BACKGROUND Total hip replacement has become one of the most successful orthopaedic procedures.The length of the femoral stem constitutes one of the most important geometrical and mechanical features of the prosthesis....BACKGROUND Total hip replacement has become one of the most successful orthopaedic procedures.The length of the femoral stem constitutes one of the most important geometrical and mechanical features of the prosthesis.Several different implants are currently available but data are limited concerning the clinical results for some of these implants.AIM To report the short-term clinical and radiological results of a novel squared section,tapered design–with four conicity-short stem in total hip replacement.METHODS This is a retrospective study of a prospectively collected data using of MINIMA?short stem in 61 consecutive patients with at least 1 year follow-up.The collected data included patients’demographics,type of arthritis,bone morphology,perioperative data,clinical results using Harris Hip Score,EuroQol(EQ-5D),pain score and satisfaction rate,complications and radiological results.RESULTS Total 61 patients were included in our study with a mean age of 56 years of age(range 25-73 years).The majority of them(68.6%)were women,thirty seven patients(56.9%)were less than 60 years of age and almost half of patients(45.1%)suffered from secondary osteoarthritis(hip dysplasia,osteonecrosis,etc.).The mean time of follow-up examination was 33.4 mo(2.8 years)with a range of 12-57 months(1-4.8 years).In 35 patients(56.9%)the follow-up examination was more than 3 years.No major complications such as revision,periprosthetic fracture,dislocation or infection were presented.Re-admission 90 d postoperatively or laterwas deemed unnecessary for any reason regarding the operation.Respectively,the mean pain score,mean Harris hip score,and mean EQ-5D were improved from 6.3,58.7 and 77.3 preoperatively to 0.1,95.1,and 79.8 postoperatively.The Satisfaction rate at the final follow-up was 9.9(SD 0.3,range 8.0-10.0).All stems were classified as stable bone ingrowth and no radiolucent lineswere revealed in any of the modified Gruens’zone at the postoperative Xrays.Stem subsidence was within acceptable limits and the incidence of distal cortical hypertrophy was relatively low.CONCLUSION The clinical and radiological results concerning the MINIMA?short stem are excellent according to this first report of this specific design of the short femoral stems.Because of the small number of cases and short-term follow-up of this study,a longer follow up time and more patients’enrollment is required.展开更多
为解决传统人工势场法(APF)进行水面无人艇路径规划时出现局部最小和路径不平滑的问题,对斥力系数进行动态调整并引入逃逸力。为使水面无人艇在动态避碰中按国际海上避碰规则(international regulations for preventing collisions at s...为解决传统人工势场法(APF)进行水面无人艇路径规划时出现局部最小和路径不平滑的问题,对斥力系数进行动态调整并引入逃逸力。为使水面无人艇在动态避碰中按国际海上避碰规则(international regulations for preventing collisions at sea,COLREGS)航行,结合无人艇性能制定了无人艇的避碰规则,并引入转向力。通过Matlab对静态未知障碍物的仿真实验,验证改进APF算法能解决局部最小问题且规划的路径更加安全平滑。通过对动态未知障碍物4种典型局面的仿真实验表明,改进APF算法在复杂环境下也能引导无人艇在符合避碰规则的前提下对多个动态障碍进行安全规避。展开更多
Continuously differentiable radial basis functions (C<sup>∞</sup>-RBFs), while being theoretically exponentially convergent are considered impractical computationally because the coefficient matrices are ...Continuously differentiable radial basis functions (C<sup>∞</sup>-RBFs), while being theoretically exponentially convergent are considered impractical computationally because the coefficient matrices are full and can become very ill- conditioned. Similarly, the Hilbert and Vandermonde have full matrices and become ill-conditioned. The difference between a coefficient matrix generated by C<sup>∞</sup>-RBFs for partial differential or integral equations and Hilbert and Vandermonde systems is that C<sup>∞</sup>-RBFs are very sensitive to small changes in the adjustable parameters. These parameters affect the condition number and solution accuracy. The error terrain has many local and global maxima and minima. To find stable and accurate numerical solutions for full linear equation systems, this study proposes a hybrid combination of block Gaussian elimination (BGE) combined with arbitrary precision arithmetic (APA) to minimize the accumulation of rounding errors. In the future, this algorithm can execute faster using preconditioners and implemented on massively parallel computers.展开更多
