Finite Element Modeling Application in Forensic Practice: A Periprosthetic Femoral Fracture Case Study

The incidence of periprosthetic fractures has rapidly increased in the last two decades and has been the cause of a large number of revision surgeries and permanent physical disability for many patients, as well as a significant socioeconomic burden for many nations. This research deals with a periprosthetic femur fracture real event, occurred following a total hip arthroplasty and treated with one of the most widespread internal fixation methods: the implant of a periprosthetic femur plate system. A Finite Element analysis was performed to investigate the implanted femur plate break after a short follow-up and to understand the plate break causes. Such events are currently object of forensic debate as more and more often hospitals, surgeons, and medical device manufacturers are denounced by patients to whom similar events occur. In this work, different load situations acting on the femur during daily and incidental activities were simulated, in order to validate the correct behavior of the plate, according to the intended use recommended by the manufacturer. The analysis demonstrates that the plate failure can occur in situations of unconventional loading such as that caused by stumbling and in presence of incomplete bone healing

Experimental validation of a subject-specific finite element model of lumbar spine segment using digital image correlation

Pathologies such as cancer metastasis and osteoporosis strongly affect the mechanical properties of the vertebral bone and increase the risk of fragility fractures. The prediction of the fracture risk with a patient-specific model, directly generated from the diagnostic images of the patient, could help the clinician in the choice of the correct therapy to follow. But before such models can be used to support any clinical decision, their credibility must be demonstrated through verification, validation, and uncertainty quantification. In this study we describe a procedure for the generation of such patient-specific finite element models and present a first validation of the kinematics of the spine segment. Quantitative computed tomography images of a cadaveric lumbar spine segment presenting vertebral metastatic lesions were used to generate the model. The applied boundary conditions replicated a specific experimental test where the spine segment was loaded in compression-flexion. Model predictions in terms of vertebral surface displacements were compared against the full-field experimental displacements measured with Digital Image Correlation. A good agreement was obtained from the local comparison between experimental data and simulation results (R2 > 0.9 and RMSE% <8%). In conclusion, this work demonstrates the possibility to apply the developed modelling pipeline to predict the displacement field of human spine segment under physiological loading conditions, which is a first fundamental step in the credibility assessment of these clinical decision-support technology

Stochastic PCA-based bone models from inverse transform sampling: Proof of concept for mandibles and proximal femurs

Principal components analysis is a powerful technique which can be used to reduce data dimensionality. With reference to three-dimensional bone shape models, it can be used to generate an unlimited number of models, defined by thousands of nodes, from a limited (less than twenty) number of scalars. The full procedure has been here described in detail and tested. Two databases were used as input data: the first database comprised 40 mandibles, while the second one comprised 98 proximal femurs. The “average shape” and principal components that were required to cover at least 90% of the whole variance were identified for both bones, as well as the statistical distributions of the respective principal components weights. Fifteen principal components sufficed to describe the mandibular shape, while nine components sufficed to describe the proximal femur morphology. A routine has been set up to generate any number of mandible or proximal femur geometries, according to the actual statistical shape distributions. The set-up procedure can be generalized to any bone shape given a sufficiently large database of the respective 3D shapes

Personalised 3D Assessment of Trochanteric Soft Tissues Improves HIP Fracture Classification Accuracy

Passive soft tissues surrounding the trochanteric region attenuate fall impact forces and thereby control hip fracture risk. The degree of attenuation is related to Soft Tissue Thickness (STT). STT at the neutral hip impact orientation, estimated using a regression relation in body mass index (BMI), was previously shown to influence the current absolute risk of hip fracture (ARF0) and its fracture classification accuracy. The present study investigates whether fracture classification using ARF0 improves when STT is determined from the subject’s Computed-Tomography (CT) scans (i.e. personalised) in an orientation-specific (i.e. 3D) manner. STT is calculated as the shortest distance along any impact orientation between a semi-automatically segmented femur surface and an automatically segmented soft tissue/air boundary. For any subject, STT along any of the 33 impact orientations analysed always exceeds the value estimated using BMI. Accuracy of fracture classification using ARF0 improves when using personalised 3D STT estimates (AUC = 0.87) instead of the BMI-based STT estimate (AUC = 0.85). The improvement is smaller (AUC = 0.86) when orientation-specificity of CT-based STT is suppressed and is nil when personalisation is suppressed instead. Thus, fracture classification using ARF0 improves when CT is used to personalise STT estimates and improves further when, in addition, the estimates are orientation specific

