Risk Factors for New Vertebral Compression Fracture After Percutaneous Vertebral Augmentation: A Retrospective Study.

BACKGROUND Percutaneous vertebral augmentation is the mainstream treatment of osteoporotic vertebral compression fracture (OVCF). New vertebral compression fracture (NVCF) after percutaneous vertebral augmentation may be an issue that cannot be ignored. Nevertheless, the risk factors for NVCF are still uncertain. This research aimed to study the risk factors for NVCF after percutaneous vertebral augmentation. MATERIAL AND METHODS All patients who underwent percutaneous vertebral augmentation for OVCF from January 2019 to December 2020 were enrolled in the study. These patients were divided into NVCF and control groups according to whether they had NVCF. The covariates including sex, age, BMI, diabetes, hypertension, smoking, alcohol, fracture level, surgical method, cement leakage, cement volume, preoperative anterior vertebral height ratio, and Hounsfield unit (HU) value were reviewed. Univariate and multivariate analyses were performed to identify risk factors. RESULTS A total of 279 patients were included in this study, of which 47 had NVCF after percutaneous vertebral augmentation. Univariate analysis demonstrated that there were significant differences in age (OR=1.040, 95% CI=1.003-1.078, P=0.033), BMI (OR=0.844, 95% CI=0.758-0.939, P=0.002) and HU value (OR=0.945, 95% CI=0.929-0.962, P<0.001) between the 2 groups. Multivariate regression analysis revealed that HU value (OR=0.942, 95% CI=0.924-0.960, P<0.001) were independent risk factor for NVCF after percutaneous vertebral augmentation. CONCLUSIONS Hounsfield unit value was an independent risk factor for new vertebral compression fracture after percutaneous vertebral augmentation, whereas age and BMI were not.

Needs, priorities, and attitudes of individuals with spinal cord injury toward nerve stimulation devices for bladder and bowel function: a survey.

STUDY DESIGN: Survey. OBJECTIVES: To investigate the needs and priorities of people with spinal cord injury for managing neurogenic bladder and bowel function and to determine their willingness to adopt neuromodulation interventions for these functions. METHODS: Anonymous online survey. It was advertised by word-of-mouth by community influencers and social media, and by advertisement in newsletters of advocacy groups. RESULTS: Responses from 370 individuals (27% female, 73% male) were included. Bladder emptying without catheters was the top priority for restoring bladder function, and maintaining fecal continence was the top priority for restoring bowel function. The biggest concerns regarding external stimulation systems were wearing a device with wires connecting to electrodes on the skin and having to don and doff the system daily as needed. The biggest concerns for implanted systems were the chances of experiencing problems with the implant that required a revision surgery or surgical removal of the whole system. Respondents were willing to accept an external (61%) or implanted (41%) device to achieve improved bladder or bowel function. CONCLUSIONS: Bladder and bowel dysfunction remain important unmet challenges for individuals living with SCI who answered our survey. These individuals are willing to accept some potential risks of nerve stimulation approaches given potential benefits. Additional consumer input is critical for guiding both research and translation to clinical use and personalized medicine.

Continuous-time causal mediation analysis.

While causal mediation analysis has seen considerable recent development for a single measured mediator (M) and final outcome (Y), less attention has been given to repeatedly measured M and Y. Previous methods have typically involved discrete-time models that limit inference to the particular measurement times used and do not recognize the continuous nature of the mediation process over time. To overcome such limitations, we present a new continuous-time approach to causal mediation analysis that uses a differential equations model in a potential outcomes framework to describe the causal relationships among model variables over time. A connection between the differential equation models and standard repeated measures models is made to provide convenient model formulation and fitting. A continuous-time extension of the sequential ignorability assumption allows for identifiable natural direct and indirect effects as functions of time, with estimation based on a two-step approach to model fitting in conjunction with a continuous-time mediation formula. Novel features include a measure of an overall mediation effect based on the "area between the curves," and an approach for predicting the effects of new interventions. Simulation studies show good properties of estimators and the new methodology is applied to data from a cohort study to investigate sugary drink consumption as a mediator of the effect of socioeconomic status on dental caries in children.

Predictive models of poly(ethylene-terephthalate) film degradation under multi-factor accelerated weathering exposures.

