Circumferential Fusion through All-Posterior Approach in Andersson Lesion

Sreekanth Reddy Rajoli,Rishi Mugesh Kanna,Siddharth N. Aiyer,Ajoy Prasad Shetty,Shanmuganathan Rajasekaran 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.3

Study Design: Retrospective case series. Purpose: To assess safety and efficacy of single stage, posterior stabilisation and anterior cage reconstruction through the transforaminal or lateral extra-cavitary route for Andersson lesions. Overview of Literature: Pseudoarthrosis in ankylosing spondylitis (Andersson lesion, AL) can cause progressive kyphosis and neurological deficit. Management involves early recognition and surgical stabilisation in patients with instability. However, the need and safety of anterior reconstruction of the vertebral body defect remains unclear. Methods: Twenty consecutive patients with AL whom presented with instability back pain and or neurological deficit were managed by single stage posterior approach with long segment pedicle screw fixation and anterior vertebral reconstruction. Radiological evaluation included- the regional kyphotic angle, measurement of anterior defect in computed tomography (CT) scan and the spinal cord status in magnetic resonance imaging. Radiological outcomes were assessed for fusion and kyphosis correction. Functional outcomes were assessed with visual analogue scale (VAS), ankylosing spondylitis quality of life (ASQoL) and Oswestry disability index (ODI). Results: The mean age of the patients was 50.1 years (male, 18; female, 2). The levels affected include thoracolumbar (n=12), lower thoracic (n=5) and lumbar (n=3) regions. The mean level of fixation was 6.2±2.4 vertebrae. The mean anterior column defect was 1.6±0.6 cm. The mean surgical duration, blood loss and hospital stay were 112 minutes, 452 mL and 6.2 days, respectively. The mean followup was 2.1 years. At final follow up, VAS for back pain improved from 8.2 to 2.4 while ODI improved from 62.7 to 18.5 (p <0.05) and ASQoL improved from 14.3±2.08 to 7.90±1.48 (p <0.05). All patients had achieved radiological union at a mean 7.2±4.6 months. The mean regional kyphotic angle was 27° preoperatively, 16.7° postoperatively and 18.1° at the final follow-up. Conclusions: Posterior stabilisation and anterior reconstruction with cage through an all-posterior approach is safe and can achieve good results in Andersson lesions.

Analysis of electrical behavior in LDPE/BaTiO3 ceramic filler nanocomposites for electrical cable insulation applications

N. Rajasekaran,C. Muniraj,T. Venkatesan,A. Kumaravel 한양대학교 청정에너지연구소 2024 Journal of Ceramic Processing Research Vol.25 No.1

Nanocomposites (LDPE + BaTiO3 ceramic) with different volume ratio of 0%, 1%, 3% and 5% were prepared by melt mixingmethod. Scanning Electron microscopy (SEM) results for nanocomposites materials shows that the nanofiller particle disperseduniformly throughout the entire surface and there is no agglomeration of nanoparticles. BaTiO3 ceramic nanoparticle structureand crystallite size were investigated using X-ray diffraction (XRD) studies. Using energy-dispersive X-ray spectroscopy (EDS),the chemical composition of the composite material has been determined. EDS can have determined the types of elementspresent in the sample and their relative concentrations. To assess the behavior of nanocomposites, experimental test wasconducted to predict the electrical parameters such as dielectric breakdown strength, DC volume resistivity, dielectric constantand Dissipation factor. The dielectric strength was estimated using a feed forward neural network (FFNN) and ArtificialNeural Network and Fuzzy Inference system (ANFIS) technique under various conditions and filler percentages. From the testresults, it was observed that nanocomposites with 3% wt has the highest dielectric strength. In Weibull analysis, feed forwardneural network (FFNN) and Artificial Neural Network and Fuzzy Inference system (ANFIS) predicted that with the inclusionof nanofiller, the electrical breakdown strength of nanocomposite materials was increased. The results show that, dielectricpermittivity and dissipation factor (tan delta) of the nanocomposites materials decreased and increased correspondingly withincrease in frequency. Further increase in mixing proportion of nanocomposites, it was found that the inter particle distanceis decreased due to that the mobility of charge carrier is increased and the material loses its dielectric property. From theexperimental test results, it was found that LDPE/BaTiO3 ceramic filler nanocomposites materials with 3% wt have betterelectrical properties compared to neat LDPE.

