Continuous Traction Research Articles

An Innovative, Cost-Effective, and Flexible Traction Alternative for Shoulder Arthroscopy in Lateral Decubitus Position

During shoulder arthroscopic surgery in the lateral decubitus position, effective and stable continuous traction is a basic requirement for the smooth progression of the surgery. Herein, we describe a safe, reliable, and cost-effective lateral decubitus traction assembly.

Clinical outcomes of gradual reduction of late-detected developmental dysplasia of the hip using ultrasound-guided flexion abduction continuous traction: a midterm follow up study.

Reducing the avascular necrosis (AVN) rate in infants treated for developmental dysplasia of the hip (DDH) is important. We previously reported the clinical outcomes of gradual reduction via ultrasound-guided flexion abduction continuous traction (FACT-R), which achieved a 99% reduction with an AVN rate of 1.0% in infants <12 months. Here, we investigated the clinical outcomes of late-detected DDH after FACT-R. Infants ≥12 months who were treated with FACT-R for DDH from January 1995 to 2007 and followed up for 6 years were enrolled. Treatment comprised continuous traction, a hip-spica cast, and an abduction brace. The rates of reduction, redislocation, AVN, and secondary osteotomy surgery were evaluated. In the study patients (n = 26, hips 30), the mean age at the time of traction therapy was 23 months (range: 13-44) and the mean follow-up was 12.5 years (range: 6-16.4). Female gender and the left side were predominant. The rates of reduction, redislocation, and AVN were 100%, 0%, and 0%, respectively. However, 25 hips (83%) required secondary osteotomy surgery, including Salter innominate osteotomy in 21 hips, Salter innominate osteotomy combined with femoral osteotomy in 3 hips, and triple pelvic osteotomy in 1 hip. They had a larger acetabular index after FACT-R (P = 0.04) and a longer duration of FACT-R (P = 0.05). All hips were successfully reduced, with no redislocation or AVN. However, most hips required a secondary osteotomy surgery because of residual dysplasia. Careful follow-up and informed consent for secondary osteotomy surgery is thus essential.

Use of a new vertical traction device for early traction-assisted staged closure of congenital abdominal wall defects: a prospective series of 16 patients

PurposeAbdominal wall closure in patients with giant omphalocele (GOC) and complicated gastroschisis (GS) remains to be a surgical challenge. To facilitate an early complete abdominal wall closure, we investigated the combination of a staged closure technique with continuous traction to the abdominal wall using a newly designed vertical traction device for newborns.MethodsFour tertiary pediatric surgery departments participated in the study between 04/2022 and 11/2023. In case primary organ reduction and abdominal wall closure were not amenable, patients underwent a traction-assisted abdominal wall closure applying fasciotens®Pediatric. Outcome parameters were time to closure, surgical complications, infections, and hernia formation.ResultsTen patients with GOC and 6 patients with GS were included. Complete fascial closure was achieved after a median time of 7 days (range 4–22) in GOC and 5 days (range 4–11) in GS. There were two cases of tear-outs of traction sutures and one skin suture line dehiscence after fascial closure. No surgical site infection or signs of abdominal compartment syndrome were seen. No ventral or umbilical hernia occurred after a median follow-up of 12 months (range 4–22).ConclusionTraction-assisted staged closure using fasciotens®Pediatric enabled an early tension-less fascial closure in GOC and GS in the newborn period.

Morphological Changes and Concentricity of the Hip Joint During Gradual Reduction in Infants with Late-Detected Developmental Dysplasia of the Hip: A Retrospective Study.

