Leader-Follower Approach for Non-Holonomic Mobile Robots Based on Extended Kalman Filter Sensor Data Fusion and Extended On-Board Camera Perception Controlled with Behavior Tree.

This paper presents a leader-follower mobile robot control approach using onboard sensors. The follower robot is equipped with an Intel RealSense camera mounted on a rotating platform. Camera observations and ArUco markers are used to localize the robots to each other and relative to the workspace. The rotating platform allows the expansion of the perception range. As a result, the robot can use observations that are not within the camera's field of view at the same time in the localization process. The decision-making process associated with the control of camera rotation is implemented using behavior trees. In addition, measurements from encoders and IMUs are used to improve the quality of localization. Data fusion is performed using the EKF filter and allows the user to determine the robot's poses. A 3D-printed cuboidal tower is added to the leader robot with four ArUco markers located on its sides. Fiducial landmarks are placed on vertical surfaces in the workspace to improve the localization process. The experiments were performed to verify the effectiveness of the presented control algorithm. The robot operating system (ROS) was installed on both robots.

Nickel ions influence the transepithelial sodium transport in the trachea, intestine and skin.

Measurements of transepithelial potential and resistance in tissue and organ model systems enable the evaluation of the Ni2+ effect on the epithelial sodium channels, aquaporin 3, and the sodium-potassium pump in the epithelial cells. The aim of the presented study was to assess the immediate and prolonged effect of nickel ions on the transport of sodium ions in tissues exposed to direct contact with nickel, including airways, digestive tract and the skin. The influence of 0.1 mM nickel solution was performed on the trachea (n = 34), intestine (n = 44), and skin (n = 51) samples descended from 16 New Zealand albino rabbits. The electrophysiological parameters were measured in a modified Ussing chamber in stationary conditions and during a 15-s mechanical-chemical stimulation. A statistically significant decrease in the electric resistance values and the smallest range of the measured potential were observed for the Ni-treated trachea specimens. The use of nickel solution did not affect the sodium transport in the intestine epithelium. The skin fragments showed altered sodium ion transport, as demonstrated by the lower range and intensity of the measured potential. The gastrointestinal tract seems to be an organ best adapted to contact with nickel ions. In airways, nickel ions most likely enter epithelial cells and the space between them, modifying proteins and the airway surface liquid. The skin turned out to be the most sensitive tissue to the intensification of sodium ion transport through nickel ions.

Assessment of the post-SARS-CoV-2 vaccination response depending on the epidemiological status, demographic parameters and levels of selected cytokines in medical personnel.

Introduction: SARS-CoV-2 is responsible for causing the COVID-19 disease, which affected 174 million people worldwide. After vaccines were launched, the focus was on their effectiveness and the degree of their safety. Aim: The authors try to find factors that may affect the response to vaccination. Material and methods: The study was conducted in 47 adults (39 women and 8 men; age: 47.3 ±11.2). Participants were vaccinated with two doses of the Comirnaty mRNA vaccine. Each patient had a medical history taken and the concentration of specific sIgG antibodies against S1 protein and SARS-CoV-2 N protein, as well as of selected cytokines (IL-8, TGF-ß, IFN-γ) was determined before and 3 weeks after the first and second dose of the vaccine. Results: There were 18 convalescents among the respondents. A statistically significant increase in the concentration of specific sIgG S1 in subsequent determinations was observed. Higher levels of sIgG S1 were found after the first dose of the vaccine in COVID-19 convalescents. There was no statistically significant influence of age, body mass index and sex on the increase in the concentration of antibodies and the concentration of the determined cytokines. It was shown that the higher the initial TGF-ß concentration, the greater the increase in sIgG S1 after administration of the vaccine. Conclusions: Vaccination did not increase the levels of IL-8, IFN-ß and TGF-γ. A higher concentration of serum TGF-ß before vaccination correlated with the higher concentration of sIgG S1 antibodies after the first dose of the vaccine.

