Rotational Deformity Research Articles

A Miniature High-Frequency Rotary Ultrasonic Encoder for Internal Ultrasound Imaging

High-speed mechanical rotation scanning is the main imaging method of current high-frequency internal ultrasound. Due to uneven drag on the catheter driveshaft leading to changes in the rotational speed, Nonuniform rotational deformity (NURD) is critically limited for the quantitative analysis of internal ultrasound use. To date there have been no techniques shown that provide effective and dynamic modulation of NURD. In this work, a micro structured high-frequency rotary ultrasonic encoder with cylinder gratings was developed, which can dynamically fix the NURD and get high quality restored image. Accordingly, a prototyped micro rotary 50-MHZ ultrasonic encoder with a miniature diameter of 3 mm and a selection of resolutions up to 64 pulses per revolution, which should be the smallest and highest frequency rotary ultrasonic encoder ever reported, was demonstrated based on an endoscopic ultrasound system. The miniature high-frequency rotary ultrasonic encoder shows great potential for ultrasonic endoscopy, OCT, and other mechanical scanning imaging.

Optimization of Robot Posture and Workpiece Setup in Robotic Milling With Stiffness Threshold

Industrial robot provides a promising alternative in freeform surface milling. However, due to its low stiffness, it is difficult to guarantee the machining quality. While existing research considers mainly the influence of robot posture on stiffness, the workpiece setup's influence is equally important. In this article, to ensure the overall workpiece's robot stiffness meets the requirement of stiffness threshold in robotic milling, a method for simultaneously optimizing the robot posture and the workpiece setup is proposed. First, to evaluate the robot stiffness during machining, this article presents a new stiffness index considering the robot's rotational deformation. And then, an optimization model is established to optimize both the robot redundancy and the workpiece setup, considering the constraints of joint limitation, singularity-free and collision-free. Moreover, for complex freeform surfaces, to obtain the minimum number of posture changes of the robot and workpiece under the premise of meeting the limit of stiffness threshold, this article constructs a minimum set covering problem, which is solved by a clustering algorithm and a greedy algorithm. Finally, simulations and experimental studies are conducted to validate the effectiveness of the proposed robot stiffness index and the proposed optimization method, showing that the robot stiffness is improved during a milling process of the entire workpiece.

Closed-form solutions for vibrations analysis of cracked Timoshenko beams on elastic medium: An analytically approach

In this paper a novel analytically method for analysing the dynamic behaviour of Timoshenko beam model, resting on Winkler-type elastic soil, under simply-supported boundary condition and with a crack is proposed. The beam is also supposed to be constrained at the ends by elastically flexible springs, with transverse stiffness and rotational stiffness. Applying the Timoshenko beam theory and employing the auxiliary functions, the equation of motion is derived. The natural frequencies are obtained by applying the Euler–Bernoulli method and are derived by the corresponding auxiliary functions of the governing equation of the Euler–Bernoulli beam in free vibration. For different values of soil parameter, taking into account the effects of rotational and shear deformation and considering the presence of crack, typical results are presented, in order to demonstrate the efficiency of the proposed approach. Finally the obtained results are compared with some results available in the literature. It is shown that very good results are obtained. This approach is very effective for the study of vibration problems of Timoshenko beams. The novelty of the proposed approach is that although the auxiliary functions, used to find the solution to the dynamic problem of a Timoshenko beam, are different for the two theories applied, in both cases, the dynamic problem is traced to the study of an Euler - Bernoulli beam subjected to an axial load.

Analysis of left ventricular rotational deformation by 2D speckle tracking echocardiography: a feasibility study in athletes

2D speckle tracking echocardiography (2DSTE) is established to analyse left ventricular (LV) longitudinal function. The analysis of LV rotational deformation is challenging and requires standardization of image acquisition as well as postprocessing analysis. The aim of this study was to test the feasibility to analyse LV rotational deformation using 2DSTE by introducing a novel algorithm for the detection of artefacts. The study was performed in 20 healthy subjects serving as a control group and in 53 competitive sportsmen. Circumferential, radial strain (CS, RS) and LV rotation were analysed by 2DSTE in parasternal short axis views. The stepwise algorithm to exclude potential artefacts starts with the visual estimation of the image quality with respect to complete visualization of all myocardial segments during the entire cardiac cycle followed by the exclusion of data sets in participants with conduction abnormalities. The next step is the optimization of tracking areas and a cross-check of implausible strain waveforms in multiple acquired comparable cineloops. The last step is the exclusion of strain curves with persisting implausible waveforms if standardization failures and incorrect LV wall tracking are fixed. Plausible physiological strain curves were observed in 89% (n = 65/73) of all subjects. In controls all implausible waveforms could be verified as artefacts. The algorithm was applied in 53 professional athletes to test and confirm its feasibility. Abnormal CS waveforms were documented in 25 athletes, verified as artefacts due to tracking failures in 22 athletes and due to incorrect image acquisition in 3 athletes. CS artefacts were mostly located in the basal posterior and lateral LV segments. (endocardial: 6%, n = 4/70; p < 0.05) and basal posterior (endocardial: 8%, n = 5/70; p < 0.05) segments were highly susceptible to artefacts. 2DSTE of parasternal short axis views to analyse circumferential and radial deformation as well as LV rotation is feasible in athletes. The proposed algorithm helps to avoid artefacts and might contribute to standardization of this technique. 2DSTE might provide an interesting diagnostic tool for the detection of viral myocarditis, e.g. in athletes.

