Instability Of Column Research Articles

First Tarsometatarsal Joint Arthrodesis for Hallux Valgus With and Without Intermetatarsal Screw Fixation: A Comparison of Correction and Maintenance of Correction

Tarsometatarsal joint arthrodesis is a commonly accepted procedure for hallux valgus associated with severe deformity and first ray hypermobility or medial column instability. This study evaluates the correction of hallux valgus deformity and the maintenance of correction with and without the use of a stabilization screw between the first and second metatarsal bases. Through retrospective review of first tarsometatarsal joint arthrodesis within our institution we evaluated 63 patients. Twenty-seven patients did not have a first to second metatarsal base screw and were placed into the no screw cohort. Thirty-six patients did have a first to second metatarsal base screw and were placed into the screw cohort. This study population had an osseous union rate of 95%. Clinical and radiographic recurrence occurred in 5 of 63 patients (8%). At 1-y postop the measurements demonstrated that the screw cohort had an average intermetatarsal angle correction of 11.6 degrees while the no screw cohort had an average correction of 7.8 degrees. Additionally, at 1-y postop the screw cohort had greater maintenance of the intermetatarsal angle correction with an average change of 0.5 degrees compared to 2.3 degrees in the no screw cohort. We conclude that the addition of the stabilization screw improves the first tarsometatarsal joint arthrodesis construct resulting in a greater degree of realignment and maintenance of correction.

Significance And Clinical Effect of Anteromedial Support Plate Assisted Reduction and Fixation in The Treatment of Complex Proximal Humeral Fractures

Background: There are more and more complex consolidated proximal fractures, and the postoperative effect is not very satisfactory. Therefore, we propose a surgical method and evaluate its effect. Methods: A total of 77 patients with complicated proximal humeral fractures who underwent surgical treatment in the Affiliated Hospital of Nantong University from June 2015 to January 2019 were collected. Among them, the internodal groove medial support plate assisted reduction and fixation technique and the lateral locking plate were used. A total of 15 cases of complicated proximal humeral fractures were used as the study group, and 62 patients with the same type of proximal humeral fractures treated with traditional reduction methods and internal fixation with lateral locking plates during the same period were used as the control group. The operation time of the two groups; intraoperative blood loss; number of effective intraoperative fluoroscopy; postoperative humeral neck shaft angle loss after reduction; postoperative shoulder joint Constant-Murley score; upper limb function DASH score and postoperative complications were retrospectively reviewed comparative analysis. Results: The number of effective intraoperative fluoroscopy was (6.18±1.869) times in the control group, more than (3.93±1.387) times in the study group, and the difference between the two was statistically significant (P<0.05);The operation time of the study group was longer than that of the control group, and the intraoperative blood loss of the study group was more than that of the control group, but the difference between the two was not statistically significant (P>0.05).In the first 1, 3, 6, and 12 months after surgery, in terms of imaging measurement, the loss angle after reduction of the humeral neck shaft angle in the control group and the study group increased with the increase in postoperative time. There was no significant difference in the lost angle after reduction of the humeral neck shaft angle between the two groups at month and 3 months (P>0.05).At the 6th and 12th months after surgery, the lost angle after reduction of the humeral neck shaft angle in the study group was smaller than that in the control group, and the difference between the two groups was statistically significant (P<0.05).For the recovery of shoulder joint function after surgery, the Constant-Murley score of the shoulder joint and the DASH score of upper limb function of the control group and the study group increased with the increase of postoperative time, while the Constant score and DASH score of the two groups were 1 after surgery. There was no significant difference at months, 3 months, 6 months and 12 months (P>0.05). Conclusions: The anteromedial support plate assisted reduction of the internodal groove can be used as a single locking plate for the treatment of complex proximal humeral fractures with medial column instability. It is an option when reduction is difficult or it is difficult to maintain stable reduction, which improves the quality of reduction and reduces surgery. Loss of posterior fracture reduction.

