 cm distal to the fusion site. The rigidity was expressed as newtons per millimeter of deflection. The torsional tests measured construct stiffness in external and internal rotation, and were expressed as newton-meters per degree of rotation. For the bending tests, the crossed screw construct was more rigid in eversion (23.1 N/mm, P = .0004) and dorsiflexion (16.9 N/mm, P = .02), while the parallel screw construct was more rigid in inversion (22.8 N/mm, P = .02) and plantarflexion (22.3 N/mm, P = .0007). In torsional testing, the crossed screw construct was at least 1.5 times stiffer than the parallel screw construct in resisting internal (1.7 N-m/deg versus 0.9 N-m/deg, P = .0001) and external (1.4 N-m/deg versus 0.9 N-m/deg, P = .02) rotation. In laboratory testing, the crossed screw technique is more rigid than the parallel screws, especially in resisting torsional stresses. Assuming that a stronger construct is desirable, and given that short leg casts commonly used after such fusions do not completely restrict torsional motion, this biomechanical analysis suggests that the crossed screw technique improves the likelihood of a successful arthrodesis.

Biomechanical Analysis of Conventional Partially Threaded Screws Versus Headless Compression Screws in Proximal Fifth Metatarsal (Jones) Fracture Fixation

2020 ◽  
pp. 193864002093166
Author(s):  
Kenrick Lam ◽  
Roger Bui ◽  
Randal Morris ◽  
Vinod Panchbhavi
Keyword(s):  
Biomechanical Analysis ◽  
Therapeutic Level ◽  
Compression Screw ◽  
Significant Difference ◽  
Headless Compression Screws ◽  
Fresh Frozen ◽  
Cantilever Bending ◽  
Fracture Stiffness ◽  
Intramedullary Screw ◽  
Cadaveric Model

Background. Intramedullary screw fixation of Jones fractures using partially threaded screws is a common method of fixation for these injuries, but refracture continues to be a problem. Various other fixation strategies, such as headless compression screws, plantar plating, and tension-band wiring. have been developed to mitigate these issues. Biomechanical studies with regard to these other fixation strategies are limited. Herein, we investigate the compression strength and angular stiffness of Jones fractures fixed with Herbert-style headless compression screws. Methods. Jones fractures were created in 10 fresh-frozen pairs of cadaveric fifth metatarsals. A bone from each pair was instrumented with either a conventional, partially threaded screw 5.0 or 6.5 mm in diameter, or a headless compression screw 5.0 or 7.0 mm in diameter. Sizes were determined via sequential tapping until a snug fit was obtained. Each metatarsal was stressed via cantilever bending over 1000 cycles. We monitored compression and displacement throughout. Results. Headless compression screws achieved a significantly higher amount of stiffness than conventional, partially threaded screws (P = 0.005). There was no statistically significant difference with respect to compression. Conclusion. In a cadaveric model, headless compression screws achieved a greater amount of fracture stiffness versus conventional, partially threaded screws. Levels of Evidence: Therapeutic, Level V: Biomechanical

scholarly journals Biomechanical analysis of four external fixation pin insertion techniques

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Dillon Arango ◽  
Nathan Tiedeken ◽  
Benjamin Clippinger ◽  
Solomon Praveen Samuel ◽  
Vilas Saldanha ◽  
...  
Keyword(s):  
Stainless Steel ◽  
External Fixation ◽  
Biomechanical Analysis ◽  
Testing System ◽  
Insertion Technique ◽  
Bending Tests ◽  
Three Point Bending ◽  
Bending Load ◽  
Insertion Techniques ◽  
Cantilever Bending

