Multiple Pinning Research Articles

Analysis on the inhomogeneous magnetization reversal in the sintered Sm-Co magnet

Domain-wall-pinning is one of the ways to realize magnetic hardening for permanent magnet materials. The sintered 2:17 Sm-Co magnets, a most typical pinning-controlled magnet, have complex nano-scaled cellular structures including cellular matrix phase, cell wall phase, and lamellar Zr-rich phase. In this paper, a multiple domain-wall-pinning with cell wall phase dominating and Zr-rich phase participating was proposed through micromagnetic simulation. The simulation results were supported by magnetic domain observation and macroscopic magnetic measurement analysis, which provided a key reference for the correlation between the magnetic properties and microstructure of this kind of magnet. Furthermore, the squareness of the demagnetization curve for the magnet was affected by multiple pinning, including multiple pinning phases and the internal inhomogeneity inside a pinning phase. Our finding can enrich the magnetic hardening mechanism and provide theoretical guidance for the optimization of magnetic properties of the pinning-controlled permanent magnets.

The joy stick technique: an easy, reliable, safe and cost effective, technique in closed reduction and percutaneous fixation of supracondylar fracture of the humerus in children

<p class="abstract"><strong>Background:</strong> Supra condylar fractures of humerus account for approximately 16% of all pediatric fractures. This produces an extension type fracture in 97–99%. Flexion type accounting for 1-3%. This often causes significant morbidity due to malunion (gun-stock deformity) reported in 12 to 20%, while neurovascular complications and compartment syndrome is documented in worse scenarios.</p><p class="abstract"><strong>Methods:</strong> A prospective study was conducted with 24 cases of supracondylar humerus fracture between June 2017 to June 2021. Both males and females aged 3 years to 12 years, within 5 days of injury, with modified Gartland’s type III and type IV, without compartment syndrome were included and followed up for 6 months to one year. The fracture was closely reduced using a 2-2.5 mm k-wire (joystick) in proximal fragment placed 5-7 cm proximal to fracture line and fixed with multiple percutaneous pinning under C-arm. All the patients were followed for rate of union and functional outcome using Flynn’s criteria.<strong></strong></p><p class="abstract"><strong>Results:</strong> All the 24 cases were managed by closed maneuver with the help of a joy stick. This reduces the surgical time and stress, preventing opening of fracture. Outcome was assessed in each follow up using Flynn’s criteria. 87.5% of patients had good to excellent outcomes.</p><p class="abstract"><strong>Conclusions:</strong> Our results demonstrate that good functional outcomes are expected in supracondylar fracture regardless of age at injury, sex, weight, side of extremity provided satisfactory reduction by closed technique with help of joy stick. This simple technique reduces surgical stress, duration of surgery and also minimizes the C-arm exposure.</p>

Large Glenoid Defects Treated by Multiple Bioresorbable Pinning-Assisted Bone-Grafting in Reverse Shoulder Arthroplasty.

