Search Results (11)

Background: Fibrous dysplasia (FD) is a rare condition in which normal spongy and cortical bone is replaced by non-neoplastic fibrous tissue, leading to weakened bone matrix and increased risk of pathological fractures and deformities. Treating these deformities poses a significant challenge for surgeons. While various cases of surgical stabilization and limb lengthening using intramedullary nails have been reported, there is limited evidence on the use of Motorized Intramedullary Limb-Lengthening Nails (MILLNs) in FD patients. This case report presents the clinical history of a patient with FD who underwent multiple surgical interventions to address severe lower limb length discrepancy (LLD) and angular deformity caused by multiple fractures. Case presentation: A sixteen-year-old Caucasian girl with polyostotic FD developed a severe post-traumatic LLD of 10 cm on the right side, associated with coxa vara, valgus knee, and patellar instability. The deformity of the proximal femur was addressed with a valgus and derotational femoral osteotomy. However, this procedure exacerbated the knee’s valgus deformity and only partially corrected the LLD, leading to the decision to proceed with femoral lengthening. A retrograde magnetic intramedullary nail (PRECICE, NuVasive) was utilized for this purpose. Approximately three months postoperatively, radiographs revealed the loosening of the proximal anchoring screw, while the nail had reached maximum distraction. We then proposed reactivating the previously implanted nail. Nine months after the final surgery, standing long-leg radiographs showed a residual shortening of 1 cm, with excellent healing at the fracture sites and the nail and screws remaining securely in place. The patient was monitored regularly, with the latest follow-up occurring four years and five months after the conclusion of the last lengthening procedure. Conclusions: This case report describes the reactivation of a MILLN in a patient with polyostotic fibrous dysplasia. While nail reactivation has been previously described in the literature, to our knowledge, it has not been reported for treating complications arising from FD. In cases of mechanical complications, this approach can equalize leg length discrepancies and correct deformities, avoiding additional invasive surgeries and reducing healthcare costs. As this is an off-label treatment, preoperative consent from both the patient and the parents is required. Full article

Iron microparticles were coated with polypyrrole in situ during the chemical oxidation of pyrrole with ammonium peroxydisulfate in aqueous medium. A series of hybrid organic/inorganic core–shell materials were prepared with 30–76 wt% iron content. Polypyrrole coating was revealed by scanning electron microscopy, and its molecular structure and completeness were proved by FTIR and Raman spectroscopies. The composites of polypyrrole/carbonyl iron were obtained as powders and characterized with respect to their electrical properties. Their resistivity was monitored by the four-point van der Pauw method under 0.01–10 MPa pressure. In an apparent paradox, the resistivity of composites increased from the units Ω cm for neat polypyrrole to thousands Ω cm for the highest iron content despite the high conductivity of iron. This means that composite conductivity is controlled by the electrical properties of the polypyrrole matrix. The change of sample size during the compression was also recorded and provides a parameter reflecting the mechanical properties of composites. In addition to conductivity, the composites displayed magnetic properties afforded by the presence of iron. The study also illustrates the feasibility of the polypyrrole coating on macroscopic objects, demonstrated by an iron nail, and offers potential application in the corrosion protection of iron. The differences in the morphology of micro- and macroscopic polypyrrole objects are described. Full article

During continuous slab casting, strand electromagnetic stirring (S-EMS) has a significant effect on improving the slab quality. In the current work, a numerical model based on the practical slab continuous casting machine and coupled electromagnetic field, flow field, solidification, and solute transport was established to investigate and evaluate the effect of the S-EMS installation position with various current intensities on metallurgical behavior. The model was verified by magnetic field measurement, infrared camera, and nail shooting experiments. The results show that moving the S-EMS installation position to the solidification end reduces the stirring effect due to the skin effect and the increasing thickness of the slab shell. A higher installation position is beneficial for improving the equiaxed grain rate, while a lower one is beneficial for reducing carbon segregation. The maximum segregation index and range decrease from 1.26 to 1.2 and from 0.42 to 0.36 with the installation position being decreased from −3 m to −12.8 m, respectively. The industrial trials show that S-EMS installed at 3 m has a significant effect on expanding the equiaxed grain zone and a deteriorating effect on reducing carbon segregation. Full article