The relationship between hip morphological changes and joint concentricity in infants with late-detected developmental dysplasia of the hip (DDH) treated with gradual reduction remains unclear. Therefore, we investigated hip morphological changes and concentricity in infants with late-detected unilateral DDH using magnetic resonance imaging (MRI) during gradual reduction. We enrolled 20 infants aged ≥ 12months with unilateral DDH. Treatment comprised continuous traction, a hip-spica cast, and an abduction brace. MRI was performed before treatment, immediately after hip-spica cast placement, after cast removal, and at the end of the brace. We evaluated the acetabulum and femoral head morphology and joint concentricity. The mean age was 25months, and female sex and the left side were predominant. Before treatment, the acetabulum was small and shallow and the femoral head was spherically flat on the affected side. Immediately after the continuous traction, the affected acetabulum and femoral head were still smaller than the healthy/contralateral one. However, they improved to a deeper acetabulum and round femoral head. Intra-articular soft tissue (IAST) and femoral-acetabular distance (FAD) continuously decreased, indicating gradual improvement in joint concentricity. Deeper formation of the acetabulum and round shaping of the femoral head had occurred even in non-concentric reduction. The shape and concentricity of the hip joint improved after treatment; however, the acetabulum and femoral head remained small. The deeper acetabulum and round femoral head were observed the non-concentric reduction before the concentric reduction was achieved. The continuous decrease in IAST and FAD indicates effective post-traction therapy.

Arthroscopic Trapeziectomy Without Traction Tower

Osteoarthritis in the thumb carpometacarpal joint causes pain, swelling, deformity, instability, loss of motion, and power, which seriously impairs overall hand function. Surgery is indicated if conservative treatment fails to relieve the pain. Trapeziectomy is the most popular surgical treatment choice and yields good range of motion and relieves pain with the fewest complications. Arthroscopic trapeziectomy is gaining popularity. In general, the arthroscopic procedure is performed under continuous traction with a traction tower. The purpose of this Technical Note is to describe the details of arthroscopic trapeziectomy without traction tower. This eliminates the need of a traction tower and continuous traction and provides a stable platform for the arthroscopic procedure.

Difficulty removing a ureteric stent due to a knotted proximal end

We present a case of a 55-year-old male who presented three days after laser lithotripsy and insertion of a 6 CH multilength JJ stent. Symptoms included abdominal pain and visible haematuria. Investigations included a CT scan showing the stent to be in a satisfactory position with no encrustation. Unexpected difficulty was encountered on cystoscopic removal as the stent would not come out entirely. Abdominal X-ray showed the proximal end of the stent to be knotted and stuck at the vesicoureteric junction. He was transferred to the operating theatre, and the stent was successfully removed with continuous traction under a general anaesthetic. Post-removal cystoscopy and retrograde pyelogram showed an intact urinary tract with inflammation at the left ureteric orifice. Knotting of ureteric stents is a rare complication but has been reported previously in the literature. The exact aetiology is not known; however, it has previously been attributed to excessive length of stent within the renal pelvis. Several methods of removing a knotted stent have been reported, including traction, ureteroscopic untying, laser destruction of the stent, retrograde removal, and open surgery. Choice of technique will vary depending on anatomical location of the knot.

Conservative management of a 3 months long standing bilateral temporomandibular joint dislocation: A case report

Temporomandibular joint (TMJ) dislocation is a type of condition where the condyle is anteriorly displaced beyond the articular eminence. Long standing cases with TMJ dislocation condition persisting for more than a month becomes challenging to treat. Its management includes closed reduction to complicated surgical procedures so as to reduce the dislocated condyles. Mandibular dislocation cases present with its own distinctive features. The aim of the report is to reduce the dislocated condyles through conservative management.This paper presents with non-invasive and conservative method for management of a long standing case (three months old) of TMJ dislocation in patient with acute renal failure and uncontrolled diabetes giving excellent outcome using elastic traction. Elastic traction with fulcrum on molars for reduction and inter-maxillary fixation was done in order to stabilize the mandibular condyles into the glenoid fossa. Here we stressed on the effectiveness of continuous traction using elastics and Inter-maxillary fixation (IMF) in achieving a complete repositioning of the mandibular condyles back into the fossaCondyles were reduced back in glenoid fossa with excellent outcome.Where manual reduction is not possible, elastic traction and IMF is the only method to reduce condyles. In long standing chronic TMJ dislocation case, only manual reduction was not sufficient. Since no standard rules for the ideal strategy are available till date, initial approach must be conservative so to preserve surgical treatment for later if needed.

