scholarly journals Mechanical Evaluation of Two Hybrid Locking Plate Designs for Canine Pancarpal Arthrodesis

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ivan Zderic ◽  
Peter Varga ◽  
Ursula Styger ◽  
Ludmil Drenchev ◽  
Boyko Gueorguiev ◽  
...  
Keyword(s):  
Locking Plate ◽  
Fixation Strength ◽  
Strain Gauges ◽  
Element Analysis ◽  
Plate Design ◽  
Increased Risk ◽  
Metacarpal Bones ◽  
Fixation Techniques ◽  
Screw Position ◽  
Two Hybrid

Hybrid locking pancarpal arthrodesis plates were designed with either a round (RH) or an oval (OH) radiocarpal hole, the latter allowing varied screw positioning. Due to concerns about potential decreased structural properties of the OH design, our aim was to compare the mechanical behavior of the contrasting plates using combined finite element analysis (FEA) and mechanical testing. Pancarpal arthrodesis plates with RH or OH design were assigned to three fixation techniques ( n = 6 ), prebent at 20°, and fixed to canine forelimb models with simulated radius and radiocarpal and 3rd metacarpal bones. OH plates were instrumented with a radiocarpal screw inserted either most proximal (OH-P) or most distal (OH-D). Specimens were axially loaded to 300 N over 10 ramped cycles at 0.5 Hz. Plate strains were measured with strain gauges placed at areas of highest deformations as predicted by FEA under identical loading conditions. FEA predicted the highest strains (μm/m) adjacent to the radiocarpal hole (2,500 [RH], 2,900 [OH-P/OH-D]) and plate bending point (2,250 [RH], 1,900 [OH-P/OH-D]). Experimentally, peak radiocarpal hole strains were not influenced by the OH screw position ( 3,329 ± 443 [OH-P], 3,222 ± 467 [OH-D]; P = 0.550 ) but were significantly higher compared to the RH design ( 2,123 ± 154 ; P < 0.001 ). Peak strains at the bending point were significantly lower for OH-P ( 1,792 ± 174 ) and OH-D ( 1,806 ± 194 ) versus RH configurations ( 2,158 ± 114 ) ( P ≤ 0.006 ). OH plates demonstrated highest peak strains next to the radiocarpal hole and were associated with more heterogenous plate strain distribution. Structural weakening associated with radiocarpal OH plate design could result in decreased fixation strength and increased risk of plate fatigue failure.

scholarly journals Biomechanical stability of complex coronal plane fracture fixation of the capitellum

2021 ◽  
Author(s):  
Paul Borbas ◽  
Rafael Loucas ◽  
Marios Loucas ◽  
Maximilian Vetter ◽  
Simon Hofstede ◽  
...  
Keyword(s):  
Fracture Fixation ◽  
Ultimate Load ◽  
Locking Plate ◽  
Distal Humerus ◽  
Coronal Plane ◽  
Fixation Strength ◽  
Biomechanical Stability ◽  
Significant Difference ◽  
Load To Failure ◽  
Headless Compression Screws

Abstract Introduction Coronal plane fractures of the distal humerus are relatively rare and can be challenging to treat due to their complexity and intra-articular nature. There is no gold standard for surgical management of these complex fractures. The purpose of this study was to compare the biomechanical stability and strength of two different internal fixation techniques for complex coronal plane fractures of the capitellum with posterior comminution. Materials and methods Fourteen fresh frozen, age- and gender-matched cadaveric elbows were 3D-navigated osteotomized simulating a Dubberley type IIB fracture. Specimens were randomized into one of two treatment groups and stabilized with an anterior antiglide plate with additional anteroposterior cannulated headless compression screws (group antiGP + HCS) or a posterolateral distal humerus locking plate with lateral extension (group PLP). Cyclic testing was performed with 75 N over 2000 cycles and ultimately until construct failure. Data were analyzed for displacement, construct stiffness, and ultimate load to failure. Results There was no significant difference in displacement during 2000 cycles (p = 0.291), stiffness (310 vs. 347 N/mm; p = 0.612) or ultimate load to failure (649 ± 351 vs. 887 ± 187 N; p = 0.140) between the two groups. Conclusions Posterolateral distal humerus locking plate achieves equal biomechanical fixation strength as an anterior antiglide plate with additional anteroposterior cannulated headless compression screws for fracture fixation of complex coronal plane fractures of the capitellum. These results support the use of a posterolateral distal humerus locking plate considering the clinical advantages of less invasive surgery and extraarticular metalware. Level of evidence Biomechanical study.

