Investigating the mechanical response of paediatric bone under bending and torsion using finite element analysis

Fractures of bone account 25% of all paediatric injuries (Cooper et al. in J Bone Miner Res 19:1976-1981, 2004. https://doi.org/10.1359/JBMR.040902 ). These can be broadly categorised into accidental or inflicted injuries. The current clinical approach to distinguish between these two is based on the clinician's judgment, which can be subjective. Furthermore, there is a lack of studies on paediatric bone to provide evidence-based information on bone strength, mainly due to the difficulties of obtaining paediatric bone samples. There is a need to investigate the behaviour of children's bones under external loading. Such data will critically enhance our understanding of injury tolerance of paediatric bones under various loading conditions, related to injuries, such as bending and torsional loads. The aim of this study is therefore to investigate the response of paediatric femora under two types of loading conditions, bending and torsion, using a CT-based finite element approach, and to determine a relationship between bone strength and age/body mass of the child. Thirty post-mortem CT scans of children aged between 0 and 3 years old were used in this study. Two different boundary conditions were defined to represent four-point bending and pure torsional loads. The principal strain criterion was used to estimate the failure moment for both loading conditions. The results showed that failure moment of the bone increases with the age and mass of the child. The predicted failure moment for bending, external and internal torsions were 0.8-27.9, 1.0-31.4 and 1.0-30.7 Nm, respectively. To the authors' knowledge, this is the first report on infant bone strength in relation to age/mass using models developed from modern medical images. This technology may in future help advance the design of child, car restrain system, and more accurate computer models of children

Performance of multiple neural networks in predicting lower limb joint moments using wearable sensors

Joint moment measurements represent an objective biomechemical parameter in joint health assessment. Inverse dynamics based on 3D motion capture data is the current 'gold standard’ to estimate joint moments. Recently, machine learning combined with data measured by wearable technologies such electromyography (EMG), inertial measurement units (IMU), and electrogoniometers (GON) has been used to enable fast, easy, and low-cost measurements of joint moments. This study investigates the ability of various deep neural networks to predict lower limb joint moments merely from IMU sensors. The performance of five different deep neural networks (InceptionTimePlus, eXplainable convolutional neural network (XCM), XCMplus, Recurrent neural network (RNNplus), and Time Series Transformer (TSTPlus)) were tested to predict hip, knee, ankle, and subtalar moments using acceleration and gyroscope measurements of four IMU sensors at the trunk, thigh, shank, and foot. Multiple locomotion modes were considered including level-ground walking, treadmill walking, stair ascent, stair descent, ramp ascent, and ramp descent. We show that XCM can accurately predict lower limb joint moments using data of only four IMUs with RMSE of 0.046 ± 0.013 Nm/kg compared to 0.064 ± 0.003 Nm/kg on average for the other architectures. We found that hip, knee, and ankle joint moments predictions had a comparable RMSE with an average of 0.069 Nm/kg, while subtalar joint moments had the lowest RMSE of 0.033 Nm/kg. The real-time feedback that can be derived from the proposed method can be highly valuable for sports scientists and physiotherapists to gain insights into biomechanics, technique, and form to develop personalized training and rehabilitation programs

Investigating rolling as mechanism for humeral fractures in non-ambulant infants : a preliminary finite element study

AIM To use personalised computed tomography (CT)-based finite element models to quantitatively investigate the likelihood of self-inflicted humeral fracture in non-ambulant infants secondary to rolling. MATERIALS AND METHODS Three whole-body post-mortem CT examinations of children at the age of rolling (two 4-month-old and one 6-month-old) were used. The mechanical moment needed by each infant to perform a rolling manoeuvre was calculated and applied to the finite element model in order to simulate spontaneous rolling from the prone to the supine position. RESULTS The maximum predicted strains were found to be substantially lower (with a difference of >80%) than the elastic limit of the bone. CONCLUSION Results of this study challenge the plausibility of self-inflicted humeral fracture caused by rolling in non-ambulant infants and indicate that it is unlikely for a humeral fracture to result from this mechanism without the assistance of an external force

Bilateral fibular fractures in a pre-ambulant infant

Multiple long-bone fractures, particularly bilateral fractures, are of moderate specificity for inflicted injury (physical abuse) in infants and young children. Bilateral healing fractures of the fibulae are rare and, depending on age, raise the suspicion of inflicted injury. We report healing undisplaced fractures of both fibulae, in almost identical positions, in a pre-ambulant infant. The caregivers reported that the infant repeatedly banged his legs against the metal frame of his playpen. A video of this mechanism was provided to the instructed radiology expert and showed that the point of impact of the infant’s legs against the metal frame was at a similar level to the radiographic abnormalities. This mechanism was therefore believed to be consistent with the injuries, resulting in a diagnosis of self-inflicted bilateral fibular fractures and not of inflicted injury

Femoral neck strain prediction during level walking using a combined musculoskeletal and finite element model approach

Recently, coupled musculoskeletal-finite element modelling approaches have emerged as a way to investigate femoral neck loading during various daily activities. Combining personalised gait data with finite element models will not only allow us to study changes in motion/movement, but also their effects on critical internal structures, such as the femur. However, previous studies have been hampered by the small sample size and the lack of fully personalised data in order to construct the coupled model. Therefore, the aim of this study was to build a pipeline for a fully personalised multiscale (body-organ level) model to investigate the strain levels at the femoral neck during a normal gait cycle. Five postmenopausal women were included in this study. The CT and MRI scans of the lower limb, and gait data were collected for all participants. Muscle forces derived from the body level musculoskeletal models were used as boundary constraints on the finite element femur models. Principal strains were estimated at the femoral neck region during a full gait cycle. Considerable variation was found in the predicted peak strain among individuals with mean peak first principal strain of 0.24% ± 0.11% and mean third principal strain of -0.29% ± 0.24%. For four individuals, two overall peaks of the maximum strains were found to occur when both feet were in contact with the floor, while one individual had one peak at the toe-off phase. Both the joint contact forces and the muscular forces were found to substantially influence the loading at the femoral neck. A higher correlation was found between the predicted peak strains and the gluteus medius (R2 ranged between 0.95 and 0.99) than the hip joint contact forces (R2 ranged between 0.63 and 0.96). Therefore, the current findings suggest that personal variations are substantial, and hence it is important to consider multiple subjects before deriving general conclusions for a target population