Synthesis and Spectral Characterization of Antifungal Sensitive Schiff Base Transition Metal Complexes

N. Raman,A. Sakthivel,K. Rajasekaran The Korean Society of Mycology 2007 Mycobiology Vol.35 No.3

Optimal lay-up of hybrid composite beams, plates and shells using cellular genetic algorithm

N.S. Poornima,S. Rajasekaran,K. Nalinaa,S. Greeshma,V. Vinoop Kumar 국제구조공학회 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.16 No.5

Solution method for the classical beam theory using differential quadrature

Rajasekaran, S.,Gimena, L.,Gonzaga, P.,Gimena, F.N. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.6

In this paper, a unified solution method is presented for the classical beam theory. In Strength of Materials approach, the geometry, material properties and load system are known and related with the unknowns of forces, moments, slopes and deformations by applying a classical differential analysis in addition to equilibrium, constitutive, and kinematic laws. All these relations are expressed in a unified formulation for the classical beam theory. In the special case of simple beams, a system of four linear ordinary differential equations of first order represents the general mechanical behaviour of a straight beam. These equations are solved using the numerical differential quadrature method (DQM). The application of DQM has the advantages of mathematical consistency and conceptual simplicity. The numerical procedure is simple and gives clear understanding. This systematic way of obtaining influence line, bending moment, shear force diagrams and deformed shape for the beams with geometric and load discontinuities has been discussed in this paper. Buckling loads and natural frequencies of any beam prismatic or non-prismatic with any type of support conditions can be evaluated with ease.

Optimal lay-up of hybrid composite beams, plates and shells using cellular genetic algorithm

Rajasekaran, S.,Nalinaa, K.,Greeshma, S.,Poornima, N.S.,Kumar, V. Vinoop Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.16 No.5

Laminated composite structures find wide range of applications in many branches of technology. They are much suited for weight sensitive structures (like aircraft) where thinner and lighter members made of advanced fiber reinforced composite materials are used. The orientations of fiber direction in layers and number of layers and the thickness of the layers as well as material of composites play a major role in determining the strength and stiffness. Thus the basic design problem is to determine the optimum stacking sequence in terms of laminate thickness, material and fiber orientation. In this paper, a new optimization technique called Cellular Automata (CA) has been combined with Genetic Algorithm (GA) to develop a different search and optimization algorithm, known as Cellular Genetic Algorithm (CGA), which considers the laminate thickness, angle of fiber orientation and the fiber material as discrete variables. This CGA has been successfully applied to obtain the optimal fiber orientation, thickness and material lay-up for multi-layered composite hybrid beams plates and shells subjected to static buckling and dynamic constraints.

Congenital Osseous Anomalies of the Cervical Spine: Occurrence, Morphological Characteristics, Embryological Basis and Clinical Significance: A Computed Tomography Based Study

N. V. Ankith, M,M. Avinash,K. S. Srivijayanand,Ajoy Prasad Shetty,Rishi Mugesh Kanna,Shanmuganathan Rajasekaran 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.4

Study Design: Observational retrospective computed tomography (CT) based study. Purpose: To analyze the congenital anomalies of the cervical spine, their morphological variations and their clinical significance. Overview of Literature: Studies published to date have focused mainly on upper cervical anomalies; no study has comprehensively reported on anomalies of both the occipitocervical and subaxial cervical spine. Methods: Nine hundred and thirty cervical spine CT scans performed in Ganga Hospital, Coimbatore, India between January 2014 and November 2017 were screened by two independent observers to document anomalies of both the upper and lower cervical spine. CT scans conducted for infection, tumor, and/or deformity were excluded. Different morphological variations, embryological basis, and clinical significance of the anomalies were discussed. Results: Of the 930 CT scans screened, 308 (33.1%) had congenital anomaly. Of these, 184 (59.7%) were males and 124 (40.2.7%) were females, with a mean age of 44.2 years (range, 14–78 years). A total of 377 anomalies were identified, with 69 cases (7.4%) having more than one anomaly. Two hundred and fifty (26.8%) anomalies of the upper cervical region (occiput to C2–C3 disk space) were identified, with the most common upper cervical anomalies being high-riding vertebral artery (108 cases, 11.6%) and ponticulus posticus (PP) (75 cases, 8%). One hundred and twenty seven (13.6%) anomalies of the lower cervical spine (C3–C7) were noted, of which double foramen transversarium was the most common anomaly observed in 46 cases (4.8%). Conclusions: We found that 33.1% of CT scans had at least one congenital anomaly. Some anomalies, such as abnormal facet complex and arch anomalies, have to be differentiated from fractures in a trauma patient. Other anomalies, like PP, have to be looked for during preoperative planning to avoid complications during surgery. Therefore, knowledge of these anomalies is important as different anomalies have different clinical courses and management.