Partial ruptures of the distal triceps tendons show only slightly lower ultimate load to failure: a biomechanical study

ObjectivePartial ruptures of the distal triceps tendon are usually treated surgically from a size of > 50% tendon involvement. The aim of this study was to compare the ultimate load to failure of intact triceps tendons with partially ruptured tendons and describe the rupture mechanism.MethodsEighteen human fresh-frozen cadaveric elbow specimens were randomly assigned to two groups with either an intact distal triceps tendon or with a simulated partial rupture of 50% of the tendon. A continuous traction on the distal triceps tendon was applied to provoke a complete tendon rupture. The maximum required ultimate load to failure of the tendon in N was measured. In addition, video recordings of the ruptures of the intact tendons were performed and analysed by two independent investigators.ResultsA median ultimate load to failure of 1,390 N (range Q0.25—Q0.75, 954 – 2,360) was measured in intact distal triceps tendons. The median ultimate load to failure of the partially ruptured tendons was 1,330 N (range Q0.25—Q0.75, 1,130 – 1.470 N). The differences were not significant. All recorded ruptures began in the superficial tendon portion, and seven out of nine tendons in the lateral tendon portion.DiscussionPartial ruptures of the distal triceps tendon demonstrate a not statistically significant lower ultimate load to failure than intact tendons and typically occur in the superficial, lateral portion of the tendon. This finding can be helpful when deciding between surgical and conservative therapy for partial ruptures of the distal triceps tendon.

Application of electric traction drive for the modernization of locomotives with hydraulic power transmission

The issue of updating the locomotive fleet of industrial enterprises by modernizing outdated diesel locomotives with hydraulic power transmission was considered. The analysis of existing modernizations shows the possibility of using traction electric drive while preserving the original group drive of wheel pairs. This approach is used by manufacturers when updating outdated and creating new diesel locomotives and traction modules for rolling stock. A possible option is the use of single-motor carts. Previous studies on the choice of the type of wheel pairs drive were analyzed and it was established that the use of a group drive of wheel pairs provides the possibility of realizing high traction forces without additional devices, and the drive itself has a lower cost. This determines the expediency of using a group drive of wheel pairs when modernizing diesel locomotives with hydraulic power transmission. To realize these advantages, it is necessary to use a traction electric drive based on electromechanical alternating current converters. This approach was implemented by Mykolaiv Locomotive Repair Plant LLC during the modernization of TGM6 diesel locomotives. The diesel locomotive is intended for shunting and hauling operations, as a result of which it was assumed during the design that the traction force when moving is equal to 320 kN, the continuous traction force is 300 kN, and the maximum speed is 50 km/h. The power plant consists of a modern Cummins diesel engine and a synchronous generator. A frequency-controlled asynchronous traction electric motor is used to drive the wheel pairs. Power and control of the electric motor is carried out using a voltage inverter. Diesel locomotives use a controlled electric drive of cooling motor-fans, and semiconductor converters are used to power auxiliary systems. The locomotive and its systems are controlled by a microprocessor control system. The application of the traction electric drive based on the asynchronous electric motor provided the estimated efficiency of the diesel locomotive and the efficiency of the diesel power at the nominal power and the estimated speed of the long-term mode, equal to 6 km/h, are 0.312 relative units and 0.69 relative units, respectively. The analysis of ways to improve the traction electric drive to reduce the consumption of fuel and energy resources was carried out. It was determined that the use of a power plant with energy storage and the use of two traction electric motors for the group drive of wheel pairs may be expedient

A verified analytical sandwich beam model for soft and hard cores: comparison to existing analytical models and finite element calculations

This paper presents a novel approach of modeling of three-layer beam. Such composites are usually known as sandwich structures if the modulus of elasticity of the core is much smaller than those of the faces. In the present approach, the faces are modeled as Bernoulli–Euler beams, the core as a Timoshenko beam. Taking into account the kinematic and dynamic interface conditions, which means that the perfect bonding assumptions hold for the displacement and each layer is subjected to continuous traction stresses across the interface, a sixth-order differential equation is derived for the bending deflection, and a second-order system for the axial displacement. No restrictions are imposed on the elastic properties of the middle layer, and hence the developed theory also yields accurate results for hard cores. The presented refined theory is compared to analytical models from the literature and to finite element calculations for various benchmark examples. Special focus is laid the boundary conditions and the core stiffness. A parametric study varying the Young modulus of the core shows that the present sandwich model agrees very well with the target solutions obtained from finite element calculations under plane stress assumptions, in particular concerning the transverse deflection, the shear stress distribution and the interfacial normal stress.

