Mechanisms Underlying Lumbopelvic Pain During Pregnancy: A Proposed Model

Up to 86% of pregnant women will have lumbopelvic pain during the 3rd trimester of pregnancy and women with lumbopelvic pain experience lower health-related quality of life during pregnancy than women without lumbopelvic pain. Several risk factors for pregnancy-related lumbopelvic pain have been identified and include history of low back pain, previous trauma to the back or pelvis and previous pregnancy-related pelvic girdle pain. During pregnancy, women go through several hormonal and biomechanical changes as well as neuromuscular adaptations which could explain the development of lumbopelvic pain, but this remains unclear. The aim of this article is to review the potential pregnancy-related changes and adaptations (hormonal, biomechanical and neuromuscular) that may play a role in the development of lumbopelvic pain during pregnancy. This narrative review presents different mechanisms that may explain the development of lumbopelvic pain in pregnant women. A hypotheses-driven model on how these various physiological changes potentially interact in the development of lumbopelvic pain in pregnant women is also presented. Pregnancy-related hormonal changes, characterized by an increase in relaxin, estrogen and progesterone levels, are potentially linked to ligament hyperlaxity and joint instability, thus contributing to lumbopelvic pain. In addition, biomechanical changes induced by the growing fetus, can modify posture, load sharing and mechanical stress in the lumbar and pelvic structures. Finally, neuromuscular adaptations during pregnancy include an increase in the activation of lumbopelvic muscles and a decrease in endurance of the pelvic floor muscles. Whether or not a causal link between these changes and lumbopelvic pain exists remains to be determined. This model provides a better understanding of the mechanisms behind the development of lumbopelvic pain during pregnancy to guide future research. It should allow clinicians and researchers to consider the multifactorial nature of lumbopelvic pain while taking into account the various changes and adaptations during pregnancy.

Orthodontic Therapeutic Biomarkers in Saliva and Gingival Crevicular Fluid

Several biologically active substances representing the bone deposition and resorption processes are released following damage to periodontal tissue during orthodontic movement. Biomarkers are by definition objective, quantifiable characteristics of biological processes. The analysis of saliva/salivary fluid and Gingival crevicular fluid (GCF) may be an accepted way to examine the ongoing biochemical processes associated with bone turnover during orthodontic tooth movement and fixed orthodontic treatment pain. Assessing the presence of these salivary physiological biomarkers would benefit the clinician in appropriate pain diagnosis and management objectively of various problems encountered during the orthodontic procedures and for better outcome of biomechanical therapy. Due to lack of standardized collection procedure, even though well accepted by patients, saliva is often neglected as a body fluid of diagnostic and prognostic value. A literature search was carried out in major databases such as PubMed, Medline, Cochrane library, Web of Science, Google Scholar, Scopus and EMBASE for relevant studies. Publication in English between 2000 to 2021 which estimated Saliva markers as indicators of orthodontic tooth movement was included. The list of biomarkers available to date was compiled and is presented in table format. Each biomarker is discussed separately based on the available and collected evidences. Several sensitive salivary and GCF biomarkers are available to detect the biomechanical changes occurring during orthodontic tooth movement and pain occurring during fixed orthodontic therapy. Further focussed research might help to analyze the sensitivity and reliability of these biomarkers or cytokines, which in turn can lead to the development of chairside tests to assess the pain experienced by patients during orthodontic therapy and finally the outcome of the fixed orthodontic therapy.

Mathematical modeling of the chest, its funnel-shaped deformation and thoracoplasty

The most common method of treating of the congenital funnel-shaped chest is thoracoplasty method by D. Nuss. During this surgery, a significant mechanical effect is created on the ribs, sternum, spinal column, which act instantly and continuously for a long time and create new biomechanical conditions for the «chest – rib – spine» system. Objective. To construct a functional model of the chest with a spinal column, which takes into account the movements in the costal-vertebral joints, it allows modeling the funnel-shaped deformation in conditions close to the reality, its operative correction, predicting the results and choosing the optimal parameters of thoracoplasty. Methods. Normal and funnel-shaped chest models based on the articular connection of the ribs to the spine were created using SolidWorks. The main calculations were made using the ANSYS program. To estimate the stress-strain state (SSS), stresses are selected by Mises. Results. The created dynamic mathematical model of the chest makes it possible to conduct a reliable analysis of the biomechanical interaction of the plate with the chest, to analyze the stress-strain state of the constructed models in the norm, with and without taking into account the movements in the costal-vertebral joints. In addition, it allows to simulate the operation by D. Nuss and to study the biomechanical changes in conditions close to reality, occurring in the «chest – rib – spine» system, to determine the areas of maximum loads and safety boundaries. Conclusions. The reproduction of articular ribs rotation in the dynamic model changes the picture of the SSS distribution. In the case of modeling the correction of funnel-shaped deformation of the chest by the method by D. Nuss, the largest zone of stress concentration was found on the outer posterior surface of the sixth pair of ribs. The most tense vertebrae were ThV– ThVI, but the maximum values did not exceed the permissible values. In the case of a lower plate conduction, the correction is achieved with better SSS values in the higher elements of the «chest – ribs – spine» system.