This procedure is performed with the patient under general anesthesia and in the beach-chair position, via a deltopectoral approach. After placing the structural graft, 5 to 10 provisional 1.5-mm Kirschner wires are inserted through the graft up the medal cortical bone of the scapula. The Kirschner wires are subsequently replaced with bioresorbable (BR) pins (1.5-mm Fixsorb Pin; TEIJIN). If more wires are needed, another set of 4 to 5 RB pins is inserted to gain initial stability. After placing the graft, the glenoid component is implanted as usual. Traditionally, 1 or 2 screws are inserted in the periphery of the graft to obtain stability. The screws either must be inserted at an angle that does not impede placement of the implant2 or are removed before the placement of the glenoid implant. One or a maximum of 2 long screws are inserted through the graft and glenoid3, meaning that the screw(s) must be aimed at a very narrow space between the central post and screws. Otherwise, these screws will represent an obstacle to the placement of the glenoid implant. In addition to facilitating initial graft stability, this procedure promotes graft incorporation. Typically, when performing this procedure, a total of 15 to 20 temporary Kirschner wires are placed in sets, with 5 to 7 wires per set. Of these, the most stable wires, usually 8 to 10 in total, are replaced by BR pins. The resultant bone holes, whether filled or unfilled with the BR pins, may promote neovascularization and osteoinduction, enabling long-lasting remodeling of and improved incorporation of the bone graft. A prior study compared the use of MBP versus angulated bony-increased offset (BIO) graft, assessing graft incorporation according to the size of the remaining graft on axial radiographs, with full incorporation defined as >75% of the original graft size1,2. In that study, all 13 patients in the MBP group showed full graft incorporation compared with only 9 (47%) of 19 patients in the angulated BIO group (p < 0.001)1. Expose all 4 quadrants of the glenoid in cases of type-2 deformity. Accurate orientation of the MBP is important.Expose the upper and lower 2 quadrants of the glenoid in cases of type-3 deformity. The bases of the scapular spine and axillary border serve as a graft scaffold.Preserve circumferential soft tissues in cases of type-3 deformity because these tissues will serve to contain cancellous bone graft.Keep the Kirschner wire that extends the most medially (reaching the most medial cortical bone of the scapula) as a future guidewire for drilling of the central peg hole. RSA = reverse shoulder arthroplastyMBP = multiple bioresorbable pinningBIO = bony-increased offsetBR = bioresorbableTSA = total shoulder arthroplastyCT = computed tomographyK-wire = Kirschner wireROM = range of motionP.O. = postoperative.

Stability of fractured end of femur in young dogs affecting the status of the hip joints using intramedullary pinning

In the study 10 dogs were sourced from 2 litters, and were randomly assorted into 3 experimental groups. The intramedullary pinning of the femur of the young dogs were evaluated to know the status of the hip joints. Fractures were created on the femur of the experimental dogs and attempts were made to oppose or align then using the retrograding and normograding techniques. It showed that retrograding techniques with multiple intramedullary pinning provide stability to the corrected fractured limb, and frequent evaluation of the radiographic status of the hip and bones in managing femoral fracture repair by intramedullary pin fixation in young dogs to determine when it is soonest and best to remove the pins.&#x0D; Key Words: Intramedullary pins. Femur. Hip joint. dogs. Status.

Inkjet-Printed Quantum Dot Fluorescent Security Labels with Triple-Level Optical Encryption.

Optical security labels play a significant role in protecting both our wealth and health. However, simultaneously meeting the requirements including low-cost fabrication, easy detection, and high-level security is still challenging for security labels. Here, we design an unclonable anti-counterfeiting system with triple-level security by using the inkjet printing technique, which can be authenticated by naked eyes, a portable microscope, and a fluorescence microscope. These labels are achieved by printing microscale quantum dot (QD) ink droplets on premodified substrates with random-distributed glass microspheres. Due to the unique capillary action induced by the glass microspheres, QDs in the ink droplets are deposited around the microspheres, forming microscale multicircular patterns. Multiple pinning of QDs at the three-phase contact lines appears during the evaporation of the droplet, resulting in the formation of a nanoscale labyrinthine pattern around the microspheres. The nanoscale labyrinth pattern and the microscale multicircular microsphere array, together with the printed macroscopic image, constitute a triple-level progressive anti-counterfeiting system. Moreover, the system is compatible with an artificial intelligence-based identification strategy that allows rapid identification and verification of the unclonable security labels.

A Sequential Approach to the Management of Posterior Glenoid Defects in RSA: Angulated BIO Versus Multiple Bioresorbable Pinning-Assisted Structural Bone-Grafting.