Layer-Specific Damage Modeling of Porcine Large Intestine under Biaxial Tension.

The mechanical behavior of the large intestine beyond the ultimate stress has never been investigated. Stretching beyond the ultimate stress may drastically impair the tissue microstructure, which consequently weakens its healthy state functions of absorption, temporary storage, and transportation for defecation. Due to closely similar microstructure and function with humans, biaxial tensile experiments on the porcine large intestine have been performed in this study. In this paper, we report hyperelastic characterization of the large intestine based on experiments in 102 specimens. We also report the theoretical analysis of the experimental results, including an exponential damage evolution function. The fracture energies and the threshold stresses are set as damage material parameters for the longitudinal muscular, the circumferential muscular and the submucosal collagenous layers. A biaxial tensile simulation of a linear brick element has been performed to validate the applicability of the estimated material parameters. The model successfully simulates the biomechanical response of the large intestine under physiological and non-physiological loads.

Influence of High-Pressure Die Casting Parameters on the Cooling Rate and the Structure of EN-AC 46000 Alloy.

The paper presents the results of the research on the impact of process parameters of high-pressure, cold-chamber die casting of an industrial casting made of aluminium alloy on the casting properties assessed macroscopically by measuring the casting average density and microscopically through the characteristics of the casting microstructure. The analysis covers the influence of three selected velocity settings of the pressing plunger, which determine the filling time, and three values of the compression pressure setting characteristic of the third phase of the casting process. The cooling and solidification simulations of the casting were performed using the ProCAST software. During the simulation tests, the impact of the filling rate of the alloy into the die cavity on the cooling rate and the alloy solidification path at selected points were determined. The conducted research allowed linking the process parameters with the parameters of the casting structure with different wall thicknesses. Metallographic examinations of the castings were carried out using a light microscopy, SEM, and EDS analysis. The fraction of the phases α(Al), the size of dendritic cells, and the size of silicon particles, in the cross-sections of the castings with wall thickness of 3, 6, and 11 mm, respectively, were determined.

Analysis of Peripheral Blood Mononuclear Cells Gene Expression Highlights the Role of Extracellular Vesicles in the Immune Response following Hematopoietic Stem Cell Transplantation in Children.

Hematopoietic stem cell transplantation (HSCT) is an effective treatment method used in many neoplastic and non-neoplastic diseases that affect the bone marrow, blood cells, and immune system. The procedure is associated with a risk of adverse events, mostly related to the immune response after transplantation. The aim of our research was to identify genes, processes and cellular entities involved in the variety of changes occurring after allogeneic HSCT in children by performing a whole genome expression assessment together with pathway enrichment analysis. We conducted a prospective study of 27 patients (aged 1.5-18 years) qualified for allogenic HSCT. Blood samples were obtained before HSCT and 6 months after the procedure. Microarrays were used to analyze gene expressions in peripheral blood mononuclear cells. This was followed by Gene Ontology (GO) functional enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and protein-protein interaction (PPI) analysis using bioinformatic tools. We found 139 differentially expressed genes (DEGs) of which 91 were upregulated and 48 were downregulated. "Blood microparticle", "extracellular exosome", "B-cell receptor signaling pathway", "complement activation" and "antigen binding" were among GO terms found to be significantly enriched. The PPI analysis identified 16 hub genes. Our results provide insight into a broad spectrum of epigenetic changes that occur after HSCT. In particular, they further highlight the importance of extracellular vesicles (exosomes and microparticles) in the post-HSCT immune response.

FTO and PLAG1 Genes Expression and FTO Methylation Predict Changes in Circulating Levels of Adipokines and Gastrointestinal Peptides in Children.

