Column Compression Research Articles

Anterior column opening structural bone grafting with posterior column compression technique for the treatment of obsolete vertebral compression fractures with severe spinal kyphosis

We aimed to evaluate the efficacy and safety of anterior column opening structural bone grafting with posterior column compression technique for the treatment of obsolete vertebral compression fractures with severe spinal kyphosis. Fourteen patients with senile obsolete vertebral compression fractures and severe spinal kyphosis were admitted to our hospital. During the treatment processing, an "eggshell" osteotomy, anterior column opening structural bone grafting with posterior column compression, and pedicle screw internal fixation were performed in all patients. The Cobb angle, Visual Analogue Scale (VAS) score, Oswestry Disability Index (ODI) pre-operatively, post-operatively, and at the last follow-up were analyzed. Furthermore, the intra-operative blood loss and the operative time were also analyzed. The average osseous fusion time was 3.6months (range from 3 to 5months). The average operative time was 236 ± 20.1min (range from 198 to 261min). The average intra-operative blood loss was 1350.5 ± 70.2ml (range from 809 to 2216ml). The Cobb angle of localized kyphosis was 63.4 ± 12.4∘ pre-operatively, while 10.0 ± 2.1∘ post-operatively, and 12 ± 3.4∘ at the last follow-up evaluation, respectively. The average VAS score was decreased significantly from 8.7 ± 3.2 pre-operatively to 1.9 ± 0.4 post-operatively. The average ODI score was decreased from 78.3 ± 2.4% pre-operatively to 19.3 ± 5.3% post-operatively. Anterior column opening structural bone grafting with posterior column compression technique is effective, can effectively restore the sagittal balance of the spine, ease pain, and improve the quality of life of the patients with obsolete vertebral compression fractures and spinal kyphosis.

Synthesis and Characterization of Pressure Resistant Agent with Double‐Layer Core/Shell Hollow‐Structure for Emulsion Explosive

AbstractA novel pressure resistant agent (PRA) for emulsion explosive was prepared by a high‐speed shear mixer with cenospheres, Al2(SO4)3, NaHCO3 and hydrophobic nano‐silica as the raw materials. The structural features of the PRAs were characterized using a scanning electron microscope, a laser particle size analyzer and an optical microscope, and the experimental results showed that the PRAs were ellipsoidal microspheres with an average particle size of 200 μm and had double‐layer core/shell hollow‐structures. The inner hollow shell of the microsphere could serve as sensitizing bubble when it was undamaged whatever the status of outer shell, and once it was broken, the materials in the outer and inner shells would react with each other and generate new sensitizing bubbles in emulsion explosive. The brisance and underwater explosion experimental results showed that when the addition of PRAs was determined to be 2 mass %, the resistance to dynamic pressure of emulsion explosive sensitized by glass microsphere (GM) would be improved significantly without affecting its power. The lead column compression of GM‐2 mass % PRAs sensitized emulsion explosive was 16.05 mm, which was close to that of GM sensitized emulsion explosive. When compressed by a RDX booster underwater at the distances of 25 and 75 cm, the dynamic pressure resistance ability of GM‐2 mass % PRAs sensitized emulsion explosive would increase by 56.54 and 62.07 %, respectively, compared to that of GM sensitized emulsion explosive at the same compression distance. This novel PRA provided double protections for improving the pressure resistant properties of emulsion explosives, especially in the condition of dynamic pressure compression.

Effect of cyclic flange local buckling on the capacity of steel members

Cyclic flange local buckling typically occurs when plastic hinges form in the beams and columns of special moment resisting frames subject to seismic excitation. While local buckling in beam plastic hinges has been investigated in the past for monotonic loading situations, the effect of cyclic flange local buckling on beam and column behaviours is not yet well understood. In order to address this shortcoming, nineteen half-scale T-section specimens are tested under cyclic axial loads in a configuration intended to replicate the cyclic demands imposed on flanges of beams and columns in their plastic hinge region. The main experimental variables are flange slenderness ratio, level of web restraint, and loading scheme (monotonic versus cyclic). Validated computational studies are performed to expand the parameter space. The test data and computational results show that T-section members that meet the current highly ductile limit can suffer excessive axial strength degradation under cyclic axial loading. The effect of slenderness ratios on column compression capacity due to strength degradation of flanges is evaluated and quantified.