The objective of this study was to determine the efficacy of the PRECICE 2^® nail in the treatment of lower limb length discrepancy in patients with a history of bone tumors. This study reports on outcomes, complications, and the safety of the PRECICE 2 limb lengthening nail in a cohort of pediatric patients with limb length discrepancy after surgery for bone tumors. Seventeen patients were treated with intramedullary magnetic nails. The average patient age at the time of surgery was 19 (range 11–32). The PRECICE 2 nail was used on 14 femurs (6 retrograde and 8 anterograde) and 3 tibias. The average consolidation time was 141 days (range 50–360) with a mean CI of 31 ± 12 days/cm. The ASAMI bone score showed 14 (82%) excellent results, 1 (6%) good result, and 2 (12%) poor results. The ASAMI functional score showed 13 (84.6%) excellent results, 3 (11.5%) good results, and 1 (3.8%) fair result. Patients treated with chemotherapy for bone cancer did not show any increase in distraction time or consolidation time. A total of 3 (17%) problems, 1 obstacle (5.5%), and 1 complication (5.5%) were encountered in our case series. The PRECICE 2 nail allows for effective and accurate lengthening preserving the range of motion in patients treated for bone tumors. Full article

In this study, a funnel mold (FM) model of a multi-mode electromagnetic braking (EMBr) device was developed, and the magnetic flux density at different currents was obtained by MAXWELL software. By using the magnetohydrodynamics (MHD) module of FLUENT software, the volume of fluid binomial flow turbulence model and the EMBr mathematical model of the steel/slag flow field were coupled, and the characteristics of the molten steel flow and the liquid-level fluctuation in the 1520 mm × 90 mm FM with the casting speed of 6 m/min were calculated under the effect of the electromagnetic field. The FM liquid-level characteristic information under production conditions was obtained in a nail board industrial experiment and compared with the magnetic-fluid coupling model. The results show that the EMBr can significantly change the flow behavior of molten steel. When the magnetic pole current is not less than 800-600 A, the maximum liquid-level fluctuation height decreases from 18 mm without EMBr to less than 5 mm, and the liquid-level cannot easily entrap slag. Considering the EMBr effect and production cost, the reasonable magnetic pole current should be 800-600 A. The reliability of numerical simulation was also verified by the industrial test results of the nail board. Full article

The structural, electrical, and magneto-elastic properties of lanthanide base nitride (Ln = Dy-Lu) anti-perovskites were investigated using density functional theory (DFT). The reported structural outcomes are consistent with the experiment and decrease from Dy to Lu due to the decrease ofatomic radii of Ln atoms. According to the electronic band profile, the metallic characteristics of these compounds are due to the crossing over of Ln-f states at the Fermi level and are also supported by electrical resistivity. The resistivity of these compounds at room temperature demonstrates that they are good conductors. Their mechanical stability, anisotropic, load-bearing, and malleable nature are demonstrated by their elastic properties. Due to their metallic and load-bearing nature, in addition to their ductility, these materials are suitable as active biomaterials, especially when significant acting loads are anticipated, such as those experienced by such heavily loaded implants as hip and knee endo-prostheses, plates, screws, nails, dental implants, etc. In thesecases, appropriate bending fatigue strength is required in structural materials for skeletal reconstruction. Magnetic properties show that all compounds are G-type anti-ferromagnetic, with the Neel temperatures ranging from 24 to 48 K, except Lu₃Nin, which is non-magnetic. Due to their anti-ferromagnetic structure, magnetic probes cannot read data contained in anti-ferromagnetic moments, therefore, data will be unchanged by disrupted magnetic field. As a result, these compounds can be the best candidates for magnetic cloaking devices. Full article

Limb lengthening has not been widely employed in the elderly population due to concerns that outcomes will be inferior. The purpose of this multicenter, retrospective case-control series was to report the bone healing outcomes and complications of lower limb lengthening in older patients (≥60 years) using magnetic intramedullary lengthening nail (MILN). Our hypothesis was that healing parameters including consolidation days, the consolidation index, maturation days, and the maturation index, as well as the number of adverse events reported in the older population, would be no different to those of the general adult population. We retrospectively reviewed charts and radiographs from patients ≥60 years of age with limb-length discrepancies who underwent femoral or tibial lengthening using a MILN. Parameters were compared among the age categories “≤19 years,” “20–39 years,” “40–59 years,” or “≥60 years” and propensity-matched cohorts for the age groups 20–59 years and ≥60 years. Complications were reported as percentages for each age category. In the study period, 354 MILN were placed in 257 patients. Sixteen nails were placed in patients 60 years of age or older (mean 65 ± 5 years; range 60–72 years). Comparisons of healing parameters showed no difference between those aged 60+ and the younger cohort. Complication percentages were not statistically significant (p = 0.816). Limb lengthening with MILN may therefore be considered a safe and feasible option for a generally healthy elderly population. Full article

