scholarly journals Biomechanical Comparison of Two Locking Plate Constructs Under Cyclic Loading in Four-Point Bending in a Fracture Gap Model: Two Screws versus Three Screws Per Fragment

2019 ◽  
Vol 32 (01) ◽  
pp. 059-066 ◽  
Author(s):  
Sophie Palierne ◽  
Baptiste Froidefond ◽  
Pascal Swider ◽  
André Autefage
Keyword(s):  
Relative Displacement ◽  
Bending Test ◽  
Test Range ◽  
Locking Screws ◽  
Four Point Bending ◽  
Plate Fracture ◽  
The Difference ◽  
Number Of Cycles ◽  
Biomechanical Comparison ◽  
Locking Screw

Objectives The number of locking screws required per fragment during bridging osteosynthesis has not been fully determined in the dog. The purpose of this study was to assess the survival of two constructs, with either two or three screws per fragment, under cyclic bending. Methods A 10-hole, 3.5-mm stainless steel locking compression plate was fixed 1 mm away from a bone surrogate in which the fracture gap was 47 mm. Two groups of 10 constructs, prepared with either two or three bicortical locking screws placed at the extremities of each fragment, were tested in a load-controlled 4-point bending test (range 0.7 to + 7 Nm) until failure. Results The 3-screw constructs were stiffer than the 2-screw constructs (19.73 ± 0.68 N/mm vs. 15.52 ± 0.51 N/mm respectively) and the interfragmentary relative displacements were higher for the 2-screw constructs (11.17 ± 0.88%) than for the 3-screw constructs (8.00 ± 0.45%). The difference between the number of cycles to failure for the 3-screw constructs (162,448 ± 30,073 cycles) and the 2-screw constructs (143,786 ± 10,103 cycles) was not significant. Failure in all constructs was due to plate fracture at the level of the compression holes. Clinical Significance Omission of the third innermost locking screw during bridging osteosynthesis subjected to bending forces led to a 20% reduction in construct stiffness and increased relative displacement (+39.6%) but did not change fatigue life.

In vitro biomechanical comparison of the effects of cerclage wires, an intramedullary pin and the combination there of on an oblique osteotomy of the canine tibia

2014 ◽  
Vol 27 (02) ◽  
pp. 91-96 ◽  
Author(s):  
J. van der Zee
Keyword(s):  
Bending Test ◽  
Single Loop ◽  
Cerclage Wire ◽  
Four Point Bending ◽  
Intramedullary Pinning ◽  
Four Point Bending Test ◽  
The Difference ◽  
Biomechanical Comparison ◽  
Steinmann Pin

SummaryTo compare the in vitro biomechanical effects of single loop cerclage wires, an intramedullary pin and the combination thereof as applied to an oblique mid-diaphyseal osteotomy of canine tibiae.Three groups of nine bones with long oblique osteotomies were repaired with the following methods: 1) Three single loop cerclage wires and a transcortical skewer pin, 2) intramedullary pinning with a smooth Steinmann pin, and 3) a combination of both methods. The repaired constructs were tested in a single cycle four-point-bending test to failure. Load displacement curves were drawn and the following parameters were calculated or extrapolated: Stiffness, load at yield, and force resisted at 2 mm actuator displacement. The latter was determined to demonstrate the difference in the amount of energy absorbed between the different groups.The stiffness and force resisted at 2 mm displacement of the groups with cerclage wires were significantly higher than the group with an intramedullary pin alone (p ≤ 0.05). The differences in stiffness (p = 0.15) and force required at 2 mm displacement (p = 0.56) between cerclage wires and the combination of cerclage wires and intramedullary pins were not significant.Cerclage wire repair results in higher stiffness than repair with an intramedullary pin. When cerclage wires are combined with an intramedullary pin, the intramedullary pin does not provide protection to the cerclage wire repair and the wires or the bone under the wires has to fail before the pin resists significant load.