Disc Geometry is an Accurate Predictor of Lordotic Correction in the Thoracolumbar Spine Following Schwab Grade 2 Osteotomy: A Cadaveric Study and Biomechanical Analysis of Disc Space Changes Following Lordotic Correction.

Posterior column osteotomy (PCO) is a powerful technique for correcting lordosis, but the surgical literature lacks objective evidence on preoperative predictors of achievable lordotic correction following PCO. To measure the correlation between disc geometry and achievable lordotic correction following Schwab grade 2 osteotomies and to describe geometric changes to disc space following lordotic correction. Schwab grade 2 osteotomies were performed from T1 to S1 in 5 cadavers. Lateral radiographs were taken before and after posterior column compression. Anterior disc height (ADH), middle disc height (MDH), posterior disc height (PDH), and lordotic angles were measured. The association between disc height and lordotic correction was analyzed using linear regression. For all spinal levels (n=79), PDH was most strongly correlated with lordotic correction (r=0.72, P<.001). Regional subset analyses showed the strongest correlation between PDH and lordotic correction achievable within the lumbar spine (n=22, r=0.77, P<.001), followed by ADH for lower thoracic spine (n=29, r=0.65, P<.001) and PDH for upper thoracic spine (n=28, r=0.61, P=.001). Postcorrection analysis of disc heights revealed that as lordotic correction increases, the PDH decreases, and the ADH expands. PDH is a strong predictor of achievable lordotic correction following Schwab grade 2 osteotomies and compression of an intact disc space. In the lumbar spine, 50% of lordotic change is predictable using PDH alone. Further testing of our linear regression equation is planned for prospective clinical studies, and further testing of postcorrection disc space geometry is planned for future biomechanical and surgical technique studies.

Efficacy comparison of pedicle screw with vertebroplasty or intermediate screw for osteoporotic thoracolumbar compression fractures

Objective To compare the efficacy of pedicle screw with vertebroplasty (PSV) or intermediate screw (PSIS) for osteoporotic thoracolumbar compression fractures. Methods A retrospective case control study was conducted to analyze the clinical data of 141 patients with osteoporotic thoracolumbar vertebral compression fractures admitted to Honghui Hospital, College of Medicine, Xi'an Jiaotong University from January 1, 2012 to December 31, 2015. There were 59 males and 82 females, aged 60-75 years, with an average age of 65.4 years. All the fractures had bone mineral density (BMD) T value 15 degrees or anterior column compression > 40%. There were 65 patients with thoracic vertebral fractures (T10-T12) and 76 with lumbar vertebral fractures (L1-L4). Among all patients, 68 received PSV treatment (PSV group) and 73 received fixed PSIS treatment (PSIS group). The operation time, intraoperative blood loss, visual analogue scale (VAS), anterior height ratio, central height ratio, and segmental kyphosis angle at 3 days, 3 months, 6 months, 1 year and 2 years after operation were compared between the two groups. The complications were recorded. Results All patients were followed up for 25-31 months, with an average of 27.9 months. There were no significant differences in operation time and intraoperative blood loss between the two groups (P>0.05). VAS at each time point of postoperative follow-up was significantly lower than those before operation in both groups (P 0.05). Anterior height ratios of PSV group were higher than those of PSIP group at postoperative 3 months, 6 months, 1 year and 2 years (P<0.05) [(95.2±5.2) vs. (92.6±7.1), (93.8±5.2) vs. (91.4±3.2), (93.3±4.9) vs. (91.2±5.1), (92.6±5.5) vs. (90.1±4.7)]. The central height ratios of PSV group were higher than those of PSIP group at postoperative 6 months, 1 year and 2 years [(91.4 ±6.9) vs. (88.9±7.2), (90.8±7.4) vs. (88.4±5.9), (90.1±7.6) vs. (87.1±7.2)](P<0.05). Segmental kyphosis angle of PSV group was lower than that of PSIP group at postoperative 3 months, 6 months, 1 year and 2 years [(2.9±0.4)° vs. (3.2±0.9)°, (3.0±0.5)° vs. (3.2±0.3)°, (3.1±0.7)° vs. (3.4±0.4)°, (3.1±0.4)° vs. (3.4±0.7)°](P<0.05 or 0.01). Bone cement leakage from screws occurred in two patients in PSV group and three patients in PSIS group. Cement leakage occurred in the injured vertebra in four patients of PSV group, with no any symptom. In PSIS group, two patients suffered from one side rod breakage at 9 months and 1 year after surgery, respectively. CT showed sound bone healing, without any further management. Conclusion For osteoporotic thoracolumbar compression fractures, PSV can attain similar pain relief compared with PSIS, but the former is more conducive to reducing the loss of anterior and middle column height and correcting kyphosis deformity. Key words: Osteoporotic fractures; Spinal fractures; Bone cement