Proximal Rotational Metatarsal Osteotomy for Treatment of Hallux Valgus: A Technique Guide

There is increasing interest in rotational correction of the first metatarsal during hallux valgus correction. This article provides a technique guide for the proximal rotational metatarsal osteotomy technique, which corrects both the intermetatarsal angle and the rotational deformity with a single oblique osteotomy. Level of Evidence: Diagnostic Level V. See Instructions for Authors for a complete description of levels of evidence.

Mechanical performance of glulam beam-to-column connections with coach screws as fasteners

The mechanical performance of beam-to-column connections plays an essential role in the design of post-and-beam glulam structures. This paper presents an investigation into the mechanical performance of glulam beam-to-column connections with coach screws as fasteners. A series of monotonic and reversed cyclic loading tests were conducted on the beam-to-column connections with coach screws, and the failure modes, moment-resisting capacity, stiffness, ductility and energy dissipation of the connections were analyzed. Results showed that the use of coach screws was an effective way to increase the initial stiffness, ductility and energy dissipation of the glulam beam-to-column connections. The strength of coach screws and glulam members was fully developed, and the moment-resisting capacity of the beam-to-column connections was improved due to the adoption of the coach screws. It was noted that the rotational deformation and energy dissipation of the beam-to-column connections was mainly governed by the mechanical performance of the screwed connections. Moreover, a separating analytical method and a finite element model were established for the tested glulam beam-to-column connections, and results indicated that the stress distribution, deformation and moment–rotation relationships of the connections can be predicted efficaciously versus the test results.

Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

Comparing Results of Syndactyly Operated Children Younger and Older Than 1 Year.

Syndactyly has a cosmetic, functional, and psychosocial impact, and surgical treatment is indicated in most cases. This study aimed to retrospectively identify whether patients undergoing surgical release of syndactyly younger than 1 year presented different results compared with those operated older than 1 year. Patients were assessed through photographic records by 3 independent specialist surgeons for the quality of scar, presence of web creep, rotational, flexion-extension, and lateral flexion deformities using the Withey score. Thirty-four patients were included in the study, totaling 51 commissures operated. The score was higher in the group operated younger than 1 year (5.83 ± 2.39) compared with the group older than 1 year (3.94 ± 1.93), being statistically significant, with a P value of 0.011. Children with syndactyly operated younger than 1 year have worse postoperative outcomes measured by the Withey score than those operated older than 1 year.

Effect of Taper on Shear Stiffness of Steel-Reinforced Neoprene Bearing Pads

Steel-reinforced elastomeric bearing pads are widely used in bridge construction to vertically support girders on piers while also accommodating translational and rotational girder deformations caused by live loads and temperature changes. To support sloped girders, flat bearing pads of uniform thicknesses are typically used with either tapered steel shim plates or an inclined concrete bearing seat. The use of tapered pads has the potential to reduce both construction time and cost by eliminating the need for tapered plates or seats to match the girder slope. However, limited research has been performed to investigate the effect of introducing taper on relevant design properties of bearing pads. In this paper, results are presented from experimental testing that was performed to quantify the effect of taper on shear stiffnesses of pads having varied geometric characteristics (plan view dimensions, elastomer thicknesses, and slope angles). An experimental bearing pad test device was designed and utilized to impose shear loads in accordance with ASTM standards, while simultaneously maintaining a constant axial load. Bearing pads chosen for testing were tapered variations of standard flat bridge bearing pads used in the state of Florida, U.S. Results obtained from the study revealed that shear stiffness was not significantly influenced by the introduction of taper angle, the direction of shear along the length of pads, or axial load level. The shear stiffness of tapered pads remained within approximately 10% of the shear stiffness of corresponding flat pads.

