Mechanical Performance of External Fixators With Wires for the Treatment of Bone Fractures—Part II: Wire Tension and Slippage

1993 ◽  
Vol 115 (1) ◽  
pp. 37-42 ◽  
Author(s):  
C. Delprete ◽  
M. M. Gola
Keyword(s):  
Mechanical Performance ◽  
Marked Decrease ◽  
Bone Fractures ◽  
Transverse Load ◽  
External Fixators ◽  
Transverse Loading ◽  
Ilizarov External Fixator ◽  
Single Wire ◽  
Wire Tension

The work shows correct procedures needed in order to gather reliable data from measurement of displacements versus axial load in a laboratory mounting of the Ilizarov external fixator. The mechanism of settling after load cycling is investigated. Detension under load is a major problem of wires. By means of vibration frequency measurements, tests on single wire allow determination of reduction in wire tension due to transverse loading: it is found that, almost independently from the amount of clamp tightening, the tension reaches a lower limit related only to the transverse load and not related to pretension. It is shown that, for higher clamp tightening torques, wire detension must be attributed to permanent plastic deformation of the wires; moreover, it is shown that the unavoidable errors in the spacing of the tensioned wires lead to marked decrease of their stiffness under transverse load.

Mechanical Performance of External Fixators With Wires for the Treatment of Bone Fractures—Part I: Load-Displacement Behavior

1993 ◽  
Vol 115 (1) ◽  
pp. 29-36 ◽  
Author(s):  
C. Delprete ◽  
M. M. Gola
Keyword(s):  
Mathematical Model ◽  
Mechanical Performance ◽  
Bone Fractures ◽  
Fracture Site ◽  
External Fixators ◽  
Axial Loads ◽  
Linear Estimate ◽  
The Common ◽  
Displacement Behavior ◽  
The Mathematical Model

Using matrix algebra, a mathematical model is formulated for a particular type of external fixator with wires (system developed by Ilizarov) for the treatment of bone fractures. The mathematical model is used to give a linear estimate of the stiffness under lateral and axial loads in a representative number of practical conditions. Relative displacements of the bone ends at the fracture site are calculated not only in the common case of a gap, but also for various angles of inclined sliding contact; in this case, a realistic load is applied and nonlinear stiffening of the wires under transversal loads is iteratively taken into account.

III. An experimental determination of the velocity of sound

1872 ◽  
Vol 20 (130-138) ◽  
pp. 34-35
Keyword(s):  
Experimental Determination ◽  
Cape Town ◽  
The Other ◽  
Velocity Of Sound ◽  
Successful Operation ◽  
Single Wire ◽  
Galvanic Current ◽  
Royal Observatory ◽  
Port Elizabeth

A galvanic current passes from the batteries at the Royal Observatory, Cape Town, at 1 o’clock, and discharges a gun at the Castle, and through relays drops a time-ball at Port Elizabeth. It appeared to the author that a valuable determination of the velocity of sound might be obtained by measuring upon the chronograph of the Observatory the interval between the time of the sound reaching some point near the gun and that of its arrival at the Observatory. As there is only a single wire between the Observatory and Cape Town, some little difficulty was experienced in making the necessary arrangements, without any interference with the 1 o’clock current to Port Elizabeth; but this difficulty was overcome by a plan which the author describes, and which was brought into successful operation on Feb. 27, 1871. The experiments could not have been carried out, on account of the encroachment they would have made on the time of the Observatory staff, had it not been for the assistance of J. Den, Esq., the acting manager of the Cape Telegraph Company, to whom the author is indebted for the preparation of a good earth-connexion near the gun, for permission to Mr. Kirby, a gentleman attached to the telegraph office, to assist in the experiments, and for a general superintendence of the arrangements at Cape Town. The observed times of hearing the sound were recorded on the chronograph by two observers, situated one (Mr. Kirby) at a distance of 641 feet from the gun, the other (Mr. Mann) at the Observatory, at a distance of 15,449 feet from the gun. The former distance was sufficient to allow the connexion of the main wire to be broken at the telegraph office after the gun had been fired, but before the sound reached the first observer.

scholarly journals The Influence of Manufacturing Parameters on the Mechanical Behaviour of PLA and ABS Pieces Manufactured by FDM: A Comparative Analysis

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1333 ◽  
Author(s):  
Adrián Rodríguez-Panes ◽  
Juan Claver ◽  
Ana Camacho
Keyword(s):  
Tensile Strength ◽  
Mechanical Behaviour ◽  
Mechanical Performance ◽  
Acrylonitrile Butadiene Styrene ◽  
Polymer Materials ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Layer Orientation ◽  
Lower Variability