Compressed linear algebra for declarative large-scale machine learning

Large-scale Machine Learning (ML) algorithms are often iterative, using repeated read-only data access and I/O-bound matrix-vector multiplications. Hence, it is crucial for performance to fit the data into single-node or distributed main memory to enable fast matrix-vector operations. General-purpose compression struggles to achieve both good compression ratios and fast decompression for block-wise uncompressed operations. Therefore, we introduce Compressed Linear Algebra (CLA) for lossless matrix compression. CLA encodes matrices with lightweight, value-based compression techniques and executes linear algebra operations directly on the compressed representations. We contribute effective column compression schemes, cache-conscious operations, and an efficient sampling-based compression algorithm. Our experiments show good compression ratios and operations performance close to the uncompressed case, which enables fitting larger datasets into available memory. We thereby obtain significant end-to-end performance improvements.

029 Biomechanical Effects of Rear Tip Extenders on Inflatable Penile Implants: A Cadaveric Study

It is speculated by many penile prosthesis implanters that rear tip extenders (RTEs) negatively affect axial loading so they should be avoided if possible but many implanters use RTE to assist with exit tubing angle thus justify their presence. However, the biomechanical effects of RTEs in the body have not been reported. In this study, two groups of Coloplast Titan inflatable penile implant (IPP) IPP-RTE pairs of total length of 20 and 24cm, respectively with lengths of RTEs ranging from 0, 2 and 4cm have been investigated to provide experimental evidence. 3 cadavers were obtained. Penile stretch length, corporal length, and pendulous shaft dimensions were obtained. Artificial erections and cavernosograms were performed on the 3 cadavers and one was excluded for Peyronie’s disease. The IPPs were surgically placed into two fresh cadavers via a penoscrotal technique by a high volume surgeon. The implants were confirmed to be placed correctly using fluoroscopy. The IPPs were assessed by column compression and cantilever deflection. A biomechanical evaluation of the properties of each IPP-RTE pairs inside the fibroelastic tunica albuginea was based on industry standard methods for assessment at 1034mmHg (20psi) fill pressure. X-ray images were obtained before and after kink formation.

Buckling Analysis and Section Optimum for Square Thin‐Wall CFST Columns Sealed by Self‐Tapping Screws

Two columns of thin‐walled concrete‐filled steel tubes (CFSTs), in which tube seams are connected by self‐tapping screws, are axial compression tested and FEM simulated; the influence of local buckling on the column compression bearing capacity is discussed. Failure modes of square thin‐wall CFST columns are, first, steel tube plate buckling and then the collapse of steel and concrete in some corner edge areas. Interaction between concrete and steel makes the column continue to withstand higher forces after buckling appears. A large deflection analysis for tube elastic buckling reflects that equivalent uniform stress of the steel plate in the buckling area can reach yield stress and that steel can supply enough designing stress. Aiming at failure modes of square thin‐walled CFST columns, a B‐type section is proposed as an improvement scheme. Comparing the analysis results, the B‐type section can address both the problems of corner collapse and steel plate buckling. This new type section can better make full use of the stress of the concrete material and the steel material; this type section can also increase the compression bearing capacity of the column.