Compression tests on large angle columns in high‐strength steel

AbstractNominated for Eurosteel 2021 Best Paper AwardThe paper addresses the instability of large angle columns in high‐strength steel subjected to compression loads. It presents a number of compression tests on such columns with different eccentricities and slenderness and the resulting different buckling failure modes observed. The experimental campaign is intended to widen our understanding of the behaviour of high‐strength steel columns with large angle sections in compression and bending and so to complement previous experimental studies. The tests were accompanied by numerical analyses and calculations of the load carrying capacities based on current Eurocode 3 design recommendations. The numerical simulations were conducted using the FEM software FINELG, which takes into account the influence of geometrical and material non‐linearities. The numerical and analytical results are compared with the corresponding experimental ones. The experimental campaign and the numerical simulations were conducted as part of the ANGELHY project funded by the European Commission's Research Fund for Coal and Steel (RFCS).

Application of finite volume particle method for axisymmetric modeling of droplet formation in dripping and Rayleigh regimes

An axisymmetric model has been developed in the finite volume particle method (FVPM). FVPM is a conservative, consistent, meshless particle method that incorporates properties of both smoothed particle hydrodynamics (SPH) and the mesh-based finite volume method (FVM). The surface tension effect amplifies capillary instability which is the main mechanism in dripping and jet disintegration. The simulations are performed in 2D cylindrical coordinates by only considering the liquid flow (one phase). The model is validated for free liquid droplet evolved from cylindrical state, dripping from a capillary tube, Rayleigh instability of capillary liquid cylinder columns, and Rayleigh breakup of viscous jets. The FVPM-predicted pressure and oscillating period are in good agreement with theoretical solution for a free droplet. The FVPM-computed dripping length shows good consistency with provided experimental data in literature. The predicted growth rate of capillary instability is in good agreement with analytical solutions for flows with different orders of Ohnesorge numbers. The numerical breakup length of jet with Weber numbers between 2.5 and 40 has been determined with good accuracy based on analytical experimental solution.

Contiguous-Level Unilateral Cervical Spine Facet Dislocation-A Report of a Less Discussed Subtype.

Unilateral facet dislocation of subaxial cervical spine trauma is characterized by dislocation of inferior facet of superior vertebra over the superior facet of inferior vertebra. The injury is due to high-velocity trauma and associated with instability of spinal column. Such unilateral facet dislocations occurring at multiple adjacent levels for some reason are not reported or studied frequently. We have reported two cases of multiple-level dislocation of unilateral facets managed in our hospital with a review of available literature. The injury occurs as one side of the motion segment translates and rotates around an intact facet on the contralateral side. The major mechanism of injury is distractive flexion injury with axial rotation component. The injury is associated with instability secondary to loss of the discoligamentous complex. In cases with multiple-level dislocations of unilateral cervical facets, there are multiple mechanisms associated with significant neurological injury and most of them succumb at the site of injury. Only three other cases are available in English language literature. The neurological outcome is invariably poor. Multiple-level facet dislocations of subaxial cervical spine are reported sparsely in literature. We suspect that due to high-velocity nature of these injuries, most of them succumb soon after injury and not often reported. This article reports two cases of contiguous-level unilateral facet dislocation of subaxial cervical spine with associated injuries and the outcomes with review of literature.

Chapter 14 - Monitoring spinal surgery for extramedullary tumors and fractures

Meningiomas are the most common intradural extramedullary tumors, followed by nerve sheath tumors that can also grow extradurally. Metastases are the most frequent extradural tumors and most commonly affect the thoracic vertebrae. Spinal fractures with column dislocation and/or instability require surgical fixation. Spine surgery for an extramedullary tumor or fracture usually involves decompression of neural elements and instrumentation for stabilization. These procedures risk spinal cord and nerve root injury. The incidence of nerve root deficits after resection of nerve sheath tumors is particularly high since the tumor grows from the rootlets. Intraoperative neurophysiologic monitoring and mapping techniques have been introduced to prevent iatrogenic neurologic deficits. These include motor and sensory evoked potentials, electromyography, compound muscle action potentials, and the bulbocavernosus reflex. The combination of techniques chosen for a particular procedure depends on the surgical level and the character of the lesion.