This paper presents a comparative study of the tensile mechanical behaviour of pieces produced using the Fused Deposition Modelling (FDM) additive manufacturing technique with respect to the two types of thermoplastic material most widely used in this technique: polylactide (PLA) and acrylonitrile butadiene styrene (ABS). The aim of this study is to compare the effect of layer height, infill density, and layer orientation on the mechanical performance of PLA and ABS test specimens. The variables under study here are tensile yield stress, tensile strength, nominal strain at break, and modulus of elasticity. The results obtained with ABS show a lower variability than those obtained with PLA. In general, the infill percentage is the manufacturing parameter of greatest influence on the results, although the effect is more noticeable in PLA than in ABS. The test specimens manufactured using PLA perform more rigidly and they are found to have greater tensile strength than ABS. The bond between layers in PLA turns out to be extremely strong and is, therefore, highly suitable for use in additive technologies. The methodology proposed is a reference of interest in studies involving the determination of mechanical properties of polymer materials manufactured using these technologies.

scholarly journals External fixation to correct tarsal-metatarsal fracture in rock pigeon (Columba livia)

Revista CERES ◽  
2017 ◽  
Vol 64 (1) ◽  
pp. 25-30
Author(s):  
Leandro Almeida Rui ◽  
Diego Carvalho Viana ◽  
Adriano Barile Dora ◽  
Paula Fratini
Keyword(s):  
Gold Standard ◽  
Minimal Invasive Surgery ◽  
Surgical Repair ◽  
Bone Fractures ◽  
Columba Livia ◽  
Minimal Invasive ◽  
External Fixators ◽  
Post Surgery ◽  
Metatarsal Fracture ◽  
Rock Pigeon

ABSTRACT Orthopedic conditions, such as bone fractures, are very common in avian medicine. External fixators have been considered the gold standard for birds, since they allow early movement of the limbs and minimal invasive surgery. Fractures in several bones have been successfully treated in pigeons. However, to the best of our knowledge, this case represents the first report of successful surgical repair of tarsal-metatarsal fracture in rock pigeon. External fixator was made with four 24G catheters, being inserted manually proximal and distal to the fracture and connected with polymerizable acrylic. Radiographic consolidation of fracture was observed 60 days post-surgery and anti-inflammatory and antibiotic protocols were successful on avoiding pain and infection during surgery and bone healing.

Alterations in myocardial lipid metabolism during lactation in the rat

1998 ◽  
Vol 275 (2) ◽  
pp. E265-E271 ◽  
Author(s):  
Xin Wang ◽  
David G. Hole ◽  
Teresa H. M. Da Costa ◽  
Rhys D. Evans
Keyword(s):  
Fatty Acid ◽  
Mechanical Performance ◽  
Marked Decrease ◽  
Low Density Lipoproteins ◽  
Nonesterified Fatty Acid ◽  
Low Density ◽  
Mechanical Function ◽  
Lipoprotein Lipase Activity ◽  
Very Low Density Lipoproteins ◽  
Lactating Mammary Gland

Metabolism of nonesterified fatty acid (palmitate, 1.1 mM) and triacylglycerol (TAG; triolein, 0.4 mM in the form of both rat chylomicrons and very low density lipoproteins) was studied in isolated perfused working hearts from fed nulliparous, lactating, and weaned rats. Hearts from virgin rats oxidized palmitate readily, but optimal cardiac mechanical performance occurred during perfusion with chylomicrons. In hearts from lactating dams, there was a significant increase in palmitate oxidation and a marked decrease in TAG oxidation from both chylomicrons and very low density lipoproteins compared with hearts from nulliparous animals. There was a concomitant decrease in lipoprotein lipase activity in hearts from lactating animals, and TAG in the absence of palmitate could not support optimal cardiac mechanical function. After litter removal, the changes in fatty acid and TAG metabolism observed in lactation returned to nulliparous values within 96 h. These results suggest that, during lactation, both exogenous and endogenous TAGs are directed away from heart and toward the lactating mammary gland; the heart, therefore, has to rely to a greater extent on nonesterified fatty acid for energy provision under these conditions.

