[Arthroscopic Subtalar Distraction Arthrodesis in Post-Traumatic Indications]

PURPOSE OF THE STUDY

This manuscript aims to present the method of arthroscopic assisted subtalar arthrodesis and to evaluate the benefi ts of this surgery on our study population.

MATERIAL AND METHODS

In the period from 9/2007 to 1/2020, a total of 33 subtalar arthrodesis were performed in 31 patients aged 19-66 years (mean 48 years, median 50 years). The indication for arthrodesis was subtalar arthritis causing pain and gait disorders, or hindfoot deformities (most commonly after a calcaneus bone fracture). The arthroscopic assisted subtalar arthrodesis was performed with autologous tricortical bone block graft harvesting from the pelvis, supplemented by autologous cancellous bone graft. Stabilization was achieved by cannulated screws inserted in neutral ankle position. Patients in our retrospective study were followed up for a mean of 48 months (range, 24-130 months). The patients were evaluated preoperatively and at 2 years after surgery. The hindfoot angles and height (TCA - talocalcaneal angle, CIA - calcaneal inclination angle, TCH - talocalcaneal height) were evaluated on radiographs, bone union was assessed on radiographs and CT scans. The clinical assessment was performed using the ankle-hindfoot scale (AHS) of AOFAS (AOFAS score).

RESULTS

The preoperative AOFAS score was 35-68 points (mean 52, median 54), the postoperative AOFAS score at 2 years after arthrodesis was 58-94 points (mean 82, median 82). Both the mean and median values of AOFAS score showed a signifi - cant progress from the poor result to the good and excellent result. After 2 years the TCA value decreased in 18 patients (56%) by no more than 3°. The CIA decrease observed in 21 patients (64%) was by 1° on average. The TCH decrease of 1-5 mm after 2 years since the surgery was seen in 16 patients. In 2 patients incomplete healing of arthrodesis was observed, manifested as a clinically asymptomatic non-union. No deep infection was reported.

DISCUSSION

In agreement with the current literature, the arthroscopic subtalar arthrodesis has been confi rmed to be a safe method for the management of consequences of hindfoot fractures, with minimum complications and leading to accelerated bone fusion. Differences can be found in the approach, position, use of cancellous bone graft and surgical techniques. In recent years, prone position, posterior approaches, use of cancellous bone graft, distraction and fi xation with 2-3 screws divergently inserted into the bone prevail. The degree of healing of the bone fusion is generally an important factor. In our study population, non-healing was recorded in 2 patients, namely in the form of a clinically silent non-union. Neurological or early complications and/or osteosynthesis material failure occurred in up to a maximum of 10% of cases. The conclusive results of minimally invasive arthrodesis based on the AOFAS score have been confi rmed by us as well as by most authors.

CONCLUSSIONS

Our study confi rmed that the arthroscopic assisted subtalar arthrodesis is a successful, reliable and safe minimally invasive method, with minimum complications, leading to stable arthrodesis.

KEY WORDS

subtalar arthrodesis, subtalar arthroscopy.

Evaluation of Bitumen Modification Using a Fast-Reacting SBS Polymer at a Low Modifier Percentage

The study presented in this paper investigates the application of asphalt bitumen modification using a fast-reacting SBS polymer at a low modifier percentage. The hypothesis is that a fast-reacting styrene-butadiene-styrene (SBS) polymer that composes only 2% to 3% of the weight of the bitumen modification could extend the life of the pavement surfacing and pavement performance at relatively low input costs, increasing the net present value produced by the pavement during its life cycle. To confirm or refute this hypothesis, two types of road bitumens CA 35/50 and 50/70 were modified with low amounts of fast-reacting SBS polymer with the expectation of attaining properties similar to a 10/40-65 modified bitumen. For each type of unmodified bitumen, bitumen modification and comparative 10/40-65 modified bitumen, the following tests were conducted: needle penetration, softening point-ring and ball test method, and ductility test. The second part of the article focuses on a comparison of asphalt mixtures with different compositions of coarse-grain curves. For each mixture, complex modulus with varying temperatures and fatigue resistances are represented by the Wöhler diagram and compared. Based on in labo testing, the impact of the modification on pavement performance is evaluated. Life cycle changes for each type of modified and unmodified mixtures are quantified as road user costs, and attained benefits are compared with increased construction costs.