Posterior open-wedge anterior longitudinal ligament release: Cadaveric technique analysis.

Anterior column release is a powerful surgical technique for achieving spinopelvic balance in adult patients with sagittal plane deformities. We present an alternative strategy for focal deformity correction from a posterior-only approach. The purpose of this study was to evaluate the feasibility and efficacy of a novel surgical technique called posterior open-wedge diskectomy and anterior longitudinal ligament (ALL) release (POWAR). A cadaveric torso underwent POWARs at the L1-L4 intervertebral disc spaces. Baseline measurements of end-plate angle (EPA), anterior intervertebral disc height (ADH), and posterior intervertebral disc height (PDH) were obtained. These measurements were repeated after three stages of correction: posterior column compression alone, posterior column compression following Schwab grade 2 osteotomies, and posterior column compression following POWAR. A second cadaver underwent posterolateral spinal dissection to demonstrate the pertinent anatomical features relevant to this novel procedure. With each stage of correction, a sequential increase in EPA and ADH and a decrease in PDH were demonstrated. The large increase in ADH seen following POWAR confirmed successful release of the ALL. In situ investigation of the aorta and inferior vena cava following anterior exposure revealed no injury to the great vessels or surrounding structures. Ex vivo testing of the aorta and inferior vena cava took place at the L3-4 level. This testing demonstrated no injury or tears to either vessel. POWAR is a new surgical technique that can provide an alternative to three-column osteotomy for surgeons performing spinal reconstructions in adults through an open, posterior-only approach. Clin. Anat. 32:348-353, 2019. © 2018 Wiley Periodicals, Inc.

Study of Double Walled Corrugated Cardboard as an Alternative Material for Eco-Friendly Designed Furniture

The global production capacity of corrugated cardboard used in packaging increased by 3.5% per year in the last decade. These packages have limited life span and, after use, contribute for increasing the waste stream on the planet. An interesting alternative for their reuse is the manufacture of unconventional furniture and objects. Nevertheless, there are few studies addressing the performance of cardboard for their application in furniture products. In this study we characterized corrugated cardboard by scanning electron microscopy, energy dispersive spectroscopy. X-ray diffraction, determination of the basic weight of paper (grammage), resistance to burst, column compression and uniaxial compression of test samples manufactured with a specific geometry. Results indicate that cardboard can be a material of great feasibility and workability to be used in furniture design.

Novel CMOS multi-bit counter for speed-power optimization in multiplier design

The paper introduces a novel multi-bit counter for efficient binary multiplication. A 7:3 counter is proposed, customized and optimized by 3-pronged approach, firstly by group-wise parallel addition using half-adders, secondly by eliminating redundant carry-generators from the design and finally, by optimizing the resultant hardware. The circuit is designed and optimized on standard static-CMOS. Corner analyses with TT, FF and SS for PVT-variation have been performed on proposed design to study reliability and robustness. A benchmarking exercise on Power-Delay-Product (PDP) with reported candidate designs demonstrates superiority of the proposed design. The study reveals that the 7:3-counter, designed using proposed strategy, has up to 36% less PDP, compared to the best candidate-design. Next, the proposed counters are employed, first to design an 8-b × 8-b Column-Compression (CC) multiplier and thereafter, using decomposition-logic on thus-designed-8-b × 8-b-multipliers, to design a 16-b × 16-b multiplier. The multipliers are optimized on 90-nm standard-CMOS technology and compared for speed-power performance with reported candidate designs at 500 MHz. Simulations show that the presented design of 16-b × 16-b multiplier using proposed 7:3 counter offers 55% less PDP, compared to the best candidate design under identical conditions. Once again, all simulations are performed on TSMC 90-nm CMOS technology at 25 °C temperature and 1.0 V supply-rail.