For automobile radar systems, the antenna array requires a low sidelobe level (SLL) to reduce interference. A low-SLL and low-cost planar antenna array are proposed in this article for millimeter-wave automotive radar applications. The proposed array consists of six linear series-fed patch arrays, a series distribution network using a grounded co-planar waveguide (GCPW), and a bed of nails. First, a hybrid HFSS-MATLAB optimization platform is set up to easily obtain good impedance matching and low SLL of the linear series-fed patch array. Then, a six-way GCPW power divider is designed to combine the optimized linear sub-array to achieve a planar array. However, since CCPW is a semi-open structure, like a microstrip line, the parasitic radiation generated by the GCPW feeding network will lead to the deterioration of the SLL. To solve this problem, a bed of nails—as an artificial magnetic conductor (AMC)—is designed and placed above the feeding networking to create an electromagnetic stopband in the working band. Its working mechanism has been explained in detail. The feeding network cannot effectively radiate electromagnetic waves into free space. Thus, the parasitic radiation can be suppressed. A low-SLL planar array prototype working at 79 GHz is designed, manufactured, and measured. The measured results confirm that the proposed low-SLL planar array has a −10 dB impedance bandwidth of 3 GHz from 77 to 80 GHz and a maximum peak gain of 21 dBi. The measured SLL is −24 dB and −23 dB in the E-plane and H-plane at 79 GHz, respectively. The proposed low SLL array can be used for adaptive cruise control (ACC) system applications. Full article

The aim of this study is to evaluate the course of the treatment and clinical and functional outcomes of femur lengthening in adolescents with congenital disorders by the application of different surgical methods. This retrospective study comprised 35 patients (39 procedures). A total of 11 patients underwent femur lengthening with the use of the intramedullary magnetic nail (IMN) Precise 2 (NuVasive, San Diego, CA, USA), 7 patients (11 procedures) with the use of the monolateral external distractor Modular Rail System (MRS) (Smith and Nephew, Memphis, TN, USA), and 17 with the use of the computer-assisted external fixator Taylor Spatial Frame (TSF) (Smith and Nephew, Memphis, TN, USA). The inclusion criteria were as follows: (1) congenital femoral length deficiency without any axial deformities and (2), independently of the finally applied treatment, the technical possibility of use of each of the analyzed methods. The distraction index did not differ significantly between the groups (p = 0.89). The median lengthening index was the lowest in the IMN group (24.3 d/cm; IQR 21.8–33.1) and statistically different in comparison to the MRS (44.2 d/cm; IQR 42–50.9; p < 0.001) and the TSF groups (48.4 d/cm; IQR 38.6–63.5; p < 0.001). Similarly, the consolidation index in the IMN group (12.9 d/cm; IQR 10.7–21.3) was statistically lower than that in the MRS (32.9 d/cm; IQR 30.2–37.6; p < 0.001) and the TSF (36.9 d/cm; IQR 26.6–51.5; p < 0.001) groups. This study indicates that IMN is a more valuable method of treatment for femoral length discrepancy without axial deformity than MRS and TSF in complication rate and indexes of lengthening and consolidation. Full article

The preferred surgical fixation of forearm shaft fractures in children is Elastic Stable Intramedullary Nailing (ESIN). Due to known disadvantageous effects of metal implants, a new surgical method using biodegradable polylactide-co-glycolide (PLGA) intramedullary nails has been developed but its long-term outcomes are unclear. The aim of this study was to compare the long-term outcomes of Biodegradable Intramedullary Nailing (BIN) to ESIN and assess the biodegradation of the study implants via magnetic resonance imaging (MRI). The study population of the prospective, randomized trial consisted of paediatric patients whose forearm shaft fractures were treated with BIN (n = 19) or ESIN (n = 16). Forearm rotation at minimally four years’ follow-up was the main outcome. There was no clinically significant difference in the recovery of the patients treated with the BIN as compared to those treated with the ESIN. More than half of the implants (57.7%, n = 15/26) were completely degraded, and the rest were degraded almost completely. The PLGA intramedullary nails used in the treatment of forearm shaft fractures in this study resulted in good function and anatomy. No unexpected disadvantages were found in the degradation of the implants. However, two implant failures had occurred in three months postoperatively. Full article

A new cost-efficient, low-loss Ka-band diplexer designed in inverted microstrip gap waveguide technology is presented in this paper. Gap waveguide allows to propagate quasi-TEM modes in the air between two metal plates without the need for contact between them by using periodic metasurfaces. The diplexer is realized by using a bed of nails as AMC (Artificial Magnetic Conductor), first modeled with a PMC (Perfect Magnetic Conductor) surface for design simplification, and two fifth order end-coupled passband filters (BPFs) along with a power divider. The experimental verification confirms that the two channels centered at 24 GHz and 28 GHz with 1 GHz of bandwidth show measured insertion losses of 1.5 dB and 2 dB and 60 dB of isolation between them. A slight shift in frequency is observed in the measurements that can be easily explained by the variation in the permittivity of the substrate. Full article