Straight Plate Research Articles

Hydraulic analysis and optimization design in Guri rehabilitation project

Recently Dongfang was awarded the contract for rehabilitation of 6 units in Guri power plant, the biggest hydro power project in Venezuela. The rehabilitation includes, but not limited to, the extension of output capacity by about 50% and enhancement of efficiency level. To achieve the targets the runner and the guide vanes will be replaced by the newly optimized designs. In addition, the out-of-date stay vanes with straight plate shape will be modified into proper profiles after considering the application feasibility in field. The runner and vane profiles were optimized by using state-of-the-art flow simulation techniques. And the hydraulic performances were confirmed by the following model tests. This paper describes the flow analysis during the optimization procedure and the comparison between various technical concepts.

Evaluation of Three Different Osteosynthesis Methods for Mandibular Angle Fractures: Vertical Load Test.

The aim of this study was to evaluate the mechanical behavior of different rigid fixation methods in mandible angle fractures. Three different plates were tested: one 4-hole grid miniplate, one 8-hole curved grid miniplate, and one 4-hole straight miniplate.For the loading tests, 30 polyurethane hemimandibles sectioned at the angle area to simulate a simple angle fracture were used: 10 hemimandibles for each group. The mechanical evaluation revealed that the straight plate positioned at the tension zone presented the best results in supporting vertical loading in the predefined displacement moments of 1, 3, and 5 mm. Regarding the grid plates, there was no statistically significant difference between the smaller and the larger plate.According to this sample, the straight plate positioned in the tension zone presented better results than the other 2 different grid plates positioned at the neutral zone.

The effect of contouring on fatigue resistance of three types of fracture fixation plates.

BackgroundMetallic reconstruction plates used for fracture stabilization typically require intraoperative contouring for patient-specific anatomical fit. Despite this, characterization of plate mechanical properties after contouring has previously been limited.The objective of this study was to assess whether contouring affects fatigue resistance for three types of Stryker seven-hole stainless steel (SS) 316LVM fracture fixation plates. The hypothesis was that for each plate type, more contouring repetitions would result in lower fatigue resistance.MethodsPlates were contoured using a bench-top plate bender to ±20° either 0×, 3×, 6×, or 9× (n = 5 per group) and tested in the straight configuration. Cyclic four-point bending was applied in an incremental stepwise staircase approach (one step = 100,000 cycles, 10 Hz) until failure (defined as brittle fracture or plastic deformation of 10° permanent bend). Moment-cycle product (MCP) was computed as the summation of maximum moment × number of cycles and used as the primary measure of fatigue resistance.ResultsNo significant differences in fatigue resistance were detected between contouring groups for Basic Fragment Set (BFS) Reconstruction Plates. Significantly lower fatigue resistance was measured for 9× contoured Matta Pelvic System (MPS) Straight Plates compared to 0× contoured plates (p = 0.023). MPS Flex Plates contoured 3× had greater fatigue resistance than 0× contoured (p = 0.031) and 9× contoured plates (p = 0.032).ConclusionsThis work provides fatigue resistance-based evidence that clinicians should avoid high repetitions of contouring for MPS Straight Plates. Meanwhile, BFS Reconstruction Plates and MPS Flex Plates are not negatively affected by contouring. These results allow for improved intraoperative decisions about using or discarding plates after multiple contouring repetitions.