Magnesium chloride and sulfate attacks on gravel-sand-cement-inorganic binder mixture

Investigation on the degradation of improved ground is crucial for predicting its life span and performance under unfavorable conditions. In this study, effects of magnesium chloride (MgCl2) and magnesium sulfate (MgSO4) attacks on gravel-sand-cement-inorganic binder mixtures were investigated. Electrical resistivity, free-free resonant column (FFRC) and uniaxial compression tests were performed at different exposure periods, and results showed that saline solutions exert considerable effects on the geophysical parameters of the mixture. As the samples were exposed to chemical attacks, the electrical resistivity and damping ratio increased, while the longitudinal wave velocity and UCS decreased. Especially, the results at 28 days showed that mixtures without inorganic binder lost approximately 40% of its initial strength in MgCl2 and 12% in MgSO4, while samples with inorganic binder (IBS) only lost about 30% and 8% in MgCl2 and MgSO4 respectively. Thus, it is expected that increasing the inorganic binder content in the mixture can enhance the performance of the grout and reduce strength degradation induced by chemical attacks.

241 Comprehensive in-vivo biomechanical study of IPPs yields interesting results

Due to the inflatable penile prosthesis (IPP) we have seen a new era ushered in the management of erectile dysfunction. A growing interest in the biomechanical properties of IPP is leading to systematic studies of the ex-vivo and in-vivo evaluation of the inflated rigidity of the IPP and comparative properties of different implants. This study is a comprehensive in-vivo biomechanical study of the 3 most popular IPPs assessed by longitudinal (column compression), Horizontal (modified cantilever deflection) and flexure (3-point bending) methods. IPPs were surgically placed in three cadavers via an infrapubic approach. The biomechanical measurements were obtained in a bind testing study performed by engineers from Rice University. Two pressures for the implants were chosen and 10 implant conditions were assessed based on mechanical measurements and visual and audio recordings of the analysis. Funding for this study was obtained from Coloplast Corporation. Compression, cantilever, and bend data were acquired for the in vivo IPP. Analysis was assessed based on kink formation in compression, max loading in cantilever testing and 3-point bend testing. Rigidity was also assessed based on plotted slopes indicating stiffness, and the differences in slope change, kinking, and IPP buckling. Data was correlated to vaginal insertion strength, horizontal load strength, and prosthesis rigidity.

Biomechanical Comparison of Inflatable Penile Implants: A Cadaveric Pilot Study

BackgroundThroughout the last decade there has been a growing interest in the biomechanical differences between inflatable penile prostheses (IPPs) and their significance with regard to the patient experience. AimTo present our findings assessing the biomechanical properties of IPPs with and without rear tip extenders (RTEs). MethodsThis is a biomechanical study of the 3 most commonly used IPPs (AMS CX, AMS LGX, and Coloplast Titan) as assessed by column compression, modified cantilever deflection, and 3-point bending methods. The IPPs were surgically placed into 3 fresh cadavers via an infrapubic technique by a single large-volume implanter. A biomechanical evaluation of the properties of each IPP inside the fibroelastic tunica albuginea was assessed in blinded testing, and analyses were based on industry standard methods for assessment. OutcomesMaximum axial load; kink formation; horizontal stiffness; and resistance to 3-point flexure testing were measured. ResultsAt maximum inflation, all 3 implants had similar performance. Differences appear to be most affected by fill pressures. In fact, only the AMS LGX at less than maximum inflation (LTMI) was unable to consistently withstand the roughly 0.9 kg (2 lbs) of pressure for column load testing mimicking vaginal intromission. The Coloplast Titan showed slightly better rigidity than the AMS LGX and CX devices in horizontal load testing, and, with 3-point flexure testing, the CX showed the best rigidity in the shortest phallus (A). Overall, the Titan showed slightly better rigidity in the longest phallus (C) and the phallus with mild Peyronie's disease (B). Clinical TranslationsPenile implants with circumferential expansion had higher rigidity on biomechanical testing and should be considered in a patient's decision during selection of a penile implant. Strengths and LimitationsStrengths include blinding of the biomechanical testing and analyses, surgical procedures performed by a highly experienced surgeon, and that this is the “closest to” in vivo evaluation (inside the tunica albuginea) of penile implant function and properties to date. Weaknesses are that this study was performed in cadavers and not in live patients. It also has a small sample size, including the use of only 3 cadavers, and there was no correlation of performance to patient satisfaction. ConclusionThe results of this study support the conclusion that all devices are capable of functionally restoring erectile capacity. However, we observed that, in general, the 2 circumferentially expanding penile prosthesis showed greater resistance in biomechanical testing when compared with longitudinal and circumferential expanding devices. This should be considered as a guide during device selection for a patient undergoing penile prosthesis.Wallen JJ, Barrera EV, Ge L, et al. Biomechanical Comparison of Inflatable Penile Implants: A Cadaveric Pilot Study. J Sex Med 2018;15:1034–1040.