Power Sharing Control of High Speed Railway Traction Networks Supplied by Dual End Substations

This paper presents a novel power sharing control for high speed railway traction networks which are supplied continuously by dual end substations without the neutral section. The power sharing between two substations is realised by droop control where the droop coefficients are updated based on the actual traction load distribution for a given specific active power sharing ratio, while the power sharing ratio is optimised for the least conductor line losses under the light-medium load condition. For the heavy load condition, power at both substations are more balanced so that the substation capacity can be set at a lower rating. The proposed approach is tested on a simplified single-track network model which supports continuous traction dynamics and auto-transformer connection, and simulation results confirm that the proposed method has advantages of increasing the supply distance compared with the conventional transformer substation scheme. It offers greater power supply capacity than the fixed frequency substation control scheme, and it also achieves less power losses than the equal power sharing strategy proposed in the existing studies.

Abstract 15014: Aberrant, Elevated Papillary Muscle and Left Ventricular Wall Forces Associated With Mitral Valve Prolapse Are Normalized by Surgical Neochordal Repair but Not by Transcatheter Edge-to-Edge Repair

Introduction: Recent studies have linked mitral valve prolapse (MVP) to localized myocardial fibrosis and ventricular arrhythmia, and early imaging work has shown altered ventricular motion with papillary muscle (PM) traction in MVP and MitraClip patients. We aimed to biomechanically compare MitraClip and neochordal repair for MVP on PM forces ex vivo . Methods: We developed a force transduction system to measure the forces exerted on the PMs throughout the cardiac cycle in a left heart simulator ( Fig A ) with consistent pressures. Using a randomized, paired procedure with porcine MVs (n=4), we measured the hemodynamics and forces for control, diseased (P2 prolapse via chordal rupture), MitraClip repair ( Fig B, C, D ) (single P2 clip), and neochordal repair (P2 primary neochord on each PM) conditions. Results: We found that MitraClip PM forces (7.19 ± 0.31 N) are higher by 9.34% compared with those of controls (6.58 ± 0.21 N, p&lt;0.001 ). This result is similar to MVP valves modeled by superior PM displacement, which showed 9.23% higher forces than those of controls (n=10, p&lt;0.001 ). Moreover, MitraClip repaired valves showed PM force increases of 6.4% compared with forces of neochordal repair (6.76 ± 0.22 N, p&lt;0.001 ), despite having similarly reduced regurgitation fractions (5.05% ± 1.98% vs. 4.25% ± 1.51%, respectively, p&gt;0.05 ) compared with those of the diseased state (16.96% ± 3.04%, p&lt;0.001 ) and controls (2.66% ± 0.87%). Additionally, neochordal repair valves had 2.79% higher forces compared to those of control valves ( p&lt;0.001 ). Conclusions: We discovered that MitraClip, while reducing regurgitation, does not restore aberrant forces on the PM induced in MVP to baseline or reduced levels, while neochordal repair does. Our work suggests that these elevated forces, associated with MVP and MitraClip, predisposes the MV to continued traction, which may present a long-term harm to patients by catalyzing localized fibrosis and ventricular arrhythmia.

Effects of combined adjustable Halo-pelvic fixation brace on cervical spine alignment in patients with severe rigid spinal deformity