Adipokines and gastrointestinal tract hormones are important metabolic parameters, and both epigenetic factors and differential gene expression patterns may be associated with the alterations in their concentrations in children. The function of the FTO gene (FTO alpha-ketoglutarate dependent dioxygenase) in the regulation of the global metabolic rate is well described, whereas the influence of protooncogene PLAG1 (PLAG1 zinc finger) is still not fully understood. A cross-sectional study on a group of 26 children with various BMI values (15.3-41.7; median 28) was carried out. The aim was to evaluate the dependencies between the level of methylation and expression of aforementioned genes with the concentration of selected gastrointestinal tract hormones and adipokines in children. Expression and methylation were measured in peripheral blood mononuclear DNA by a microarray technique and a restriction enzyme method, respectively. All peptide concentrations were determined using the enzyme immunoassay method. The expression level of both FTO and PLAG1 genes was statistically significantly related to the concentration of adipokines: negatively for apelin and leptin receptor, and positively for leptin. Furthermore, both FTO methylation and expression negatively correlated with the concentration of resistin and visfatin. Cholecystokinin was negatively correlated, whereas fibroblast growth factor 21 positively correlated with methylation and expression of the FTO gene, while FTO and PLAG1 expression was negatively associated with the level of cholecystokinin and glucagon-like peptide-1. The PLAG1 gene expression predicts an increase in leptin and decrease in ghrelin levels. Our results indicate that the FTO gene correlates with the concentration of hormones produced by the adipose tissue and gastrointestinal tract, and PLAG1 gene may be involved in adiposity pathogenesis. However, the exact molecular mechanisms still need to be clarified.

Steroid Receptors in Breast Cancer: Understanding of Molecular Function as a Basis for Effective Therapy Development.

Breast cancer remains one of the most important health problems worldwide. The family of steroid receptors (SRs), which comprise estrogen (ER), progesterone (PR), androgen (AR), glucocorticoid (GR) and mineralocorticoid (MR) receptors, along with a receptor for a secosteroid-vitamin D, play a crucial role in the pathogenesis of the disease. They function predominantly as nuclear receptors to regulate gene expression, however, their full spectrum of action reaches far beyond this basic mechanism. SRs are involved in a vast variety of interactions with other proteins, including extensive crosstalk with each other. How they affect the biology of a breast cell depends on such factors as post-translational modifications, expression of coregulators, or which SR isoform is predominantly synthesized in a given cellular context. Although ER has been successfully utilized as a breast cancer therapy target for years, research on therapeutic application of other SRs is still ongoing. Designing effective hormone therapies requires thorough understanding of the molecular function of the SRs. Over the past decades, huge amount of data was obtained in multiple studies exploring this field, therefore in this review we attempt to summarize the current knowledge in a comprehensive way.

A literature review on large intestinal hyperelastic constitutive modeling.

Impacts, traumas and strokes are spontaneously life-threatening, but chronic symptoms strangle patient every day. Colorectal tissue mechanics in such chronic situations not only regulates the physio-psychological well-being of the patient, but also confirms the level of comfort and post-operative clinical outcomes. Numerous uniaxial and multiaxial tensile experiments on healthy and affected samples have evidenced significant differences in tissue mechanical behavior and strong colorectal anisotropy across each layer in thickness direction and along the length. Furthermore, this study reviewed various forms of passive constitutive models for the highly fibrous colorectal tissue ranging from the simplest linearly elastic and the conventional isotropic hyperelastic to the most sophisticated second harmonic generation image based anisotropic mathematical formulation. Under large deformation, the isotropic description of tissue mechanics is unequivocally ineffective which demands a microstructural based tissue definition. Therefore, the information collected in this review paper would present the current state-of-the-art in colorectal biomechanics and profoundly serve as updated computational resources to develop a sophisticated characterization of colorectal tissues.

Methylation and Expression of FTO and PLAG1 Genes in Childhood Obesity: Insight into Anthropometric Parameters and Glucose-Lipid Metabolism.

