Biocompatibility Evaluation of PEO-treated Magnesium Alloy Implants Placed in Rabbit Femur Condyle Notches and Paravertebral Muscles

Background: Magnesium alloys have been receiving much attention for use in biodegradable metal implants because of their excellent mechanical properties and biocompatibility. However, their rapid breakdown and low bioactivity can cause the implant to lose mechanical integrity before the bone is completely healed. Moreover, hydrogen gas released during degradation can significantly delay the tissue regeneration process. To solve the instability of magnesium alloys, Zn and Ca can be added to improve the mechanical properties and biocompatibility. One other way to improve the mechanical properties of Mg is plasma electrolytic oxidation (PEO), which provides a dense, thick ceramic-like coating on the Mg surface. In this study, high-purity Mg was selected as the control, and Mg-1wt%Zn-0.1wt%Ca alloy and PEO-treated Mg-1wt%Zn-0.1wt%Ca alloy were selected as the test materials; the results of radiographic and histological analyses of their biocompatibility are reported herein. Materials and method: Nineteen New Zealand white rabbits were used in the study. Rod-bars (Ø2.7x13.6mm) were placed on both paravertebral muscles, and cannulated screws (Ø2.7x10mm) were placed on both femur condyle notches. Each animal was implanted in all four sites. X-rays were taken at 0, 2, 4, 8, and 12 weeks, micro-CT, and live-CT were taken at 4, 8, and 12 weeks. At weeks 4, 8, and 12, individuals representing each group were selected and sacrificed to prepare specimens for histopathological examination. Result: The results confirm that in vivo, Mg-1wt%Zn-0.1wt%Ca alloy had higher corrosion resistance than high-purity Mg and safely degraded over time without causing possible side effects (foreign body or inflammatory reactions, etc.). In addition, PEO treatment of Mg-1wt%Zn-0.1wt%Ca alloy had a positive effect on fracture recovery by increasing the bonding area with bone. Conclusion: Our results suggest that PEO treatment of Mg-1wt%Zn-0.1wt%Ca alloy can be a promising biomaterials in the field of various clinical situations such as orthopedic and maxillofacial surgerys.

Association between Neurologic Outcomes and Changes of Muscle Mass Measured by Brain Computed Tomography in Neurocritically Ill Patients

This study aimed to investigate whether skeletal muscle mass estimated via brain computed tomography (CT) could predict neurological outcomes in neurocritically ill patients. This is a retrospective, single-center study. Adult patients admitted to the neurosurgical intensive care unit (ICU) from January 2010 to September 2019 were eligible. Cross-sectional areas of paravertebral muscles at the first cervical vertebra level (C1-CSA) and temporalis muscle thickness (TMT) on brain CT were measured to evaluate skeletal muscle mass. The primary outcome was the Glasgow Outcome Scale score at 3 months. Among 189 patients, 81 (42.9%) patients had favorable neurologic outcomes. Initial and follow-up TMT values were higher in patients with favorable neurologic outcomes compared to those with poor outcomes (p = 0.003 and p = 0.001, respectively). The initial C1-CSA/body surface area was greater in patients with poor neurological outcomes than in those with favorable outcomes (p = 0.029). In multivariable analysis, changes of C1-CSA and TMT were significantly associated with poor neurological outcomes. The risk of poor neurologic outcome was especially proportional to changes of C1-CSA and TMT. The follow-up skeletal muscle mass measured via brain CT at the first week from ICU admission may help predict poor neurological outcomes in neurocritically ill patients.

Limitations of Muscle Ultrasound Shear Wave Elastography for Clinical Routine—Positioning and Muscle Selection

Shear wave elastography (SWE) is a clinical ultrasound imaging modality that enables non-invasive estimation of tissue elasticity. However, various methodological factors—such as vendor-specific implementations of SWE, mechanical anisotropy of tissue, varying anatomical position of muscle and changes in elasticity due to passive muscle stretch—can confound muscle SWE measurements and increase their variability. A measurement protocol with a low variability of reference measurements in healthy subjects is desirable to facilitate diagnostic conclusions on an individual-patient level. Here, we present data from 52 healthy volunteers in the areas of: (1) Characterizing different limb and truncal muscles in terms of inter-subject variability of SWE measurements. Superficial muscles with little pennation, such as biceps brachii, exhibit the lowest variability whereas paravertebral muscles show the highest. (2) Comparing two protocols with different limb positioning in a trade-off between examination convenience and SWE measurement variability. Repositioning to achieve low passive extension of each muscle results in the lowest SWE variability. (3) Providing SWE shear wave velocity (SWV) reference values for a specific ultrasound machine/transducer setup (Canon Aplio i800, 18 MHz probe) for a number of muscles and two positioning protocols. We argue that methodological issues limit the current clinical applicability of muscle SWE.

Personalized multitarget biologic injection in the spine: prospective case series of multitarget platelet-rich plasma for low back pain

Aim: To evaluate the use of a multitarget platelet-rich plasma (PRP) injection approach for the treatment of chronic low back pain (LBP). Materials & Methods: Forty-six patients with more than 12 weeks of LBP who failed conservative treatments were injected with PRP into the facet joints, intervertebral discs, epidural space and/or paravertebral muscles. Visual analog pain scale and Roland-Morris Disability Questionnaire scores were measured at baseline and predefined intervals. Results: Mean visual analog pain scale was reduced from 8.48 to 5.17 and mean Roland-Morris Disability Questionnaire from 18.0 to 10.98 at 12 weeks (p < 0.001). These statistically significant improvements were sustained over 52 weeks. No adverse effects were observed. Conclusion: Our PRP approach demonstrated clinically favorable results and may be a promising treatment for chronic LBP.

