Patient-specific modelling of contact characteristics in the ankle joint following triple arthrodesis in valgus, neutral and varus hindfoot positions.

The aim of the current study was to understand the importance of the joint alignment following triple arthrodesis by analysing the contact characteristics in a normal and arthritic ankle joint using a patient-specific numerical model developed using open source software. The alignment of the hindfoot with respect to tibia is calculated from CT scans and the ankle joint model was numerically analysed for neutral, valgus and varus positions in both normal and arthritic conditions. The contact area, the magnitude and distribution of the contact pressure on the articular surface of the talar dome was evaluated using a cell-centred Finite Volume Method implemented in open-source software OpenFOAM. It was found that all positions of the hindfoot predict higher lateral pressures during heel strike. The varus position predicts the maximum increase in lateral pressures. Comparing the valgus and neutral positions, although the neutral position predicts 9.1 % higher increase in lateral pressures during heel strike than valgus, it predicts 33.6 % decrease in pressures during heel-rise and the distribution is more medial during toe-off. In the case of arthritic ankle, it could be observed that the neutral and varus hindfoot fusion positions result in a concentrated increase of lateral pressures in heel strike and flat-foot. In the case of toe-off, the neutral alignment results in an increase of 62.3 % in the contact pressures compared to the arthritic pressure of the unfused foot and is 20.8 % higher than the valgus alignment. The study helps to conclude that the fusion is more beneficial at the neutral position of the hindfoot for the patient specific ankle. However, the 5° valgus position of hindfoot alignment could be more beneficial in the arthritic ankle. Patient-specific approach to the placement of the hindfoot with the help of numerical analysis could help address the issue of ankle degradation following arthrodesis.

A novel surrogate lung material for impact studies: Development and testing procedures.

This work focuses on the development of a surrogate lung material (SLM) that reproduces the dynamic response of a human lung under various loading conditions and also allows for the analysis of the extent and distribution of damage. The SLM consists of polyurethane foam used to mimic the spongy lung tissue and fluid-filled gelatine microcapsules used to simulate the damage of alveoli. The bursting pressure of the microcapsules was investigated by conducting low and high rate compression tests on single microcapsules. A bursting pressure of around 5bar was measured which is comparable to the reported lung overpressure at injury level. Low and high rate compression tests were conducted on the SLMs. From the measured mechanical properties and mass density, the stress wave speed was calculated and found to be well in the range of the reported values for human lungs (16-70m/s). In order to study the extent and distribution of damage in the SLMs, as represented by burst microcapsules, a CT scan analysis was carried out before and after the impacts. The CT scan results clearly demonstrated the magnitude and distribution of damage within the specimen. The results are then compared to the Bowen curves, the most often used criteria for predicting blast injuries in humans. An excellent agreement was found between the observed damage in the surrogate lungs and the expected damage in real human lungs. In general, the SLM showed similar stress wave speed, bursting pressure and damage to that of the real lungs.

The genetic diversity and structure of 18 sheep breeds exposed to isolation and selection.

The phylogenetic layout of the genotyped (30 microsatellite) 18 sheep breeds in this study demands and provides the opportunity to evaluate both neutral and adaptive components of genetic diversity in a naturally and artificially selected and subdivided sheep population. Seven Pramenka strains from Bosnia and Herzegovina and Croatia characterized by a very low intensity of artificial selection, preserved the highest neutral genetic variability. Eight central and north-western European breeds under considerable artificial isolation and selection preserved the lowest genetic variability. Only combinations of various phylogenetic parameters offer a reasonable explanation for underlying evolutionary forces working in the investigated island and mainland sheep breeds under variable natural and artificial selection. More than 60% of total genetic, diversity was allocated to virtually unselected Pramenka strains, and an additional 25% to native moderately selected Graue Gehoernte Heidschnucke and intensively selected Ostfriesische Milchschafe. Some economically very important breeds and strains did not contribute to a pool with maximal genetic diversity, while they play an important role in the cultural heritage of respective countries.

Development of mapped stress-field boundary conditions based on a Hill-type muscle model.

Forces generated in the muscles and tendons actuate the movement of the skeleton. Accurate estimation and application of these musculotendon forces in a continuum model is not a trivial matter. Frequently, musculotendon attachments are approximated as point forces; however, accurate estimation of local mechanics requires a more realistic application of musculotendon forces. This paper describes the development of mapped Hill-type muscle models as boundary conditions for a finite volume model of the hip joint, where the calculated muscle fibres map continuously between attachment sites. The applied muscle forces are calculated using active Hill-type models, where input electromyography signals are determined from gait analysis. Realistic muscle attachment sites are determined directly from tomography images. The mapped muscle boundary conditions, implemented in a finite volume structural OpenFOAM (ESI-OpenCFD, Bracknell, UK) solver, are employed to simulate the mid-stance phase of gait using a patient-specific natural hip joint, and a comparison is performed with the standard point load muscle approach. It is concluded that physiological joint loading is not accurately represented by simplistic muscle point loading conditions; however, when contact pressures are of sole interest, simplifying assumptions with regard to muscular forces may be valid.