The occurrence of childhood obesity is influenced by both genetic and epigenetic factors. FTO (FTO alpha-ketoglutarate dependent dioxygenase) is a gene of well-established connection with adiposity, while a protooncogene PLAG1 (PLAG1 zinc finger) has been only recently linked to this condition. We performed a cross-sectional study on a cohort of 16 obese (aged 6.6-17.7) and 10 healthy (aged 11.4-16.9) children. The aim was to evaluate the relationship between methylation and expression of the aforementioned genes and the presence of obesity as well as alterations in anthropometric measurements (including waist circumference (WC), body fat (BF_kg) and body fat percent (BF_%)), metabolic parameters (lipid profile, blood glucose and insulin levels, presence of insulin resistance) and blood pressure. Expression and methylation were measured in peripheral blood mononuclear cells using a microarray technique and a method based on restriction enzymes, respectively. Multiple regression models were constructed to adjust for the possible influence of age and sex on the investigated associations. We showed significantly increased expression of the FTO gene in obese children and in patients with documented insulin resistance. Higher FTO expression was also associated with an increase in WC, BF_kg, and BF_% as well as higher fasting concentration of free fatty acids (FFA). FTO methylation correlated positively with WC and BF_kg. Increase in PLAG1 expression was associated with higher BF%. Our results indicate that the FTO gene is likely to play an important role in the development of childhood adiposity together with coexisting impairment of glucose-lipid metabolism.

An in vitro comparison of flow dynamics of the Magna Ease and the Trifecta prostheses.

Objectives: We aimed to compare the in vitro flow dynamics of the Perimount Magna Ease™ (PME) and the Trifecta™ (TF) bioprostheses.Material and methods: A new flow chamber was designed to compare the flow patterns of the PME (Edwards Lifesciences, Irvine, CA, USA) and the TF (SJM, St. Paul, MN, USA) aortic valve prostheses. This new channel offered the possibility of 2D-particle-image-velocimetry (2D-PIV) to completely evaluate the flow field downstream from the aortic valve to the middle of the aortic arch. Maximum average velocities, vorticity, shear strength, maximum orifice diameters and jet flow diameters were analyzed. Valve sizes of 21, 23 and 25 mm were evaluated.Results: Average velocity values, shear strength and vorticities were smaller in the flow field of the TF (maximum average velocity: 0.81 ± 0.03m/s, PME 23 mm vs. 0.7 ± 0.02m/s TF 23 mm, P < .001) under pulsatile flow conditions (70 Hz, 70 mL stroke volume). The evaluation of the upper orifice area revealed bigger maximum diameters during the peak flow phase for the TF, but more leaflet-flutter.Conclusions: Our flow chamber allowed a precise and highly sensitive characterization and comparison of complex fluid dynamics of different aortic valve prostheses. Both the Trifecta™ and the Perimount Magna Ease™ showed a good performance on a high level.

The Fluid Dynamical Performance of the Carpentier-Edwards PERIMOUNT Magna Ease Prosthesis.

The aim of the present in vitro study was the evaluation of the fluid dynamical performance of the Carpentier-Edwards PERIMOUNT Magna Ease depending on the prosthetic size (21, 23, and 25 mm) and the cardiac output (3.6-6.4 L/min). A self-constructed flow channel in combination with particle image velocimetry (PIV) enabled precise results with high reproducibility, focus on maximal and local peek velocities, strain, and velocity gradients. These flow parameters allow insights into the generation of forces that act on blood cells and the aortic wall. The results showed that the 21 and 23 mm valves have a quite similar performance. Maximal velocities were 3.03 ± 0.1 and 2.87 ± 0.13 m/s; maximal strain Exx , 913.81 ± 173.25 and 896.15 ± 88.16 1/s; maximal velocity gradient Eyx , 1203.14 ± 221.84 1/s and 1200.81 ± 61.83 1/s. The 25 mm size revealed significantly lower values: maximal velocity, 2.47 ± 0.15 m/s; maximal strain Exx , 592.98 ± 155.80 1/s; maximal velocity gradient Eyx , 823.71 ± 38.64 1/s. In summary, the 25 mm Magna Ease was able to create a wider, more homogenous flow with lower peak velocities especially for higher flow rates. Despite the wider flow, the velocity values close to the aortic walls did not exceed the level of the smaller valves.