The Biomechanical Study of the Bioabsorbable Plates in Finger Fracture Fixation

Objectives: Plates and screws have been proven to be a strong construct for the treatment of finger fractures as it allows for immediate postoperative mobilization. However, plates made in metal can be high in profile and may lead to both adjacent tendons and soft tissue irritation. Meanwhile bioabsorbable plates and screws have the advantage of being more conforming and low in profile. Yet there are concerns on its biomechanical strength. This study aims to explore the biomechanical strength of bioabsorbable construct by comparing with its titanium counterpart. Materials and Methods: Fifty-four simulated bone models of hand with a transverse osteotomy were used to simulate a finger fracture. A control group of 18 bone models (group 0) were fixed with a standard 4-hole, 1.5-mm titanium straight plates. A second set of 18 bone models (group 1) were fixed by 1.5-mm bioabsorbable mesh plate which was fashioned to cover half of the circumference of the bone. For the remaining set of 18 bone models, similar fixation was employed using the bioabsorbable plates except that it covered two-third instead of half of the circumference of the bone. All bone models were mounted to the Servo-hydraulic MTS 858 Bionix testing machine for biomechanical testing. Six bone models from each group were tested for maximum bending force, maximum torsional force, and fatigue property. The fatigue property was to simulate the load that the fixation construct would encounter over a 6 weeks period, ie, a period that allows the bone to heal with callous. It was set at 100 000 cycles at a displacement rate of 1 mm/s. Results: The average maximum bending force for group 0, group 1, and group 2 were 67.0 ± 10.2 N, 40.8 ± 15.0 N, and 43.3 ± 15.0 N, respectively. There was a significance between the metal and both the bioabsorbable groups with P < .001. For the average maximum torsional force, group 0 was 0.66 ± 0.06 Nm, group 1 was 0.27 ± 0.06 Nm and group 2 was 0.32 ± 0.07 Nm. A significance difference between the metal and both the bioabsorbable groups was noted at P < .001. For the fatigue tests, all constructs, except 2 in group 1, were able to withstand 1 000 000 cycles. The subsequent force to failure of both the bioabsorbable constructs were only 10% of the titanium constructs (6.8 N vs 67.6 N) of which the P was <.001. No significant difference was noted in maximum bending strength, maximum torsion force, and fatigue stress between the 2 groups of bioabsorbable constructs. Conclusion: The biomechanical strength of the bioabsorbable plates is inferior to the titanium plates. Yet as the requirement of finger fracture fixation is mainly to provide a stable environment for finger mobilization, the fatigue property of a construct appears to be more important. Thus, the strength of bioabsorbable plate and screw construct may still be strong enough to allow the fracture to heal.

Biomechanical comparison of straight and helical compression plates for fixation of transverse and oblique bone fractures: Modeling and experiments

Total deformation and stability of straight and helical compression plates were studied by means of the finite element method (FEM) and in vitro biomechanical experiments. Fixations of transverse (TF) and oblique (45°) bone (OF) fractures have been analyzed on sheep tibias by designing the straight compression (SP) and Helical Compression Plate (HP) models. The effects of axial compression, bending and torsion loads on both plating systems were analyzed in terms of total displacements. Numerical models and experimental models suggested that under compression loadings, bone fracture gap closures for both fracture types were found to be in the favor of helical plate designs. The helical plate (HP) fixations provided maximum torsional resistance compared to the (SP) fixations. The fracture gap closure and stability of helical plate fixation for transverse fractures was determined to be higher than that found for the oblique fractures. The comparison of average compression stress, bending and torsion moments showed that the FEM and experimental results are in good agreement and such designs are likely to have a positive impact in future bone fracture fixation designs.

Stability of the permanently bent plates used in mandibular reconstructive surgery.

In mandibular reconstructive surgery, straight surgical plates are predominantly used for osteotomy. In this process, a straight plate is bent to fit to the shape of the patient's defect. This potentially compromises the stability of the plate because of changes in mechanical properties resulting from plastic deformation; however, the effect of plastic deformation on stability has yet been investigated. In this study, we assess the stability of three types of commonly used bent plates for two types of mandible defect cases, using three-dimensional finite element analysis (FEA). We compare the stability of plastically deformed plates with customized plates having the same shape, but not the residual stresses from plastic deformation. The results indicate that while the bearing strength of the bent plate is sufficient, there is much higher stress in the plate due to the residual stresses from the bending process that may significantly decrease the safety of the reconstruction surgery.

An osteosynthesis plate analytical model

Osteosynthesis plates are used to fix broken bones to help the healing process consolidation. It consists in fixing a plate on a long-bone external surface with screws, sharing forces, and moments between bone and plate. In this paper, a straight osteosynthesis plate is analyzed using an analytical bi-material model, based on mechanics of solids, to estimate the mechanical stress distributions at plate medial cross sections. The analytical model results show good performance in comparison with the commercial finite-element software used as reference.

