VIBRATIONS OF STEPPED ONE-WAY THIN RECTANGULAR PLATES SUBJECTED TO IN-PLANE TENSILE/ COMPRESSIVE FORCE IN Y-DIRECTION ON WINKLER'S FOUNDATION

Differential equations of free/forced vibrations of n_step one_way thin rectangular plates subjected to in_plane tensile/compressive force in y_direction on Winkler's foundation are established by using singular functions, their general solutions solved for, expression of vibration mode function and frequency equation on usual supports derived with W operator. Influence functions for various cases deduced here may also be used to solve problems of static buckling or stability for beams and plates in relevant circumstances.

A Simple Empirical Formula for Predicting the Ultimate Strength of Ship Plates with Elastically Restrained Edges in Axial Compression

An investigation is conducted on the static ultimate limit state assessment of ship hull plates with elastically restrained edges subjected to axial compression.Both material and geometric non-linearities were considered in finite element(FE)analysis.The initial geometric imperfection of the plate was considered,while the residual stress introduced by welding was not considered.The ultimate strength of simply supported ship hull plates compared well with the existing empirical formula to validate the correctness of the applied boundary conditions,initial imperfection and mesh size.The extensive FE calculations on the ultimate strength of ship hull plates with elastically restrained edges are presented.Then a new simple empirical formula for plate ultimate strength is developed,which includes the effect of the rotational restraint stiffness,rotational restraint stiffness,and aspect ratios.By applying the new formula and FE method to ship hull plates in real ships,a good coincidence of the results between these two methods is obtained,which indicates that the new formula can accurately predict the ultimate strength of ship hull plates with elastically restrained edges.

Influence of dent on residual ultimate strength of 2024-T3 aluminum alloy plate under axial compression

Drop-weight impact tests were conducted on 2024-T3 aluminum plates with five types of impactors, and then the effects of the dent on the residual ultimate strength of the 2024-T3 specimens were investigated through axial compression tests. Results indicate that with increase in dent depth, the five types of dents affect the ultimate strength of the plate in different trends. Nevertheless, other than the plate global deflection caused by impacting, the dent itself has unremarkable effect on the ultimate strength. The mathematical expressions are derived regarding the relationship between impact energy factor and the dent depth factor as well as the compressive ultimate strength reduction rate and the dent depth factor.

A Biomechanical Comparison of Conventional versus an Anatomic Plate and Compression Bolts for Fixation of Intra-articular Calcaneal Fractures

The purpose of this study was to compare the biomechanical stability obtained by using our technique featured an anatomical plate and compression bolts versus that of the conventional anatomic plate and cancellous screws in the fixation of intraarticular calcaneal fractures.Eighteen fresh frozen lower limbs of cadavers were used to create a reproductive Sanders type-Ⅲ calcaneal fracture model by using osteotomy.The calcaneus fractures were randomly selected to be fixed either using our anatomical plate and compression bolts or conventional anatomic plate and cancellous screws.Reduction of fracture was evaluated through X radiographs.Each calcaneus was successively loaded at a frequency of 1 Hz for 1000 cycles through the talus using an increasing axial force 20 N to 200 N and 20 N to 700 N,representing the partial weight bearing and full weight bearing,respectively,and then the specimens were loaded to failure.Data extracted from the mechanical testing machine were recorded and used to test for difference in the results with the Wilcoxon signed rank test.No significant difference was found between our fixation technique and conventional technique in displacement during 20-200 N cyclic loading(P=0.06),while the anatomical plate and compression bolts showed a great lower irreversible deformation during 20-700 N cyclic loading(P=0.008).The load achieved at loss of fixation of the constructs for the two groups had significant difference:anatomic plate and compression bolts at 3839.6±152.4 N and anatomic plate and cancellous screws at 3087.3±58.9 N(P=0.008).There was no significant difference between the ultimate displacements.Our technique featured anatomical plate and compression bolts for calcaneus fracture fixation was demonstrated to provide biomechanical stability as good as or better than the conventional anatomic plate and cancellous screws under the axial loading.The study supports the mechanical viability of using our plate and compression bolts for the fixation of calcaneal fracture.