ObjectiveTo evaluate the effect of continuous traction with a combined adjustable Halo-pelvic fixation brace on the cervical spine alignment in patients with severe rigid spinal deformity and analyze its related factors.MethodsWe conducted a retrospective cohort study of 21 patients with severe rigid spinal deformity treated in our department between 2015 and 2019. All subjects received combined adjustable Halo-pelvic fixation brace traction before secondary orthopedic surgery. The influence of the Halo-pelvic fixation brace on the cervical spine alignment was evaluated by measuring the parameters of lateral cervical X-ray at three time points: before traction, at the end of traction, and 6 months after orthopedic surgery. The correlation between parameter changes and total traction duration was analyzed to explore factors influencing cervical alignment.ResultsThe C2L-C7L angle was 22.40 ± 15.91° before traction, which decreased to 5.91 ± 6.78° at the end of traction but increased to 14.51 ± 10.07° after orthopedic surgery (BT vs ET p < 0.005, ET vs AOS p < 0.005, BT vs AOS p < 0.005). Accordingly, C2L-C7U angle, C2L-C6L angle, C2L-C6U angle, C2L-C5L angle, C7 or T1 slope, C2-C7 SVA, SCA, C2-T1 Ha, C0 slope, and C0-C2 angle also changed similarly to C2L-C7L angle. Furthermore, moderate correlation was observed between C2L-C7L angle and total traction volume (r = 0.563, p = 0.008) and SCA and traction duration (r = 0.525, p = 0.015). However, no significant correlation was found between other cervical alignment parameters and total traction volume and traction duration.ConclusionsThe continuous traction of a combined adjustable Halo-pelvic fixation brace can affect the cervical spine alignment of patients with severe rigid spinal deformity and straighten the physiological curvature of the cervical spine. However, the sagittal alignment gradually recovers after the traction, without any adverse effects on the orthopedic surgery and global balance after the operation; therefore, this apparatus is worthy of wide application.

155 Fracture of Pubic Rami During Hip Fracture Fixation - a Rare Case of Traction Table Related Injury

Abstract Background Traction tables form the mainstay of closed reduction techniques for lower limb fracture and in particular hip fractures. They offer a versatile solution to continuous traction required in a variety of operations such as closed intramedullary femoral fixation and hip fixation. Counter traction on the table is provided by the perineal post, this has been associated with significant complications such as neuropraxia, erectile dysfunction, cutaneous necrosis, and urethral injuries. Case presentation We present a case of an elderly and co-morbid patient who was scheduled to undergo a hip fracture fixation using an intramedullary nail. Unfortunately, this was delayed by 3 weeks as the patient was unfit to undergo this procedure. She was placed onto the traction table and intra-operatively sustained a superior and inferior pubic rami fracture while attempting reduction on the traction table. Conclusions Closed reduction techniques using traction tables and perineal posts are not without morbidity. Risk factors such as osteoporosis and delayed fixation should be accounted for when managing this complex and often frail group of patients.

Experimental and finite element analysis studies of a reduction-force reducing traction method for pelvic fracture surgeries

Pelvic fracture is among the most complicated fractures in traumatic orthopedics, with high mortality and morbidity rates. The main difficulty associated with the reduction surgery is significant muscle resistance. It then becomes necessary to decrease the reduction force against this strong muscle resistance, for improving surgical safety. Here, we propose a novel traction method for decreasing the reduction force during pelvic reduction, and investigate the performance of the elastic traction method on decreasing the reduction force using experimental tests and simulation-based analyses. From the experimental results, the reduction force decreased by 59.2% when 10 ​kg of elastic traction was applied. We also establish a musculoskeletal model of the pelvic fracture reduction, for analyzing the muscle resistance and the optimal traction force applied in reduction surgeries. The elastic traction method can counteract the muscle resistance increase in the non-traction direction owing to its flexibility. We conclude that the optimal traction force applied should be in the 10–15 ​kg range, and recommend adopting a dynamic traction strategy rather than continuous traction in clinical settings. Elastic traction is very promising for various surgeries that require traction, including pelvic reduction. It significantly reduces force, which can significantly reduce the physical exertion of the operating surgeon, the possibility of additional injuries to the operated patient, and promotes robot-assisted reduction surgeries.