Oral mucosa lesions and gingival bleeding can indicate the progression of liver disease in children and adolescents aged two to 18 years.

AIM: This study assessed correlations between systemic disturbances of paediatric chronic liver diseases (CLD) and oral symptoms in subjects aged 2-18 years. METHODS: It was carried out during outpatient appointments at the Children's Memorial Health Institute, Warsaw, Poland, from 2010 to 2015 and comprised 52 CLD patients with a mean age of 12.3 ± 4.6. We also recruited 54 generally healthy controls with a mean age of 12.0 ± 3.7 from the Department of Paediatric Dentistry at the Medical University of Warsaw. The study used various measures, including the Child-Pugh score, which assesses CLD prognosis. We also assessed the causes of liver disease and the medication taken by the patients with CLD. RESULTS: A total of 24 patients received a Child-Pugh score of seven or more points, while 28 patients were awarded five or six points. More severe cases of gingivitis and a greater prevalence of oral lesions were evident in patients suffering from liver disease. Oral candidiasis, telangiectasia, bald tongue, cracked strawberry lip, yellowish-brown gum discoloration, petechiae and gingival bleeding all correlated with the severity of liver dysfunction, coagulopathy, protein, bilirubin and creatinine levels and portal hypertension. CONCLUSION: This study found that oral lesions and gingival bleeding may indicate the progression of liver failure.

Geometric analysis and clinical outcome of two cemented stems for primary total hip replacement with and without modular necks.

INTRODUCTION: Restoration of the physiological biomechanical principles of the hip is crucial in total hip replacement. The aim of this study was to compare an arthroplasty system with different offset options (a: Exeter®) with a dual-modular stem (b: Profemur Xm®). MATERIALS AND METHODS: A local and an inertial coordinate system were used to assist the description of the components' assembly in the prosthesis. A resection line of the femoral head in standard position was added to the arthroplasties and geometric parameters were measured. The outcomes of 93 patients were clinically evaluated (a: n = 50, b: n = 43). Preoperative planning was compared to postoperative radiographs (femoral offset, leg-length), and clinical scores (HHS, WOMAC, total range of motion) were assessed preoperatively, and then 1 and 2 years after surgery. RESULTS: The Exeter® offers an offset range from 32.1 to 56.9 mm and the Profemur Xm® a range from 29.3 to 55.3 mm. The leg-length variability of the Profemur Xm® has a range of 25.9 mm, the Exeter® a range of 13.7 mm. The Profemur Xm® offers more possible combinations of offset and leg-length reconstruction. The neck-stem angles of the Exeter® range from 125.2° to 126.3°, of the Profemur Xm® from 127.2° to 142.6°. There was no statistically significant difference in clinical outcome and radiological parameters. CONCLUSIONS: We conclude that both stems offer a wide range of options for anatomical reconstruction of the hip resulting in similarly good clinical results. The Profemur Xm® stem has advantages for the reconstruction of hips that deviate from standard anatomy but has the drawback of additional corrosive wear at the stem/neck interface.

Simultaneous optimisation of earwig hindwings for flight and folding.

Earwig wings are highly foldable structures that lack internal muscles. The behaviour and shape changes of the wings during flight are yet unknown. We assume that they meet a great structural challenge to control the occurring deformations and prevent the wing from collapsing. At the folding structures especially, the wing could easily yield to the pressure. Detailed microscopy studies reveal adaptions in the structure and material which are not relevant for folding purposes. The wing is parted into two structurally different areas with, for example, a different trend or stiffness of the wing veins. The storage of stiff or more flexible material shows critical areas which undergo great changes or stress during flight. We verified this with high-speed video recordings. These reveal the extent of the occurring deformations and their locations, and support our assumptions. The video recordings reveal a dynamical change of a concave flexion line. In the static unfolded state, this flexion line blocks a folding line, so that the wing stays unfolded. However, during flight it extends and blocks a second critical folding line and prevents the wing from collapsing. With these results, more insight in passive wing control, especially within high foldable structures, is gained.