Distal radius fractures – A volar plate is not just a volar plate

Trauma ◽  
2017 ◽  
Vol 20 (3) ◽  
pp. 203-207
Author(s):  
Richard Knight ◽  
Lucy Elliott ◽  
Mark Brewster ◽  
Michelle Spiteri ◽  
Dominic Power
Keyword(s):  
Distal Radius ◽  
Locking Plate ◽  
Cost Savings ◽  
Fracture Pattern ◽  
Distal Radius Fractures ◽  
Volar Plate ◽  
Radius Fractures ◽  
Potential Cost ◽  
Plate Design ◽  
Column Variable

Introduction Increasingly complex distal radius plate designs are available for treating distal radius fractures. As a result, many fractures are being ‘over-treated’ with more complex volar plate designs than necessary. We hypothesise that significant cost savings could be made by rationalising the use of complex locking plate designs. Methods Over a two-year period, radiographs of 250 consecutive distal radius fractures fixed with volar locking plates were reviewed and the type of plate, and type and number of screws used for fixation were noted. Preoperative radiographs were independently reviewed to ascertain if it would have been possible to stabilise the fracture with a simpler, extra-articular plate design. Potential cost savings were then calculated. Results It was deemed that 89 (36.5%) of the 250 cases originally treated with a more complex 2 column variable angle plate could have been treated with an extra-articular construct, leading to potential savings of £19,224. Conclusion It is clear from our data that many distal radius fracture patterns are being ‘over-treated’ with complex locking plate designs with multiple rows of screws and that substantial cost savings could be made by selecting an appropriate construct to suit the fracture pattern.

Clinical Application and Outcomes of Upper Extremity Double Plating

2019 ◽  
Vol 158 (02) ◽  
pp. 227-237 ◽  
Author(s):  
J. Christoph Katthagen ◽  
Benedikt Schliemann ◽  
Philipp A. Michel ◽  
Lukas F. Heilmann ◽  
Felix Dyrna ◽  
...  
Keyword(s):  
Upper Extremity ◽  
Mechanical Stability ◽  
Distal Humerus ◽  
Fixation Strength ◽  
Anterior Plate ◽  
Proximal Ulna ◽  
Lesser Tuberosity ◽  
Dual Plating ◽  
Fixation Techniques ◽  
Complex Proximal Humeral Fractures

AbstractDual plating in fractures of the upper extremity is well established for the distal humerus. The indication for the use of dual plating has been expanded over the last few years. While dual plating was originally frequently used in revisions of non-unions, it is nowadays also used in primary fixation of diverse complex fractures of the upper extremity. The high biomechanical fixation strength of dual plating is advantageous in regions with high bending and torsional stresses, such as the humeral shaft. An additional anterior plate provides high fixation strength and reduces the risk of loss of reduction in complex proximal humeral fractures and allows for direct fixation of lesser tuberosity fragments. Low-profile plates have been introduced for complex proximal ulna fractures. In dual plating the improved mechanical stability is combined with a reduced risk of implant related soft tissue irritations. The present article provides an overview of current indications for dual plating of upper extremity fractures and outlines technical aspects as well as advantages over conventional fixation techniques.

scholarly journals Increased Risk of Cut-out With the use of 45 mm Screws or Longer When Fixing Proximal Humerus Fracture With a Locking Plate