The effect of clamping a tensioned wire: Implications for the Ilizarov external fixation system

2003 ◽  
Vol 217 (2) ◽  
pp. 91-98 ◽  
Author(s):  
M A Watson ◽  
K J Mathias ◽  
N Maffulli ◽  
D W L Hukins
Keyword(s):  
Finite Element ◽  
Standard Deviation ◽  
External Fixator ◽  
Clinical Situation ◽  
Engineering Problem ◽  
Fe Model ◽  
Ilizarov External Fixator ◽  
Wire Tension ◽  
The Wire ◽  
Fixation System

This study demonstrates that clamping a tensioned wire can cause a reduction in wire tension. Tension (about 1275 N) was applied to a wire that was subsequently clamped, using cannulated bolts, to the steel half-ring of an Ilizarov external fixator. The tension in the wire was monitored before, during and after clamping. The apparatus was disassembled and the deformations in the wire caused by the clamps were measured. This experiment was repeated 15 times. When the wire was clamped to the frame, the wire tension was reduced by 22 ± 7 per cent (mean ± standard deviation, SD). The drop in wire tension was linearly correlated ( r = 0.96; p < 0.001) with the deformation caused by the bolts. A finite element (FE) model of the wire was also constructed. The model was pre-stressed (tensioned), and the clamping effect replicated. This analysis showed that clamping the wire could be considered to squeeze the wire outwards (like toothpaste from a tube) and so reduce its tension during fixator assembly. To assess the magnitude of this effect in the clinical situation, the FE model analysis was repeated to replicate clamping a 1.8-mm-diameter wire to a 180-mm-diameter steel Ilizarov ring component. The analysis showed that for these conditions the tension reduced by 8–29 per cent. The results of this study highlight a general engineering problem: how can a tensioned wire be secured to a structure without an appreciable loss of tension? If the performance of the structure depends on the wire tension, this performance will change when the wire is secured.

Treatment of Long Bone Fractures in Calves with Ilizarov External Fixator

2018 ◽  
Vol 31 (05) ◽  
pp. 364-372
Author(s):  
Murat Sarierler ◽  
Ali Gülaydin
Keyword(s):  
External Fixator ◽  
Bone Fractures ◽  
Long Bone ◽  
Ilizarov External Fixator ◽  
Injured Limb ◽  
Radiographic Findings ◽  
Advantages And Disadvantages ◽  
The Third ◽  
Long Bone Fractures ◽  
Tract Infections

In this study, the advantages and disadvantages of Ilizarov external fixator in the treatment of long bone fractures in calves were investigated. For this purpose, 26 calves of different breeds, ages and genders, having metacarpal (n = 12), metatarsal (n = 5) and antebrachial (n = 9) fractures underwent surgery under general anaesthesia. Frames, which were prepared before surgery in accordance with the radiographic findings, were applied under open reduction in 18 cases, and under closed reduction in eight cases. In the postoperative period, all calves except one started to bear some weigh on the injured limb on the first day, while the remaining calf did the same on the second day. The consolidation started in the first 2 weeks for 24 of the calves and was completed by the day 55. In the two remaining cases, it started in the third week and was completed on day 71 and day 90, respectively.The soft tissue wounds were completely healed in all calves and no complications occurred. In five calves that were not kept in our clinic pin tract infections formed. They were controlled rapidly, and there was no change in the fracture reduction or healing duration.In conclusion, in our study, the Ilizarov external fixator system was applied to long bone fractures in cattle calves, in cases where the fragments were not large enough to apply pins and plates, and which became open and infected after defective bandage practices or unsuitable treatment. Fractures completely healed in all cases, without any complications. These results show that many of the long bone fractures experienced by calves, that were considered for amputation due to the anticipated inability to treat them successfully, could be treated with the use of the Ilizarov system.

Comparison of Manufacturing Techniques Subject to High Speed Impact

2014 ◽  
Author(s):  
Kenneth Gollins ◽  
Jack Chiu ◽  
Feridun Delale ◽  
Benjamin Liaw ◽  
Ali Gursel
Keyword(s):  
High Speed ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Compression Molding ◽  
Epoxy Composites ◽  
Fiber Density ◽  
Vacuum Infusion ◽  
High Speed Impact ◽  
Manufacturing Techniques

In this paper we compare two manufacturing techniques namely vacuum infusion and compression molding, used in manufacturing S2 glass fabric/epoxy composites for high-speed impact applications. Even though compression molding and vacuum infusion are two widely used manufacturing techniques, the resulting product may be very different. Compression molding has the advantage of achieving a much higher fiber density for the same thickness. With a higher fiber density, the composites made by compression molding have better mechanical properties than a composite made by vacuum infusion. However, vacuum infusion is faster and more economical. The mechanical performance of the composites manufactured by these two processes are compared by performing tensile tests and high speed impact tests for the determination of the limit speed V50. For the same number of plies, preliminary results for compression molded specimens indicate a 50% increase in stiffness and a 40% increase in strength. Also, for panels of the same thickness, the V50 was higher for compression molding specimens.

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