The investigation of systolic and diastolic leaflet kinematics of bioprostheses with a new in-vitro test method.

OBJECTIVES: We aimed to investigate leaflet kinematics of bioprostheses with a novel high-speed imaging method. MATERIAL AND METHODS: High-speed-imaging (1000 Hz) was used to evaluate leaflet kinematics of the Carpentier-Edwards Perimount Magna (PM) and Magna Ease (PME) aortic bioprostheses. Both prostheses (diameter 23 mm) were placed inside a model aorta under pulsatile flow conditions. Frequencies (F) and different stroke volumes (S) were simulated. Maximum aortic valve area (AVA), total ejection time (TET), rapid valve opening time (RVOT) and rapid valve closing time (RVCT) as well as opening (OS) and closing (CS) speeds were evaluated. RESULTS: Both bioprostheses showed different results dependent on flow conditions. The test setup was capable of identifying small AVA-differences between both valves (235 vs. 202 mm², F60/S60; 272 vs. 207 mm²; F70/S80), as well as differences in OS and CS (2.36 vs. 1.62 mm²/ms; 2.97 vs. 2.44 mm²/ms, F80/S60). TET was comparable (638 vs. 645 ms F60/S60; 341 vs. 343 ms, F90/S60), while results for RVOT and RVCT were equal, and dependent on frequency and stroke volume. CONCLUSIONS: The novel evaluation method is sensitive to detect differences between valves, although differences were found to be small. PM has a larger visible AVA associated with higher opening and closing speeds in contrast to PME.

Geometric analysis of an expandable reamer for treatment of avascular necrosis of the femoral head.

"Advanced core decompression" (ACD) is a treatment option for osteonecrosis of the femoral head (ONFH) that aims at complete removal of the necrotic tissue using a percutaneous expandable reamer and refilling of the head with an osteoconductive bone-graft substitute. The objective of this study was to evaluate if the success of ACD depends on the amount of necrotic tissue remaining after the procedure and how efficiently the necrotic tissue can be removed with the current reamer. Three-dimensional models of proximal femora including ONFH were generated from the preoperative MRIs of 50 patients who underwent ACD. Best-case removal was calculated by geometrical analysis. In 28 of 50 cases, postoperative MRI was used to determine how much necrotic tissue had been removed. Prognostic values and correlations were evaluated in order to assess success or failure of the treatment. The amount of preoperative and remaining necrosis correlates significantly with treatment failure. The larger both volumes are, the more likely it is that treatment will fail. In patients with remaining necrosis of less than 1000 mm(3), no treatment failure was observed. The amount of necrosis actually removed differed significantly from the amount calculated as the best possible result. Simulation of the removal procedure showed that complete removal is not possible. These results led to the conclusion that the success of ACD depends on the amount of necrotic tissue remaining in the femoral head after the procedure. Modifications to the instrument are necessary to increase the amount of necrotic tissue that can be removed.

Oral health and liver function in children and adolescents with cirrhosis of the liver.