Having multiple external fixation pin designs and insertion techniques has led to debate as to which combination creates the stiffest construct. This study sought to biomechanically evaluate construct strength using self-drilling (SD) and self-tapping (ST) pins inserted with either bicortical or unicortical fixation. SD and ST 5.0 mm stainless steel pins were used in combination with bicortical self-drilling (BCSD), bicortical self-tapping (BCST), unicortical self-drilling (UCSD), and unicortical selftapping (UCST) techniques. Pre-drilling for the self-tapping pins was completed with a 4.0 mm drill bit using ¾ inch polyvinyl chloride (PVC) pipe as the insertional medium. The PVC pin constructs were then loaded to failure in a cantilever bending method using a mechanical testing system. Ten trials of each technique were analyzed. BCSD insertion technique had the highest maximum failure force and stiffness of all tested techniques (P<0.0001). SD pins were significantly stronger to bending forces than ST pins in both the unicortical and bicortical setting (P<0.0001). Three point bending tests of the 5.0 mm SD and ST threaded area showed that threaded portion of the SD pins had a 300 N greater maximum failure force than the ST pins. Biomechanical analysis of external fixation pin insertion techniques demonstrates that bicortical fixation with SD pins achieved the greatest resistance to bending load. Despite both pins being 5.0 mm and constructed from stainless steel, ST and SD behaved differently with regard to maximum failure force and stiffness. This study demonstrates that insertion technique and pin selection are both important variables when attempting to achieve a stiff external fixation construct.

scholarly journals Seawater effects on static loads and interlayer cracking performance for polyvinyl chloride foam-cored sandwich composites

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880734
Author(s):  
Jian He ◽  
Dongyuan Xie ◽  
Qichao Xue ◽  
Yangyang Zhan
Keyword(s):  
Energy Release ◽  
Polyvinyl Chloride ◽  
Glass Fibre ◽  
Critical Energy ◽  
Bending Tests ◽  
Rate Dependent ◽  
Reinforced Plastic ◽  
Glass Fibre Reinforced Plastic ◽  
Glass Fibre Reinforced ◽  
Cantilever Bending

The diffusion influence of seawater on the static and interlayer cracking properties of a polyvinyl chloride foam sandwich structure is investigated in this study. After soaking specimens in seawater for various durations, various comparison tests are performed to investigate the effects of seawater. Compression tests for H60 and H200 polyvinyl chloride foam specimens are conducted to study strength and modulus degradation, and the results show that immerging time and temperature have significant effects on polyvinyl chloride foam properties. Tensile tests for glass-fibre-reinforced plastic panels, four-point bending tests and double cantilever bending tests for polyvinyl chloride foam sandwich specimens are also performed. The results show that seawater immerging treatment has a noticeable influence on glass-fibre-reinforced plastic tensile properties and interlayer critical energy release rate values, but has almost no effect on bending properties of foam sandwich specimen. Furthermore, a rate-dependent phenomenon is observed in double cantilever bending tests, in which higher loading rate will lead to larger critical energy release values. Numerical simulation is also performed to illustrate the cracking process of double cantilever bending tests and shows a certain accuracy. The simulation also demonstrates that the viscoelasticity of foam material after immerging treatment results in the rate-dependent characterization of double cantilever bending tests.

scholarly journals Prediction of steel resistance to stress corrosion cracking in seawater based on accelerated tests and structural studies

2019 ◽  
Vol 121 ◽  
pp. 04009
Author(s):  
Svetlana Mushnikova ◽  
Oleg Kharkov
Keyword(s):  
Structural Phase ◽  
Real Life ◽  
Austenitic Stainless Steels ◽  
Test Results ◽  
Mechanical Fracture ◽  
Bending Tests ◽  
Laboratory Test Results ◽  
Resistance To Stress ◽  
Concentrated Solution ◽  
Cantilever Bending

The paper presents the tests results of resistance of various structural steel classes to SCC in chloride solutions. The experiments were performed using cantilever bending tests developed by NRC “Kurchatov Institute” – CRISM “Prometey” with stepwise increasing load of Charpy-type precracking specimens. The criterion estimation of resistance to SCC when β = σSCC/σC > 0.85 was confirmed by the laboratory test results compared with the case studies of corrosion-mechanical fracture of shipbuilding structures in real life service conditions. A new approach of SCC susceptibility of austenitic stainless steels in marine conditions is proposed. It is based on estimation of the critical temperature of SCC when testing for SSRT in a concentrated solution of calcium chloride at temperatures from 20°C to 100°C. Specific features of the structural-phase composition of steels that detrimentally affect the resistance to SCC were discovered during the complex testing.