Hordeum murinum aspiration revealed by a pneumopleurocutaneous fistula in a 15-month-old infant

Background Hordeum murinum is a specie of grass rarely reported among the aspirated foreign body. It has high tissue penetration power and may cause lung damages. Case presentation We report the case of a 15-month-old girl who choke while playing in the grass without any evident cause. This episode was immediately followed by vomiting and coughing with traces of blood. While she was fine during the following week, she relapsed at day (D) 7 with fever. At D10, she was finally hospitalized for signs of respiratory distress. The chest CT-scan revealed a voluminous right sub pleural empyema with an aerial component, responsible for the collapse of the right lower lobe, and complicated by a pneumopleurocutaneous fistula to the right paravertebral muscles. Intravenous antibiotics were prescribed, but no invasive procedure was performed. At D18, the spikelet of a false barley spontaneously externalized through the fistula. Evolution was favorable thereafter with disappearance of the fever and progressive decrease of the biological inflammatory syndrome. The follow-up at 4 months was reassuring, with normal clinical evaluation, and complete regression of the empyema on the chest X-rays. Conclusions Hordeum murinum is a rare type of foreign body, and the aspiration often goes unnoticed. In these peculiar cases, CT-scans can be as informative as bronchoscopies, and the evolution is usually favorable after fistulization.

Evaluating the Effectiveness of Distance Learning Physical Education for Disabled Students

The article discusses the effectiveness of the application of the distance learning program at the level of the functional state and reserve capacities of the organism of students with disabilities: for 12 students of 17-19 years old with idiopathic structural scoliosis of II and III degrees of S-shaped type, engaged in a full-time program (stage I) and for the same students studying remotely (stage II), it was studied the functional indicators of the cardiovascular and autonomic nervous system, the function of external respiration, the tone of the paravertebral muscles of the back and neck, as well as indicators of strength and endurance. Then a comparison was made of the studied indicators of stages I and II. It is shown that distance learning has a negative impact on the health of students: hypertonicity of the muscles of the back and neck significantly increases almost twice (the most sensitive is the cervicothoracic region), there is a shift of autonomic tone by 10.73% towards sympathicotonia: heart rate blood pressure increased by 19.06% by 7.9%, respiratory rate by 7.92%, tidal and minute volumes by 17.8-20%, respectively. At the same time, strength endurance and the level of performance decrease by 11.7%. Such changes contribute to the tension of neurohumoral mechanisms of self-regulation, which leads to a decrease in the stock of functional reserves and significantly narrows the range of possible adaptive responses. It is shown that the informatization of the educational system in the edu cational process of students with disabilities should be of a mixed type, where the traditional form of classes remains the leading one.

Genetically modified mesenchymal stem cells promote spinal fusion through polarized macrophages

Spinal fusion is an effective treatment for low back pain and typically applied with prosthetic fixation devices. Spinal fusion can be improved by transplantation of mesenchymal stem cells (MSCs) into the paraspinal muscle. However, in contrast to the direct contribution of MSCs to spinal fusion, the indirect effects of MSCs on spinal infusion have not been studied and were thus addressed here. The correlation between the outcome of spinal fusion and the local macrophage number, polarization and the levels of placental growth factor (PlGF) in patients was analyzed. MSCs were genetically modified to overexpress PlGF, and its effects on macrophage proliferation and polarization were analyzed in vitro in a transwell co-culture system, as well as in vivo in a mouse model for spinal fusion, for which the cells were bilaterally injected into paravertebral muscles of the mouse lumbar spine. The effects on spinal fusion were assessed by microcomputed tomography and a custom four-point bending apparatus for structural bending stiffness. Local macrophages were analyzed by flow cytometry. We found that posterior spinal fusion could be improved by PlGF-expressing MSCs, compared to the control MSCs, evident by significant improvement of bone bridging of the targeted vertebrae. Mechanistically, PlGF-expressing MSCs appeared to attract macrophages and induce their M2 polarization, which in turn promotes the bone formation. Together, our data suggest that PlGF-expressing MSCs may improve spinal fusion through macrophage recruitment and polarization.

An externally validated deep learning model for the accurate segmentation of the lumbar paravertebral muscles

Purpose. Imaging studies about the relevance of muscles in spinal disorders, and sarcopenia in general, require the segmentation of the muscles in the images which is very labour-intensive if performed manually and poses a practical limit to the number of investigated subjects. This study aimed at developing a deep learning-based tool able to fully automatically perform an accurate segmentation of the lumbar muscles in axial MRI scans, and at validating the new tool on an external dataset. Methods. A set of 60 axial MRI images of the lumbar spine was retrospectively collected from a clinical database. Psoas major, quadratus lumborum, erector spinae, and multifidus were manually segmented in all available slices. The dataset was used to train and validate a deep neural network able to segment muscles automatically. Subsequently, the network was externally validated on images purposely acquired from 22 healthy volunteers. Results. The Jaccard index for the individual muscles calculated for the 22 subjects of the external validation set ranged between 0.862 and 0.935, demonstrating a generally excellent performance of the network. Cross-sectional area and fat fraction of the muscles were in agreement with published data. Conclusions. The externally validated deep neural network was able to perform the segmentation of the paravertebral muscles in axial MRI scans in an accurate and fully automated manner, and is therefore a suitable tool to perform large-scale studies in the field of spinal disorders and sarcopenia, overcoming the limitations of non-automated methods.