Short-Term Outcomes of the Lapicotton Technique in the Treatment of Progressive Collapsing Foot Deformity

Category:Midfoot/ForefootIntroduction/Purpose:Medial column instability (MCI) in Progressive Collapsing Foot Deformity (PCFD) is not solely determined by forefoot varus (FV). First ray hypermobility, hallux valgus, midfoot arthritis, gapping at the tarsometatarsal joint and dorsal metatarsal migration are findings associated with MCI. Acknowledgement of this instability requires inclusion of a procedure to the medial column in order to correct the forefoot varus, stabilize the ray and bring the foot to a plantigrade tripod position. Cotton opening wedge medial cuneiform osteotomy and Lapidus tarsometatarsal arthrodesis are procedures of choice in these scenarios. We have combined these 2 procedures into one called Lapicotton. The purpose of this study was to present the short-term outcomes of this technique.We hypothesized that Lapicotton will improve both clinical and radiological outcomes.Methods:We performed an IRB-approved retrospective study comprising 3 PCFDs having benefited from a Lapicotton procedure. Clinical outcomes were assessed with the European Foot and Ankle Society Score (EFAS), the Foot Function Index Score (FFI) and the Pain Catastrophizing Scale (PCS). Radiographic outcomes were assessed using weight-bearing computed tomography (WBCT) assessments. Middle Cuneiform Floor distance, Forefoot Arch Angle, Middle Facet uncoverage percentage, Talonavicular Coverage angle and the Foot and Ankle Offset (FAO) were measured. All these data were both preoperatively and postoperatively collected. Comparison between preoperative and postoperative results were done as described below. The Kruskal-Wallis H-test for independent groups was used to compare median values of the EFAS. The Wilcoxon signed-rank test for paired samples was used to compare preoperative and postoperative variables of FFI and PCS. For the radiographic measurements, normality was assessed using Shapiro-Wilk test. Comparisons were made using Student tests for normal variables and Mann-Whitney for non-normals.Results:This small series included 2 female and 1 male, with a mean age of 56 and a mean BMI of 31.8 kg/m2. Mean follow up was 2.9+/-0.2 (range from 2.7 to 3.1) months. 2 out of 3 patients simultaneously benefited of a Medial Calcaneal Displacement Osteotomy (MDCO 10mm) and a Lateral Column Lengthening (LCL 8mm). The wedge sizes used for the Lapicotton were 8 mm in all cases. Regarding clinical outcomes, EFAS (p=0.79) and FFI (p=0.99) did not showed any significant improvement whereas PCS were significantly improved (Δ=-5.67[-9.2–2.2];p=0.03). Regarding radiological outcomes, fusion was present in all the cases at the maximal follow-up. Middle cuneiform floor distance and Forefoot Arch Angle were significantly increase (respectively Δ=6.9;CI95%=[6.4;7.4];p< 0.01 and Δ=7.5;CI95%=[4.3;10.8]p<0.05). Middle Facet uncoverage was significantly improved (Δ=- 28.8;CI95%=[-33.1;-24.5]p< 0.01). Statistical power of the serie did not allowed comparison regarding the Talonavicular Coverage Angle (Δ=-14;CI95%=[-24;-3.9]) and the FAO (Δ=-3.9;CI95%=[-10.7;2.9]).Conclusion:The Lapicotton procedure showed encouraging outcomes with fusion in all cases at 3 months postoperatively, improvement in pain, correction of forefoot varus and of the of the Peritalar subluxation represented by the Middle Facet Uncoverage. These results should be moderate because other procedures (MDCO and LCL) were performed in 2/3 of the patients, and the outcomes were issued from a small cohort with short-term follow-up. Longer follow-up and a larger cohort are needed to confirm these results.