Stochastic PCA-based bone models from inverse transform sampling: proof of concept for mandibles and proximal femurs

Principal components analysis is a powerful technique which can be used to reduce data dimensionality. With reference to three-dimensional bone shape models, it can be used to generate an unlimited number of models, defined by thousands of nodes, from a limited (less than twenty) number of scalars. The full procedure has been here described in detail and tested. Two databases were used as input data: the first database comprised 40 mandibles, while the second one comprised 98 proximal femurs. The “average shape” and principal components that were required to cover at least 90% of the whole variance were identified for both bones, as well as the statistical distributions of the respective principal components weights. Fifteen principal components sufficed to describe the mandibular shape, while nine components sufficed to describe the proximal femur morphology. A routine has been set up to generate any number of mandible or proximal femur geometries, according to the actual statistical shape distributions. The set-up procedure can be generalized to any bone shape given a sufficiently large database of the respective 3D shapes

Linking ethical leadership and ethical climate to employees’ ethical behavior: the moderating role of person–organization fit

Purpose – With the growing demand for ethical standards in the prevailing business environment, ethical leadership has been under increasingly more focus. Based on the social exchange theory and social learning theory, this study scrutinized the impact of ethical leadership on the presentation of ethical conduct by employees through the ethical climate. Notably, this study scrutinized the moderating function of the person organization fit (P-O fit) in relation to ethical climate and the ethical conduct of employees. Design/methodology/approach – To evaluate the research hypotheses, two-wave data were collected from 295 individuals who are currently employed in various Iraqi organizations (i.e. manufacturing, medical, and insurance industries). Findings – In line with the hypotheses, the outcomes from a sample of 295 workers working in different Iraqi entities exhibited a positive relationship between the ethical behavior of leaders and the ethical conduct of employees in the ethical climate. Moreover, it was observed that the P-O fit of employees moderated the relationship between ethical climate and the ethical conduct of employees such that the relationship was more robust for those with a high P-O fit in comparison to those with a low P-O fit. Research limitations/implications – The primary limitation of this study is in the data, which was obtained from a single source. Although the study conducted two surveys and utilized a mediation and moderation variables model that was less likely to be influenced by common method bias (CMB) (Podsakoff et al., 2012), one cannot completely rule out CMB. Apart from the potential effects of the CMB, the consistency of the empirical findings could have also been compromised since self-reported data were utilized in measuring ethical behavior, which can be a very complex and sensitive issue. For this reason, the social desirability response bias cannot be ruled out completely. When possible, future studies must gather data from multiple sources. Furthermore, supervisors must evaluate the ethical behavior of employees. Another limitation was that the findings of this study were based on a sample in a Middle Eastern cultural context such as in Iraq. Perhaps, the particular cultural features of this context, which encompassed, among other things, strong adherence to religious values (Moaddel, 2010), could have influenced the findings of this study. It is true that the effects of differences (P–O fit) are highly likely to replicate across cultural contexts (Triandis et al., 1988). However, it can be seen that further studies are needed to evaluate the context-sensitivity of these findings (Whetten, 2009) by analyzing other cultures, where the importance of religiosity is on the decline (i.e. in Western countries, Ribberink et al., 2018) or where the cultural features are very much different from those that apply to Iraq. Lastly, other external factors were not taken into account by this study as it tried to explain ethical behavior. Ethics is a highly complex subject and is influenced by numerous variables at the organizational, individual, and external environment levels. Thus, caution must be observed when making inferences from the present study which, to a certain degree, offered a simplified version of ethical behavior by concentrating on a few variables such as the Arab culture’s traditional ideology, which dominates even science (Abu Khalil, 1992). In addition, there are political conflicts in the Middle Eastern cultural context such as what is happening in Iraq (Harff, 2018). Thus, it is important to include such aspects in future researches. Practical implications – In terms of management, the findings send a clear signal to those in the upper echelon that, without ignoring the issue of ethics in organizations, employees are a critical aspect to be taken into account to encourage ethical behavior at the workplace. This study has important practical implications. First, this study determined that ethical leadership (here, of the supervisors) positively influences the behavior of subordinates (refers to the supervisors here); this, in turn, further improves the ethical behavior of employees. It is vital that managers or supervisors are motivated to practice ethical leadership because they directly influence the employees. It has been suggested that top managers, especially chief executive officers, have the ability to shape the ethical climate, which also influences the ethical behavior of employees further. This study offered several feasible ways that managers can apply to achieve that. In particular, top managers may utilize the ethical climate as a way of communicating the ethical values that they have to their subordinates, thereby serving as a motivation for the subordinates to adopt ethical behavior. It was also suggested by this study that ethical climate and the P–O fit may, to some degree, substitute each other as they influence the ethical behavior of employees. Therefore, firms that were identified to have a low level of ethical standards, practices, and policies, at least from the employees’ perspective, are better poised to conduct ethical issues in order to construct the ethical behavior of their subordinates. More importantly, it is highly essential that the value congruence between an organization and its followers be considered. Social implications – This study highlighted the notion of ethics and how it’s essential for society. Ethics refers to the norms, standards, and values that direct the behavior of an individual. Ethical behavior is vital in society because we need to be treated with respect as human beings. Originality/value – This study responds to recent calls for more research to identify factors that may strengthen or mitigate the influence of ethical behavior in the workplace such as ethical leadership, ethical climate, and Person–Organization