Background:Large posterior glenoid defects pose problems in reverse shoulder arthroplasty (RSA). We have adopted a sequential approach to the management of posterior glenoid defects using asymmetrical reaming, the placement of a ring graft around the central peg (bony-increased offset, or BIO), or structural bone-grafting, depending on the amount of glenoid retroversion. Furthermore, we have devised multiple bioresorbable pinning (MBP)-assisted bone-grafting, in which as many bioresorbable pins as required are inserted, from whichever aspects of the graft necessary, to achieve initial stability.Methods:We reviewed 52 shoulders with posterior glenoid defects undergoing RSA between 2014 and 2019 (mean follow-up, 4.8 years; range, 2 to 6 years). Twenty (38.5%) of the shoulders had glenoid retroversion of <15° and were treated by asymmetrical reaming (Group A), 19 (36.5%) of the shoulders had retroversion of ≥15° to <30° and were treated with asymmetrical reaming combined with angulated ring graft around the central peg (Group B), and 13 (25.0%) of the shoulders had retroversion of ≥30° and were treated with MBP-assisted bone-grafting (Group C).Results:Mean version correction was 10.6° ± 4.3° in Group A, 20.7° ± 8.8° in Group B, and 33.8° ± 9.6° in Group C. The mean postoperative active anterior elevation was 138.3° ± 12.3°, 128.3° ± 12.3°, and 126.5° ± 15.3° in the 3 groups, respectively. The mean postoperative Constant score was 66.8 ± 14.6, 62.2 ± 13.5, and 61.7 ± 16.7, respectively. The mean preoperative active anterior elevation was significantly higher in Group A than in Group C (p = 0.037). The full or partial graft-incorporation rate (≥25% of original size) was 89.5% in Group B and 100% in Group C. One glenoid fracture and 1 case of transient brachial plexus palsy occurred in Group B (10.5%), and 1 acromion fracture and 2 cases of transient brachial plexus palsy occurred in Group C (23.1%).Conclusions:The results of the present sequential approach to management of posterior glenoid defects by the 3 modalities were acceptable. The present MBP-assisted bone-grafting procedure is an effective treatment for cases of shoulder arthropathy with severe posterior glenoid defects. Angulated ring grafting around the central peg may yield equally acceptable results, although its graft-incorporation rate requires further follow-up.Level of Evidence:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Intelligent Pinning Based Cooperative Secondary Control of Distributed Generators for Microgrid in Islanding Operation Mode

Motivated by the fact that the location(s) and structural properties of the pinning node(s) affect the algebraic connectivity of a network with respect to the reference value and thereby, its dynamic performance, this paper studies the application of intelligent single and multiple pinning of distributed cooperative secondary control of distributed generators (DGs) in islanded microgrid operation. It is shown that the intelligent selection of a pinning set based on the degree of connectivity and distance of leader DG(s) from the rest of the network improves the transient performance for microgrid voltage and frequency regulation. The efficacy of the distributed control strategy based on the proposed algorithms is illustrated via numerical results simulating typical scenarios for a variety of microgrid configurations.

Improvements in Pinning Fixation for Distal Radius Fractures.

Despite the increasingly widespread use of the volar plate, the pinning of the distal radius keeps its place as a basic technique in the treatment of extra-articular and intra-articular fractures with dorsal displacement and little comminution. To date, there are 2 types of pinning recognized as stable and reliable: the "cross-pinning" with 2 styloid pins and a dorso-ulnar one and the multiple mixed pinning, which is an improved version of the classical technique of Kapandji. This article offers a modified technique of mixed multiple pinning: the pinning type Fort-de-France, which offers a more stable reduction. However, our technique would have to be confirmed by clinical and biomechanical studies.

Controlled vortex motion in multiple interpenetrating pinning arrays

We study the effect of multiple interpenetrating pinning arrays on the vortex motion in the presence of an ac driving force, f d (t), by using extensive molecular dynamics (MD) simulations. Firstly, the response to a square ac wave f d (t) has been explored for the vortices interacting with a periodic square pinning array which has different pinning strengths and sizes. The effect of the type of an ac drive and its amplitude on the oscillatory dynamics of vortices have been investigated in detail. For very low displacements of the vortices, we have found that the single-particle model can produce results analytically similar to the ones obtained by the MD simulations. It is shown that the collective motion of vortices can be controlled easily by varying the number of multiple interpenetrating square pinning lattices (N SPSL). A regular sequence of peaks has been observed for N SPSL = 3 in the time evolution of the average velocity of the vortices (i.e., V x - t curves). The number of peaks (N peak) strongly depends on the magnitude of f d (t), and increases with increasing the magnitude of f d . The close relation between N peak and f d is considered as an indication of controlling vortex motion in a multiple periodic pinning structure. Finally, the variation of the power spectrum of noise S(ν) with N SPSL has been investigated. For N SPSL = 3, it has been found that the plastic motion of the row of vortices evolves at low frequencies, i.e., 1/ν behavior, whereas, at high frequencies, S(ν) shows a typical behavior of Gaussian white noise.