Locking compression plate+T-type steel plate for postoperative weight bearing and functional recovery in complex tibial plateau fractures

Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in different types of tibial plateau fractures.Violent trauma can lead to displaced fracture,serious soft tissue injury,and potentially,dislocation of the knee joint.Therefore,tibial plateau fractures are extremely unstable.AIM To assess the use of locking compression plate(LCP)+T-type steel plate for postoperative weight bearing and functional recovery of complex tibial plateau fractures.METHODS Ninety-seven patients with complex tibial plateau fractures who underwent surgery at our hospital were selected for retrospective study.Forty-nine patients had been treated with LCP+T-type steel plate limited internal fixation(study group),and 48 patients with bilateral ordinary steel plate support(control group).The operation process index,postoperative rehabilitation related index,Rasmussen score of the knee joint,tibial plateau varus angle(TPA),tibial plateau retroversion angle(PA),and surgical complications of the two groups were compared.RESULTS The operation time and intraoperative bone graft volume in the study group were lower than those in the control group(P<0.05).There were no significant differences in surgical bleeding,anterior external incision length,postoperative drainage,hospital stay duration,and fracture healing time between the groups(P>0.05).There was no significant difference in the TPA and PA angle between the groups immediately and 18 mo after surgery(P>0.05).At 12 mo after surgery,the Rasmussen scale score was higher in the study group than in the control group(P<0.05).There was no significant difference in the Rasmussen scale score at 18 mo after surgery,and the radiology score at 12 and 18 mo after surgery,between the two groups(P>0.05).The postoperative complication rate in the study group(3.77%)was lower than that in the control group(15.09%;P<0.05).CONCLUSION LCP+T-type steel plate internal fixation has advantages in terms of minimizing trauma and enabling early postoperative functional exercise,promoting functional recovery and lower limb weight-bearing,and reducing postoperative complications.

Supracutaneous Locking Compression Plate for Grade I &II Compound Fracture Distal Tibia—A Case Series

Background: Supracutaneous plating using a locking compression plate (LCP) as an external fixator in compound periarticular areas is facilitated by the development of anatomical plates. The soft tissue around the distal tibia is easily compromised by trauma and subsequent operative fracture treatment posing a definitive challenge in the distal tibia compound fractures. The purpose of this report is to describe our successful results using the metaphyseal locking compression plate (LCP) as an external fixator in the treatment of Grade I & II compound fractures of distal tibia. Methodology: A total of five (05) patients underwent “supracutaneous plating” of the tibia using a metaphyseal locking compression plate. Average age was 36 years. Regular screw tract dressings were done. Average period of follow-up was 15 months. Results: The plate was in situ for an average of 24 weeks. There were no clinically significant screw site infections. In all five patients the plate was kept in place until there was complete consolidation both clinically and radiologically. At the latest follow-up (average 15 months), all patients were fully weight bearing with a fully healed tibia. All patients were infection-free with well-healed wounds. Conclusion: Routinely, after initial debridement and temporary bony stabilization is provided by external fixation in compound fractures of the distal tibia with significant soft tissue injury. Most external frames for the lower leg are bulky and cumbersome, causing significant problems for the patient. To circumvent these issues, we have successfully used an anatomically-contoured supracutaneous metaphyseal locking compression plate as external fixator in a series of five patients for grade I & II compound fracture of the distal tibia.

Ultimate Compressive Strength Computational Modeling for Stiffened Plate Panels with Nonuniform Thickness

The aim of this paper is to develop computational models for the ultimate compressive strength analysis of stiffened plate panels with nonuniform thickness.Modeling welding-induced initial deformations and residual stresses was presented with the measured data.Three methods,i.e.,ANSYS finite element method,ALPS/SPINE incremental Galerkin method,and ALPS/ULSAP analytical method,were employed together with existing test database obtained from a full-scale collapse testing of steel-stiffened plate structures.Sensitivity study was conducted with varying the difference in plate thickness to define a representative(equivalent)thickness for plate panels with nonuniform thickness.Guidelines are provided for structural modeling to compute the ultimate compressive strength of plate panels with variable thickness.

