Gunti Ranga Srinivas

Long-Term Effects of Segmental Lumbar Spinal Fusion on Adjacent Healthy Discs: A Finite Element Study.

Study Design Experimental study. Purpose The aim of the study was to develop a finite element (FE) model to study the long-term effects of various types of lumbar spinal interventions on the discs adjacent to the fused segment. Overview of Literature Earlier FE studies have been limited to one particular type of fusion and comparative quantification of the adjacent disc stresses for different types of surgical interventions has not been reported. Methods A computer aided engineering (CAE) based approach using implicit FE analysis assessed the stresses in the lumbar discs adjacent to the fused segment following anterior and posterior lumbar spine fusions at one, two and three levels (with and without instrumentation). Results It was found that instrumentation and length of fusion were the most significant factors in increasing adjacent level stresses in the lumbar discs. Conclusions In the present study, a calibrated FE model that examined spinal interventions under similar loading and boundary conditions was used to provide quantitative data which would be useful for clinicians to understand the probable long-term effect of their choice of surgical intervention.

Adjacent Disc Stress Following Floating Lumbar Spine Fusion: A Finite Element Study

Study Design Experimental study. Purpose The study aimed to develop a finite element (FE) model to determine the stress on the discs adjacent to the fused segment following different types of floating lumbar spinal fusions. Overview of Literature The quantification of the adjacent disc stress following different types of floating lumbar fusions has not been reported. The magnitude of the stress on the discs above and below the floating fusion remains unknown. Methods A computer-aided engineering-based approach using implicit FE analysis was employed to assess the stress on the lumbar discs above and below the floating fusion segment (L4–L5) following anterior and posterior lumbar spine fusions at one, two, and three levels (with and without instrumentation). Results Both discs suprajacent and infrajacent to the floating fusion experienced increased stress, but the suprajacent disc experienced relatively high stress level. Instrumentation increased the stress on the discs suprajacent and infrajacent to the floating fusion, but the magnitude of stress on the suprajacent disc remained relatively high. Conclusions The FE model was employed under similar loading and boundary conditions to provide quantitative data, which will be useful for clinicians to understand the probable long-term effects of floating fusions.

Large Cystic Renal Cell Carcinoma Leading to Diagnostic Dilemma: A Case Report

Large cystic renal tumours can be confused with hepatic lesions even on crosssectional imaging. Careful clinical, sonographic and imaging analysis is needed for establishing correct diagnosis. We report a case of papillary cystic renal carcinoma in a 60 year old man, which was confused with amoebic liver abcess and was initially drained. Subsequent recurrence of symptoms prompted us to re-evaluate the case and repeat sonography confirmed the extrahepatic origin of mass based on simple observation that the liver and mass were moving separately on inspiration. Later guided aspiration from solid component of the mass confirmed the diagnosis as renal cell carcinoma. He was successfully treated with radical nephrectomy with uneventful post-operative recovery.

Experimental and Numerical Modeling of Hemp–Polyester Composites

In this study, hemp–polyester composites were prepared with two volume fraction of hemp fibers and characterization for tensile properties. The mechanical characterization provided the quantitative insights into the elasto-plastic behavior of hemp–polyester composites. Young’s modulus, yield strength, ultimate tensile strength and failure strain were obtained by testing the specimens in a uniaxial testing machine. Tensile strength and modulus of the composites were superior in the composites with higher volume fraction of hemp. The numerical modeling was then performed to simulate the constitutive behavior through out nonlinear range of hemp–polyester composite and study the effect of volume fraction of fibers/matrix on mechanical properties. Finite element model calibration was done to establish the validity of the modeling procedures and accuracy of prediction by comparing the numerical results with experimentally determined results. Understanding the elasto-plastic behavior through experimental and numerical simulations is considered to be a more viable tool for analyzing products made of hemp–polyester composites for possible use in automotive and other industrial applications in advanced simulations.