Probabilistic Properties of Fatigue Damage and an Equivalent Damage Simplification Model for Multi-Level Load Spectra

An equivalent fatigue damage simplification model for multi-level load spectrum is proposed. On the basis of the probabilistic fatigue damage model which takes load sequence effect into account and the constant amplitude fatigue tests, probabilistic properties of damage accumulated in one loading block are achieved quantitatively by statistical methods. The new simplification model can ensure that, for the original spectrum and simplified spectrum, the probabilistic properties of fatigue damage are almost the same. Fatigue tests for Al-alloy straight plates are performed to test the validity of the model. The test results are in good agreement with predicted results.

Pre-arthroplasty simultaneous maxillomandibular distraction osteogenesis for the correction of post-ankylotic dentofacial deformities

The aim of this study was to evaluate the hard and soft tissue changes after pre-arthroplasty simultaneous maxillomandibular distraction osteogenesis for the correction of post-ankylotic dentofacial deformities. This prospective study included 10 patients with unilateral temporomandibular joint (TMJ) ankylosis who presented with a facial deformity and a maxillary cant. Informed patient consent was obtained for participation. Simultaneous maxillomandibular distraction was planned based on clinical and radiographic examinations. A horizontal mandibular osteotomy was performed in the ramus and the distractor device was fixed. A bilateral Le Fort I osteotomy was then performed and a four-hole straight plate was fixed on the contralateral zygomatic buttress to act as a fulcrum. After a latency period of 5 days, the distractor was activated twice daily by 0.5mm until the required vertical lengthening was achieved. Intermaxillary fixation was maintained during the entire distraction period. After a consolidation period of 8–12 weeks, the distractor was removed. The TMJ ankylosis was released and a temporal fascia interpositional arthroplasty was performed as second surgery, along with a genioplasty if needed. All patients were followed up for a period of 12–24 months. A marked improvement in the facial asymmetry was noted in all cases. The occlusal cant and mandibular retrusion improved satisfactorily, and the average postoperative inter-incisal opening was 35.6mm. Pre-arthroplasty simultaneous maxillomandibular distraction offers a good treatment outcome, as it allows improvements in facial aesthetics as well as function.

Screw Layout Optimization to Solve Fatigue Fracture of Femoral Ti Alloy Metal Plate

After femoral shaft fractures, metal plates can be implanted to help its recovery. However, the main problem is that a bone fracture plate could crack or fail in the process of recovery, which cause a secondary damage to the patient. The stress concentration caused by the screw layout of the implanted plate is one of the main reasons for the fracture or failure. Since different screw layout solutions lead to different features of stress concentration, taking the femoral straight Ti alloy metal plate as the object, this research employed the optimization theory and the finite element analysis method to optimize the screw layout. Finally the optimal solution is obtained, which can improve fatigue strength of the fixation system and reduce the failure probability of the system, avoiding the secondary damage to the patient.

Assessment of the Biomechanical Performance of 5 Plating Techniques in Fixation of Mandibular Subcondylar Fracture Using Finite Element Analysis

The aim of this study was to compare the performances of 5 plating techniques for fixation of unilateral mandibular subcondylar fracture. Five titanium plating techniques for fixation of condylar fracture were analyzed using the finite element method. The modeled techniques were 1) 1 straight plate, 2) 2 parallel straight plates, 3) 2 angulated straight plates, 4) 1 trapezoidal plate, and 5) 1 square plate. Three-dimensional models were generated using patient-specific geometry for the mandible obtained from a computerized tomographic image of a healthy living man. Plates were designed and combined with the mandible and analyzed under a 500-N load. The single straight plate presented the most inferior performance; it presented maximum displacement and strain on cortical bone. The trapezoidal plate induced the least amount of strain on cortical bone and was best at resisting displacement. The trapezoidal plate is recommended for fixation of subcondylar fracture.