Does a “Spot Weld” with a 1st to 2nd Metatarsal Base Screw Maintain Correction of the Modified Lapidus Procedure? A Retrospective Radiographic Review

Category:Bunion; Midfoot/ForefootIntroduction/Purpose:The Lapidus 1st tarsometatarsal (TMT) arthrodesis has gained popularity for its ability to correct large deformities especially in cases of medial column instability. Even with solid fusion, instability between the 1st and 2nd columns can result in loss of intermetatarsal (IM) angle correction over time. Anecdotally, a 'spot weld' between the lateral 1stmetatarsal and medial 2nd metatarsal bases seems to predict long term maintenance of IM correction. The purpose of the study is to review cases of Lapidus 1st TMT arthrodesis with supplemental screw fixation from the 1stto 2nd metatarsal base for maintenance of IM correction and determine whether a 'spot weld' is predictive of maintenance and identify an optimum position of the 1st to 2nd metatarsal screw to achieve the 'spot weld.Methods:A retrospective radiographic review of cases by a single surgeon over the past five years was performed. All cases of tarsometatarsal fusion were queried and reviewed. Inclusion criteria included primary arthrodesis of the 1st TMT joint with supplemental fixation between the 1st and 2nd metatarsal bases, availability of appropriate radiographic image and at least 4 months follow up. Exclusion criteria included 1st TMT fusion without 1st-2nd metatarsal screw fixation, multiple TMT or midfoot fusion, Charcot neuroarthropathy, and revision fusion. A standard surgical technique was utilized with an in situ joint debridement, specific preparation to the medial 2ndmetatarsal base and adjacent lateral 1st metatarsal base, autogenous bone grafting and hardware construct at the 1stTMT joint consisting of compression screw from the 1st metatarsal to the 2nd cuneiform, screw fixation from 1st to 2ndmetatarsal bases and either locking plate or compression staple fixation dorsally across the 1st TMT joint.Results:90 cases (77 patients) met the inclusion criteria with average follow up of 309 days. Fusion of the 1st TMT occurred in 87/90 (96.7%) cases with 76 dorsal plate, 10 with dorsal staple and 4 with all screws. There was no incidence of complications related to the 1-2 screw. The mean pre-operative IM 1-2 angle was 14.90 degrees, with mean correction to 6.22 degrees post operative and final maintained correction at 7.10 degrees with mean loss of 0.87 degrees. There were 'spot welds' in 65/90 (72.2%) with a mean loss of correction of 0.48 degree versus loss of 1.88 degrees in the 'no spot weld' subgroup (p<0.001). Cases with no spot weld and screw lucency lost 2.25 degrees (p<0.001).Conclusion:Loss of IM 1-2 correction can occur due to instability between the 1st and 2nd columns even in cases of solid 1st TMT arthrodesis. The achievement of a 'spot weld' via careful preparation, bone grafting and use of a 1st to 2nd metatarsal base screw as part of a Lapidus construct was found to maintain correction with minimal loss (0.87 degree) versus cases where no 'spot weld' was achieved. Cases with no 'spot weld' that developed screw lucency had the greatest loss of correction. No statistical difference in screw position between groups was found.

Influence of Weight-Bearing Computed Tomography in the New Staging System of Progressive Collapsing Foot Deformity Classification