scholarly journals Biomechanical comparison of two locking plate constructs under cyclic torsional loading in a fracture gap model

2015 ◽  
Vol 28 (05) ◽  
pp. 323-330 ◽  
Author(s):  
A. Bilmont ◽  
S. Palierne ◽  
M. Verset ◽  
P. Swider ◽  
A. Autefage
Keyword(s):  
Locking Plate ◽  
Torsional Loading ◽  
Screw Head ◽  
The Third ◽  
Cyclic Torsion ◽  
Locking Screws ◽  
Locking Compression Plates ◽  
Number Of Cycles ◽  
Biomechanical Comparison ◽  
Locking Screw

SummaryObjectives: The number of locking screws required per fragment during bridging osteo-synthesis in the dog has not been determined. The purpose of this study was to assess the survival of two constructs, with either two or three screws per fragment, under cyclic torsion.Methods: Ten-hole 3.5 mm stainless steel locking compression plates (LCP) were fixed 1 mm away from bone surrogates with a fracture gap of 47 mm using two bicortical locking screws (10 constructs) or three bicortical locking screws (10 constructs) per fragment, placed at the extremities of each LCP. Constructs were tested in cyclic torsion (range: 0 to +0.218 rad) until failure.Results: The 3-screws constructs (29.65 ± 1.89 N.m/rad) were stiffer than the 2-screws constructs (23.73 ± 0.87 N.m/rad), and therefore, were subjected to a greater torque during cycling (6.05 ± 1.33 N.m and 4.88 ± 1.14 N.m respectively). The 3-screws constructs sustained a significantly greater number of cycles (20,700 ± 5,735 cycles) than the 2-screws constructs (15,600 ± 5,272 cycles). In most constructs, failure was due to screw damage at the junction of the shaft and head. The remaining constructs failed because of screw head unlocking, sometimes due to incomplete seating of the screw head prior to testing.Clinical significance: Omitting the third innermost locking screw during bridging osteosynthesis led to a reduction in fatigue life of 25% and construct stiffness by 20%. Fracture of the screws is believed to occur sequentially, starting with the innermost screw that initially shields the other screws.

Unstable Vancouver B1 Periprosthetic Femoral Fracture Fixation: A Biomechanical Comparison Between Cerclage Wiring and C-Shaped Shape Memory Alloy Implant

2020 ◽  
Author(s):  
Seog-Hyun Oh ◽  
Yu-Sung Suh ◽  
Emmanuel Eghan-Acquah ◽  
Kollerov Mikhail Yurevich ◽  
Sung-Hun Won ◽  
...  
Keyword(s):  
Axial Compression ◽  
Femoral Fracture ◽  
Torsion Test ◽  
Bending Test ◽  
Periprosthetic Femoral Fracture ◽  
Bending Tests ◽  
Four Point Bending ◽  
Cerclage Wiring ◽  
Distal Fixation ◽  
Biomechanical Comparison

Abstract Although cerclage wiring is a very useful implant, it has many problems. We manufactured an alphabet C-shaped clip with nitinol (C-clip) that has superelastic property to replace the cerclage wiring.This study aimed to compare the biomechanical stability of cerclage cable and the C-clip. Eighteen synthetic femora were tested. An unstable VB1 fractures model was constructed that oblique fracture line was 8cm below the lesser trochanter with fracture gab. The distal fixation was repaired with a locking plate and four bi-cortical screws. The proximal fixation was repaired two different methods: (1) four-threaded cerclage cables and (2) four new C-clip. In axial compression test, the C-clip was stiffer than the cerclage cable (median stiffness of C-clip = 39.28 N/mm [IQR; 38.84-41.19], cerclage cable = 34.90 N/mm [34.84-35.08], p<0.05). In the torsion test, the C-clip was 0.44 Nm/° [IQR; 0.44-0.45] and cerclage cable = 0.30 Nm/° [0.30-0.33], p<0.05). In the four-point bending test, the C-clip = 39.35 N/mm [IQR; 38.91-40.97] and cerclage cable = 28.38 N/mm, [28.33-30.79], p<0.05) The C-clip may be biomechanically superior to cerclage wiring in terms of stiffness, axial compression, torsion, and four-point bending tests and is a valuable alternative in Vancouver type B1 periprosthetic femoral fracture.