INTRODUCTION: People with cirrhosis of the liver are predisposed to developing oral lesions. The occurrence and type of lesion depend on the degree of liver function impairment and its type, and on the severity and duration of systemic diseases. In children, the age at which the early symptoms of liver disease are experienced is also of great importance. AIM: To assess the prevalence of oral pathological lesions in children and adolescents with cirrhosis of the liver, and their correlation with the degree of liver function impairment. MATERIAL AND METHODS: Clinical and laboratory results of liver function tests (Model of End-Stage Liver Disease/Score of Paediatric End-Stage Liver Disease, Child-Pugh score) were assessed in 35 patients with cirrhosis of the liver. The average age of the patients was 10.7 ±4.74 years. All patients also had their oral cavities examined (mucosa, gingiva - GI, hygiene - PLI, teeth - dmft/dmfs and DMFt/DMFs, DDE Index and Candida spp. presence) and this was then correlated to the degree of liver function impairment. RESULTS: According to the Child-Pugh scale, 16 patients were class A and 19 were class B/C. Jaundice during the first 3 years of life occurred in 9 patients. Mucosal lesions were found in 26 out of 35 patients (74%), including 10 out of 16 (63%) in Child-Pugh group A, and 16 out of 19 (84%) in group B/C (NS - non significant). Oral candidiasis occurred more often in class B/C than in class A (47.4% vs. 12.5%; p < 0.05). The GI index (Gingival Index) and PLI index (Dental Plaque Index) did not differ between the groups (A vs. B/C) but correlated in the whole group (R = 0.58) as well as in subgroups A (R = 0.65) and B/C (R = 0.59). Dmft/dmfs and DMFt/DMFs indexes did not differ between groups A and B/C, and neither did the DMFt/DMFs in patients with/without enamel defects. CONCLUSIONS: Oral mucosal lesions are commonly found in children with cirrhosis of the liver. Advanced liver disease promotes oral candidiasis. Severity of gingivitis correlates with the presence of dental plaque.

A prospective randomized peri- and post-operative comparison of the minimally invasive anterolateral approach versus the lateral approach.

There is still controversy as to whether minimally invasive total hip arthroplasty enhances the postoperative outcome. The aim of this study was to compare the outcome of patients who underwent total hip replacement through an anterolateral minimally invasive (MIS) or a conventional lateral approach (CON). We performed a randomized, prospective study of 75 patients with primary hip arthritis, who underwent hip replacement through the MIS (n=36) or CON (n=39) approach. The Western Ontario and McMaster Universities Osteoarthritis Index and Harris Hip score (HHS) were evaluated at frequent intervals during the early postoperative follow-up period and then after 3.5 years. Pain sensations were recorded. Serological and radiological analyses were performed. In the MIS group the patients had smaller skin incisions and there was a significantly lower rate of patients with a positive Trendelenburg sign after six weeks postoperatively. After six weeks the HHS was 6.85 points higher in the MIS group (P=0.045). But calculating the mean difference between the baseline and the six weeks HHS we evaluated no significant differences. Blood loss was greater and the duration of surgery was longer in the MIS group. The other parameters, especially after the twelfth week, did not differ significantly. Radiographs showed the inclination of the acetabular component to be significantly higher in the MIS group, but on average it was within the same permitted tolerance range as in the CON group. Both approaches are adequate for hip replacement. Given the data, there appears to be no significant long term advantage to the MIS approach, as described in this study.

Advanced core decompression, a new treatment option of avascular necrosis of the femoral head--a first follow-up.

Aseptic necrosis of the femoral head (AVN) leads to destruction of the affected hip joint, predominantly in younger patients. Advanced core decompression (ACD) is a new technique that may allow better removal of the necrotic tissue by using a new percutaneous expandable reamer. A further modification is the refilling of the drill hole and the defect with an injectable, hard-setting, composite calcium sulphate (CaSO4)-calcium phosphate (CaPO4) bone graft substitute. Compression tests were performed on seven pairs of femoral cadaver bones. One femur of each pair was treated with ACD, while the opposite side remained untreated. Clinically, the postoperative outcome of 27 hips in 23 patients was performed by physical examination 6 weeks after ACD and at average follow-up of 9.69 months, and compared with the preoperative results. MRI was used to assess the removal of the necrotic tissue, any possible progression of AVN and evaluation of collapse. In the biomechanical analysis, the applied maximum compression force that caused the fracture did not significantly differ from the untreated opposite side. The overall results of postoperative physical examinations were significantly better than preoperatively. Five hips (18.5%) were converted to a total hip replacement. The follow-up MRIs of the other patients showed no progression of the necrotic area. The first follow-up results of ACD have been encouraging for the early stages of aseptic necrosis of the femoral head. In our opinion, an assured advantage is the high stability of the femoral neck after ACD, which allows quick rehabilitation.