Compressive Behavior of Steel Members Reinforced by Patch Plate with Welding and Bonding

Repair and reinformcement of aged civil steel structures is one of the important issues for maintaining and using them for a long term. For repair and reinforcement of deteriorated civil steel structures due to fatigue and corrosion, patch plate reinforcement is widely applied. Bolting is generally used because of easy quality control and many construction achievements. However, bolting has downsides including holes made and weight increase. Welding is considered to overcome these demerits but in reality the application of welding is unsatisfactory due to the possibility of fatigue crack occurring from the welded part. In this study, a patch plate strengthening system of welded joint assisted with bonding has been proposed. The compressive behaviors of weld-bond jointed specimen were investigated by a series of experiments and FE analysis. It was confirmed that use of welding and bonding was effective to enhance compressive strength of specimen, due to better load-carrying capacity of patch plate compared with sole use of welding.

The Effects of Bone Screw Configurations on the Interfragmentary Movement in a Long Bone Fixed by a Limited Contact Locking Compression Plate

The locking compression plates (LCP) are efficient tools in open reduction and internal fixation (ORIF), especially in osteoporotic bones. Two important factors of screw density and screw position can affect the functionality of the bone plate. Several studies have assessed the influence of the screw configurations on the bone-plate stiffness, but the effects of screw positions on the interfragmentary strain, εIF of LCP construct have not been investigated yet. In this study, finite element method was used to investigate the influence of screws number and position on the interfragmentary strain of LCP-femur system for a mid-shaft fracture. Results of this study showed that by insertion of screws closer to the fracture site, εIF decreases by 2nd degree polynomial function versus screw position, but by adding the screws from the ends of the plate, or by moving and placing the screws towards the fracture site, the reduction of εIF will be linear. Results of this study were compared and are in agreement with some studies in the literature, even though their scope was mostly stability of the bone-implant system, whereas our scope was focused on the interfragmentary strain.

Application of proximal femur locking compression plate for unstable four part intertrochanteric fractures

Objective To evaluate the clinical results of proximal femur locking compression plate (LCP) for unstable four-part intertrochanteric femoral fractures.Methods Clinical data of53patients wiith unstable four-part intertrochanteric

Comparison of effect of locking compression plate internal fixation and reconstruction plate fixation for treatment of mid-shaft clavicular fracture

Objective:To compare the effect of locking compression plate internal fixation and reconstruction plate fixation for the treatment of mid-shaft clavicular fracture.Methods: In this study, the medical records of 68 patients with mid-shaft clavicular fractures treated in our department from May 2014 to May 2017 were retrospectively analyzed. 32 patients in the control group received the reconstruction plate fixation, while 36 patients in the observation group received the locking compression plate internal fixation. Patients were followed up for 12 months, thereafter, various indicators including operative indexes, Constant-Murley (CM) score, disability of arm shoulder and hand (DASH) score, activities of daily living (ADL), and complications were compared between groups.Results: The incision length, intraoperative blood loss, operation time, and fracture healing time of the observation group were significantly lower than the control group (P<0.05). The postoperative CM scores of the two groups were significantly increased, moreover, the scores of muscle strength, daily life and activity were significantly in the observation group were higher than those of the control group (P<0.05), and no difference was found in the pain degree (P>0.05). There was a decrease trend in the DASH score and an increase trend in the ADL score in both groups, while both indexes were better in the observation group than in the control group (P<0.05). The total incidence of complications in the observation group was significantly lower than that in the control group (8.33% vs 18.75%,P<0.05).Conclusion: Compared with the reconstruction plate fixation, locking compression plate internal fixation has the advantages of more mini invasive, better amelioration of shoulder joint function and less complication for patients with mid-shaft clavicular fractures.