HYBRID PLATING SHOWS EQUIVALENT BIOMECHANICAL BENDING STRENGTH TO UNICORTICAL LOCKED PLATING

2014 ◽  
Vol 14 (05) ◽  
pp. 1450071
Author(s):  
JEREMY S. SOMERSON ◽  
JAKE P. HEINEY ◽  
SUNEEL BATTULA ◽  
ANDREW J. SCHOENFELD
Keyword(s):  
Bending Strength ◽  
Screw Fixation ◽  
Bending Test ◽  
Locked Plating ◽  
Treatment Groups ◽  
Locking Screws ◽  
Prosthetic Implants ◽  
Diaphyseal Fractures ◽  
Hybrid Construct ◽  
Locking Screw

Locking unicortical screw fixation of diaphyseal fractures may be clinically necessary due to internal constructs or prosthetic implants. The biomechanical effects of substituting one or more bicortical nonlocking screws to create a "hybrid" construct are unknown. Use of an initial nonlocking screw may be clinically desirable for creating initial plate-to-bone fixation prior to locking. A validated transverse fracture model was used with eighteen synthetic humerus models. Plate and screw fixation was performed in three treatment groups (n = 6): Unicortical locking screws only, fixation with two unicortical locking screws and one bicortical nonlocking screw on either side of the fracture and fixation with one unicortical locking screw and two bicortical locking screws on either side of the fracture. Displacement and gap strain measurements were made with a cyclic 4-point bending test. No significant differences were noted for construct stiffness or gap micromotion among the three groups on cyclic testing. Measurements at 1000, 5000, and 10,000 cycles showed stable fixation of all construct types with no significant changes in stiffness or micromotion. Substitution of one or more bicortical nonlocking screws in a unicortical locked construct does not affect construct stiffness or fracture gap strain. Data proven through controlled laboratory study.

Biomechanical comparison of mono- and bicortical screws in an experimentally induced gap fracture

2014 ◽  
Vol 27 (06) ◽  
pp. 422-429 ◽  
Author(s):  
T. C. Garcia ◽  
M. G. Serdy ◽  
K. Hayashi ◽  
B.-A. Nir ◽  
S. M. Stover ◽  
...  
Keyword(s):  
Bone Fracture ◽  
Locking Compression Plate ◽  
Torsional Stiffness ◽  
Screw Placement ◽  
Screw Loosening ◽  
Locking Screws ◽  
Four Point Bending ◽  
Diaphyseal Fractures ◽  
Biomechanical Comparison ◽  
Bicortical Screw

SummaryObjectives: To compare the bending and torsional mechanical properties of mono- and bicortical locking screws in a canine cadaveric tibial gap ostectomy bridged by a locking compression plate (LCP).Methods: A 10-hole 3.5 mm LCP was applied medially to the tibia with a gap ostectomy using locking screws in the two proximal and distal plate holes. One tibia of each pair was randomly assigned monocortical screws and the other bicortical screws. Constructs were tested non-destructively in mediolateral and caudocranial four-point bending and torsion, and then to failure in four-point bending. Stiffness, yield and failure variables were compared between screw lengths and load conditions using analysis of variance.Results: Caudocranial and mediolateral fourpoint bending stiffnesses were not different between screw constructs. Torsional stiffness was greater and neutral zone smaller for bicortical constructs. Constructs were stiffer and stronger in caudocranial bending than in mediolateral bending. In caudocranial bending, bicortical constructs failed by bone fracture and monocortical constructs by screw loosening.Conclusion: Bicortical constructs were stiffer than monocortical constructs in torsion but not bending. Bicortical screw constructs failed by bone fracture under the applied loads whereas monocortical screw constructs failed at the bone-screw interface.Clinical relevance: Bicortical screw placement may be a safer clinical alternative than monocortical screw placement for minimally invasive percutaneous osteosynthesis LCPplated canine tibiae with comminuted diaphyseal fractures.