Biomechanical Measurements of Stiffness and Strength for Five Types of Whole Human and Artificial Humeri

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Mina S. R. Aziz ◽  
Bruce Nicayenzi ◽  
Meghan C. Crookshank ◽  
Habiba Bougherara ◽  
Emil H. Schemitsch ◽  
...  
Keyword(s):  
Bending Strength ◽  
Shear Stiffness ◽  
Shaft Fracture ◽  
Biomechanical Properties ◽  
Torsional Stiffness ◽  
Mineral Density ◽  
Statistical Equivalence ◽  
Fresh Frozen ◽  
Cantilever Bending ◽  
Loading Modes

The human humerus is the third largest longbone and experiences 2–3% of all fractures. Yet, almost no data exist on its intact biomechanical properties, thus preventing researchers from obtaining a full understanding of humerus behavior during injury and after being repaired with fracture plates and nails. The aim of this experimental study was to compare the biomechanical stiffness and strength of “gold standard” fresh-frozen humeri to a variety of humerus models. A series of five types of intact whole humeri were obtained: human fresh-frozen (n = 19); human embalmed (n = 18); human dried (n = 15); artificial “normal” (n = 12); and artificial “osteoporotic” (n = 12). Humeri were tested under “real world” clinical loading modes for shear stiffness, torsional stiffness, cantilever bending stiffness, and cantilever bending strength. After removing geometric effects, fresh-frozen results were 585.8 ± 181.5 N/mm2 (normalized shear stiffness); 3.1 ± 1.1 N/(mm2 deg) (normalized torsional stiffness); 850.8 ± 347.9 N/mm2 (normalized cantilever stiffness); and 8.3 ± 2.7 N/mm2 (normalized cantilever strength). Compared to fresh-frozen values, statistical equivalence (p ≥ 0.05) was obtained for all four test modes (embalmed humeri), 1 of 4 test modes (dried humeri), 1 of 4 test modes (artificial “normal” humeri), and 1 of 4 test modes (artificial “osteoporotic” humeri). Age and bone mineral density versus experimental results had Pearson linear correlations ranging from R = −0.57 to 0.80. About 77% of human humeri failed via a transverse or oblique distal shaft fracture, whilst 88% of artificial humeri failed with a mixed transverse + oblique fracture. To date, this is the most comprehensive study on the biomechanics of intact human and artificial humeri and can assist researchers to choose an alternate humerus model that can substitute for fresh-frozen humeri.

scholarly journals Hip Capsular Closure: A Biomechanical Analysis of Failure Torque

2016 ◽  
Vol 45 (2) ◽  
pp. 434-439 ◽  
Author(s):  
Jorge Chahla ◽  
Jacob D. Mikula ◽  
Jason M. Schon ◽  
Chase S. Dean ◽  
Kimi D. Dahl ◽  
...  
Keyword(s):  
External Rotation ◽  
Arthroscopic Surgery ◽  
Testing Machine ◽  
Biomechanical Analysis ◽  
Biaxial Testing ◽  
Improved Outcomes ◽  
Significant Difference ◽  
Fresh Frozen ◽  
Hip Capsule ◽  
Optimal Quantity