Behavior and modeling of high-strength concrete tied columns under axial compression

ABSTRACTThis article presents experimental and analytical results of 21 high-strength concrete tied columns under axial compression. Each 1500-mm-tall column had a 500 by 500 mm section reinforced with 12 D25 longitudinal bars enclosed by perimeter hoops only, or perimeter hoops plus typical crossties, or perimeter and intermediate hoops. The concrete strengths of cylinder tests ranged between 55 and 99 MPa. The column compression tests showed that the longitudinal bars could be laterally supported by hoop corners or 135-degree seismic hooks of crossties, but not restrained by 90-degree hooks, which lost effectiveness after spalling of cover concrete. The proposed analytical approach used the existing Mander model and the Euler equation to determine the confined concrete strength and the buckling strength of longitudinal bars, respectively. With rational assumptions of confinement effectiveness and unsupported lengths, the proposed analytical approach can well predict the complete load-deformation response of test columns.

Pattern graph for sparse Hessian matrix determination

In a recent work, we have proposed the pattern graph as a unifying framework for methods that exploit sparsity by matrix compression: row compression, column compression or a combination of the two in sparse Jacobian matrix determination. Utilization of structural similarity between the matrix and its graph has been found to be beneficial. In this paper, we show that an important structural property, symmetry, can be exploited in the formulation of sparse Hessian matrix calculations using the pattern graph model. Using the notion of ‘direct cover’, we present a new general direct method for the determination of sparse Hessian matrices with fixed sparsity pattern and a multicolouring interpretation of it on the pattern graph associated with the matrix. A heuristic procedure for finding direct covers is sketched and some preliminary numerical test results are provided.

Axial loading tests of thin-walled circular steel tubes infilled with cast-in-place concrete and precast segments containing DCLs

A green technique of filling coarsely-crushed demolished concrete lumps (DCLs) and fresh concrete (FC) alternately into steel tubes has been conceived, and realized for years, intended primarily to simplify old concrete recycling. In this study, precast approach is introduced in the foregoing recycling technique trying to improve its applicability.Large precast segments (PSs), prefabricated with DCLs and FC, are proposed to be installed into hollow steel tubes which are then poured full of cast-in-place concrete (CC). The resulting clad, composite columns were examined in full-scale axial compression tests. The key variables were the size and number of PSs assembled in each single tube, and the compressive strength of CC. Using higher strength CC was found to somewhat enhance a column's compression resistance, but it compromised the column's axial deformability significantly. A homogenization-based design equation is formulated, which is shown to predict quite well the axial capacity of the proposed columns. Overall, the semi-precast columns proposed are easy-to-construct, and behave comparably to their cast-in-situ counterparts, showing potential for future precast applications.