The Influence of Recycled Materials on Cold Mix with Foamed Bitumen Properties

The utilization of recycled materials is an important issue in the context of environmental protection. The large amounts of recycled material recovered from the demolition of asphalt road structures indicate the need to find new ways of utilizing them. In the case of road renovation projects, large amounts of recycled materials are, in most cases, recovered in the form of reclaimed asphalt pavement (RAP), reclaimed concrete (RC) and recycled aggregate (RA). To focus on the effects of the use of recovered materials (RAP, RC and RA), the same composition was used for all of the analyzed mixtures in terms of foamed bitumen (FB) and Portland cement (CEM) content. The scope of laboratory tests included the specification of the following parameters: the amount of air void content Vm, the determination of axial compression strength at +25 °C, indirect tensile strength (ITS) at +25 °C, water resistance, TSR, water and frost resistance, WR_W+M stiffness modulus (IT-CY) at 13 °C, dynamic dynamicmodulus. The plan of the experiment assumed addition recycled material in quantities between 20% and 80% in increments of 20%. The obtained results indicate that both the type and quantity of recycled material significantly affect the properties of the cold-recycled mixture with foamed bitumen. Using reclaimed asphalt pavement and recycled cement concrete guarantees high levels of stiffness in the recycled mixture. Howeverin the case of recycled aggregate, the authors did not observe any visible changes in the dynamicdynamic modulus, irrespective of the loading conditions. It was also indicated that it is necessary to reduce the quantity of reclaimed asphalt pavement in the composition of the FB-RCM mix to maintain the required air void content.

Composition Optimisation of Selected Waste Polymer-Modified Bitumen

Waste plastomer disposal is currently a major challenge facing modern economies. This article reports on a study and analysis regarding the implementation of plastomers into bitumen, with a special focus on the influence of mixing process factors. Two plastomers were selected for analysis, PP and PET, and two bitumen types, 20/30 and 70/100, were modified. Determination of the basic characteristics, such as penetration, softening temperature, cohesion energy, and Fraass temperature, was complemented with advanced multiple-stress creep recovery (MSCR) rheological testing. The entire experimental process followed the Plackett−Burman design. Rheological effects of modified bitumen were evaluated using the generalized Maxwell model. Microstructural analysis with epi-fluorescence microscopy showed the ability of plastomer-modified bitumen to obtain a fine-grained structure with a particle size of <10 μm. In addition, creep susceptibility (Jnr) was found to be statistically significantly dependent on the polymer type and particle size, rotational speed, and bitumen type. In turn, the particle dispersion structure in the bitumen matrix significantly depended on the rotational speed, plastomer particle size, and mixing temperature. Ultimately, the process of bitumen 70/100 modification was optimized. It was demonstrated, following the experimental design, that by using fine-grained PP for a temperature of 160 °C, rotational speed of about 6300 rpm and time of 105 min, it is possible to obtain modified bitumen with rheological properties very similar to those of modified bitumen PmB 45/80-55.

The Relationship between Dynamic and Static Deformation Modulus of Unbound Pavement Materials Used for Their Quality Control Methodology

In the present study, credible analytical and numerical models are developed in order to explain the apparent discrepancies in the ratios of static and dynamic deformation models for assessing the quality of mechanical efficiency of transport structures in Central Europe. Through of experience, authors specifically deal with the comparison of two commonly used methods: the dynamic load plate test, known as the lightweight dynamic test and the static plate load test. This paper presents the relevant correlation dependency of the most commonly used quantification characteristics in earthworks quality control. Their correlation was obtained by applying the static theory of impact to earthworks quality control, which allows for the application of several quality control methods, in line with other member states of the European Union, specifically with regard to constructions under various boundary conditions (climate, soil moisture of the specified layer). According to an analysis of the results of comparisons of static and dynamic load tests, analytical and numerical models of the subsoil formed by soils and uncemented structural materials, respectively, the linear calculation usually used in the conditions of Central Europe does not have universal validity. Rather than relying on the analytical and FEM models for the soil, the authors have determined that the above dependence is a power dependence.

[Management of care of HIV-positive pregnant women in the period 1996-2014]

OBJECTIVE

The evaluation of multidisplinary care about HIV positive pregnant women in the Czech Republic.

DESIGN

Review.

SETTINGS

Gynekologicko-porodnická klinika 1. LF UK a Nemocnice na Bulovce, Praha.

METHODS

The vertical transmission of HIV infection from mother to fetus occurs most often during birth, still 1-2% of HIV-positive pregnant women will transfer the virus transplacenta. Due to careful screening for HIV during pregnancy, counselling, combination antiretroviral (cART) therapy, childbirth planning and its performance by C-section there appears a significant decrease of the virus transmission to the fetus, its occurrence is around 2%. If the HIV infection is detected in the context of screening for sexually transmitted infections (STIs), we begin with combined antiretroviral therapy (cART) depending on the level of viremia and CD4 as soon as possible. All HIV-positive pregnancies are tested for possible coinfection with hepatitis C. Since the first application of the antiretroviral treatment, the therapy is applies throughout the duration of the pregnancy. The labours of the HIV- positive women in the Czech Republic are scheduled. The primary choice is a caesarean section during the 38th week of pregnancy.

CONCLUSION

From 1996-2014 the HIV positive status at 18 months of child age was confirmed in 4 cases in the Czech Republic. Three children were born to mothers whose HIV status was unknown at the time of the birth. Thanks to strict adherence to the interdisciplinary care, HIV positive woman have a chance to deliver a HIV-negative newborn and the risk of the transmission of the virus is significantly low.