Clinical Faceoff: Are Distal-third Diaphyseal Humerus Fractures Best Treated Nonoperatively?

D istal-third diaphyseal fractures of the humerus are so variably treated that they seem to be a paradigm for bias and misconceptions in surgery. Conceptually, a functional brace seems ‘‘too low,’’ but the fractures almost always heal, although some fractures heal with varus deformity. The surgery is not easy because there is often a butterfly fragment—meaning that the plate must extend proximal, placing the radial nerve at risk. In order to get good fixation, one needs to extend the plate down the posterior, nonarticular part of the lateral column, which makes it difficult to use a straight plate. Consequently, the most distal screws might be unicortical, and subject to pull out in osteoportic bone. I invited two experts in the field of orthopaedic surgery to discuss the many treatment options associated with distal-third diaphyseal fractures of the humerus. Andrew Jawa MD is an orthopaedic surgeon at New England Baptist Hospital in Boston, MA, USA, whose primary clinical interests include shoulder reconstruction for instability, arthritis, and trauma. Lisa K. Cannada MD is an orthopaedic traumatologist from Saint Louis University Hospital and St. John’s Mercy Medical Center in Saint Louis, MO, USA. Her major interests include long bone malunion, pilon fractures, and general trauma orthopaedics.

Locomotive wheel failure from gauge widening/condemning: Effect of wheel profile, brake block type, and braking conditions

A finite element model accounting for heat partitioning at brake block–wheel and rail–wheel interfaces is used to investigate the effect of locomotive wheel profile, wheel diameter, brake block type, nature of braking (independent, synchronized, and drag), braking frequency and braking cycles on wheel gauge for tread braked, locomotive wheel sets. A train running model estimates heat generation rates during braking for assumed operating and braking conditions. Wheel profiles and brake block types used in the work, match with that used by Indian Railways. Bending at hub–disc and disc–rim interfaces is seen to primarily control axial deflection of wheels. While gauge reduction is observed during braking, gauge increase is seen during subsequent cooling. Maximum gauge increase occurs as the wheels finally cool down to room temperature. S-shaped wheels are seen to be better suited than straight plate and parabolic profile wheels for avoiding excessive gauge change. Locomotive wheel failure from gauge widening and condemning, albeit at different times, is seen to occur with independent braking for locomotives fitted with straight plate, S-shaped as well as parabolic profile wheels.

AN INVESTIGATION OF EIGENVALUES OF SHEET METAL UNDERGOING BENDING STRESSES

Accurate prediction of dynamic properties of system is important to ensure the dynamic based design integrity of its member is not compromise. It will reduce or possibly eliminate the possibilities of further modifications in-situ of real system. On this account, this study investigates the modal parameters of the pre-stress sheet metals undergoing bending stresses which is commonly used in practice as structural members. In addressing this issue, three different shapes of sheet metals of similar thickness were studied i.e. straight plate, U-shaped and V-shaped plates. The natural frequencies of these configurations were determined experimentally using the Operational Modal Analysis (OMA). Numerical values were obtained using ANSYS software. Results of these shapes acquired experimentally and numerically were then compared and analyzed. Significant reduction in the eigenvalues of is observed on bent plates both experimentally and numerically as compared to flat plate.

Design and Validation of an Open-Source, Partial Task Trainer for Endonasal Neuro-Endoscopic Skills Development: Indian Experience