Background: Hip capsulotomy is routinely performed during arthroscopic surgery to achieve adequate exposure of the joint. Iatrogenic instability can result after hip arthroscopic surgery because of capsular insufficiency, which can be avoided with effective closure of the hip capsule. There is currently no consensus in the literature regarding the optimal quantity of sutures upon capsular closure to achieve maximal stability postoperatively. Purpose/Hypothesis: The purpose of this study was to determine the failure torques of 1-, 2-, and 3-suture constructs for hip capsular closure to resist external rotation and extension after standard anterosuperior interportal capsulotomy (12 to 3 o’clock). Additionally, the degree of external rotation at which the suture constructs failed was recorded. The null hypothesis of this study was that no significant differences with respect to the failure torque would be found between the 3 repair constructs. Study Design: Controlled laboratory study. Methods: Nine pairs (n = 18) of fresh-frozen human cadaveric hemipelvises underwent anterosuperior interportal capsulotomy, which were repaired with 1, 2, or 3 side-to-side sutures. Each hip was secured in a dynamic biaxial testing machine and underwent a cyclic external rotation preconditioning protocol, followed by external rotation to failure. Results: The failure torque of the 1-suture hip capsular closure construct was significantly less than that of the 3-suture construct. The median failure torque for the 1-suture construct was 67.4 N·m (range, 47.4-73.6 N·m). The median failure torque was 85.7 N·m (range, 56.9-99.1 N·m) for the 2-suture construct and 91.7 N·m (range, 74.7-99.0 N·m) for the 3-suture construct. All 3 repair constructs exhibited a median 36° (range, 22°-64°) of external rotation at the failure torque. Conclusion: The most important finding of this study was that the 2- and 3-suture constructs resulted in comparable biomechanical failure torques when external rotation forces were applied to conventional hip capsulotomy in a cadaveric model. The 3-suture construct was significantly stronger than the 1-suture construct; however, there was not a significant difference between the 2- and 3-suture constructs. Additionally, all constructs failed at approximately 36° of external rotation. Clinical Relevance: Re-establishing the native anatomy of the hip capsule after hip arthroscopic surgery has been reported to result in improved outcomes and reduce the risk of iatrogenic instability. Therefore, adequate capsular closure is important to restore proper hip biomechanics, and postoperative precautions limiting external rotation should be utilized to protect the repair.

scholarly journals A quantitative, biomechanical analysis of radioulnar deviation between fresh frozen and soft embalmed human forearms

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Craig Bradley Casier ◽  
Ron Easteal ◽  
Rick Sellens ◽  
Andrew Dickinson ◽  
Jessica Clark
Keyword(s):  
Biomechanical Analysis ◽  
Fresh Frozen

scholarly journals Micro-cantilever bending tests for understanding size effect in gradient elasticity

2022 ◽  
pp. 110398
Author(s):  
Jae-Hoon Choi ◽  
Hojang Kim ◽  
Ji-Young Kim ◽  
Kwang-Hyeok Lim ◽  
Byung-Chai Lee ◽  
...  
Keyword(s):  
Size Effect ◽  
Gradient Elasticity ◽  
Bending Tests ◽  
Micro Cantilever ◽  
Cantilever Bending

Surface Modification of Steel Using Liquid Jet Peening (Fatigue Performance)

2007 ◽  
Vol 539-543 ◽  
pp. 1140-1145
Author(s):  
R. Gnanamoorthy ◽  
A. Sahaya Grinspan
Keyword(s):  
Residual Stress ◽  
Surface Modification ◽  
Residual Stresses ◽  
Liquid Jet ◽  
Bending Tests ◽  
Modification Process ◽  
Improved Performance ◽  
Cantilever Bending ◽  
Oil Jet ◽  
Compressive Residual Stresses

Oil jet peening is a surface modification process developed for the introduction of compressive residual stresses. In this process, a high-pressure oil jet impinges on the surface to be peened. Specimens made of AISI 1040 steel were peened at oil pressure of 50 MPa. Residual stresses induced on the oil jet peened specimen was in the order of -200 MPa. Standoff distance influenced the residual stress induced and also the erosion and surface roughness. Fully reversed cantilever bending tests conducted on the peened and unpeened conditions revealed the improved performance of the oil jet peened specimens.

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