Study of a constrained finite element elbow prosthesis: the influence of the implant placement

Background: The functional results of total elbow arthroplasty (TEA) are controversial and the medium- to long-term revision rates are relatively high. The aim of the present study was to analyze the stresses of TEA in its classic configuration, identify the areas of greatest stress in the prosthesis–bone–cement interface, and evaluate the most wearing working conditions. Materials and methods: By means of a reverse engineering process and using a 3D laser scanner, CAD (computer-aided drafting) models of a constrained elbow prosthesis were acquired. These CAD models were developed and their elastic properties, resistance, and stresses were studied through finite element analysis (finite element method—FEM). The obtained 3D elbow-prosthesis model was then evaluated in cyclic flexion–extension movements (> 10 million cycles). We highlighted the configuration of the angle at which the highest stresses and the areas most at risk of implant mobilization develop. Finally, we performed a quantitative study of the stress state after varying the positioning of the stem of the ulnar component in the sagittal plane by ± 3°. Results: The greatest von Mises stress state in the bone component for the 90° working configuration was 3.1635 MPa, which occurred in the most proximal portion of the humeral blade and in the proximal middle third of the shaft. At the ulnar level, peaks of 4.1763 MPa were recorded at the proximal coronoid/metaepiphysis level. The minimum elastic resistance and therefore the greatest stress states were recorded in the bone region at the apex of the ulnar stem (0.001967 MPa). The results of the analysis for the working configurations at 0° and 145° showed significant reductions in the stress states for both prosthetic components; similarly, varying the positioning of the ulnar component at 90° (− 3° in the sagittal plane, 0° in the frontal plane) resulted in better working conditions with a greater resulting developed force and a lower stress peak in the ulnar cement. Conclusion: The areas of greatest stress occur in specific regions of the ulnar and humeral components at the bone–cement–prosthesis interface. The heaviest configuration in terms of stresses was when the elbow was flexed at 90°. Variations in the positioning in the sagittal plane can mechanically affect the movement, possibly resulting in longer survival of the implant. Level of evidence:

Study of a constrained finite element elbow prosthesis: the influence of the implant placement

BackgroundThe functional results of total elbow arthroplasty (TEA) are controversial and the medium- to long-term revision rates are relatively high. The aim of the present study was to analyze the stresses of TEA in its classic configuration, identify the areas of greatest stress in the prosthesis-bone-cement interface, and evaluate the most wearing working conditions.Materials and methodsBy means of a reverse engineering process and using a 3D laser scanner, CAD (computer-aided drafting) models of a constrained elbow prosthesis were acquired. These CAD models were developed and their elastic properties, resistance, and stresses were studied through finite element analysis (finite element method-FEM). The obtained 3D elbow-prosthesis model was then evaluated in cyclic flexion-extension movements (> 10 million cycles). We highlighted the configuration of the angle at which the highest stresses and the areas most at risk of implant mobilization develop. Finally, we performed a quantitative study of the stress state after varying the positioning of the stem of the ulnar component in the sagittal plane by +/- 3 degrees.ResultsThe greatest von Mises stress state in the bone component for the 90 degrees working configuration was 3.1635 MPa, which occurred in the most proximal portion of the humeral blade and in the proximal middle third of the shaft. At the ulnar level, peaks of 4.1763 MPa were recorded at the proximal coronoid/metaepiphysis level. The minimum elastic resistance and therefore the greatest stress states were recorded in the bone region at the apex of the ulnar stem (0.001967 MPa). The results of the analysis for the working configurations at 0 degrees and 145 degrees showed significant reductions in the stress states for both prosthetic components; similarly, varying the positioning of the ulnar component at 90 degrees (- 3 degrees in the sagittal plane, 0 degrees in the frontal plane) resulted in better working conditions with a greater resulting developed force and a lower stress peak in the ulnar cement.ConclusionThe areas of greatest stress occur in specific regions of the ulnar and humeral components at the bone-cement-prosthesis interface. The heaviest configuration in terms of stresses was when the elbow was flexed at 90 degrees. Variations in the positioning in the sagittal plane can mechanically affect the movement, possibly resulting in longer survival of the implant.Level of evidence:

Evaluation of building and occupant response to temperature and humidity: non-traditional heat stress considerations A comparison of different construction types used by the Texas Department of Criminal Justice

This study examined the effects of construction types on the indoor environment of selected prison facilities in the State of Texas. Three collocated facilities of the Texas Department of Criminal Justice were monitored for temperature, relative humidity and barometric pressure over a period of fifteen months. The objectives of the study were to examine the response of the built environment to the stressors of ambient conditions, characterize the influence of the construction method for each facility and study the responses of the occupants of the buildings. From the data, an apparent temperature was calculated and then compared to the data collected by the regional National Weather Service facility for ambient conditions. A relationship between the type of facility and the resulting indoor environmental conditions was established. The construction materials chosen for a particular facility affected not only the rate of heating of the indoor environment but also the maximum temperature, apparent temperature and thermal variation experienced by the occupants. The peak temperature and relative humidity were higher in the metal facilities when compared to the concrete facility. Therefore, the difference in occupant living conditions was considerable when the internal environmental conditions (temperature and humidity) were compared between construction types. The concrete construction also moderated the changes in the occupant environment through a lag of internal conditions behind those of the external environment. This resulted in a slower apparent temperature rise over the course of the day in the concrete buildings and a delay in the internal high temperature of the day. Finally, the data shows that measures of aggression vary with the seasonal changes, Increasing in the warming months and decreasing in the cooling months. This increase in the metal constructed facilities is greater than the rate of increase found in the concrete constructed facility