2019 ◽  
Vol 3 (4) ◽  
pp. 256
Author(s):  
Dominique M. Rouleau ◽  
Philippe Moisan ◽  
Julien Goulet ◽  
G.-Yves Laflamme
Keyword(s):  
Proximal Humerus Fracture ◽  
Locking Plate ◽  
Proximal Humerus ◽  
Humerus Fracture ◽  
Increased Risk

scholarly journals Finite Element- and Design of Experiment-Derived Optimization of Screw Configurations and a Locking Plate for Internal Fixation System

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Wei Sheng ◽  
Aimin Ji ◽  
Runxin Fang ◽  
Gang He ◽  
Changsheng Chen
Keyword(s):  
Finite Element ◽  
Internal Fixation ◽  
Locking Plate ◽  
Orthogonal Design ◽  
Structural Parameters ◽  
Uniform Design ◽  
Fracture Site ◽  
Element Analysis ◽  
Internal Fixation System ◽  
Fixation System

Objectives. The optimization for the screw configurations and bone plate parameters was studied to improve the biomechanical performances such as reliable internal fixation and beneficial callus growth for the clinical treatment of femoral shaft fracture. Methods. The finite element analysis (FEA) of internal fixation system under different screw configurations based on the orthogonal design was performed and so was for the different structural parameters of the locking plate based on the combination of uniform and orthogonal design. Moreover, orthogonal experiment weight matrixes for four evaluation indexes with FEA were analyzed. Results. The analytical results showed the optimal scheme of screw configuration was that screws are omitted in the thread holes near the fracture site, and single cortical screws are used in the following holes to the distal end, while the double cortical screws are fixed in thread holes that are distal to the fracture; in the other words, the length of the screws showed an increasing trend from the fracture site to the distal end in the optimized configuration. The plate structure was optimized when thread holes gap reached 13 mm, with a width of 11 mm and 4.6 mm and 5 mm for thickness and diameter of the screw, respectively. The biomechanical performance of the internal fixation construct was further improved by about 10% based on the optimal strain range and lower stress in the internal fixation system. Conclusions. The proposed orthogonal design and uniform design can be used in a more efficient way for the optimization of internal fixation system, which can reduce the simulation runs to about 10% compared with comprehensive test, and the methodology can be also used for other types of fractures to achieve better internal fixation stability and optimal healing efficiency, which may provide a method for an orthopedist in choosing the screw configurations and parameters for internal fixation system in a more efficient way.

scholarly journals Treatment of Thoracolumbar Fractures Through Different Short Segment Pedicle Screw Fixation Techniques: A Finite Element Analysis

2020 ◽  
Vol 12 (2) ◽  
pp. 601-608
Author(s):  
Tie‐nan Wang ◽  
Bao‐lin Wu ◽  
Rui‐meng Duan ◽  
Ya‐shuai Yuan ◽  
Ming‐jia Qu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Thoracolumbar Fractures ◽  
Short Segment ◽  
Element Analysis ◽  
Fixation Techniques

scholarly journals Towards a Planar Cruciform Specimen for Biaxial Characterisation of Polymer Matrix Composites

2010 ◽  
Vol 24-25 ◽  
pp. 115-120 ◽  
Author(s):  
Michael R.L. Gower ◽  
Richard M. Shaw
Keyword(s):  
Strain Distribution ◽  
Stress Raiser ◽  
Test Method ◽  
Image Correlation ◽  
Strain Gauges ◽  
Test Machine ◽  
Element Analysis ◽  
Full Field ◽  
Cruciform Specimen ◽  
Gauge Section

