Comparison and prediction of pullout strength of conical and cylindrical pedicle screws within synthetic bone

<p>Abstract</p> <p>Background</p> <p>This study was designed to derive the theoretical formulae to predict the pullout strength of pedicle screws with an inconstant outer and/or inner diameter distribution (conical screws). For the transpedicular fixation, one of the failure modes is the screw loosening from the vertebral bone. Hence, various kinds of pedicle screws have been evaluated to measure the pullout strength using synthetic and cadaveric bone as specimens. In the literature, the Chapman's formula has been widely proposed to predict the pullout strength of screws with constant outer and inner diameters (cylindrical screws).</p> <p>Methods</p> <p>This study formulated the pullout strength of the conical and cylindrical screws as the functions of material, screw, and surgery factors. The predicted pullout strength of each screw was compared to the experimentally measured data. Synthetic bones were used to standardize the material properties of the specimen and provide observation of the loosening mechanism of the bone/screw construct.</p> <p>Results</p> <p>The predicted data from the new formulae were better correlated with the mean pullout strength of both the cylindrical and conical screws within an average error of 5.0% and <it>R</it>²= 0.93. On the other hand, the average error and <it>R</it>²value of the literature formula were as high as -32.3% and -0.26, respectively.</p> <p>Conclusion</p> <p>The pullout strength of the pedicle screws was the functions of bone strength, screw design, and pilot hole. The close correlation between the measured and predicted pullout strength validated the value of the new formulae, so as avoid repeating experimental tests.</p

Use of Seasonal Influenza Vaccination and Its Associated Factors among Elderly People with Disabilities in Taiwan: A Population-Based Study

Influenza immunization among elderly people with disabilities is a critical public health concern; however, few studies have examined the factors associated with vaccination rates in non-Western societies.By linking the National Disability Registration System and health service claims dataset from the National Health Insurance program, this population-based study investigated the seasonal influenza vaccination rate among elderly people with disabilities in Taiwan (N = 283,172) in 2008. A multivariate logistic regression analysis was conducted to adjust for covariates.Nationally, only 32.7% of Taiwanese elderly people with disabilities received influenza vaccination. The strongest predictor for getting vaccinated among older Taiwanese people with disabilities was their experience of receiving an influenza vaccination in the previous year (adjusted odds ratio [AOR] = 6.80, 95% confidence interval [CI]: 6.67-6.93). Frequent OPD use (AOR = 1.85, 95% CI: 1.81-1.89) and undergoing health examinations in the previous year (AOR = 1.66, 95% CI: 1.62-1.69) also showed a moderate and significant association with receiving an influenza vaccination.Although free influenza vaccination has been provided in Taiwan since 2001, influenza immunization rates among elderly people with disabilities remain low. Policy initiatives are required to address the identified factors for improving influenza immunization rates among elderly people with disabilities

Bone-Derived Modulators That Regulate Brain Function: Emerging Therapeutic Targets for Neurological Disorders

Bone has traditionally been regarded as a structural organ that supports and protects the various organs of the body. Recent studies suggest that bone also acts as an endocrine organ to regulate whole-body metabolism. Particularly, homeostasis of the bone is shown to be necessary for brain development and function. Abnormal bone metabolism is associated with the onset and progression of neurological disorders. Recently, multiple bone-derived modulators have been shown to participate in brain function and neurological disorders, including osteocalcin, lipocalin 2, and osteopontin, as have bone marrow-derived cells such as mesenchymal stem cells, hematopoietic stem cells, and microglia-like cells. This review summarizes current findings regarding the roles of these bone-derived modulators in the brain, and also follows their involvement in the pathogenesis of neurological disorders. The content of this review may aide in the development of promising therapeutic strategies for neurological disorders via targeting bone

Smoking, Alcohol, and Betel Quid and Oral Cancer: A Prospective Cohort Study

We aimed to investigate the association between smoking, alcoholic consumption, and betel quid chewing with oral cancer in a prospective manner. All male patients age ≥18 years who visited our clinic received an oral mucosa inspection. Basic data including personal habits were also obtained. A multivariate logistic regression model was utilized to determine relevant risk factors for developing oral cavity cancer. A total of 10,657 participants were enrolled in this study. Abnormal findings were found in 514 participants (4.8%). Three hundred forty-four participants received biopsy, and 230 patients were proven to have oral cancer. The results of multivariate logistic regression found that those who smoked, consumed alcohol, and chewed betel quid on a regular basis were most likely to develop cancer (odds ratio: 46.87, 95% confidence interval: 31.84–69.00). Therefore, habitual cigarette smokers, alcohol consumers, and betel quid chewers have a higher risk of contracting oral cancer and should receive oral screening regularly so potential oral cancer can be detected as early as possible