Progression of a Fracture Site Impaction as a Prognostic Indicator of Impacted Femoral Neck Fracture Treated with Multiple Pinning

BackgroundWe evaluated the clinical and radiologic results of impacted femoral neck fractures treated with multiple pinning and determined the influence of the progression of impaction at the fracture site on clinical outcome.MethodsThere were 34 patients with a mean age of 65.5 years. The mean follow-up period was 3.4 years. Progression of fracture site impaction was measured using an articulo-trochanteric distance index and the percentage decrease in the articulo-trochanteric distance index between follow-up intervals. The failure of treatment was clarified as non-union and avascular necrosis. Other characteristics of the patients, including mean waiting time for surgery, preoperative Singh index score, and body mass index, were also measured to evaluate the influence on the clinical outcome of surgery.ResultsThere were 6 fractures which were not treated successfully (3 non-union, 8.8% and 3 avascular necrosis, 8.8%). The mean percentage decrease of the articulo-trochanteric distance index within the first 6 weeks after surgery was 4.5% in the successful group and 25.1% in the failure group (p < 0.001). There was also a significant mean percentage decrease in the articulo-trochanteric distance index between 6 weeks and 3 months (p < 0.001).ConclusionsPrimary stabilization with Knowles pins for impacted femoral neck fractures had a reasonable clinical outcome with low morbidity. Despite a significant difference of a mean percentage decrease in the articulo-trochanteric distance index between the successful group and the failure group, we could not verify it as a risk factor for failure of treatment because the odds ratio was not statistically significant.

Could We Prevent Displacing the Undisplaced Fracture Neck of Femur? To the Editor

To the Editor: I have read the article Progression of a fracture site impaction as a prognostic indicator of impacted femoral neck fracture treated with multiple pinning by Yoon et al.1) in the current issue of your esteemed journal and congratulate the authors. Yet, I would like to elaborate on a few important relevant concepts in the same regard. The authors have not considered the other vector in the femoral neck collapse. The articulo-trochanteric distance (ATD) in the article and also in the 'capital impaction index' by Shimizu et al.,2) is only the 'vertical' vector of the femoral neck collapse force. This vector only indicates the 'shear' and not the 'impaction' at the fracture site, as is indicated in the title. The true impaction at the fracture site will be determined by the 'horizontal' ATD, that is from the medial most point of head articular surface to the tangent drawn along the lateral most part of the greater trochanter. Hence, more the impaction, greater the decrease in the 'horizontal' ATD and lesser the change in the 'vertical' ATD. Like-wise, greater the shear at the fracture site, greater the decrease in the 'vertical' ATD than 'horizontal' ATD. With this background, it is stated in this article that there was a greater decrease in the 'vertical' ATD index in the unsuccessful patients i.e., 36% at 3 months (as compared to 7% in successful patients). A decrease in the 'vertical' ATD indicates a shear which means a higher type Pauwel's angle (type III). It would have been very useful if the Pauwel's fracture configuration in the unsuccessful patients would have been stated in the article. Now the trend in osteosynthesis is towards using an angle stable implant in Pauwel's type III neck femur fractures rather than pins or screws3,4) to counter the shear. Some even prefer a valgus osteotomy with screws to convert shear into compression. At this point, I would want to know, if a preoperative CT scan be useful to determine the Pauwel's angle in an undisplaced neck femur fracture5) and then embark on the operative plan rather than waiting for the decrease in 'vertical' ATD in the postoperative period. If the angle is high, a fixed angle implant be preferred over pins at the primary fixation itself. The age range of participants is 28 to 86 years. Osteomalacia is very common among patients with neck femur fracture.6) The authors have not mentioned the mode of trauma and have not screened any patients, especially with undisplaced neck femur fracture, for osteomalacia. The authors have also not mentioned about any perioperative and postoperative calcium and vitamin D supplementation which affects healing and collapse. Some papers discount the value of vitamin D levels in elderly but calcium supplementation is advisable. I also wish to suggest the use of AO 6.5 partially threaded cannulated cancellous screws be better than using Knowles pins with sharp pointed tips in osteoporotic bone. The possibility of joint penetration in Fig. 4 in the article could have been possibly averted.