Development of a hip joint model for finite volume simulations.

This paper establishes a procedure for numerical analysis of a hip joint using the finite volume method. Patient-specific hip joint geometry is segmented directly from computed tomography and magnetic resonance imaging datasets and the resulting bone surfaces are processed into a form suitable for volume meshing. A high resolution continuum tetrahedral mesh has been generated, where a sandwich model approach is adopted; the bones are represented as a stiffer cortical shells surrounding more flexible cancellous cores. Cartilage is included as a uniform thickness extruded layer and the effect of layer thickness is investigated. To realistically position the bones, gait analysis has been performed giving the 3D positions of the bones for the full gait cycle. Three phases of the gait cycle are examined using a finite volume based custom structural contact solver implemented in open-source software OpenFOAM.

Analysis of genetic and cultural conservation value of three indigenous Croatian cattle breeds in a local and global context.

It is widely accepted that autochthonous cattle breeds can be important genetic resources for unforeseeable environmental conditions in the future. Apart from that, they often represent local culture and tradition and thus assist in the awareness of ethnic identity of a country. In Croatia, there are only three indigenous cattle breeds, Croatian Busa, Slavonian Syrmian Podolian and Istrian Cattle. All of them are threatened but specialized in a particular habitat and production system. We analysed 93 microsatellites in 51 animals of each breed to get thorough information about genetic diversity and population structure. We further set them within an existing frame of additional 16 breeds that have been genotyped for the same marker set and cover a geographical area from the domestication centre near Anatolia, through the Balkan and alpine regions, to the north-west of Europe. The cultural value was evaluated regarding the role in landscape, gastronomy, folklore and handicraft. The overall results recognize Croatian Busa being partly admixed but harbouring an enormous genetic diversity comparable with other traditional unselected Busa breeds in the Anatolian and Balkan areas. The Podolian cattle showed the lowest genetic diversity at the highest genetic distance to all remaining breeds but are playing an important role as part of the cultural landscape and thus contribute to the tourist industry. The genetic diversity of the Istrian cattle was found in the middle range of this study. It is already included in the tourist industry as a local food speciality. Current and future conservation strategies are discussed.

Validation of a fluid-structure interaction numerical model for predicting flow transients in arteries.

Fluid-structure interaction (FSI) numerical models are now widely used in predicting blood flow transients. This is because of the importance of the interaction between the flowing blood and the deforming arterial wall to blood flow behaviour. Unfortunately, most of these FSI models lack rigorous validation and, thus, cannot guarantee the accuracy of their predictions. This paper presents the comprehensive validation of a two-way coupled FSI numerical model, developed to predict flow transients in compliant conduits such as arteries. The model is validated using analytical solutions and experiments conducted on polyurethane mock artery. Flow parameters such as pressure and axial stress (and precursor) wave speeds, wall deformations and oscillating frequency, fluid velocity and Poisson coupling effects, were used as the basis of this validation. Results show very good comparison between numerical predictions, analytical solutions and experimental data. The agreement between the three approaches is generally over 95%. The model also shows accurate prediction of Poisson coupling effects in unsteady flows through flexible pipes, which up to this stage have only being predicted analytically. Therefore, this numerical model can accurately predict flow transients in compliant vessels such as arteries.

A finite-element analysis study of the metatarsophalangeal joint of the hallux rigidus.

Hallux rigidus was first described in 1887. Many aetiological factors have been postulated, but none has been supported by scientific evidence. We have examined the static and dynamic imbalances in the first metatarsophalangeal joint which we postulated could be the cause of this condition. We performed a finite-element analysis study on a male subject and calculated a mathematical model of the joint when subjected to both normal and abnormal physiological loads. The results gave statistically significant evidence for an increase in tension of the plantar fascia as the cause of abnormal stress on the articular cartilage rather than mismatch of the articular surfaces or subclinical muscle contractures. Our study indicated a clinical potential cause of hallux rigidus and challenged the many aetiological theories. It could influence the choice of surgical procedure for the treatment of early grades of hallux rigidus.

Towards early diagnosis of atherosclerosis: the finite volume method for fluid-structure interaction.