Personalised 3D assessment of trochanteric soft tissues improves HIP fracture classification accuracy

Passive soft tissues surrounding the trochanteric region attenuate fall impact forces and thereby control hip fracture risk. The degree of attenuation is related to Soft Tissue Thickness (STT). STT at the neutral hip impact orientation, estimated using a regression relation in body mass index (BMI), was previously shown to influence the current absolute risk of hip fracture (ARF0) and its fracture classification accuracy. The present study investigates whether fracture classification using ARF0 improves when STT is determined from the subject’s Computed-Tomography (CT) scans (i.e. personalised) in an orientation-specific (i.e. 3D) manner. STT is calculated as the shortest distance along any impact orientation between a semi-automatically segmented femur surface and an automatically segmented soft tissue/air boundary. For any subject, STT along any of the 33 impact orientations analysed always exceeds the value estimated using BMI. Accuracy of fracture classification using ARF0 improves when using personalised 3D STT estimates (AUC = 0.87) instead of the BMI-based STT estimate (AUC = 0.85). The improvement is smaller (AUC = 0.86) when orientation-specificity of CT-based STT is suppressed and is nil when personalisation is suppressed instead. Thus, fracture classification using ARF0 improves when CT is used to personalise STT estimates and improves further when, in addition, the estimates are orientation specific

Efficacy and safety of dalbavancin in the treatment of acute bacterial skin and skin structure infections (ABSSSIs) and other infections in a real-life setting: data from an Italian observational multicentric study (DALBITA study)

Objectives: We evaluated the efficacy and safety of dalbavancin in ABSSSI and ‘other sites’ infections’ (OTA). Methods: Observational study involving 11 Italian hospitals including patients that received ≥1 dose of dalbavancin in 2016–2019. The outcome was end-of-treatment efficacy and safety in ABSSSI and OTA in a real-life setting. Results: 206 patients enrolled (males 50%, median age 62 [IQR 50–76] years), 60.2% ABSSSI, 39.8% OTA. 69.7% ABSSSI vs 90.7% OTA (p&nbsp;=&nbsp;0.003) and 46.3% ABSSSI vs 37.2% OTA (p&nbsp;=&nbsp;0.786) received previous and concomitant antibiotics, respectively. 82.5% reached clinical cure. Eleven (5.4%) patients had non-serious adverse events (AE). OTA patients showed longer hospitalization (13.5&nbsp;days, 5.5–22 vs 3, 0–11.7; p&lt;0.0001) and received longer previous (18&nbsp;days, 9–30 vs 11, 7–19; p =&nbsp;0.007)/concomitant antibiotic treatments (21&nbsp;days, 14–52 vs 11, 8–14; p &lt;&nbsp;0.0001), compared to ABSSSI. ABSSSI and OTA showed similar efficacy (85.5% vs 75%, p =&nbsp;0.459) and safety (no AE: 81.5% vs 64.3%, p =&nbsp;0.258); efficacy was independent of previous/concomitant therapies. Conclusions: Dalbavancin demonstrated a success rate of &gt;80%, with similar efficacy/safety in ABSSSI and off-label indications. The preferential use of dalbavancin as second-line or combination therapy would seem to suggest the need for in-depth studies focused on its off-label use