Box trainers are ideal simulators, given they are inexpensive, accessible, and use appropriate fidelity. The development and validation of an open-source, partial task simulator that teaches the fundamental skills necessary for endonasal skull-base neuro-endoscopic surgery. We defined the Neuro-Endo-Trainer (NET) SkullBase-Task-GraspPickPlace with an activity area by analyzing the computed tomography scans of 15 adult patients with sellar suprasellar parasellar tumors. Four groups of participants (Group E, n = 4: expert neuroendoscopists; Group N, n =19: novice neurosurgeons; Group R, n = 11: neurosurgery residents with multiple iterations; and Group T, n = 27: neurosurgery residents with single iteration) performed grasp, pick, and place tasks using NET and were graded on task completion time and skills assessment scale score. Group E had lower task completion times and greater skills assessment scale scores than both Group N and R (P ≤ 0.03, 0.001). The performance of Groups N and R was found to be equivalent; in self-assessing neuro-endoscopic skill, the participants in these groups were found to have equally low pretraining scores (4/10) with significant improvement shown after NET simulation (6, 7 respectively). Angled scopes resulted in decreased scores with tilted plates compared with straight plates (30° P ≤ 0.04, 45° P ≤ 0.001). With tilted plates, decreased scores were observed when we compared the 0° with 45° endoscope (right, P ≤ 0.008; left, P ≤ 0.002). The NET, a face and construct valid open-source partial task neuroendoscopic trainer, was designed. Presimulation novice neurosurgeons and neurosurgical residents were described as having insufficient skills and preparation to practice neuro-endoscopy. Plate tilt and endoscope angle were shown to be important factors in participant performance. The NET was found to be a useful partial-task trainer for skill building in neuro-endoscopy.

Locomotive wheel failure from gauge widening/condemning: Finite element modeling and identification of underlying mechanism

Gauge change in straight plate, locomotive, railway wheels is studied using finite element analysis. The study accounts for residual stresses generated during wheel manufacturing and fitment of the wheel on locomotive axle. A validated thermal model accounting for heat loss to rail, brake blocks and ambient air is considered for accurate prediction of wheel temperatures for a given train running and braking history. Results are obtained for low- and high-friction, composite brake blocks used by Indian Railways for two limiting braking scenarios: (i) synchronized braking where braking effort is uniformly distributed on all brake blocks and (ii) independent braking where braking effort to decelerate a train is provided solely by locomotive brake blocks. Results show that bending at hub–disc interface predominantly governs the gauge change. While compressive hoop stresses in the tread region, occurring from rim heating during braking, cause gauge reduction, tensile hoop stresses in the tread region, occurring during wheel cool down cause an increase in wheel gauge. Importantly, while gauge condemning is a transient phenomenon occurring only during braking, gauge widening is “permanent” as it exists even after the wheels cool to room temperature. Allowable reduction of wheel gauge of 0.5mm, currently used by Indian Railways, is found to be highly restrictive. In fact, in service wheel failure based on this criterion is observed in all braking scenarios considered.

Unicortical fixation of metacarpal fractures: is it strong enough?

Unicortical fixation has some practical and theoretical advantages over bicortical fixation. Questions have been raised to its adequacy for post-operative mobilization. We hypothesized that fixation using a plate and eight unicortical screws would be as strong as using a plate and four bicortical screws. A total of 40 unicortical and 40 bicortical fixations were compared using a cadaveric metacarpal model. Unicortical fixation was performed using an eight-hole parallel plate and bicortical fixation with a four-hole straight plate. Fixations were tested to failure using four-point bending load. The mean load to failure was 414 N SD 38(SE) for the unicortical group and 296 N SD 29(SE) for the bicortical group. Significant differences between these two constructs were observed. The mean stiffness of the fixation was higher for the bicortical group than the unicortical, although this difference did not reach significance. Unicortical fixation alone is sufficient to enable early post-operative mobilization in a live model.

A comparative study on the customized design of mandibular reconstruction plates using finite element method

Mandible defects and its deformities are serious complications and its precise reconstruction is one of the most challenging tasks in oral maxillofacial surgery. The commercially available standard mandible implants are manually bended before surgery to custom fit the patient’s jaw. A slight mismatch in the plate and bone alignment may result in the implant failure. However, with the integration of computer-aided design, rapid prototyping, and advanced imaging systems (computed tomography or magnetic resonance imaging), it is possible to produce a customized mandible implant that can precisely fit the patient’s jaw. The aim of this article is to compare a new design of customized mandible implant (sinewave plate) and compare it with the commonly used straight implant design. The finite element–simulated results reveal that the commonly used straight reconstruction plates are more prone to loosening of the screws due to its higher strain concentration on the screw hole when compared to newly designed sinewave reconstruction plate. Moreover, the straight plate is more sensitive to the chewing load variations and develops almost 20% increase in the stresses when compared to sinewave plate. The study reveals that the sinewave reconstruction plate can significantly enhance the stability and safety of the mandible implant.

