19 research outputs found
Clinical and Radiographic Outcomes of Oblique Lumbar Interbody Fusion at 1 Year: A Preliminary Report of a Single Institution Experience
Get PDFObjective Oblique lumbar interbody fusion (OLIF) is a minimally invasive surgical technique that is becoming popular due to lowering the risk of lumbar plexus injuries compared to other transpsoas fusion techniques while yielding comparable clinical outcomes. We evaluated the 1-year clinical and radiologic outcomes of OLIF performed in a single institution of Korea. Methods We retrospectively reviewed patients who underwent OLIF for degenerative lumbar spinal disease at our institution between July 2015 and December 2018. Patients with a follow-up period of longer than 1 year were included. Among 36 patients, 22 patients (9 male, 13 female) and 26 surgical levels were analyzed. The patients’ demographic data, surgical procedures, clinical outcomes and complications were reviewed. Results The patients’ mean age was 64 years (range 44-78). Spinal stenosis was the most common pathology. In all cases, the demineralized bone matrix was used for fusion. The disc height and sagittal angle of the index level showed statistically significant increases at the 1-year follow-up (3.5 mm, p<0.001; 5°, p=0.02, respectively), but the foraminal height did not. The 1-year fusion rate was 69.6%. Good clinical outcomes, as evaluated by visual analogue scale pain scores, Oswestry disability index, EQ-5D-3L index and EQ-VAS, were observed throughout the 1-year follow-up period. No serious complications were observed. Conclusion OLIF appears to be a suitable and safe surgical option for treating degenerative lumbar spinal disease. It showed good clinical outcomes in the short-term follow-up. However, close-long term observations would be necessary since the fusion rates were unsatisfactory
Power Diagrams and Sparse Paged Grids for High Resolution Adaptive Liquids
Get PDF© ACM, 2017. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in Aanjaneya, M., Gao, M., Liu, H., Batty, C., & Sifakis, E. (2017). Power Diagrams and Sparse Paged Grids for High Resolution Adaptive Liquids. ACM Trans. Graph., 36(4), 140:1–140:12. https://doi.org/10.1145/3072959.3073625We present an efficient and scalable octree-inspired fluid simulation framework with the flexibility to leverage adaptivity in any part of the computational domain, even when resolution transitions reach the free surface. Our methodology ensures symmetry, definiteness and second order accuracy of the discrete Poisson operator, and eliminates numerical and visual artifacts of prior octree schemes. This is achieved by adapting the operators acting on the octree's simulation variables to reflect the structure and connectivity of a power diagram, which recovers primal-dual mesh orthogonality and eliminates problematic T-junction configurations. We show how such operators can be efficiently implemented using a pyramid of sparsely populated uniform grids, enhancing the regularity of operations and facilitating parallelization. A novel scheme is proposed for encoding the topology of the power diagram in the neighborhood of each octree cell, allowing us to locally reconstruct it on the fly via a lookup table, rather than resorting to costly explicit meshing. The pressure Poisson equation is solved via a highly efficient, matrix-free multigrid preconditioner for Conjugate Gradient, adapted to the power diagram discretization. We use another sparsely populated uniform grid for high resolution interface tracking with a narrow band level set representation. Using the recently introduced SPGrid data structure, sparse uniform grids in both the power diagram discretization and our narrow band level set can be compactly stored and efficiently updated via streaming operations. Additionally, we present enhancements to adaptive level set advection, velocity extrapolation, and the fast marching method for redistancing. Our overall framework gracefully accommodates the task of dynamically adapting the octree topology during simulation. We demonstrate end-to-end simulations of complex adaptive flows in irregularly shaped domains, with tens of millions of degrees of freedom.National Science FoundationNational Sciences and Engineering Research Council of Canad