Biomechanical characteristics of allogeneic cortical bone pins designed for fracture fixation

2008 ◽  
Vol 21 (02) ◽  
pp. 140-146
Author(s):  
M. R. Edwards ◽  
S. P. James ◽  
W. S. Dernell ◽  
R. J. Scott ◽  
A. M. Bachand ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Cortical Bone ◽  
Fracture Fixation ◽  
Impact Testing ◽  
Left Tibia ◽  
Four Point Bending ◽  
And Gender ◽  
The Right ◽  
Biomechanical Comparison ◽  
Better Than

SummaryThe biomechanical characteristics of 1.2 mm diameter allogeneic cortical bone pins harvested from the canine tibia were evaluated and compared to 1.1 mm diameter stainless steel pins and 1.3 mm diameter polydioxanone (PDS) pins using impact testing and four-point bending. The biomechanical performance of allogeneic cortical bone pins using impact testing was uniform with no significant differences between sites, side, and gender. In four-point bending, cortical bone pins harvested from the left tibia (204.8 ± 77.4 N/mm) were significantly stiffer than the right tibia (123.7 ± 54.4 N/mm, P=0.0001). The site of bone pin harvest also had a significant effect on stiffness, but this was dependent on interactions with gender and side. Site C in male dogs had the highest mean stiffness in the left tibia (224.4 ± 40.4 N/mm), but lowest stiffness in the right tibia (84.9 ± 24.2 N/mm). Site A in female dogs had the highest mean stiffness in the left tibia (344.9 ± 117.4 N/mm), but lowest stiffness in the right tibia (60.8 ± 3.7 N/mm). The raw and adjusted bending properties of 1.2 mm cortical bone pins were significantly better than 1.3 mm PDS pins, but significantly worse than 1.1 mm stainless steel pins (P<0.0001). In conclusion, cortical bone pins may be suitable as an implant for fracture fixation based on initial biomechanical comparison to stainless steel and PDS pins used in clinical practice.

scholarly journals Development of Highly Sensitive Strain Sensor Using Area-Arrayed Graphene Nanoribbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1701
Author(s):  
Ken Suzuki ◽  
Ryohei Nakagawa ◽  
Qinqiang Zhang ◽  
Hideo Miura
Keyword(s):  
Graphene Nanoribbons ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Sensitive Strain ◽  
Bending Test ◽  
Gauge Factor ◽  
Four Point Bending ◽  
Current Voltage ◽  
Highly Sensitive ◽  
Current Voltage Relationship

In this study, a basic design of area-arrayed graphene nanoribbon (GNR) strain sensors was proposed to realize the next generation of strain sensors. To fabricate the area-arrayed GNRs, a top-down approach was employed, in which GNRs were cut out from a large graphene sheet using an electron beam lithography technique. GNRs with widths of 400 nm, 300 nm, 200 nm, and 50 nm were fabricated, and their current-voltage characteristics were evaluated. The current values of GNRs with widths of 200 nm and above increased linearly with increasing applied voltage, indicating that these GNRs were metallic conductors and a good ohmic junction was formed between graphene and the electrode. There were two types of GNRs with a width of 50 nm, one with a linear current–voltage relationship and the other with a nonlinear one. We evaluated the strain sensitivity of the 50 nm GNR exhibiting metallic conduction by applying a four-point bending test, and found that the gauge factor of this GNR was about 50. Thus, GNRs with a width of about 50 nm can be used to realize a highly sensitive strain sensor.

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