Blood flow through arteries represents a very complex, fluid-structure interaction (FSI) problem. Strong coupling between the blood and artery is due to the relatively low stiffness of the artery compared to that of blood. Hence, the pressure exerted by the flowing blood on the artery wall can result in considerable deformations of the artery, and vice-versa, arterial deformations can in turn affect the blood flow. In the present work, the finite volume method is employed to solve the problem where compressible fluid, representing blood, flows in healthy arteries as well as in unhealthy, i.e., partly stiffened arteries. The stiffening of the arterial wall is assumed to be the first key stage in the development of atherosclerosis. The comparison between various deformation profiles of healthy and unhealthy arteries demonstrates significant and measurable differences, in particular in the radial direction. This is hoped to help toward establishing procedures for early diagnosis of the disease.

Genetic diversity of three donkey populations in the Croatian coastal region.

Genetic variation in three Croatian donkey populations, Istrian (IS), North Adriatic (NA) and Littoral-Dinaric (LD), was analysed using eight microsatellite loci and by sequence and SSCP analysis of the proximal portion of the mtDNA D-loop region. The analysis of microsatellite loci revealed observed heterozygosities in the range of 0.37 (MPZ002 in LD) to 0.85 (AHT21 in LD) and polymorphic information content values in the range of 0.36 (MPZ002 in NA) to 0.78 (AHT21 in LD). The overall probability of exclusion was 0.991. Two populations (IS and NA) were closely related (Fst=0.0034), whereas genetic distances between IS and LD (Fst=0.021) and NA and LD (Fst=0.027) were higher. Using AMOVA, 97.6% of the total genetic variance was portioned within populations, while 2.7% was portioned between the Littoral-Dinaric population and the Istrian/North Adriatic population group. Sequencing of the proximal part of the mtDNA D-loop region revealed 36 polymorphic sites representing 19 haplotypes which clustered into three haplotype groups (Y, W, Ws). Only the Y haplotype was found in the IS population which is characterized by a large body size. Haplotypes W and Ws were found in the NA and LD populations which include smaller animals. All three haplotypes were found in the LD population, indicating sporadic migration events from the IS into LD donkey population.

Assessment of the current status of iodine prophylaxis in Bosnia and Herzegovina Federation.

Assessment of the status of iodine prophylaxis was studied in 5,523 schoolchildren randomly selected in all cantons in Bosnia and Herzegovina Federation (BHF). According to the iodine content of household salt samples, all cantons of BHF were divided into two groups: Group A: 95.5% of the salt used is produced in the Tuzla plant, in which the salt is iodized at 5-15 mg KI/kg salt, and 4.5% of the salt used is produced in the Pag plant, in which the salt is iodized at 20-30 mg KI/kg of salt, and Group B: 19.9% of the salt used is produced in the Tuzla plant and 80.1% in the Pag plant. In Group A the amount of iodine in salt was significantly lower than in Group B (11.4 mg/kg vs 18.9 mg/kg, P < 0.001). In Group A the prevalence of goiter was significantly higher than in Group B (32.6% vs 19.7%, P < 0.001). The highest prevalence of goiter was in Bosnian Podrinje Canton (51.2%) and Central Bosnian Canton (42.6%) while the lowest was in West Herzegovina Canton (12.9%). Significantly higher concentrations of urinary iodine were found in Group B than in Group A (82.6 microg/l vs 75.2 microg/l, P < 0.001). In Group A the percentage of urine samples below 50 microg/l iodine was significantly higher than in Group B (35.6% vs 26.9%, P < 0.001), but there was no difference in the percentage of urine samples with iodine values less than 100 microg/l (70.7 microg/l vs 68.25 microg/l, P > 0.05). We conclude that FBH is an iodine deficient area and that the improvement of iodine prophylaxis is urgently required, primarily by increasing salt iodine content to 20-30 mg/kg, in order to eradicate endemic goiter.

[Iodine deficiency in the Federation of Bosnia and Herzegovina]. / Jodni deficit u Federaciji Bosne i Hercegovine.