The Role of Fibular Fixation in Distal Tibia-Fibula Fractures: A Meta-Analysis.

Objectives The necessity of fibular fixation in distal tibia-fibula fractures remains controversial. This study aimed to assess its impact on radiographic outcomes as well as rates of nonunion and infection. Methods A systematic search of the electronic databases of PubMed, Embase, and Cochrane library was performed to identify studies comparing the outcomes of reduction and internal fixation of the tibia with or without fibular fixation. Radiographic outcomes included malalignment and malrotation of the tibial shaft. Data regarding varus/valgus angulation, anterior/posterior angulation, internal/external rotation deformity, and the rates of nonunion and infection were extracted and then polled. A meta-analysis was performed using the random-effects model for heterogeneity. Results Additional fibular fixation was statistically associated with a decreased rate of rotation deformity (OR = 0.13; 95% CI 0.02–0.82, p=0.03). However, there was no difference in the rate of malreduction between the trial group and the control group (OR = 0.86; 95% CI 0.27–2.74, p=0.80). There was also no difference in radiographic outcomes of varus-valgus deformity rate (OR = 0.17; 95% CI 0.03–1.00, p=0.05) or anterior-posterior deformity rate (OR = 0.76; 95% CI 0.02–36.91, p=0.89) between the two groups. Meanwhile, statistical analysis showed no significant difference in the nonunion rate (OR = 0.62; 95% CI 0.37–1.02, p=0.06) or the infection rate (OR = 0.81; 95% CI 0.18–3.67, p=0.78) between the two groups. Conclusions Additional fibular fixation does not appear to reduce the rate of varus-valgus deformity, anterior-posterior deformity, or malreduction. Meanwhile, it does not appear to impair the union process or increase the odds of infection. However, additional fibular fixation was associated with decreased odds of rotation deformity compared to controls.

Behaviour of Precast Concrete Beam-to-Column Connection with SHS Hidden Corbel Subjected to Monotonic Load

Beam-to-column connection is the most critical part of a precast concrete (PC) structure as it governs the integrity of the entire structure. In this study, a beam-to-column connection with square hollow section (SHS) hidden corbel was developed. A full-scale test was conducted on eleven T-subframe specimens with various configurations to investigate the behaviour of the connection under an incremental static load. The behaviour of the connection was evaluated in terms of the moment-rotation response and the mechanical properties were obtained by using the beam-line method. Due to the extensive usage of steel elements, the PC connect possessed a higher ultimate strength than the reinforced concrete (RC) connection. The moment resistance of the connection was largely contributed to by the hidden corbel embedded in the beam and column. However, the PC connection gave a lower stiffness, which resulted in a larger rotation deformation than the RC connection, and thus lowered its design strength. The PC connection was classified as semi-rigid and partial strength, and only specimen PC-3 was considered feasible for PC structures.

Problems, Complications, and Factors Predisposing to Failure of Fassier-Duval Rodding in Children With Osteogenesis Imperfecta: A Double-center Study.

Although Fassier-Duval (FD) rods have been used for almost 2 decades, knowledge of factors predisposing to their failure is limited. Thus, the purpose of this study was to: (1) present the most common complications of FD rodding, (2) present tips on how to avoid or overcome them, and (3) identify factors predisposing to treatment failure. Fifty-eight rod segments in 19 patients with osteogenesis imperfecta (mainly type III) underwent analysis with a median follow-up (FU) time of 4.4 years. We assessed the total number of complications clinically and radiographically. Next, the possible predisposing factors leading to failure were assessed using the Mann-Whitney U test. In addition, we evaluated the cutoff age for the increased rate of complications using the Youden index. A P<0.05 was considered significant. The total number of complications reached 44.8%. The most common complications included: migration of the male or female implant (45.7% and 25.7% out of the total number of complications, respectively), bone fracture with bending of the rod (8.6%), and rotational deformities (8.6%). Significant differences in patients' ages at the time of surgery were found between the group with and without complications (P=0.04), while sex, segment treated, preceding surgeries, length of FU, FD rod diameter, and length of bisphosphonate treatment were not significant. The Youden index showed that the risk of complications rose significantly in patients treated when younger than 5.5 years of age (P<0.05). This series displays the effectiveness and utility of FD rods at a median FU of over 4 years. Complication rates were comparable with the existing literature, with a notable increase in the number of side effects observed in younger patients (below the age of 5). Level IV-therapeutic study.