A Biomechanical and Clinical Comparison of Midshaft Clavicle Fixation Performed With Either Two Or Three Screws On Each Side Of The Plate

Objectives:Plate fixation with six cortices of purchase (three screws) on each side of the fracture has been the standard of care when operatively treating displaced midshaft clavicle fractures. The use of locking plates and screws may afford equivalent biomechanical strength and clinical outcomes with only four cortices of purchase (two screws) on each side of the fracture. The purpose of this study is to compare the biomechanical and clinical performance of three-screw and two-screw constructs for displaced midshaft clavicle fractures.Methods:Biomechanical studies employing cantilever bending, deemed most physiologic of midshaft clavicle fracture models, have demonstrated that plate bending and fracture through the end screw hole are the common modes of failure. After simulating midshaft fractures in 10 pairs of embalmed cadaveric clavicles, the biomechanically inferior lateral fragments were randomly assigned to plate fixation with either three non-locking screws or two locking screws. Cyclic tensile loads (10 N to 75 N in a sinusoidal pattern at a rate of 1 Hz) were applied for 5 minutes along the long axis of the clavicle. Then, the constructs were loaded to failure at a rate of 0.5 mm/s with pullout forces applied parallel to the long axis of the screws. Additionally, we retrospectively identified 41 patients who had midshaft clavicle fractures surgically repaired with a minimum follow-up of 6 months: 21 patients were treated with three-screw constructs and 20 patients with two-screw constructs. Patient reported outcomes, radiographic time to union, and complication rates were compared.Results:Biomechanically, there were no significant differences in cyclic displacement (p=0.17), stiffness (p=0.94), yield load (p=0.65), or ultimate load (p=0.622) between the two groups. Clinically, there were no significant differences in American Shoulder and Elbow Surgeons score (ASES) (p=0.35), Constant score (p=0.34), Visual Analog Scale (VAS) pain score (p=0.34), Single Assessment Numeric Evaluation (SANE) score (p=0.99), or average time to union (p=0.74). Complication rates (painful hardware, non-union, hardware failure) trended toward being higher in the three-screw group (p=0.20).Conclusion:Plate fixation of displaced midshaft clavicle fractures with four cortices of purchase using two locking screws performs biomechanically and clinically equivalent to fixation with six cortices of purchase using three non-locking screws. Potential beneficial clinical implications include decreased surgical exposure, morbidity, time, and cost. Particularly, with regards to midshaft clavicle fractures, the reduction of the required number of points of cortical fixation from six to four allows the surgeon, in most instances, to use shorter and non contoured straight plates, eliminating the extra time and technical difficulty typically required to fit longer contoured plates to the variable and complex anatomy of the clavicle.

Research into acetone removal from air by biofiltration using a biofilter with straight structure plates

The biological air treatment method is based on the biological destruction of organic compounds using certain cultures of microorganisms. This method is simple and may be applied in many branches of industry. The main element of biological air treatment devices is a filter charge. Tests were carried out using a new-generation laboratory air purifier with a plate structure. This purifier is called biofilter. The biofilter has a special system for packing material humidification which does not require additional energy inputs. In order to extend the packing material's durability, it was composed of thermally treated birch fibre. Pollutant (acetone) biodegradation occurred on thermally treated wood fibre in this research. According to the performed tests and the received results, the process of biodestruction was highly efficient. When acetone was passed through biofilter's packing material at 0.08 m s−1 rate, the efficiency of the biofiltration process was from 70% up to 90%. The species of bacteria capable of removing acetone vapour from the air, i.e. Bacillus (B. cereus, B. subtilis), Pseudomonas (P. aeruginosa, P. putida), Stapylococcus (S. aureus) and Rhodococcus sp., was identified in this study during the process of biofiltration. Their amount in the biological packing material changed from 1.6 × 107 to 3.7 × 1011 CFU g−1.