Treatment of the displaced femoral neck fracture, as reflected in Acta Orthopaedica Scandinavica

Treatment of the displaced femoral neck fracture, as reflected in Acta Orthopaedica Scandinavica

Two-Plate Fixation for Humeral Shaft Nonunions

PURPOSE. To review 22 patients who underwent 2-plate fixation for non-union of the humeral shaft. METHODS. 13 women and 9 men aged 32 to 76 (mean, 48) years underwent fixation for non-union of the humeral shaft, using a 2-plate construct, together with decortication, debridement, and bone grafting. The two 3.5-mm reconstruction plates were parallel and lying at 90 degrees to each other and fixed with screws purchasing into at least 6 cortices of each fragment for both plates. Fractures were located in the upper third (n=8) or middle third (n=14) of the humerus. Initial treatments included casting (n=9), coaptation splinting (n=8), multiple retrograde pinning (n=4), and Marchetti-Vicenzi nailing (n=1). 18 non-unions were atrophic and 4 were hypertrophic. Shoulder and elbow range of motion as well as functional results were evaluated. RESULTS. The time for union was 4.6 (range, 4-6) months. No implants were loose or broken. No nonunion or infection was noted. Functional results were excellent in 17 and good in 5 patients. One patient had iatrogenic radial nerve palsy that recovered within 3 months. CONCLUSION. Two-plate fixation achieves good results for humeral shaft non-unions.

Vortex Pinning by Nanoparticles in Melt-Textured LREBa2Cu3Oy

Magnetic measurements in a wide temperature range of several ternary LREBa2Cu3Oy samples differently doped by secondary phase nanoparticles of different sizes are analysed in terms of a thermally activated depinning process. Evolution of the involved parameters with temperature and particle size is discussed. Zr contamination of the secondary phase particles facilitates the particles size reduction during meltgrowth process up to nanometre scale. Critical current at low fields, facilitated by multiple vortex pinning, is inversely proportional to (a small power of) the mean particle size. With such defects both critical currents and irreversibility field are high enough for industrial applications up to 90.2K (boiling point of liquid oxygen).

The role of preoperative bone scan for determining the treatment method for femoral neck fracture

To evaluate the role of preoperative bone scintigraphy in determining the operative treatment method for femoral neck fracture, we reviewed the data of 83 patients who underwent preoperative bone scanning after femoral neck fracture. Fractures were classified using the Garden staging system. Radioisotope uptake in femoral heads was evaluated visually. Of 28 patients with Garden stage I or II, radioactivity of the femoral head was normal in 26, partially reduced in one, and generally reduced in one patient. Twenty-seven patients were treated by closed reduction and multiple pinning, and one patient was treated by bipolar hemiarthroplasty. Of 55 patients with Garden stage III or IV, femoral-head radioactivity was normal in three, partially reduced in seven and generally reduced in 45 patients. Fifty-four patients were treated by bipolar hemiarthroplasty or total hip arthroplasty, and one patient was treated by closed reduction and multiple pinning. In only one of the 83 cases was the operative method changed because of bone scan findings. Isotope uptake of the femoral head after femoral neck fracture generally corresponded with the degree of fracture displacement. Preoperative bone scans appear to have no significant role to play in determining the operative treatment method for femoral neck fracture.

Multiple switching fields and domain wall pinning in single Co nanowires

We have measured the low temperature magnetoresistance (MR) of ferromagnetic cobalt nanowires of 30 nm thickness and widths between 32 and 700 nm. The wires are in situ capped with a 2 nm Pt layer to prevent oxidation. Single wires exhibit sharp resistance peaks at the coercive fields Hc—where Hc increases with decreasing wire width—which can be completely understood in terms of an in-plane switching process. Adding 2 × 2 µm2 nucleation pads at the wire ends clearly reduces the coercive fields of the wires. By fabricating wires with two different widths a two-step switching process can be achieved where the wider nanowire switches first. In this case, a single domain wall is introduced in the constriction between the wider and the narrower part of the wire. The MR can be studied in more detail and with higher accuracy by adding additional voltage leads close to the domain wall. The results are discussed to distinguish between contributions resulting from domain wall magnetoresistance and anisotropic magnetoresistance (AMR).