Solution method for the classical beam theory using differential quadrature

S. Rajasekaran,L. Gimena,P. Gonzaga,F.N. Gimena 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.6

In this paper, a unified solution method is presented for the classical beam theory. In Strength of Materials approach, the geometry, material properties and load system are known and related with the unknowns of forces, moments, slopes and deformations by applying a classical differential analysis in addition to equilibrium, constitutive, and kinematic laws. All these relations are expressed in a unified formulation for the classical beam theory. In the special case of simple beams, a system of four linear ordinary differential equations of first order represents the general mechanical behaviour of a straight beam. These equations are solved using the numerical differential quadrature method (DQM). The application of DQM has the advantages of mathematical consistency and conceptual simplicity. The numerical procedure is simple and gives clear understanding. This systematic way of obtaining influence line, bending moment, shear force diagrams and deformed shape for the beams with geometric and load discontinuities has been discussed in this paper. Buckling loads and natural frequencies of any beam prismatic or non-prismatic with any type of support conditions can be evaluated with ease.

Reciprocal Changes in Sagittal Alignment in Adolescent Idiopathic Scoliosis Patients Following Strategic Pedicle Screw Fixation

Srikanth Reddy Dumpa,Ajoy Prasad Shetty,Siddharth N. Aiyer,Rishi Mugesh Kanna,S Rajasekaran 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.2

Study Design: Retrospective observational study. Purpose: To analyze the effect of low-density (LD) strategic pedicle screw fixation on the correction of coronal and sagittal parameters in adolescent idiopathic scoliosis (AIS) patients. Overview of Literature: LD screw fixation achieves favorable coronal correction, but its effect on sagittal parameters is not well established. AIS is often associated with decreased thoracic kyphosis (TK), and the use of multi-level pedicle screws may result in further flattening of the sagittal profile. Methods: A retrospective analysis was performed on 92 patients with AIS to compare coronal and sagittal parameters preoperatively and at 2-year follow-up. All patients underwent posterior correction via LD strategic pedicle screw fixation. Radiographs were analyzed for primary Cobb angle (PCA), coronal imbalance, cervical sagittal angle (CSA), TK, lumbar lordosis (LL), pelvic incidence, pelvic tilt (PT), sacral slope (SS), C7 plumb line, spino–sacral angle, curve flexibility, and screw density. Results: PCA changed significantly from 57.6°±13.9° to 19°±8.4° (p <0.0001) with 67% correction, where the mean curve flexibility was 41% and screw density was 68%. Regional sagittal parameters did not change significantly, including CSA (from 10.76° to 10.56°, p =0.893), TK (from 24.4° to 22.8°, p =0.145), and LL (from 50.3° to 51.1°, p =0.415). However, subgroup analysis of the hypokyphosis group (<10º) and the hyperkyphosis group (>40º) showed significant correction of TK (p <0.0001 in both). Sacro–pelvic parameters showed a significant decrease of PT and increase of SS, suggesting a reduction in pelvic retroversion SS (from 37° to 40°, p =0.0001) and PT (from 15° to 14°, p =0.025). Conclusions: LD strategic pedicle screw fixation provides favorable coronal correction and improves overall sagittal sacro–pelvic parameters. This technique does not cause significant flattening of TK and results in a favorable restoration of TK in patients with hypokyphosis or hyperkyphosis.

Electrodeposition of Ni-W/Al₂O₃ Nano-Composites and the Influence of Al₂O₃ Incorporation on Mechanical and Corrosion Resistance Behaviours

M. Ramaprakash,R. Nivethida,A. Muthukrishnan,A. Jerom Samraj,M. G. Neelavannan,N. Rajasekaran The Korean Electrochemical Society 2023 Journal of electrochemical science and technology Vol.14 No.4

Ni-W/Al₂O₃ nano-composites were electrodeposited on mild steel substrate for mechanical and corrosion resistance applications. This study focused on the preparation of Ni-W/Al₂O₃ nano-composite coating with various quantity of Al₂O₃ incorporations. The addition of Al₂O₃ in the electrolytes were varied from 1-10 g/L in electrolytes and the Al₂O₃ incorporation in Ni-W/Al₂O₃ nano-composite coatings were obtained from 1.82 to 13.86 wt.%. The incorporation of Al₂O₃ in Ni-W alloy matrix influenced the grain size, surface morphology and structural properties were observed. The distributions of Al₂O₃ particle in alloy matrix were confirmed using electron microscopy (FESEM and TEM) and EDAX mapping analysis. The crystal structure informations were studied using X-ray diffraction method and it confirms that the deposits having cubic crystal structure. The better corrosion rate (0.87 mpy) and microhardness (965 HV) properties were obtained for the Ni-W/Al₂O₃ nano-composite coating with 13.86 wt.% of Al₂O₃ incorporations.