Iodine deficiency which causes the wide spectrum of disorders for all ages, is one of the significant public health problem worldwide. From the ancient times different iodine deficiency disorders were noticed in Bosnia and Herzegovina and in its some areas the goiter existed in endemic form. These facts confirm that its soil bas been iodine deficient and that necessity for iodine prophylaxis is obvious on its territory. The study was based on 5,523 children, of both sex boys and girls school age from 7 to 14 years, randomly selected with the equal participate subjects in relation to the age. The sample is representative and it has been assessed based on: total number of school children aged from 7 to 14 years, anticipated prevalence of goiter 5% level of probability 95%, relative punctuality 30% and the factor called "design effect" which is 3. The study was carried out in whole ten cantons in the schools with equal representation among cities and villages. In examining of prevalence of giter we used inspection and palpation. Determination of iodine concentration in urine was carried out by the method is based on Sandel-kolthof's reaction. The technique used for determination of concentration of iodine in salt was iodinemetric titration. The prevalence of goiter was 27.6% in Federation of Bosnia and Heryegovina. The highest prevalence of goiter was in Bosnia Podrinje Canton (51.20%) while the lowest was in West Herzegovina Canton (12.90%). The urinary iodine excretion in investigated children varied from 1 to 208 *mg/L with median of 77.6 *mg/L. Iodine contetn in household salt samples was from 3 to 29.8 mg/kg, range 14.4 + 5.9 mg/kg. The results of our study show the persistence of mild to moderate iodine deficiency in Bosnia and Herzegovine Federation. Therefore according to the recommendations of the World Health Organisation, UNICEF and International Council for Control of Iodine Deficiency Disorders, the salt for human, and animal consumption as well as for food industry which is consuming on its teritory, has to be iodinated on the place of its production without looking back whether or not it is produced or imported in Bosnia and Herzegovina Federation, lodination has to be performed with 20 to 30 mg KI per one kg of salt, thereby an average the iodine content has to be 25 mg per kg. In this way it will be prevented the wide spectrum of disorders, which we often are not aware for that its are caused by iodine deficiency. In addition it will be prevented many very important socioeconomical consequences of iodine deficiency.

Financing of dental health care in the Federation of Bosnia and Herzegovina.

Financing dental health care in the Federation of Bosnia and Herzegovina (FBH) over the last 10 years was analyzed with respect to time before the war, during the 1992-1995 war, and after the war. In the first period (until 1991) the system was centralized, well structured, financed through the communities of interest, and burdened with a lack of financial discipline and high inflation. By the end of 1991, all citizens in the territory of BH Federation had the right to dental health insurance and participated in the price of dental service with 10-50%. During the 1992-1995 war, insurance and financial institutions ceased their work until the establishment of civilian governing authorities. The system of dental services was legalized within the health system as its integral part, yet, because of insufficient financial support, the rights of the insured were not fulfilled. Following the Dayton Peace Agreement in 1995, two systems (Croat and Muslim) were in function in FBH, each based on different legal grounds, and dental care stagnated considerably. The 1997 FBH Law on Health Care and Health Insurance and the Law on the Privatization of companies introduced a unique health system, widening the sources of financing and categories of health insurance. The process of health care privatization has been legalized, but not yet implemented. Lack of definitions of ownership diminish foreign investments, and without foreign financial support the improvements will be slower than needs. The process of health care restructuring will thus directly depend on the solving the political crisis in the country.

Doctor in the house: trends in GPs home visiting in Croatia 1990-1995 compared to current trends in USA and UK.

During the period of intensive economic, political and epidemiological transition in Croatia (1990-1995), significant changes in patterns, intensity and organization of home visiting were registered and reported. Quantitative instruments were employed to determine changes in trends of financing, health manpower policy and use of services before and after 1993 health care reforms. The qualitative part of research (e.g., cross-sectional and cross-national comparison of trends) was used to compare the significance of a reduction in the number of home visits as well as how its pattern fitted into the international trends (outburst of home visits in the USA and stagnation or decrease in the UK).

Cerebral hemodynamics following internal maxillary artery ligation in the goat.

Changes in cerebral and extracerebral blood flow in the goat after ligation of the internal maxillary artery and deliberate thrombosis of the extracerebral arteries (buccinator, ethmoidal, and ophthalmic) with thrombin were compared to changes seen in animals after internal maxillary artery ligation only and in normal animals where no surgical manipulations were performed. Blood flow was measured by injecting 51-Cr-labeled microspheres into the internal maxillary artery via a catheter placed into the temporal artery. Analysis of the radioactivity in extracerebral and intracerebral tissues indicated that when the internal maxillary artery is ligated and the extracerebral arteries are thrombosed, virtually all of the blood flow from the carotid artery is destined from the brain. However, if only the internal maxillary artery is ligated nearly one-fourth of the blood flow from the maxillary travels to extra-cerebral tissues. In normal animals, it was determined that only one-fourth of the blood flow in the internal maxillary is destined for the cerebral circulation. Results from this study indicate that if the former method is employed an accurate measure of cerebral blood flow is possible without the complications of extra-cerebral flow. If the latter technique is used care must be taken in evaluating cerebral blood flow since a large component of extra-cerebral blood flow is present.