Characterization of Micro-Threaded Stem Taper Surfaces of Cementless Hip Endoprostheses.

We investigated micro-threaded stem taper surface and its impact on premature failures, aseptic loosening, and infection in cementless hip endoprostheses. Our study focused on the fretting, and crevice corrosion of micro-threaded tapers, as well as the characterization of the microstructure and surface properties of two new and three retrieved Zweymüller stem tapers. The retrieved samples were selected and examined based on the head-stem taper interface being the sole source of modularity with a metallic component, specifically between the Ti alloy taper stem and the ceramic head. To determine the surface chemistry and microstructures of both new and retrieved hip endoprostheses stem taper titanium alloy, scanning -electron microscopy (SEM) was employed for morphological and microstructural analyses. Energy dispersive spectroscopy (EDS) was utilized for characterizing chemical element distribution, and electron backscattered diffraction (EBSD) was used for phase analysis. The roughness of the micro-threated stem tapers from different manufacturers was investigated using an optical profilometer, with standard roughness parameters Ra (average surface roughness) and Rz (mean peak to valley height of the roughness profile) being measured. Electrochemical studies revealed no fretting corrosion in retrieved stem tapers with ceramic heads. Consequently, three retrieved tapers and two new ones for comparison underwent potentiodynamic measurements in Hank's solution to determine the corrosion rate of new and retrieved stem taper surfaces. The results showed a low corrosion rate for both new and prematurely failed retrieved samples due to aseptic loosening. However, the corrosion rate was higher in infected and low-grade infected tapers. In conclusion, our study suggests that using ceramic heads reduces taper corrosion and subsequently decreases the incidence of premature failures in total hip arthroplasty.

The Impact of Al2O3 Particles from Grit-Blasted Ti6Al7Nb (Alloy) Implant Surfaces on Biocompatibility, Aseptic Loosening, and Infection.

For the improvement of surface roughness, titanium joint arthroplasty (TJA) components are grit-blasted with Al2O3 (corundum) particles during manufacturing. There is an acute concern, particularly with uncemented implants, about polymeric, metallic, and corundum debris generation and accumulation in TJA, and its association with osteolysis and implant loosening. The surface morphology, chemistry, phase analysis, and surface chemistry of retrieved and new Al2O3 grit-blasted titanium alloy were determined with scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and confocal laser fluorescence microscopy, respectively. Peri-prosthetic soft tissue was studied with histopathology. Blasted retrieved and new stems were exposed to human mesenchymal stromal stem cells (BMSCs) for 7 days to test biocompatibility and cytotoxicity. We found metallic particles in the peri-prosthetic soft tissue. Ti6Al7Nb with the residual Al2O3 particles exhibited a low cytotoxic effect while polished titanium and ceramic disks exhibited no cytotoxic effect. None of the tested materials caused cell death or even a zone of inhibition. Our results indicate a possible biological effect of the blasting debris; however, we found no significant toxicity with these materials. Further studies on the optimal size and properties of the blasting particles are indicated for minimizing their adverse biological effects.

Information and communication technology used by people with lower limb loss in Slovenia.

World demography is changing as the population ages and there are more people with disabilities having problems to stay independently at home. Innovative technologies could help extend the independence of older people living at home. As part of a collaborative project, we investigated ownership and use of information and communication technologies (ICT) among older people with lower limb loss (LLL) using questionnaires and retrospective analysis. Our aim was to analyse factors associated with ICT use among people with LLL. We identified age as the main factor that limits ownership and use of ICT among older people with LLL in Slovenia. Cause of amputation also appears to be relevant, whereby those who had amputation because of peripheral vascular disease are more likely to use a personal or tablet computer, social networks, messaging apps, email and internet than those who had amputation because of diabetes. In addition, those living in the suburbs are more likely to use a health monitoring device than those living in the countryside.

An empirical evaluation of a hands-free computer interaction for users with motor disabilities.

Standard computer input devices such as a mouse or a keyboard are not well suited to the needs of users with severe motor disabilities in their interaction with standard computer interfaces. The emergence of contemporary human computer interfaces has allowed for the development of innovative solutions for hands-free Human-Computer Interaction (HCI), which can improve the quality and accessibility of Information and Communication Technology (ICT) for motor-impaired users. The objectives of this study were to design, develop and evaluate a solution for a hands-free HCI, based on the Emotiv EPOC+ device, which, among other capabilities, also enables controlling the computer with facial expressions and motion sensors. Ten non-disabled adults and eight adults with a severe motor disability participated in an experiment to evaluate the proposed HCI solution. Eighteen users completed six experimental tasks successfully using both their existing computer use approach as well as the proposed hands-free computer use approach. The times necessary to complete the tasks were measured and analyzed, along with users' subjective observations about the difficulty level of both computer use approaches. Users' perceptions about the new hands-free computer use approach were assessed as well. Although there were no significant differences in both user types regarding the difficulty level in completing the tasks, disabled users solved the tasks with less effort. Positive perceptions about perceived usefulness, ease of use, appropriateness of the technology, and satisfaction with the proposed solution for touchless interaction were assessed for both user types. Scores were significantly higher for disabled users in the case of measuring the perceived usefulness, perceived ease of use and satisfaction with the solution. This study showed that users with severe motor difficulties find new HCI less challenging compared to their existing computer use approach than the non-disabled who use standard HCI. When compared with non-disabled users, the disabled ones can be equally effective when confronted with a new HCI technology. Future work is needed to improve the proposed solution and to analyze the impact of different factors on users with motor disabilities and their adoption of an innovative technology for touchless interaction with a computer.

Simple and choice reaction times of healthy adults and patients after stroke during simulated driving.

We examined whether driving-related reaction times differ between 26 healthy adults (university students) and 26 patients after stroke, and how distractors and leg-dominance affect reaction time and correctness of reactions of healthy adults. Reaction times were measured with the Fiat Mediatester driving simulator using 18-lamps reaction test (simple reaction time measurement) and choice reaction test (scored as reaction time and number of correct reactions). There was no statistically significant difference between the groups in simple reaction time. As expected, choice reaction times of the healthy adults were shorter on average and their reactions more accurate than those of the patients. Under the influence of distractors, healthy adults had statistically significantly longer choice and simple reaction times and made fewer correct choices compared to normal conditions. Leg dominance statistically significantly affected choice reaction times and correctness of reactions, but not simple reaction times. Our results confirm validity and usefulness of the Fiat Mediatester driving simulator for research purposes.