Effect of muscle forces on femur during level walking using a virtual population of older women

Aging is associated with a greater risk of muscle and bone disorders such as sarcopenia and osteoporosis. These conditions substantially affect one’s mobility and quality of life. In the past, muscles and bones are often studied separately using generic or scaled information that are not personal-specific, nor are they representative of the large variations seen in the elderly population. Consequently, the mechanical interaction between the aged muscle and bone is not well understood, especially when carrying out daily activities. This study presents a coupling approach across the body and the organ level, using fully personal-specific musculoskeletal and finite element models in order to study femoral loading during level walking. Variations in lower limb muscle volume/force were examined using a virtual population. These muscle forces were then applied to the finite element model of the femur to study the variations in predicted strains. The study shows that effective coupling across two scales can be carried out to study the muscle-bone interaction in elderly women. The generation of a virtual population is a feasible approach to augment anatomical variations based on a small population that could mimic variations seen in a larger cohort. This is a valuable alternative to overcome the limitation or the need to collect dataset from a large population, which is both time and resource consuming

In vivo and in vitro studies on renal uptake of radiolabeled affibody molecules for imaging of HER2 expression in tumors

Contains fulltext : 118633.pdf (publisher's version ) (Closed access)Affibody molecules (6-7 kDa) are a new class of small robust three-helical scaffold proteins. Radiolabeled subnanomolar anti-HER2 affibody ZHER2:342 was developed for imaging of HER2 expression in tumors, and a clinical study has demonstrated that the (111)In- and (68)Ga-labeled affibody molecules can efficiently detect HER2 expressing metastases in breast cancer patients. However, a significant renal accumulation of radioactivity after systemic injection of a radiolabeled anti-HER2 affibody conjugate is observed. The aim of this study was to investigate the mechanism of renal reabsorption of anti-HER2 affibody at the molecular level. Renal accumulation of radiolabeled anti-HER2 affibody molecules was studied in a murine model and in vitro using opossum-derived proximal tubule (OK) cells. It was found that kidney reabsorption of affibody molecule was not driven by megalin/cubilin. Amino acids in the target-binding side of affibody molecule were involved in binding to OK cells. On OK cells, two types of receptors for anti-HER2 affibody molecule were found: KD1=0.8 nM, Bmax1=71,500 and KD2=9.2 nM, Bmax2=367,000. The results of the present study indicate that affibody molecule and other scaffold-based targeting proteins with a relatively low kidney uptake can be selected using in vitro studies with tubular kidney cells.Altai, Mohamed Varasteh, Zohreh Andersson, Karl Eek, Annemarie Boerman, Otto Orlova, Anna Research Support, Non-U.S. Gov't United States Cancer Biother Radiopharm. 2013 Apr;28(3):187-95. doi: 10.1089/cbr.2012.1304. Epub 2013 Mar 5

Finite element modelling of the developing infant femur using paired CT and MRI scans

Bone finite element (FE) studies based on infant post-mortem computed tomography (CT) examinations are being developed to provide quantitative information to assist the differentiation between accidental and inflicted injury, and unsuspected underlying disease. As the growing skeleton contains non-ossified cartilaginous regions at the epiphyses, which are not well characterised on CT examinations, it is difficult to evaluate the mechanical behaviour of the developing whole bone. This study made use of paired paediatric post mortem femoral CT and magnetic resonance imaging (MRI) examinations at two different stages of development (4 and 7 months) to provide anatomical and constitutive information for both hard and soft tissues. The work aimed to evaluate the effect of epiphyseal ossification on the propensity to shaft fractures in infants. The outcomes suggest that the failure load of the femoral diaphysis in the models incorporating the non-ossified epiphysis is within the range of bone-only FE models. There may however be an effect on the metaphysis. Confirmation of these findings is required in a larger cohort of children

Išorinio viešojo audito vaidmuo užtikrinant finansinį besivystančių šalių biudžetų stabilumą

The system of external state audit reveals the potential for structural changes in terms of making effective management decisions that ensure the rational consumption of investment and other resources, taking into account the organizational and economic level of development. Based on the experience of foreign countries, it should be noted that in developed countries audit is the leading form of independent control. The purpose of this article is to determine the role of external public audit in ensuring the financial stability of the budgets of developing countries. To assess the financial stability of budgets, traditional methodological approaches, i.e. the analysis of absolute indicators and analysis of relative coefficients are used. In the study, financial stability was examined in the context of the possibility of evaluating the state audit of the budgets of developing countries for all expenses of the republican budget without raising the level of public debt. As a result of consideration of the budgets of developing countries, the problems were identified and the directions for their solution were proposed. In addition, tools which allow not only assess the financial stability of the budget, but also determine recommendations for managerial impacts aimed at strengthening the state budget are proposed. Thus,conducting a state audit in order to increase financial stability will lead to an increase in the efficiency of public administration and to a greater alignment of mechanisms for implementing state programs and projects with strategic planning mechanisms