Acculturation of Japanese and American Intermarried Couples: Case Study of Their Marital Experiences and Parenting

This qualitative case study sought to gain in-depth understanding of Japanese and American family unions and the intermarried couples’ acculturation processes. It explored how intermarried couples view cultural differences, and how they negotiate and compromise in conflicts caused by such differences. Qualitative interviews were conducted with four couples comprising Japanese wives and their European-American husbands residing in the Midwestern United States. Interview questions included couples’ communication style, marital expectations, and parenting, from their perspective. The study found factors such as communication style, gender role expectations, marital expectations, and parenting style, contributed to conflicts in co-parenting and communication. Further investigation including sociopolitical aspects and cultural adaptation are recommended for future research.

Development of a predictive model for the shelf-life of Atlantic mackerel (Scomber scombrus)

Despite its commercial value, the shelf-life of the Atlantic mackerel (Scomber scombrus) during refrigerated storage was poorly investigated. In this regard, the Quality Index Method (QIM) was proposed as a suitable scoring system for freshness and quality sensorial estimation of fishery products. This study aims to develop a deterministic mathematical model based on dynamic temperatures conditions and a suc-cessive statistical analysis of the results obtained. This model will be exploited to predict the shelf-life of the Atlantic mackerel based on specific storage temperatures. A total of 60 fresh fishes were subdivided into two groups and respectively stored in ice for 12 days at a constant temperature of 1±0.5°C (Group A) and a fluctuating temperature ranging between 1 and 7°C (Group B). Microbiological analysis and sensory evaluation through the QIM were performed on each fish at regular time inter-vals. A critical value of 6 Log cfu/g of spoilage bacteria (mainly psychotropic) associated with a significant decay of the sensorial characteristics was exceeded after 9 days of storage for Group A and 3 days for Group B. A reliable prediction of fish freshness was obtained by modelling the QIM as a function of the spoilage bacteria behaviour. A coefficient β of correlation was determined to convert the spoilage bacteria load into a Quality Index score. The adoption of mathematical predictive models to assess microbial behaviour under different environmental conditions is an interest-ing tool for food industries to maximize production and reduce waste

CO-PARENTING FACTORS THAT CONTRIBUTE TO ACADEMIC SUCCESS

This study assessed factors contributed from parents who live in two different households and that lead to academic success. Data were collected from undergraduates enrolled in a Midwestern satellite university. Academic success was defined by university enrollment, grade point average, and standardized testing scores. Co-parenting factors that were hypothesized to lead to academic success included the distance between parents homes (which further influenced time spent with the child, participation in child‘s activities, and participation in decision making) and financial stability (which also influenced participation in decision making and the level of conflict within the family). The original structural equation model revealed that the relationship linking the distance between homes and the time spent with the child was accurately described. Added to the model, after the Lagrange test, was a path from finances to participation in child‘s activities and time spent with the child. The financial stability of a family predicted the participation of the non-custodial parent in the child‘s activities, in the decision-making for the child, conflict, and the time spent with the child. Implications for practitioners who work with families with co-parenting responsibilities are discussed

Salient Factors in Predicting Student Success, Including Course Modality

Much discussion in higher education has focused upon predicting student learning, and how to identify students who may be at particular risk of failure. Little research has actually tackled that challenge, and research on the scholarship of teaching and learning (SoTL) in this areas is scarce; this study does so by measuring students across three semester of study in a variety of courses and course formats. Our results indicate that a set of characteristics predicting student success can be identified, and that course modality affects overall student success rate. Our results are discussed in terms of how they might inform faculty and administrators how best to identify at risk groups of students, and who other researchers might expand on these results to produce a more nuanced interactive understanding of the interplay among students, courses, course modalities, and other characteristics to identify ideal combinations of those factors leading to student success

CO-PARENTING FACTORS THAT CONTRIBUTE TO ACADEMIC SUCCESS

This study assessed factors contributed from parents who live in two different households and that lead to academic success. Data were collected from undergraduates enrolled in a Midwestern satellite university. Academic success was defined by university enrollment, grade point average, and standardized testing scores. Co-parenting factors that were hypothesized to lead to academic success included the distance between parents homes (which further influenced time spent with the child, participation in child‘s activities, and participation in decision making) and financial stability (which also influenced participation in decision making and the level of conflict within the family). The original structural equation model revealed that the relationship linking the distance between homes and the time spent with the child was accurately described. Added to the model, after the Lagrange test, was a path from finances to participation in child‘s activities and time spent with the child. The financial stability of a family predicted the participation of the non-custodial parent in the child‘s activities, in the decision-making for the child, conflict, and the time spent with the child. Implications for practitioners who work with families with co-parenting responsibilities are discussed