Category:Hindfoot; Midfoot/ForefootIntroduction/Purpose:The same Consensus that proposed a new nomenclature for Flatfoot, Progressive Collapsing Foot Deformity (PCFD), also introduced a new classification system for the disease. The idea of staging was supplemented by the construction of a system combining deformity classes and its flexibilities, using clinical and radiographic signs. The capacity of the weight-bearing computed tomography (WBCT) in evaluating PCFD and all components of peritalar subluxation has been established. The objective of this study was to compare PCFD classifications performed utilizing clinical and conventional radiographs (CR) findings with classifications established using clinical and WBCT findings. We hypothesized that evaluations considering WBCT would significantly change PCFD classifications, portraying a different picture of the disease.Methods:This retrospective IRB-approved case-control diagnostic study evaluated 89 consecutive PCFD feet (84 patients) with different presentations of the disease. Three fellowship-trained foot and ankle surgeons performed chart reviews and CR evaluations, determining PCFD classifications for the studied subjects. After a two-week washout period, the sequence was randomized, and a new classification was executed using clinical data and WBCT assessment. One of the readers repeated the WBCT evaluation two weeks later for intrarater reliability purposes. Assessments included presence or absence of classes, such as hindfoot valgus (A), midfoot abduction/sinus tarsi impingement (B), medial column instability (C), subtalar joint subluxation/subfibular impingement (D) and valgus of the ankle joint (E) as well as flexibility (1) and rigidity (2) of existing deformities. Fleiss kappa was used for interrater and Cohen's kappa for intrarater agreements. Differences between studied groups were determined by distribution comparison.Results:Mean BMI and age were 54.4 (+-17.1) and 33.6 (+-7.6) respectively. Interrater reliability was found to be moderate (0.55) and intrarater to be excellent (0.98). Evaluation using CR produced 22.8% of 1ABC, 13% of 1AC, 8,7% of 1ABCD and 7% of 2EABCD as most prevalent classifications. WBCT assessment found 31.5% of 1ABC, 11.2% of 1ABCD, 10.1% of 2ABCDE and 5.6% 1ABCDE. Class A was the most frequent component in CR (93.5%) and WBCT (94.5%). Class B had a higher prevalence in WBCT (94.38%) than in CR (71.7%) as well as Classes C (89.9% and 88.0%), D (44.9% and 29.3%) and E (31.5% and 23.9%). The percentage of combined flexible (1) and rigid (2) deformities was also higher in the WBCT evaluation (39.3% compared to 35.8%).Conclusion:As the new classification proposes the combination of different PCFD components to better support clinical decisions, proper identification of the classes is mandatory for a complete diagnosis. WBCT showed a different rate of deformity recognition, which increased the incidence of all classes, especially B (midfoot abduction/sinus tarsi impingement) and D (peritalar subluxation/subfibular impingement). An excellent intrarater agreement was found, which infers reliability of patient assessment combining clinical and WBCT evaluation. The obtained information could help providers to enhance comprehension of the disease and to supply patients with the most precise individual care.

A comparison between the Bluman et al. and the progressive collapsing foot deformity classifications for flatfeet assessment.

Bluman et al., flatfoot classification is based on posterior tibial tendon (PTT) dysfunction leading to a chronological appearance of several foot deformities. An expert consensus recently proposed a new classification named Progressive Collapsing Foot Deformity (PCFD) in which the focus was shifted to five different independent foot and ankle deformities and their flexibility or rigidity. The aim of this study was to compare Bluman and PCFD classifications. We hypothesize that both classifications will be reliable and that the PCFD classification will allow a larger distribution of the different types of foot deformity. We performed a retrospective IRB-approved study including 92 flatfeet. Three foot and ankle surgeons reviewed patient files and radiographs to classify each foot using both classifications. Bluman classification was performed one time as initially described and a second time after removing the Angle of Gissane sclerosis sign. Interobserver reliabilities were determined with Fleiss' kappa values. Interobserver reliabilities of Bluman and PCFD classifications were, respectively, substantial 0.67 and moderate 0.55. PCFD Class C and D reliabilities were, respectively, slight 0.07 and fair 0.28. The 276 readings were spread into 10 substages in Bluman and 65 subclasses in PCFD. The progressivity of the Bluman classification prevented the combination of flexible hindfoot valgus (II Bluman, 1A PCFD), midfoot abduction (IIB, 1B) and medial column instability (IIC, 1C) which was frequent in our study (112/276 readings, 40.6%). By removing the Angle of Gissane sclerosis sign from the Bluman classification, the prevalence of stage III decreased from 44.2 to 10.1%. Bluman and PCFD classifications were reliable. The PCFD classification showed a larger distribution of different types of flatfeet but Classes C and D need better definition. The progressivity of Bluman classification causes inconsistencies and Gissane angle sclerosis sign is inappropriately used and might lead to incorrect surgical indications.