Effect of locking compression plate internal fixation on the injury extent and bone metabolism of Robinson 2A and 2B middle clavicular fractures

Objective:To investigate the effect of locking compression plate internal fixation on the injury extent and bone metabolism of Robinson 2A and 2B middle clavicular fractures.Methods:Totally 80 cases of patients with Robinson 2A and 2B middle clavicular fractures admitted to our hospital between March 2017 and January 2019 were divided into the control group(n=41)receiving conventional kirschner wire internal fixation and the observation group(n=39)receiving locking compression plate internal fixation according to the operation plans.The differences in serum contents of inflammatory factors,oxidative stress indexes and bone metabolism indexes were compared between the two groups of patients before patients entered operating room,24 h after surgery and 48 h after surgery.Results:Before patients entered operating room,there were no statistically significant differences in the serum contents of inflammatory factors,oxidative stress indexes or bone metabolism indexes between the two groups(P>0.05).At 24 h and 48 h after surgery,serum inflammatory factors interleukin-1(IL-1),interleukin-17(IL-17),high-sensitivity C-reactive protein(hs-CRP)and tumor necrosis factorα(TNF-α)contents in the observation group were lower than those in the control group;serum reactive oxygen species(ROS)and lipid hydroperoxide(LHP)contents were lower than those in the control group,while catalase(CAT)and glutathione peroxidase(GSH-Px)contents were higher than those in the control group;serum N-terminal propeptide of procollagen type I(PINP),bone gla protein(BGP)and alkaline phosphatase(ALP)contents were higher than those in the control group,while N-telopeptide of typeⅠcollagen(NTX),C-telopeptide of typeⅠcollagen(CTX)and tartrate-resistant acid phosphatase 5b(TRACP5b)contents were lower than those in the control group(P<0.05).Conclusion:Locking compression plate internal fixation can reduce the postoperative trauma extent and help promote the fracture healing in patients with Robinson 2A and 2B middle clavicular fracture.

Effect of Locking Compression Plate on the Treatment of Limb Fracture and the Effect of Operative Success Rate and Postoperative Recovery Time

Objective:To analyze the effect of locking compression plate on the success rate of operation and the time of postoperative recovery.Methods:120 patients with limb fractures from March 2018 to March 2020 were randomly divided into control group(60 cases)and observation group(60 cases).The control group was treated with plate screw internal fixation,The observation group used locking compression plate internal fixation,Compare the effect of treatment,the success rate of operation and the time of postoperative recovery.results:compared the effective rate of the two groups,the observation group(93.33%)was significantly higher than the control group(75.00%).Compared with the two groups,the success rate of operation and the time of postoperative recovery,the observed composition power was higher than that of the control group,and the postoperative recovery time was lower than that of the control group,P<0.05.Conclusion:The use of locking compression plate for the treatment of limb fracture can significantly increase the probability of successful operation,shorten the recovery time after operation,the overall curative effect is ideal,and the clinical popularization value is high.

Postoperative Fracture Healing Effects of Locking Compression Plate for the Treatment of Limb Fractures

Objectives To study the effects of applying locking compression plates in the treatment of patients with limb fractures on postoperative fracture healing.Methods:115 patients with limb fractures who were treated in our hospital from November 2019 to November 2020 were selected.In order to study the effective treatment method,the random-number table method was used in this study to divide the patients into two groups,namely the experimental group and the control group,and the locking compression plate treatment method and the pure plate and screw internal fixation treatment method were administered respectively to study their clinical application effects.Results:Compared with the control group,patients in the experimental group had a lower incidence of complications,shorter hospitalizations and shorter recovery time.Meanwhile,the experimental group had a better quality of recovery,and all data were significantly different from those of the control group,P<0.05,the intervention effect of the experimental group was better.Conclusion:The application of the locking compression plate in the treatment of patients with limb fractures is more conducive to promoting the postoperative healing of the patients'fractures,reducing the incidence of postoperative complications,and promoting the rapid recovery of patients,which has positive significance for clinical development.