Theoretical prediction of effective stiffness of nonwoven fibrous networks with straight and curved nanofibers

The nonwoven random fibrous network materials have been widely used in many fields due to their excellent physical and chemical properties. To understand the mechanical behavior of these nonwoven fibrous networks, a theoretical model is developed based on the network microstructure and microstructure evolution in the loading process. It is revealed that the effective stiffness of nonwoven fibrous networks is not only contributed by the fiber stretching and bending, but also depending on the rotation deformation of crosslinks between fibers. Since the nonwoven fibrous networks are constructed by straight or curved fibers, especially at nanoscale, the curvature effects on the effective stiffness are also studied systematically. Furthermore, finite element simulation is conducted to verify the theoretical predictions on the elastic properties of nonwoven fibrous networks consisting of straight and curved fibers, respectively. The theoretical model presented here is a general model, enabling to capture the elastic mechanical behavior of many complex nonwoven network systems from micro to nano length scales.

Numerical modelling for elastic wave equations including rotational deformation and strain gradient

In this work, through introducing the first and second derivatives of strain gradient into the strain energy density function that depends only on the classical strain in conventional continuum mechanics theory to describe the microscopic interactions, the elastic wave equations including rotational deformation and strain gradient based on the Aifantis’s strain gradient theory is derived. The elastic wave equations including rotational deformation and strain gradient with consideration of the scale effects caused by the microscopic interactions will make seismograms appear obvious changes, which are reflected in amplitude attenuation and dispersion, especially P-wave and S-wave propagate in a dispersive manner based on this theory. The results of numerical modelling and theoretical analysis verify this conclusion. The closer the wavelength is to the characteristic scale of the media (lattice size and interparticle distance), the macroscopic response which results from the microscopic interactions becomes more prominent. To further study the effects of microstructure interactions, we compare the results of numerical modelling with the real data when high-speed train passed the piers in Dingxing County in both time and frequency domains, some conclusions are drawn from the comparison.

An optimal method for a staggered-grid finite-difference solution of elastic wave equations including rotational deformation

The staggered-grid finite-difference (SGFD) method is one of the most popular means used in seismic numerical modelling because of its computational efficiency and it is easy to implement. However, it will lead to serious numerical errors while using coarse grids or wavelet with high-frequency. In this work, we proposed an optimal spatial SGFD method based on a new improved particle swarm optimization (PSO) algorithm. Then the dispersion of numerical solution of the first-order spatial derivatives is analyzed. Meanwhile, numerical modelling of elastic wave equations and elastic wave equations including rotational deformation are performed with the optimal spatial SGFD method based on the improved PSO algorithm. Numerical dispersion analysis and numerical modeling results indicate that the optimal spatial SGFD method based on the improved PSO algorithm has high modeling accuracy and can efficiently suppress the numerical dispersion.

Three-Dimensional Correction of Hallux Valgus Deformity: A Novel Technique

Background: Minimally invasive techniques for forefoot surgery are increasingly used nowadays with short operative time and smaller incisions allowing early rehabilitation. Consequently, the purpose of this study was to evaluate a novel technique for 3-dimensional correction of hallux valgus deformity using small incisions. Materials and methods: A single-center, prospective study was conducted from February 2016 to February 2019. The study included a total of 36 feet in 34 patients with hallux valgus deformity treated with soft tissue release combined with osteotomy of the first metatarsal base with correction of angular, rotational deformities of the hallux and fixation by transverse pinning to the second metatarsal. Patients were assessed radiographically for union and measurements as well as clinically using the “The American Orthopedic Foot and Ankle Society (AOFAS)” for functional assessment. Results: Union was achieved in all cases. Hallux valgus angle improved from a mean of 40±5.9 degrees to a mean of 9.1±2.3 degrees (P&lt;0.001). Intermetatarsal angle improved from a mean of 17.5±2.1 degrees to a mean of 6.1±1.5 degrees (P&lt;0.001). At the final follow-up period (2 y), the mean hallux valgus angle was 10.9±2.8 degrees (P&lt;0.001) and the mean intermetatarsal angle was 7±1.7 degrees (P&lt;0.001). Conclusion: This technique yielded good radiographic and functional outcomes and can be a viable option in management of mild, moderate, and severe cases of hallux valgus deformity. Level of Evidence: Level IV, Therapeutic study.