Coupling Effect of Eccentricity and Slenderness Ratios on RCFST Column Instability Modes

The instability damage modes of rectangle concrete-filled steel tube (RCFST) columns that are subjected to eccentric compression can be divided into two types based on the modified Jezek analytical procedure, namely, the eccentricity ratio (γ) and the slenderness ratio (λ) coupling effect. The RCFST columns have unilateral compression yield failure mode when γ is small. However, it has compressive and tensile mode on both sides when the value of γ is large. In this work, parametric analyses were performed to test 32 RCFST long columns by varying γ with different λ combinations. From the analysis, it was found that the results of the theoretical analysis of the load-tension strain (P-ε) responses and the instability modes of the RCFST long columns are similar to the experimental results. Further, the proposed analytical method aids in better understanding the effects of γ and λ coupling on the stability behavior of the RCFST columns.

Radiological and mid- to long-term patient-reported outcome after stabilization of traumatic thoraco-lumbar spinal fractures using an expandable vertebral body replacement implant

BackgroundFor the treatment of unstable thoraco-lumbar burst fractures, a combined posterior and anterior stabilization instead of a posterior-only instrumentation is recommend in the current literature due to the instability of the anterior column. Data on restoring the bi-segmental kyphotic endplate angle (BKA) with expandable vertebral body replacements (VBR) and on the mid- to long-term patient-reported outcome measures (PROM) is sparse.MethodsA retrospective cohort study of patients with traumatic thoraco-lumbar spinal fractures treated with an expandable VBR implant (Obelisc™, Ulrich Medical, Germany) between 2001 and 2015 was conducted. Patient and treatment characteristics were evaluated retrospectively. Radiological data acquisition was completed pre- and postoperatively, 6 months and at least 2 years after the VBR surgery. The BKA was measured and fusion-rates were assessed. The SF-36, EQ-5D and ODI questionnaires were evaluated prospectively.ResultsNinety-six patients (25 female, 71 male; age: 46.1 ± 12.8 years) were included in the study. An AO Type A4 fracture was seen in 80/96 cases (83.3%). Seventy-three fractures (76.0%) were located at the lumbar spine. Intraoperative reduction of the BKA in n = 96 patients was 10.5 ± 9.4° (p < 0.01). A loss of correction of 1.0 ± 2.8° at the first follow-up (t1) and of 2.4 ± 4.0° at the second follow-up (t2) was measured (each p < 0.05). The bony fusion rate was 97.9%. The total revision rate was 4.2%. Fifty-one patients (53.1% of included patients; age: 48.9 ± 12.4 years) completed the PROM questionnaires after 106.4 ± 44.3 months and therefore were assigned to the respondent group. The mean ODI score was 28.2 ± 18.3%, the mean EQ-5D VAS reached 60.7 ± 4.1 points. Stratified SF-36 results (ISS < and ≥ 16) were lower compared to a reference population.ConclusionThe treatment of traumatic thoraco-lumbar fractures with an expandable VBR implant lead to a high rate of bony fusion. A significant correction of the BKA could be achieved and no clinically relevant loss of reduction occurred during the follow-up. Even though health related quality of life did not reach the normative population values, overall satisfactory results were reported.

Deformation and instability properties of cemented gangue backfill column under step-by-step load in constructional backfill mining.

Constructional backfill mining with cemented gangue backfill column can solve the environmental issues caused by mining activities and the accumulation of waste gangue at a low cost. To study the deformation and instability properties of cemented gangue backfill columns during the advancement of coal mining face, five step-by-step loading paths were adapted to mimic the different loading processes of the roof. The lateral deformation at different heights and axial deformation of the sample were monitored. The results show that the deformation and instability of the backfill column have the properties of loading paths and are affected by the step-by-step loading path. When stress-strength ratio (SSR) is less than 0.6, the lateral of backfill column shrinks during the creeping process. In high-stress levels, lateral creep strain develops faster than axial creep strain. The backfill column has characteristics of axial creep hardening and lateral creep softening during the step-by-step loading process. The instantaneous deformation modulus and instantaneous Poisson's ratio show an upward trend. The strength of backfill column under the step-by-step load is related to loading paths and is no less than uniaxial compressive strength. The non-uniformity of the lateral deformation of backfill column leads to excessive localized deformation that mainly occurs in the middle, causing the overall instability. The development of cracks of backfill column under step-by-step load could be divided into 4 stages according to SSR. Under different step-by-step loading paths, the axial creep strain rate is nearly a constant before entering the accelerated creep stage. A nonlinear creep constitutive model with a creep strain rate trigger was proposed to depict the development of axial strain under step-by-step load. This research could provide a scientific reference for the design of the advancing distance and cycle for the hydraulic support, and reinforcement of the backfill column.