肌肉负荷对股骨干骨折早期愈合生物力学影响的有限元分析

背景:以往的研究多通过忽略肌肉负荷和采用简化股骨负荷的方式,进行骨折早期愈合的生物力学分析。然而,肌肉负荷对骨折早期愈合产生的生物力学影响尚不清楚。目的:构建不同的股骨负荷模型,研究肌肉负荷对骨折愈合的生物力学影响,帮助临床医生更好地理解骨折愈合的生物力学过程,优化治疗方案。方法:利用AnyBody Modeling System软件构建个性化的人体肌肉骨骼系统,通过仿真分析以获取体内的肌肉骨骼负荷模型。该模型和采用改进简化负荷方法、简化负荷方法构建的股骨负荷模型,分别作为有限元输入的边界条件,对站立状态下锁定加压钢板应力应变、骨折块应变进行分析。结果与结论:(1)与简化负荷方法相比,肌肉骨骼方法得到的锁定加压钢板应力、应变和骨折块应变分别小了31.9%;38.9%和19.5%;(2)肌肉骨骼方法与改进简化负荷方法对比发现,忽略肌肉负荷则会造成锁定加压钢板的应力、应变和骨折块应变分别高估16.8%,14.3%和19.5%,肌肉负荷对骨折块的剪切运动大小无明显影响,而对运动方向有明显的影响;(3)结果表明,简化股骨负荷和忽略肌肉负荷的方法与肌骨骨骼负荷情况存在一定的偏差,因此,在研究骨折愈合时需考虑肌肉负荷的生物力学影响。

纤维带与无头加压螺钉治疗第1,2跖骨近端粉碎性骨折Lisfranc损伤

背景:Lisfranc韧带是维持足部横弓与纵弓的重要结构,Lisfranc损伤为一种严重的中足损伤。Lisfranc韧带损伤是复杂的,其治疗以及首选的固定方法有争议。目的:比较钢板联合Suturetape与钢板联合无头加压螺钉治疗第1,2跖骨近端粉碎性骨折Lisfranc损伤的短期疗效。方法:回顾性分析东莞市中医院骨七科2019年1月至2022年6月因第1,2跖骨近端粉碎性骨折Lisfranc损伤患者48例,其中25例采用钢板联合Suture tape固定(观察组),23例采用钢板联合无头加压螺钉固定(对照组)。术前参照影像学资料,根据Myerson分类系统进行分型;术后随访根据骨折愈合时间、目测类比评分、美国足踝外科学会标准评估足功能恢复情况,并对两组术后并发症进行比较分析。结果与结论:①两组患者均顺利完成手术并获得随访,随访时间12-36个月,平均(18.0±5.42)个月;②两组患者手术时间、术中出血量比较差异均无显著性意义(P>0.05);③观察组较对照组骨折愈合时间稍长,差异有显著性意义(P<0.05);④术后3,6,12个月随访,观察组较对照组目测类比评分明显降低(P<0.05);⑤术后6,12个月,观察组术后各时间点随访足功能AOFAS评分较螺钉组明显改善(P<0.05),且均较术前显著提高(P<0.05);⑥术后观察组出现1例创伤性关节炎,对照组出现1例切口感染、1例螺钉断裂及2例创伤性关节炎,两组比较差异无显著性意义(P>0.05),考虑与样本量偏少有关;⑦提示对于第1,2跖骨近端粉碎性骨折Lisfranc损伤,实施钢板联合Suture tape内固定治疗Lisfranc关节损伤效果可靠,可改善患者足关节功能,且具有手术创伤小、术后并发症少、远期医源性创伤性关节炎风险低的优势,较无头加压钉更有利于足功能的恢复。