Concentration Changes of Peripheral Blood Mesenchymal Stem Cells of Sprague Dawley Rats during Distraction Osteogenesis

ObjectivesTo observe the changes in the concentrations of circulating peripheral blood mesenchymal stem cells (PBMSCs) in Sprague Dawley (SD) rats and explore the pattern of changes in PBMSCs during the process of distraction osteogenesis.MethodsSD rats were randomly divided into the osteotomy with lengthening group (lengthening group), the osteotomy without lengthening group (osteotomy group), and the blank control group (control group). Each group included 24 rats. Percutaneous pinning with external fixation of the left femur was carried out in lengthening group and osteotomy group, but control group received no surgical treatment. On day 5 after operation, continuous traction was carried out at a rate of 0.25 mm/d in lengthening group, while no traction was carried out in osteotomy group. Peripheral blood was collected from all rats on days 1, 3, 7, and 16 after the start of traction. PBMSCs were isolated by density gradient centrifugation. CD105, CD34, and CD45 were selected as cell surface markers. The concentration of PBMSCs was detected by flow cytometry and compared between groups at different time points. X‐ray films were taken during and after the operation to observe whether the osteotomy end was pulled and the growth and mineralization of the new bone in the osteogenic area of the femur. Color ultrasound was used to monitor the width of the distraction space, the formation of new bone, and the blood supply of soft tissue around the distraction.ResultsAll rats were able to tolerate the operation well, and the external fixation was firm and reliable. X‐ray showed that, in lengthening group, the distraction space of femur gradually widened and new bone gradually formed in the distraction space; after 8 weeks, the samples were taken out, which showed that the new bone tissue in the lengthened area healed well. In osteotomy group, the average healing time of osteotomy was (7.12 ± 0.78) weeks. Ultrasonic examination showed that after the end of traction, the high echo callus shadow was seen in the traction space, and the blood flow signal was obviously rich at an earlier stage. In lengthening group and osteotomy group, the average concentrations of PBMSCs (3.02% ± 0.87% vs 2.95% ± 0.74%, respectively) were significantly increased in the early stage after osteotomy, and the average concentrations of PBMSCs on days 3, 7, and 16 after the start of traction were 5.34% ± 1.13% vs 3.28% ± 1.22%; 6.41% ± 1.05% vs 3.16% ± 0.92%; and 5.94% ± 1.23% vs 1.48% ± 0.52%, respectively. The concentration of PBMSCs in peripheral blood of lengthening group and osteotomy group was the same at osteotomy stage, and the difference between the two groups was not statistically significant (P > 0.05). After that, compared with lengthening group, the concentration of PBMSCs in osteotomy group gradually decreased and maintained at a certain level; the difference between the two groups was statistically significant (P < 0.05).ConclusionsDistraction osteogenesis of femur can significantly increase PBMSCs in SD rats and participate in the process of bone formation.

Initial single centre experience of Aquablation of the prostate using the AquaBeam system with athermal haemostasis for the treatment of benign prostatic hyperplasia: 1-year outcomes.

Aquablation using the AquaBeam system combines real-time image guidance and robotics to enable precise and heat-free removal of prostatic tissue with a high velocity water jet. The aim of this study is to report the outcomes of Aquablation up to 1year in a single centre within the UK employing an athermal approach to haemostasis. Fifty-five consecutive men underwent Aquablation between September 2017 and December 2018 (as part of OPEN WATER trial). Standard Aquablation was performed with the AquaBeam system (PROCEPT® BioRobotics) with 2 passes of Aquablation followed by bladder washout with application of continuous bladder irrigation via a catheter on a continuous traction device. Patients were followed up at 3 and 12months. The data were prospectively collected on patient demographics, uroflowmetry, prostate volume, International Prostate Symptom Score (IPSS), Male Sexual Health Questionnaire for Ejaculatory Dysfunction (MSHQ-EjD) and International Index of Erectile Function (IIEF-15). The mean age was 64.1 ± 7.9years. Operating time was 26.9 ± 9.2min. Mean prostate volume decreased from 58.2 ± 23.9cc to 33.2 ± 12.9cc (p < 0.0001). There were significant improvements at the 12month follow-up in maximum urinary flow rate (9.9 ± 5.1ml/s vs. 23.9 ± 11.6ml/s), IPSS (21.7 ± 7.4 vs. 6.1 ± 4.2) and quality of life score (4.8 ± 1.1 vs. 1.4 ± 1.4) (p < 0.0001). There was no significant change in IIEF-15 and MSHQ-EjD scores. There were 8 (14.5%) Clavien grade 2 or higher complications. Our single centre experience suggests Aquablation using an entirely athermal approach is a safe cavitating procedure resulting in significant LUTS improvement comparable to standard cavitating procedures with greater preservation of sexual function.

