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

Reasons for non-vaccination in pediatric patients visiting tertiary care centers in a polio-prone country

BACKGROUND: The Expanded Program on Immunization (EPI) was initiated by World Health Organization (WHO) in 1974 in order to save children from life threatening, disabling vaccine-preventable diseases (VPDs). In Pakistan, this program was launched in 1978 with the main objectives of eradicating polio by 2012, eliminating measles and neonatal tetanus by 2015, and minimizing the incidence of other VPDs. However, despite the efforts of government and WHO, this program has not received the amount of success that was desired. Hence, the objectives of this study were to elucidate the main reasons behind not achieving the full immunization coverage in Pakistan, the awareness of children’s attendant about the importance of vaccination, their attitudes, thoughts and fears regarding childhood immunization, and the major hurdles faced in pursuit of getting their children vaccinated. METHODS: This was an observational, cross-sectional, questionnaire-based study conducted during a one year period from 4th January, 2012 to 6th January, 2013 at the pediatric outpatient clinics of Civil Hospital (CHK) and National Institute of Child Health (NICH). We attempted to interview all the parents who could be approached during the period of the study. Thus, convenience sampling was employed. The parents were approached in the clinics and interviewed after seeking informed, written consent. Those patients who were not accompanied by either of their parents were excluded from the study. The study instrument comprised of three sections. The first section consisted was concerned with the demographics of the patient and the parents. The second section dealt with the reasons for complete vaccination or under-vaccination. The last section aimed to assess the knowledge, attitudes and beliefs of the respondents. RESULTS: Out of 1044 patients, only 713(68.3%) were fully vaccinated, 239(22.9%) were partially vaccinated while 92(8.8%) had never been vaccinated. The vaccination status showed statistically significant association with ethnicity, income, residence, number of children and paternal occupation (p < 0.05 for all). The most common provocative factor for vaccination compliance was mass media (61.9%). The most common primary reason for non-vaccination was lack of knowledge (18.1%), whereas the most common secondary reason for non-vaccination was religious taboos (31.4%). Majority of the respondents demonstrated poor knowledge of EPI schedules or VPDs. However, most believed that there was a need for more active government/NGO involvement in this area. CONCLUSION: The most common primary reason for non-vaccination, i.e. lack of knowledge, and the most common secondary reason, i.e. religious taboos, imply that there is dire need to promote awareness among the masses in collaboration with NGOs, and major religious and social organizations

Uptake of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) by river water fish:the case of River Chenab

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in eleven edible fish species (5 herbivorous and 6 carnivorous) collected from the River Chenab, Pakistan, during 2007–2009. Total OCP and PCB concentrations (ng g− 1 wet weight, ww) ranged between 13–107 (mean: 38) and 3.1–93.7 (mean: 20) for five herbivorous fish species and 21.6–365 (mean: 148) and 2.5–108 (mean: 30) for six carnivorous species, respectively. The trends of detected organochlorine pesticides (OCPs) in fish samples were: DDTs > PCBs > chlordanes > HCHs. The mean concentration(s) (ng g− 1 ww) of OCPs were relatively higher in all fish species collected near industrial areas followed by urban and agricultural areas. Risk assessment of OCPs and PCBs indicated that fish intake may pose health risk to humans with a consumption rate of > 8 g/person/day. The hazardous ratios for the 50th and 95th percentile data of OCPs and PCBs in fish exceeded the value of 1, suggesting that the daily exposure to OCPs and PCBs yield a lifetime cancer risk greater than 1 in 10,000