计算机模拟复位联合骨盆复位架治疗APC-Ⅲ型骨盆骨折

背景:骨盆骨折类型多样,使用骨盆复位架进行复位时缺乏系统的复位路径,需要根据术者经验结合透视结果进行调整,具有不确定性与不可重复性。目的:探讨计算机模拟复位技术联合骨盆复位架治疗前后压缩(anteroposterior compression,APC)-Ⅲ型骨盆骨折的临床疗效。方法:回顾性分析2018年1月至2021年12月术前采用计算机模拟复位,术中采用骨盆复位架辅助复位的APC-Ⅲ型骨盆骨折患者19例,其中7例使用前环双钢板、12例采用单钢板联合前环皮下内置外固定架固定,所有患者均使用2枚骶髂螺钉固定后环。记录手术时间、术中复位时间、术中透视次数、出血量和随访时间,观察骨折愈合时间及术后并发症情况。根据Matta评分标准评定骨折复位情况,末次随访采用Majeed骨盆功能评分评估患者功能。结果与结论:①19例患者均完成手术,7例前环使用双钢板、12例采用单钢板联合前环皮下内置外固定架固定,后环均使用2枚骶髂螺钉,分别固定S1、S2椎体;②手术时间74-147 min,平均(101.63±19.55)min;术中复位时间26-41 min,平均(38.11±3.31)min;术中透视次数35-81次,平均(62.68±13.11)次;术中出血60-130 mL,平均(85.37±20.57)mL;③所有患者均获得随访,随访时间12-26个月,骨折愈合时间12-20周,平均(16.37±2.50)周;④术后1 d按Matta标准评定复位情况:优14例,良5例;末次随访Majeed功能评分:优16例,良3例;⑤2例患者术区切口出现红肿、渗液等脂肪液化现象,经积极换药后逐渐愈合;所有患者术后均未出现内固定物松动、骨折复位丢失、神经损伤等并发症。提示采用计算机模拟复位技术联合骨盆复位架治疗APC-Ⅲ型骨盆骨折,在提高复位效率、改善骨盆功能方面均具有优势。

High-temperature Compressive Performance of Mg Alloy Foams Coated with Ni-P Layer

Mg/Ni hybrid foams were fabricated by the electroless method.The Ni-P(Nickel-Phosphorous)coatings were deposited on the surface of closed-cell Mg alloy foams.The composition,microstructure and phases of the Ni-P coatings were characterized by scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS)and X-ray diffraction(XRD),respectively.The compressive tests were performed on the Mg/Ni hybrid foams at 400℃using the Mg alloy foams as a reference.The experimental results show that the yield strength,plateau stress and energy absorption capacity of the closed-cell Mg alloy foams at high temperature were improved by the Ni-P coating.And there are four main modes for the Mg/Ni hybrid foam failure at 400℃,i e,shearing in cell wall,bending in cell edge,shedding and cracking in Ni-P coating.

BUCKLING ANALYSIS UNDER COMBINED LOADING OF THIN-WALLED PLATE ASSEMBLIES USING BUBBLE FUNCTIONS

Bubble functions are finite element modes that are zero on the boundary of the element but nonzero at the other point. The present paper adds bubble functions to the ordinary Complex Finite Strip Method(CFSM) to calculate the elastic local buckling stress of plates and plate assemblies. The results indicate that the use of bubble functions greatly improves the convergence of the Finite Strip Method(FSM) in terms of strip subdivision, and leads to much smaller storage required for the structure stiffness and stability matrices. Numerical examples are given, including plates and plate structures subjected to a combination of longitudinal and transverse compression, bending and shear. This study illustrates the power of bubble functions in solving stability problems of plates and plate structures.

Is Distal Femur Locking Plate a Superior Implant in Distal Femur Fracture?

In spite of advances in techniques and improvements in surgical implants, confusion still prevails regarding use of specific implants in distal femur fracture. Fractures in the distal femur have posed considerable therapeutic challenges throughout the history of fracture treatment. Most of these surgical failures were due to inadequate fixation of the fracture fragments. The Aim of the study is to determine whether distal femur locking plates are superior implants than dynamic condylar screw and distal femur nail. A prospective and observational study was done in Department of Orthopaedics and Traumatology, Sri Ramachandra Medical Collage, Chennai between Jan. 2011 and Jan. 2015. Patients with distal femoral fractures, admitted into the hospital, were treated using various modes of internal fixation and followed up over a period of six months to one year and their functional outcome was evaluated. The functional and radiological assessment of patients during follow-up was done using Neer’s criteria. The use of any one of the implant, i.e. distal femur locking plates, dynamic condylar screw or distal femur nailing for internal fixation, depends on the type of fracture and the pre operative planning and intra operate decision of the surgeon. In our study, 38% of fractures treated by Dynamic condylar screw, 72% of fractures treated by distal femur locking plate and 42% of fractures treated by Distal femur supracondylar nail had excellent/satisfactory results. Locking plates had better outcome in both extra-articular and intra-articular group. They also had better outcome in both younger and older age groups.