Recommendations for the selection of parameters for shunting locomotives

Shunting is an integral part of the partial process. In 1520 mm gauge countries, shunting operations are performed by outdated locomotives, which are being replaced by modern models; the technical parameters best match the conditions of the shunting work performed. The article analyzes recommendations for the selection of parameters of shunting locomotives and the actual indicators of their work. On the basis of this analysis, a requirement was made on the necessity of compulsory consideration of the operating conditions of the locomotive when determining its technical characteristics. As the main technical parameters of shunting locomotives, the tractive power and starting tractive force are taken and their influence on the duration of an elementary shunting movement of the "acceleration-deceleration" type is investigated. This approach advises the regulatory documentation for the organization of shunting work. Tha developed mathematical model allows to carry out research on the influence of tractive power and starting tractive force on the time of acceleration and deceleration. Calculations of the time of the train's acceleration are carried out with varying their mass and the slope of the track at different values of the tractive power starting tractive force. The calculations were carried out for the mass of compositions 1000...5000 Mg for the profile slopes equal to 0 and 1.5 ‰. The speed of the finish of acceleration was taken equal to 15 and 25 km/h. The thrust starting tractive force varied in the range of 150...300 kN, the tractive power - 200 ... 1100 kW. According to the results of calculations, it was found that the reduction in the duration of the elementary shunting movement is more significantly affected by the power of the locomotive than by the starting traction force. The “saturation” effect was noted, in which a significant increase in power or traction force during starting does not cause a significant reduction in the acceleration time. In this regard, for shunting locomotives with AC traction drive, it is recommended to take a pulling force of an equal continuous traction force.

Phase-inherent linear visco-elasticity model for infinitesimal deformations in the multiphase-field context

A linear visco-elasticity ansatz for the multiphase-field method is introduced in the form of a Maxwell-Wiechert model. The implementation follows the idea of solving the mechanical jump conditions in the diffuse interface regions, hence the continuous traction condition and Hadamard’s compatibility condition, respectively. This makes strains and stresses available in their phase-inherent form (e.g. varepsilon ^{alpha }_{ij}, varepsilon ^{beta }_{ij}), which conveniently allows to model material behaviour for each phase separately on the basis of these quantities. In the case of the Maxwell-Wiechert model this means the introduction of phase-inherent viscous strains. After giving details about the implementation, the results of the model presented are compared to a conventional Voigt/Taylor approach for the linear visco-elasticity model and both are evaluated against analytical and sharp-interface solutions in different simulation setups.

Changes of MRI in inter-spinal distraction fusion for lumbar degenerative disease: A retrospective analysis covering 3 years

ObjectiveTo assess the preoperative and postoperative changes in MRI image and the short-term efficacy of the ISDF with BacFuse covering 3 years. Methods32 patients who underwent ISDF were involved in this retrospective study. The symptoms assessment including VAS, ODI, and SF-12 were evaluated preoperative and postoperative at 1 year and 3 years. The X-ray was used to measure posterior disk height (PDH), foramina height (FH), foramina width (FW), and MRI was taken to assess the cross-sectional area of dura sac (CSADS), cross-sectional area of canal (CSAC), herniated disc area, ligamentum flavum area. The preoperative ratio of herniated disc area and ligamentum flavum area to CSAC were compared with post-operative ratio. The modified Pfirrmann grade system was used to assess the surgical lumbar disc. ResultsThe symptom indexes were significantly improved after surgery. PDH and FH increased significantly (P < 0.05) after surgery compared with that before surgery, but there was no statistical difference in FW (P > 0.05). CSADS and CSAC increased obviously (P < 0.05), while the area of herniated disc and ligamentum flavum decreased significantly (P < 0.05). The ratio changes showed a significant difference between last follow-up and pre-operation (P < 0.05), but there was no statistical significance in grade changes of surgical disc. ConclusionISDF with BacFuse could relieve clinical symptoms and expanse the spinal canal area in MRI. During 3-year observation, it could provide continuous traction and maintain the area of spinal canal, so as to partially retract the herniated disc and make it possible to repair the disc.