Design and Comparison of Wallace Multiplier Based on Symmetric Stacking and High Speed counters

High latency and efficient addition of multiple operands is an essential operation in any computational unit. The latency, power efficiency and area of multiplier circuits is of critical importance in the performance of processors. Multiplier circuits are an essential part of an arithmetic logic unit, or a digital signal processor system for performing filtering and convolution. The binary multiplication of integers or fixed-point numbers results in partial products that must be added to produce the final product. The addition of these partial products dominates the latency and power consumption of the multiplier. In order to combine the partial products efficiently, column compression is commonly used. Many methods have been presented to optimize the performance of the partial product summation previously. To achieve higher efficiency, more number of bits need to be reduced at a time. For this, the column compression techniques can be used. By using this, the critical path delay can be reduced and also the latency of the multiplier. When higher compression unit is used the energy of the multiplier is also reduced. In this paper, the column compression techniques are compared. The stacking circuits presented in, show an improvement over algorithmic Wallace multiplier which uses the generic equations for the column compression units. In stacking units, the 7:3 and 6:3 counters are derived from a basic 3-bit stacking circuit reducing usage of XOR gates. This reduces the usage of XOR gates and thus the critical delay. While the algorithmic units use generic equations using the generation and propagation functions of an adder.

Lateral closing wedge osteotomy and modified cross pinning with external tension band fixation in the treatment of cubitus varus deformity in childrenLateral closing wedge osteotomy and modified cross pinning with external tension band fixation in the treatment of cubitus varus deformity in children

To explore the therapeutic effects of distal humeral lateral closing wedge osteotomy followed by modified pinning combined with external tension band fixation in the treatment of cubitus varus deformity in children. Total 26 adult patients with cubitus varus deformity were treated by operation from March 2011 to June 2015, 15 patients were boys and the other 11 patients were girls, ranging in age from 4 to 13 years, with an average of 7.8 years. The cubitus varus angel ranged from 11 degrees to 24 degrees, with a mean(17.50±6.73) degrees, 3 patients complicated more than 10 degrees constriction of flexion. Lateral closing wedge osteotomy retaining the medial 3 to 4 mm intact cortex by lateral elbow approach was applied in these 26 patients. The wedge defect were closed and fixed by crossing pinning. The lateral column compression was achieved with external tension band(the crossing pins were bended laterally and the pin ends were hooked mutually). The pre-operative, post-oparetive and contralateral carrying angles were compared and Laupattarakasem criteria was used to evaluate the results at follow-up. All the patients got bony union 2 months after operation and there was no infection or nerve palsy. The average follow-up period was 18.8 months (ranged, 13 to 29 months). The carrying angle was restored to(11.50±3.17) degrees(ranged, 8 to 14 degrees). According to the Laupattarakasem evaluation criteria, 14 patients got an excellent result, 13 good and 1 fair. Normal carrying angle and elbow flexion could be restored by lateral closing wedge osteotomy, and stable fixation could be achieved with crossing pinning and external tension band, which is available for early mobilization.

Modeling of a viscoelastic damper and its application in structural control.

Conventional seismic rehabilitation methods may not be suitable for some buildings owing to their high cost and time-consuming foundation work. In recent years, viscoelastic dampers (VEDs) have been widely used in many mid- and high-rise buildings. This study introduces a viscoelastic passive control system called rotary rubber braced damper (RRBD). The RRBD is an economical, lightweight, and easy-to-assemble device. A finite element model considering nonlinearity, large deformation, and material damage is developed to conduct a parametric study on different damper sizes under pushover cyclic loading. The fundamental characteristics of this VED system are clarified by analyzing building structures under cyclic loading. The result show excellent energy absorption and stable hysteresis loops in all specimens. Additionally, by using a sinusoidal shaking table test, the effectiveness of the RRBD to manage the response displacement and acceleration of steel frames is considered. The RRBD functioned at early stages of lateral displacement, indicating that the system is effective for all levels of vibration. Moreover, the proposed damper shows significantly better performance in terms of the column compression force resulting from the brace action compared to chevron bracing (CB).