Accelerated weathering exposures were performed on poly(ethylene-terephthalate) (PET) films. Longitudinal multi-level predictive models as a function of PET grades and exposure types were developed for the change in yellowness index (YI) and haze (%). Exposures with similar change in YI were modeled using a linear fixed-effects modeling approach. Due to the complex nature of haze formation, measurement uncertainty, and the differences in the samples' responses, the change in haze (%) depended on individual samples' responses and a linear mixed-effects modeling approach was used. When compared to fixed-effects models, the addition of random effects in the haze formation models significantly increased the variance explained. For both modeling approaches, diagnostic plots confirmed independence and homogeneity with normally distributed residual errors. Predictive R2 values for true prediction error and predictive power of the models demonstrated that the models were not subject to over-fitting. These models enable prediction under pre-defined exposure conditions for a given exposure time (or photo-dosage in case of UV light exposure). PET degradation under cyclic exposures combining UV light and condensing humidity is caused by photolytic and hydrolytic mechanisms causing yellowing and haze formation. Quantitative knowledge of these degradation pathways enable cross-correlation of these lab-based exposures with real-world conditions for service life prediction.

Validating continuous digital light processing (cDLP) additive manufacturing accuracy and tissue engineering utility of a dye-initiator package.

This study tested the accuracy of tissue engineering scaffold rendering via the continuous digital light processing (cDLP) light-based additive manufacturing technology. High accuracy (i.e., <50 µm) allows the designed performance of features relevant to three scale spaces: cell-scaffold, scaffold-tissue, and tissue-organ interactions. The biodegradable polymer poly (propylene fumarate) was used to render highly accurate scaffolds through the use of a dye-initiator package, TiO2 and bis (2,4,6-trimethylbenzoyl)phenylphosphine oxide. This dye-initiator package facilitates high accuracy in the Z dimension. Linear, round, and right-angle features were measured to gauge accuracy. Most features showed accuracies between 5.4-15% of the design. However, one feature, an 800 µm diameter circular pore, exhibited a 35.7% average reduction of patency. Light scattered in the x, y directions by the dye may have reduced this feature's accuracy. Our new fine-grained understanding of accuracy could be used to make further improvements by including corrections in the scaffold design software. Successful cell attachment occurred with both canine and human mesenchymal stem cells (MSCs). Highly accurate cDLP scaffold rendering is critical to the design of scaffolds that both guide bone regeneration and that fully resorb. Scaffold resorption must occur for regenerated bone to be remodeled and, thereby, achieve optimal strength.

Childhood lead exposure and uptake in teeth in the Cleveland area during the era of leaded gasoline.

Childhood uptake of lead from exposure to atmospheric leaded gasoline in the United States has been studied using mainly blood lead levels. Since reliable blood lead techniques were used only after the peak use of leaded gasoline, the prior exposure history is unclear. The well-documented decline in blood lead levels after the mid-1970s could represent the continuation of a historic steady decline in exposure from many sources. Alternatively, the post-1970s decline might represent the declining phase of a unimodal rise and fall corresponding closely to usage of leaded gasoline. To assess these possibilities, lead concentration and 207Pb/206Pb isotope ratios were measured in the enamel of permanent molar teeth formed between 1936 and 1993 in mainly African-American donors who grew up in the Cleveland area. Tooth enamel preserves the lead concentration and isotope ratio that prevails during tooth formation. Historical trends in enamel lead concentration were significantly correlated with surrogates of atmospheric lead exposure: lead in sediments of two dated Lake Erie cores, and lead consumed in gasoline. About two-thirds of the total lead uptake into enamel in this period was attributable to leaded gasoline, and the remainder to other sources (e.g. paint). Enamel 207Pb/206Pb isotope ratios were similar to those of one lake sediment. Multivariate analysis revealed significant correlation in neighborhoods with higher levels of traffic, and including lake sediment data, accounted for 53% of the variation in enamel lead levels. Enamel lead concentration was highly correlated with reported African-American childhood blood levels. The extrapolated peak level of 48microg/dL (range 40 to 63) is associated with clinical and behavioral impairments, which may have implications for adults who were children during the peak gasoline lead exposure. In sum, leaded gasoline emission was the predominant source of lead exposure of African-American Cleveland children during the latter two-thirds of the 20th century.