Deformation and vibration analysis of compressor rotor blades based on fluid-structure coupling

Under the influence of aerodynamic and rotational load, deformation and vibration could occur to rotor blades of axial compressor, which may cause fatigue fracture, and threaten the exist of tip clearance because it is the assurance of operation safety by separating the rotor from the case. The overall performance will be deteriorated by the change of blade shape due to the deformation and vibration. Three different materials, titanium alloy, aluminum alloy and stainless steel are compared quantitatively under various operating conditions by fluid-structure coupling method. First the CFD method is validated by experimental data, the obtained pressure distribution on blade surface is exerted to the structure as boundary condition, then deformation characteristic and the corresponding maximum equivalent stresses are analyzed, at last vibration modal is analyzed and resonance points, the main reason for the vibration-induced failure, are predicted by Campbell diagrams. The results show that deformation increases with rotation speed and outlet pressure; the aluminum alloy has the largest deformation of the three materials. The equivalent stress of the blade is mainly caused by rotation, large stress regions are often near the blade root. The tip clearance of rotor blades can be reduced by deformation in the radial direction, for titanium and aluminum alloy blade, the maximum stretched length of blade at 100% rotation can account for 30% of the designed tip clearance. Centrifugal loading is the main reason for the increase of natural frequency while the increased amplitude with rotation speed is extremely small compared to the first order natural frequency.

Deviation and Atrophy of Middle Phalanx of Hand Following Partial Separation in Syndactyly Patient: Their Fault or Ours?

Backgrounds: Syndactyly is failure of differentiation in which the fingers fail to separate into individual appendages. It is the most common congenital hand anomaly, with an incidence of 1 in 2,000 to 2,500 live births. Surgical separation of fingers as early as 6 month-old is indicated when syndactyly involves digits of unequal length (i.e., ring and little fingers). Early separation is also required in complex syndactyly and cases of acrosyndactyly. The timing of surgery of all other cases of syndactyly remains somewhat controversial; most suggest surgical correction before age of 18 months, whereas others prefer to wait until after this age.Case Presentation and Operation Technique: A 13-year old boy, presented with fusion of all fingers of the right hand at birth. Prior to his current visit, he underwent partial separation of the right fingers at the age of 6 y.o. at a local hospital. Following partial separation, the fingers did not grow normally. Current X-ray showed atrophy and deviation of middle phalanx. We performed separation of syndactyly between index and middle finger, and between fourth and small finger in our hospital. Interdigital webbings are released using local flap and the remaining raw surface is covered using full-thickness skin grafts. On follow up, the patient showed good functional and aesthetic outcome. He is able to write with his right hand with better coordination.Discussion: Complex syndactyly reconstruction is a challenging surgical problem. Common post surgical findings include rotational deformity, angular deformity, and nail deformity. We describe how we have altered our approach in these findings.Conclusion: Congenital syndactyly should be corrected early in life. Careful dissection, the use of a dorsal rectangular flap in combination with 2 volar triangular flaps, and use of full thickness skin grafts ensure a satisfactory outcome and minimize the number of operations per web

Dynamic response of sandwich beam with star-shaped reentrant honeycomb core subjected to local impulsive loading

The star-shaped reentrant honeycomb produces lateral shrinkage but also rotation under compression. With the consideration of such interesting deformation characteristics, the dynamic deformation evolution of the sandwich beam with star-shaped reentrant honeycomb core (SSRHC) was carried out for the first time. In this experiment, the aluminum foam projectile was used to produce local impulsive loading on the sandwich beam to research failure/deformation modes and deformation evolution of the SSRHC. The experimental results demonstrated the simultaneous shrinking and rotating deformations in the core. Finite element model (FEM) was employed to capture the dynamic mechanical response of panels and SSRHC on account of experimental results. Numerical results illustrated that the face panel moved toward the loading area in the early stage of impact, and local shrinkage or expansion was found within different regions of the star honeycomb cores during the entire compression process. In addition, it was found that the rotational deformation of the star honeycomb cells mainly occurred in the local indentation stage of the sandwich beam.

Evaluation of Tensile Shear Strength for Lap Joint of Dissimilar Steels

The influence of different thickness combinations was investigated on the strength of the lap joint of dissimilar steels. In this study, lap joints of dissimilar steels were welded by laser welding. The tensile shear test was conducted for the lap joints. Rotational deformation process around the weld bead of the lap joint was observed by a digital video camera during the test. Motion analysis from the video of the tensile shear test indicated that the rotation angle around the weld bead was reduced by overlapping higher strength grade steel. Three-dimensional elastic-plastic finite element analysis was performed for the tensile shear test of the lap joint. The numerically calculated deformation behavior of the lap joint subjected to tensile shear loading showed reasonable agreement with the experimental record. It was found that the rotation angle was reduced and tensile shear strength of the lap joint increase by overlapping higher strength grade steel sheet.