Multi-scale numerical analysis of the eccentricity on the instability of RCFST long columns

Damage modes of the rectangle concrete-filled steel tube (RCFST) long columns under the eccentric compression were investigated by combining the finite element method (FEM) and the extended finite element method (XFEM) on the ABAQUS platform. The three-dimensional (3D) aggregates and the interfacial transition zone (ITZ) were generated at the middle height of RCFST. The parametric analyses were performed to test four RCFST long columns by varying the eccentricity ratio (γ). The results agreed well with the experimental results. The proposed multi-scale numerical simulation procedure can be used to understand the instability behavior of the RCFST long columns.

The throat of Brazilian Agricole production: The breakdown of vertical silos

In the current world economical conjecture, the accentuated growth in Brazilian production and exportation in the Agro-Food industry sets the country as a central role in the field. Implementing storage units in Agricole properties and industrial sites constitutes a necessary premise to keep the country as a competitive member in the global scenery. The vertical silos present themselves as alternative solutions. However, a great sum of the existent silos does not match the ideal conditions of operation due to the insufficient knowledge of the pressure variations that happen in time and inner space, of the flow, and the variables that affect the behavior of the stored products. Such situations have contributed to accidents and breakdowns in silos. With this increasing demand for the storage capacity in silos, the full understanding of the structural functioning, failure prevention, and optimization of the structural components became of great importance. Thus, this work aimed to present some events that happened in the country in the last years and bring the main causes of structural failures, highlighting the failures that are directly related to the type of flow in the interior of the silo; wacky charging and/or discharging; change in the properties of the stored products (specified weight, actual inner friction angle, friction angle against the wall) and instability in the support columns. It follows that a great number of accidents in these structures could have been avoided or reduced with previous knowledge, from the silo designer and those responsible for the operation, about the most important occurrences in silos.

Seismic design of columns in two-story steel concentrically braced frames with bracing members intersecting columns between floors

A new seismic design method is proposed for the columns in two-story steel concentrically braced frames with bracing members intersecting columns between the floors. The method is intended to improve the stability of braced frame columns taking into account the interaction between the stories when the braces respond in the inelastic range. Furthermore, the proposed method aims to prevent excessive inelastic deformation in the braces intersecting columns between the floors considering the interaction between the stories, which otherwise may lead to brace fracture. The proposed design method is first presented in the framework of the North American steel design standards, followed by a design example to illustrate the method. Dynamic analyses are then performed to validate the design method and evaluate the seismic performance of the frame designed with and without the consideration of the method. The adequacy of the proposed method is assessed using further dynamic analyses when the location of the weakest braced panel is altered, oversized braces are used, and column orientation is changed. The results show that the proposed method can appropriately predict the column design forces, prevent column instability taking into consideration the interaction between inelastic brace responses in adjacent stories, thus improving the seismic response of the braced frame.