The Role of Preoperative Bone Scan in Determining the Treatment Method of Femoral Neck Fracture

Purpose: To evaluate the role of a preoperative bone scan in determining the operative treatment method of a femoral neck fracture. Materials and Methods: Between January 2001 and December 2003, 62 out of 257 patients, who underwent a preoperative bone scan after a femoral neck fracture were included. The fractures was classified according to the stage of Garden. The uptake of the Tc-99m methylenediphosphonate () isotope was estimated visually, and categories as -2 (the femoral head activity in the fractured side is general reduction compared with the opposite side), -1 (the activity is partial reduction), 0 (the activity is normal) and 1 (the activity is general increase ). Results: 62 patients, 17 male and 45 female, with a mean age of 67.4 years (range 18 to 93) were investigated. Of the 19 patients with Garden stages I and II 17 were 0, and 1 each were -1 and -2. Eighteen patients were operated on with multiple pinning, and 1 with bipolar hemiarthroplasty. Of the 43 patients with Garden stages III and IV 37 were -2, 4 were -1 and 2 were 0. Thirty-eight patients were operated on with bipolar hemiarthroplasty. Four patients were operated on with total hip arthroplasty. One patient was operated on with multiple pinning. The operative method was changed in only 1 of the 62 patients due to the bone scan finding. Conclusion: The isotope uptake of the preoperative bone scan after a femoral neck fracture generally corresponded with the degree of fracture displacement. Therefore, a preoperative bone scan seems to play no significant role in determining the operative treatment method of a femoral neck fracture.

Physeal Remodeling after Internal Fixation of Slipped Capital Femoral Epiphysis

Purpose: To evaluate physeal remodeling after internal fixation of slipped capital femoral epiphysis, We performed a retrospective review of the medical records and radiographs of 14 children (17 cases) who had had slipped capital femoral epiphysis. Materials and Methods: We reviewed 14 patients who had slipped capital femoral epiphysis. They were divided two groups. Group I were in situ pinning with single screw and group II were corrective osteotomy with multiple pinning. We identified physeal remodeling camparing with their preoperative, postoperative and last follow-up radiographs with measuring physeal-shaft angle. Results: Early closure of the physis was observed in 6 cases among 14 patients (17 hips). Compared with their postoperative radiographs, the last follow up radiographic study revealed that physeal remodeling was observed in 4 patients (4 hips) at group I (mean, ), in 2 patients (3 hips) at group II (mean, ). Conclusion: In this study, physeal remodeling was observed in 4 patients (4 hips) in group I and 2 patients (3 hips) in group II. The incidence of physeal remodeling was related with degree of epiphyseal slippage, and age was not related with physeal remodeling potential.

Factors Predicting Complications After Multiple Pinning of Femoral Neck Fractures

Purpose : To report upon factors predicting complication after multiple pinning of femoral neck fractures, the authors performed a comparative study upon a success group and a failure group and reviewed the literature. Materials and Methods : Among cases of multiple pinning from July 1990 to June 1998, we defined 63 cases as successful that had more than 2 years follow-up and had no complications, and 18 cases as unsuccessful that had complications like avascular necrosis, nonunion and required a secondary operation. We analyzed the two groups from the viewpoints of age, cause of injury, classification of fracture, degree of displacement, degree of osteoporosis, time interval to operation and accuracy of reduction. Results : Statistically significant factors were the degree of displacement by Garden classification (p=0.007), the degree of displacement and anatomical position by AO classification (p=0.005), the time interval to operation after 7 days (p=0.012) and the postoperative accuracy of reduction (p=0.010). However, age, Singh index and the type of internal fixation device did not show statistical significance. Conclusion : Displaced subcapital fracture, time interval to operation after 7 days and reduction accuracy may be prediction of complications.

Complications and Affecting Factors for Intracapsular Femoral Neck Fractures Treated by Multiple Pinning

Complications and Affecting Factors for Intracapsular Femoral Neck Fractures Treated by Multiple Pinning