This paper details work undertaken towards the development of a standard test method for the biaxial response of planar cruciform specimens manufactured from carbon fibre-reinforced plastic (CFRP) laminates and subject to tension-tension loading. Achieving true biaxial failure in a cruciform specimen without the need for the inclusion of a stress raiser, such as a hole, in the gauge-section, is a subject attracting much research globally and is by no means a trivial exercise. Coupon designs were modelled using finite element analysis (FEA) in order to predict the stress and strain distributions in the central region of the specimen. An Instron biaxial strong-floor test machine was used to test the specimens. Strain gauges were used to measure the strain in the specimen arms and to assess the degree of bending. Digital image correlation (DIC) was used to measure the full-field strain distribution in the central gauge-section of the specimen and this was compared to values measured using strain gauges. The strain readings obtained from strain gauges, DIC and FEA predictions were in good agreement and showed that the strain distribution was uniform in the central gauge-section, but that strain concentrations existed around the tapered thickness zone. These regions of strain concentration resulted in interlaminar failure and delamination of the laminate propagating into the specimen arms.

Finite Element Modeling of Effect of Adhesive Layer and Carrier Thickness Used for Strain Gauge Mounting

2015 ◽  
Vol 1119 ◽  
pp. 828-832
Author(s):  
K. Vadivuchezhian ◽  
K. Subrahmanya ◽  
N. Chockappan
Keyword(s):  
Finite Element ◽  
Strain Gauge ◽  
Adhesive Layer ◽  
Element Model ◽  
Strain Gauges ◽  
Single Element ◽  
Metal Foil ◽  
Engineering Structures ◽  
Element Analysis ◽  
Typical Strain

Metal foil strain gauges are most widely used for the stress analysis in engineering structures. Typical strain gauge system includes strain sensitive grid, carrier material, and adhesive layer. Strain measurement from the strain gauge is partially affected by carrier and adhesive materials and their thickness. In the present work, a Finite Element Model is developed in order to study the effect of both adhesive layer and carrier thickness on strain measurements while using strain gauges. To understand the behavior of the adhesive material, mechanical characterization is done on bulk adhesive specimen. Finite Element Analysis (FEA) is carried out with different materials namely epoxy and polyurethane. Initially a single element foil loop is considered for the analysis and further this is extended to metal foil strain gauge with nine end-loops. Finally, the strain variation through thickness of adhesive layer, carrier and strain sensitive grid is obtained from FEA. The results thus obtained are compared with analytical results from Basic Strength of Materials approach.

Validation for External Tieback Connector Bending Capacity by Strain Measurement

2019 ◽  
Author(s):  
Adam Christopherson ◽  
Young-Hoon Han
Keyword(s):  
Axial Strain ◽  
Combined Loading ◽  
Strain Gauges ◽  
Working Pressure ◽  
Element Analysis ◽  
Linear Pattern ◽  
Internal Working ◽  
Industry Standards ◽  
Bending Capacity ◽  
Crucial Information

Abstract Strain gauges provide a convenient and affordable method to accurately measure the strain field for complex systems. Not only do they provide crucial information for predicting the fatigue life of components, but they can also determine the principle stresses which can be used to compare design factors with accepted industry standards. The use of electrical resistance strain gauges for load verification has become an ever-increasing practice in the design of subsea connectors as evidenced by the recent application in the industry guidance API 17TR7 [1]. The design is aided by the development of a Finite Element Analysis (FEA) which is used to predict the load capacities for normal, extreme, and survival conditions. The present work describes the experimental validation of a 18-3/4in 10,000 psi subsea collet connector model by applying linear pattern CEA-06-062UW-350 strain gauges at discrete points along the circumferentially spaced collet segments. The collet segments are the selected components for strain gauge placement because not only are they the primary connecting element between the subsea wellhead and the connector body, but they also only support axial loads. The axial strain of the collet segments in tension were compared at two combined loading cases: maximum bending capacity with and without internal working pressure and found to be in good correlation with the elastic-plastic FEA. The experimentally validated FEA is a crucial tool in determining the connector’s application to project or customer specific load and fatigue requirements and eliminates the need for unnecessary experimentation.

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