Study on the role of the accident statistics in the design of coal mine safety signs

Accident statistics is an important basis in designing coal mine safety signs. In this paper, we study the process and feasibility for accident statistics as the design basis of the coal mine enterprise safety signs. This paper comes into a conclusion of unsafe actions which cause the accident can be divided into two categories: illegal action and error action. Illegal action could be subdivided into habitual illegal action and accident illegal action, while error action could be subdivided action into skills, decisionmaking and physiological perceptual action. In this paper, we specifically analyze five coal mine accident cases as examples, in order to conclude unsafe actions and unsafe states in every case. Specifically, unsafe acts are: bolt pretightening does not reach the designated position, sitting on the belt, no remote operating point column, maintenance without power cuts and operating under pressure. In addition, these unsafe acts lead to relative unsafe states, which are insufficient bolt pressure, point column instability, machine charging electricity and hydraulic pipe under pressure? Finally, these unsafe states become causations of accidents. Based on statistical analysis, we found out illegal actions of coal mine accident cases and specifically designed five safety signs, which are ‘bolt must be preloaded in place’, ‘be careful of the column’, ‘ban to sit on belts’, ‘forbidden pressing operation’ and ‘maintenance must be power outages’.

ХИРУРГИЧЕСКОЕ ЛЕЧЕНИЕ КОНСТРИКТИВНОЙ МИЕЛОПАТИИ У СОБАК

Article describes the examination and treatment of dogs with a constrictive myelopathy (CM). CM is a degenerative pathology of the spinal cord associated with instability of the spinal column in the thoracolumbar region due to dysplasia of the caudal articular processes (aplasia or hypoplasia), which leads to microtraumas of the spinal cord and requires surgical treatment. Орerative technique was used to stabilize the spinal column by installing a system of multiaxial screws in the vertebrae with dysplasia of the caudal articular processes for the treatment of CM. Positive dynamics of neurological status was observed in 8 of 13 operated animals, in 3 patients the progression of clinical signs significantly slowed down, the neurological status of two dogs did not change after operation. The described method of stabilization of the spinal column prevents abnormal mobility of the spinal column in the area of dysplasia of the articular processes of the vertebrae. Our observations confirm that one of the causes of pia-arachnoid fibrosis is chronic spinal cord injury due to instability of the spinal column.

Differentiated Approach to the Diagnosis and Treatment of Tuberculous Spondylitis in Adults

The purpose of this study is to generalize the results of a complex clinical-laboratory, radiological and immunological study of patients with spinal tuberculosis. A comprehensive examination analysis was carried out in 192 patients with tuberculous spondy litis who were in the department of surgery for osteoarticular tuberculosis of the Republican Specialized Scientific and Practical Medical Center of Tuberculosis and Pulmonology in Tashkent, Uzbekistan. Severe degrees of spinal disorders were found in 48.7% of patients. Magnetic resonance imaging (MRI) and multi-slice spiral computed tomography (MSCT) allow establishing the stage and activity of a specific process in the spine, as well as complications. Spinal column instability was detected in 143 (74.5%) patients, paravertebral abscesses in 116 (60.4%) patients, and epidural abscesses in 75 (39.0%) patients. Changes in immunological parameters in patients with spinal tuberculosis were associated both with impaired regulation of immunogenetic and with the direct influence of the immune system at various stages of the process. The detection of certain patterns of immune system disorders in patients with tuberculous lesions of the spine allowed us to make a differentiated approach to their treatment in order to increase the effectiveness of the treatment. It can be concluded that at present, tuberculosis of bones and joints, especially the spine, is detected in an advanced stage in 50-80% of cases and has a widespread and complicated character with profound anatomical and functional changes and the presence of severe spinal disorders in 48.7% patients in Uzbekistan. Regarding spondylitis, it is immensely important to make an accurate diagnosis based on the clinical presentations, laboratory, radiological and immunological findings and by periodic assessment of the response to treatment, which is essential in atypical cases.

Impinging liquid jets on flat fluid interfaces

We study the impact of a liquid jet on a liquid bath in the presence of an external Newtonian liquid. Attention is given to the impact zone where we find a stationary wave-like behavior of the liquid column. We unravel new dynamics, seen at high acquisition frame rates, of the instability of the liquid column at the critical distance between the capillary tip and the surface of the fluid bath. A dominant critical frequency of oscillation is found. Particle Image Velocimetry measurements of the velocity field, in the vicinity of the impact zone, are also performed, with emphasis on the vortex structure that develops near the flat interface.