Development of a Computational Approach to Assess Hip Fracture and Repair: Considerations of Intersubject and Surgical Alignment Variability

Hip fracture remains a major public health concern due to the significant number of occurrences and mortality rates. Intertrochanteric fractures are the most common type of fracture and are typically caused by a fall. Intramedullary osteosynthesis is a common surgical practice to repair intertrochanteric fractures, but revisions are often required. The work presented in this thesis aims to improve the realism and fidelity of computational models of hip fracture, which can be an effective alternative to costly and labor-intensive clinical in-vivo and experimental in-vitro testing. Intersubject variability is inherently present in anatomy and material relations. Statistical shape and intensity models can be used to characterize anatomic and material property variability in a training set population and can be used to evaluate subject-specific fracture behavior. While prior computational models of hip fracture have evaluated bone strains to assess fracture risk, the current study advances the state of the art by utilizing a novel technique in the extended finite element method (XFEM) to assess hip fracture and develops a computational approach to evaluate fracture repair. Natural and implanted finite element models were used to predict fracture patterns and evaluate bone-implant load share in subjects with varying geometry and bone quality. A model validation study demonstrated the capability of XFEM in generating unique subject-specific fracture patterns. Femurs generated from a previously published statistical model were fractured to capture the range of patient variability in fracture pattern and load at the onset of fracture. Overall femur size, bone thickness, and bone quality had large effects on load at the onset of fracture. Using one of the average subject models, a study was performed to investigate the effects of surgical alignment, implant material, and loading variability on hip fracture repair. Although, surgical alignment had little effect on load share in the bone-implant construct, mal-alignment caused an increase in peak implant stress and bone strain, which could result in implant failure and delayed fracture healing. Muscles were added to a fracture repair model to capture loading condition variability, which resulted in a more balanced load share between the bone and the implant, indicating the importance of musculoskeletal modeling. These studies included novel techniques for evaluating hip fracture and repair that could be used to aid the surgical community by providing guidance on how implant alignment can promote ideal bone healing conditions

Decomposition of Changes in Poverty Measures: Sectoral and Institutional Considerations for the Poverty Reduction Strategy Paper of Pakistan

Two extremely significant empirical questions on the relationship between growth, distribution and poverty have remained the focus of attention for researchers and academicians. First, how does a change in aggregate poverty reflect intrasectoral gains/losses versus intersectoral shifts in population? Second, how much of an observed change in poverty can be attributed to the changes in the distribution of income, as distinct from growth in average incomes? Standard inequality measures like the Gini coefficient can be misleading in this context. At any rate, the change in an inequality measure can be a poor guide to its quantitative impact on poverty. Ravallion and Huppi (1991) proposed decomposition formulae to throw light on the contributions of sectoral gains and population shifts (on the one hand) and economic growth and changes in inequality (on the other) to aggregate changes in poverty. They found that both population shifts and gains to the urban and rural sectors alleviated aggregate poverty in Indonesia over the 1984–87 period. In addition, they obtained estimates of the relative contributions of growth and greater equity to poverty alleviation in Indonesia. Datt and Ravallion (1992) extended the analysis to study poverty in Brazil and India during the 1980s. Kakwani (1993) explored the relation between economic growth and poverty for Cote d’Ivoire from 1980–85. He developed his own methodology to measure separately the impact of changes in average income and income inequality on poverty. Kakwani (2000) applied the same methodology to analyse changes in poverty in Thailand covering the period from 1988–94. Recently, Contreas (2003) examined the evolution of poverty and inequality in Chile between 1990 and 1996. Using the “Datt-Ravallion decomposition”, he computed that economic growth accounted for over 85 percent of the poverty reduction in Chile.

Fragmentation As Gender Trap: A Feminist Reading Of Selected Dramas By Henrik Ibsen And George Bernard Shaw

Henrik Ibsen dan George Bernard Shaw sering dianggap sebagai individu yang memperjuangkan hak wanita Henrik Ibsen and George Bernard Shaw have often been regarded as advocates of women’s rights

Model Optimasi Perencanaan Investasi Galangan Kapal Dengan Pendekatan Programasi Tujuan Ganda

Optimation model of planning investment dockyard with approach multi objective goal programming. The purpose of this research is to determine decision variable, goal function, alternative priority and achievement function in investment planning. From this optimation component, the model of ship yard investment planning could be achieved. The model of developed model in this research was the optimation of ship yard investment planning using multi objective goal programming approach. The model consist of 5 decision variable, 11 goal function, 2 alternative priority and 11 achievement functions. The model implementation was done toward PT ASSI investment planning. The calculation using from Quantitative System 3.0 was that the quantity of decision variable parameters could be achieved. The first alternative was based on the difference goal priority, and the second alternative based on similiar goal priority

Specimen-Specific Natural, Pathological, and Implanted Knee Mechanics Using Finite Element Modeling

There is an increasing incidence of knee pain and injury among the population, and increasing demand for higher knee function in total knee replacement designs. As a result, clinicians and implant manufacturers are interested in improving patient outcomes, and evaluation of knee mechanics is essential for better diagnosis and repair of knee pathologies. Common knee pathologies include osteoarthritis (degradation of the articulating surfaces), patellofemoral pain, and cruciate ligament injury and/or rupture. The complex behavior of knee motion presents unique challenges in the diagnosis of knee pathology and restoration of healthy knee function. Quantifying knee mechanics is essential for developing successful rehabilitation therapies and surgical treatments. Researchers have used in-vitro and in-vivo experiments to quantify joint kinematics and loading, but experiments can be costly and time-intensive, and contact and ligament mechanics can be difficult to measure directly. Computational modeling can complement experimental studies by providing cost-effective solutions for quantifying joint and soft tissue forces. Musculoskeletal models have been used to measure whole-body motion, and predict joint and muscle forces, but these models can lack detail and accuracy at the joint-level. Finite element modeling provides accurate solutions of the internal stress/strain behavior of bone and soft tissue using subject-specific geometry and complex contact and material representations. While previous FE modeling has been used to simulate injury and repair, models are commonly based on literature description or average knee behavior. The research presented in this dissertation focused on developing subject-specific representations of the TF and PF joints including calibration and validation to experimental data for healthy, pathological, and implanted knee conditions. A combination of in-vitro experiment and modeling was used to compare healthy and cruciate-deficient joint mechanics, and develop subject-specific computational representations. Insight from in-vitro testing supported in-vivo simulations of healthy and implanted subjects, in which PF mechanics were compared between two common patellar component designs and the impact of cruciate ligament variability on joint kinematics and loads was assessed. The suite of computational models developed in this dissertation can be used to investigate knee pathologies to better inform clinicians on the mechanisms surrounding injury, support the diagnosis of at-risk patients, explore rehabilitation and surgical techniques for repair, and support decision-making for new innovative implant designs