Biomechanical changes on the typical sites of pressure ulcers in the process of turning over from supine position: theoretical analysis, simulation and experiment

Background Pressure ulcer is a typical disease, which is common in long-term bedridden patients and difficult to cure. It is necessary to study the biomechanics of the typical sites of pressure ulcers in turning over from supine position, which is an important reference for clinical medical nursing and and guides an assisted exoskeleton robot design. Methods The typical sites of pressure ulcers mainly focus on the scapula and the hip-sacrum of the trunk in turning over from the supine position. Based on the requirements of rehabilitation technical aids and the anatomy theory, the simple model of the scapula and the hip-sacrum were established for a force analysis in the process of turning over from the supine position, and the theoretical contact pressure between the human body and the bed surface was obtained. Then, three-dimensional models of the scapula and hip- sacrum were reconstructed and the maximum stress under different boundary conditions was obtained by finite element analysis. Finally, the pressure distribution sensor was used to carry out the human experiment of turning over from the supine position, and the pressure cloud diagram and the maximum contact pressure curve of the shoulder blade and the hip were obtained under different angles of turning over. Results The results from theoretical analysis, simulation and experiment were almost the same change trends, and the curves and the stress diagrams showed the contact pressure change of the typical sites of pressure ulcers in turning over. The angle threshold of the optimal comprehensive pressure can improve the use efficiency of the equipment to assist human turning over and reduce the incidence of pressure ulcers in the use of assisted bed in long-term bedridden patients. Conclusions In response to the less research on the mechanism of pressure ulcer, biomechanical changes have been revealed, which helps to explain the causes of pressure ulcer disease and provide basis for improving clinical nursing, and the relevant results provided a reference that contributes to the man-machine coupling design of the assisted rollover robot.

Text neck: An adverse postural phenomenon

BACKGROUND: The excessive use of hand-held mobile devices (HHMD) leads to a postural phenomenon known as text neck. OBJECTIVE: The aim of this paper is to discuss the anatomical, biomechanical and muscle activation changes within the cervical and thoracic regions associated with the sustained, forward, flexed neck posture, observed with excessive usage of hand-held mobile devices. Additionally, this paper examines the relationship of gender, as well as the effects of carrying backpack loads by youth, on this forward, flexed neck posture. METHODS: Multiple aspects of the text neck position that occur when an individual uses a HHMD are described. RESULTS: Prolonged use of hand-held mobile devices results in adverse anatomical and biomechanical changes in the cervical and thoracic spine, muscular imbalances, and postural compensations, all of which contribute to muscular overuse and fatigue resulting in pain. CONCLUSIONS: Physical therapists must educate their patients about proper posture while using hand-held mobile devices. Proper posture includes: holding the device close to eye level, using the device while standing or sitting and holding the device with a line of sight perpendicular to the surface of the device, using a larger screen, and texting with both hands. Also, because children are using hand held mobile devices at younger ages, parents and teachers must be educated about the dangers of prolonged use of hand-held devices.

Load bearing analysis on Lumbosacral Disc in Pre-operative and Post-operative Thoracic Scoliosis Patient

Scoliosis is a musculoskeletal disorder seen all around the world. It affects both the alignment of the vertebra and intervertebral disc. Scoliosis can be treated conservatively with a cast and brace or surgically with spinal instrumentation. During planning for surgical instrumentation, several factors need to be considered. Among those, biomechanical changes in the non-scoliotic vertebrae and discs are important. This is vital in determining the future degenerative changes of the spine. For this reason, this study was conducted with a finite element model of the lumbosacral joint using CT scan files to find the total deformation and equivalent static strain of the lumbosacral disc between pre and post-operative thoracic scoliosis patient. From the results, it is evident that there is a biomechanical change in the lumbosacral disc and structural change in the vertebral alignment followed immediately after corrective surgery. The correction in the alignment of the scoliotic spine brings changes to the biomechanical functionality and load-bearing capacity of the lumbosacral intervertebral disc before and after surgery.

Heart Valve Biomechanics: The Frontiers of Modeling Modalities and the Expansive Capabilities of Ex Vivo Heart Simulation

The field of heart valve biomechanics is a rapidly expanding, highly clinically relevant area of research. While most valvular pathologies are rooted in biomechanical changes, the technologies for studying these pathologies and identifying treatments have largely been limited. Nonetheless, significant advancements are underway to better understand the biomechanics of heart valves, pathologies, and interventional therapeutics, and these advancements have largely been driven by crucial in silico, ex vivo, and in vivo modeling technologies. These modalities represent cutting-edge abilities for generating novel insights regarding native, disease, and repair physiologies, and each has unique advantages and limitations for advancing study in this field. In particular, novel ex vivo modeling technologies represent an especially promising class of translatable research that leverages the advantages from both in silico and in vivo modeling to provide deep quantitative and qualitative insights on valvular biomechanics. The frontiers of this work are being discovered by innovative research groups that have used creative, interdisciplinary approaches toward recapitulating in vivo physiology, changing the landscape of clinical understanding and practice for cardiovascular surgery and medicine.