文摘BACKGROUND Total hip replacement has become one of the most successful orthopaedic procedures.The length of the femoral stem constitutes one of the most important geometrical and mechanical features of the prosthesis.Several different implants are currently available but data are limited concerning the clinical results for some of these implants.AIM To report the short-term clinical and radiological results of a novel squared section,tapered design–with four conicity-short stem in total hip replacement.METHODS This is a retrospective study of a prospectively collected data using of MINIMA?short stem in 61 consecutive patients with at least 1 year follow-up.The collected data included patients’demographics,type of arthritis,bone morphology,perioperative data,clinical results using Harris Hip Score,EuroQol(EQ-5D),pain score and satisfaction rate,complications and radiological results.RESULTS Total 61 patients were included in our study with a mean age of 56 years of age(range 25-73 years).The majority of them(68.6%)were women,thirty seven patients(56.9%)were less than 60 years of age and almost half of patients(45.1%)suffered from secondary osteoarthritis(hip dysplasia,osteonecrosis,etc.).The mean time of follow-up examination was 33.4 mo(2.8 years)with a range of 12-57 months(1-4.8 years).In 35 patients(56.9%)the follow-up examination was more than 3 years.No major complications such as revision,periprosthetic fracture,dislocation or infection were presented.Re-admission 90 d postoperatively or laterwas deemed unnecessary for any reason regarding the operation.Respectively,the mean pain score,mean Harris hip score,and mean EQ-5D were improved from 6.3,58.7 and 77.3 preoperatively to 0.1,95.1,and 79.8 postoperatively.The Satisfaction rate at the final follow-up was 9.9(SD 0.3,range 8.0-10.0).All stems were classified as stable bone ingrowth and no radiolucent lineswere revealed in any of the modified Gruens’zone at the postoperative Xrays.Stem subsidence was within acceptable limits and the incidence of distal cortical hypertrophy was relatively low.CONCLUSION The clinical and radiological results concerning the MINIMA?short stem are excellent according to this first report of this specific design of the short femoral stems.Because of the small number of cases and short-term follow-up of this study,a longer follow up time and more patients’enrollment is required.
文摘为解决传统人工势场法(APF)进行水面无人艇路径规划时出现局部最小和路径不平滑的问题,对斥力系数进行动态调整并引入逃逸力。为使水面无人艇在动态避碰中按国际海上避碰规则(international regulations for preventing collisions at sea,COLREGS)航行,结合无人艇性能制定了无人艇的避碰规则,并引入转向力。通过Matlab对静态未知障碍物的仿真实验,验证改进APF算法能解决局部最小问题且规划的路径更加安全平滑。通过对动态未知障碍物4种典型局面的仿真实验表明,改进APF算法在复杂环境下也能引导无人艇在符合避碰规则的前提下对多个动态障碍进行安全规避。
文摘Continuously differentiable radial basis functions (C<sup>∞</sup>-RBFs), while being theoretically exponentially convergent are considered impractical computationally because the coefficient matrices are full and can become very ill- conditioned. Similarly, the Hilbert and Vandermonde have full matrices and become ill-conditioned. The difference between a coefficient matrix generated by C<sup>∞</sup>-RBFs for partial differential or integral equations and Hilbert and Vandermonde systems is that C<sup>∞</sup>-RBFs are very sensitive to small changes in the adjustable parameters. These parameters affect the condition number and solution accuracy. The error terrain has many local and global maxima and minima. To find stable and accurate numerical solutions for full linear equation systems, this study proposes a hybrid combination of block Gaussian elimination (BGE) combined with arbitrary precision arithmetic (APA) to minimize the accumulation of rounding errors. In the future, this algorithm can execute faster using preconditioners and implemented on massively parallel computers.
