Biomechanical Characteristics Research Articles

Visible trephine-based foraminoplasty in PTED leads to asymmetrical stress changes and instability in the surgical and adjacent segments: a finite element analysis

This study aimed to construct a multi-segment lumbar finite element model (FEM) of PTED surgery to analyze the changes in stress and ROM after visible trephine-based foraminoplasty. The CT scans of a 35-year-old healthy male were used to develop a multi-segment lumbar FEM with Mimic, Geomagic Studio, Hypermesh and MSC.Patran. Different foraminoplasty was performed on the model, and these were grouped into normal group (A), the ventral resection group (B), the apex resection group (C), the ventral + apex + isthmus resection group (D), and the SAP + isthmus + lateral recess resection group (E). A vertical load of 500N and a torque of 10N·M were applied to the upper surface of the L3 vertebral body to simulate the biomechanical characteristics under the motion of flexion, extension, lateral bending, and rotation. The von Mises stress maps of the intervertebral f, vertebral body, facet joints, and the ROM of the L3-S1 intervertebral disk were calculated and analyzed. The changes of peak stress on the vertebral body for each group were not significant in the same motion state. Significant stress differences were observed in the L4/5 intervertebral disks, while no obvious stress changes were observed for the L3/4 and L5/S1 intervertebral disks. The stress of the L3/4 and L5/S1 facet joints decreased after L4/5 foraminoplasty, while the stress of L4/5 facet joints displayed an overall increasing trend. Significant asymmetrical stress changes of bilateral facet joints were observed in all three segments, particularly during bilateral rotation movements. The ROM of L3-S1 gradually increased from Group A to Group E, especially during flexion, left lateral bending, and right rotation, with the highest elevation observed for the L45 ROM. Our FEM indicated that enlarged resection and exposure of the articular surface could lead to significant asymmetrical stress changes in the bilateral facet joints and ROM instability of the surgical and adjacent segments. These findings suggested that unnecessary and excessive resection should be avoided in PTED to reduce the incidence of low back pain and the risk of postsurgical degeneration.

Polymeric Based Hydrogel Membranes for Biomedical Applications.

The development of biomedical applications is a transdisciplinary field that in recent years has involved researchers from chemistry, pharmacy, medicine, biology, biophysics, and biomechanical engineering. The fabrication of biomedical devices requires the use of biocompatible materials that do not damage living tissues and have some biomechanical characteristics. The use of polymeric membranes, as materials meeting the above-mentioned requirements, has become increasingly popular in recent years, with outstanding results in tissue engineering, for regeneration and replenishment of tissues constituting internal organs, in wound healing dressings, and in the realization of systems for diagnosis and therapy, through the controlled release of active substances. The biomedical application of hydrogel membranes has had little uptake in the past due to the toxicity of cross-linking agents and to the existing limitations regarding gelation under physiological conditions, but now it is proving to be a very promising field This review presents the important technological innovations that the use of membrane hydrogels has promoted, enabling the resolution of recurrent clinical problems, such as post-transplant rejection crises, haemorrhagic crises due to the adhesion of proteins, bacteria, and platelets on biomedical devices in contact with blood, and poor compliance of patients undergoing long-term drug therapies.

Comparison of bilateral differential characteristics of corneal biomechanics between keratoconus and normal eyes.

Purpose: To compare bilateral differences in corneal biomechanics between keratoconus and normal eyes. Methods: In this case-control study, 346 eyes of 173 patients (aged 22.1 ± 6.1years) with keratoconus (KC group) and 378 eyes of 189 patients (aged 26.7 ± 5.6years) with ametropia (control group) were enrolled. Corneal tomography and biomechanical properties were examined using Pentacam HR and Corvis ST, respectively. The corneal biomechanical parameters were compared between eyes with forme fruste keratoconus (FFKC) and normal eyes. Bilateral differences in corneal biomechanical parameters were compared between the KC and control groups. Receiver operating characteristic (ROC) analysis was used to assess discriminative efficacies. Results: The areas under the ROC curves (AUROCs) of stiffness parameter at the first applanation (SP-A1) and Tomographic and Biomechanical Index (TBI) for identifying FFKC were 0.641 and 0.694, respectively. The bilateral differential values of major corneal biomechanical parameters were significantly increased in the KC group (all p < 0.05), except for the Corvis Biomechanical Index (CBI). The AUROCs of the bilateral differential values of the deformation amplitude ratio at 2mm (ΔDAR2), Integrated Radius (ΔIR), SP-A1 (ΔSP-A1), and the maximum inverse concave radius (ΔMax ICR) for discriminating keratoconus were 0.889, 0.884, 0.826, and 0.805, respectively. The Logistic Regression Model-1 (comprising of ΔDAR2, ΔIR, and age) and the Logistic Regression Model-2 (comprising of ΔIR, ΔARTh, ΔBAD-D, and age) had AUROCs of 0.922 and 0.998, respectively, for discriminating keratoconus. Conclusion: The bilateral asymmetry of corneal biomechanics was significantly increased in keratoconus compared with normal eyes, which may be helpful for the early detection of keratoconus.

Risk Factors for Keratoconus Progression in Children Compared with Young and Middle-aged Adults.

Abstract Background To investigate the risk factors for keratoconus progression in children (10 – 18 years old; age group 1) compared to young adults (19 – 35 years old; age group 2) and middle-aged adults (36 – 55 years old; age group 3). Patients/Methods Ninety-seven children, 445 young adults, and 342 middle-aged adults underwent total ophthalmic examination including clinical refraction, slit lamp examination, corneal tomography, eye biometry, and biomechanical properties measurements. Comparisons were assessed among three age groups and between progressive and nonprogressive eyes. Logistic regression was applied to determine the potential prognostic factors for keratoconus progression in the three age groups. Results Univariate logistic regression analysis show that the most prominent factors associated with progression were corneal posterior vertical radius (RVP), eye rubbing (RUB), slit lamp corneal thinning (SLT), contact lens use (CL), and central corneal thickness (CCT) in all age groups. Additionally, the anterior chamber volume (ACV) and keratoconus match index (KMI) were associated with progression in age group 1. Location of the thinnest corneal thickness at the vertical axis (TCTy), distance from apex to the thinnest point (BADISTAPEX), scissor reflection in retinoscopy (SKIAREFLEX), and Vogt striae were associated with progression in age group 2, and TCTy, anterior and posterior asphericity (ASPA and ASPP, respectively), BADISTAPEX, SKIAREFLEX, and Vogt striae were associated with progression in age group 3. The multivariate model with the highest predictability indicated RVP, ACV, and SLT as independent determinants of progression in age group 1 (AUC: 90%, sensitivity: 88.9%, specificity: 90.9%), RVP, ACV, SLT, and SKIAREFLEX in group 2 (AUC: 81.6%, sensitivity 88.5%, specificity: 70.3%), and RVP, SLT, Vogt striae, and CL in age group 3 (AUC: 80%, sensitivity 82.8%, specificity: 73%). Conclusion ACV and KMI seem to play a major role in the progression of pediatric KC compared to adults. This is probably due to different anatomical and biomechanical characteristics of a childʼs eye globe.

Change of direction deficit is an important indicator for agility test

&lt;p&gt;變向 (change of direction, COD) 是運動員執行多方向移動的必要能力，變向能力可以透過專項訓練、敏捷性訓練、和技術發展提升，俾使競技運動比賽時的戰略成功達到攻防合一。過去發展許多關於變向、敏捷性的測驗，如：折返跑、505敏捷測驗或專業敏捷測驗等，這些田野方法通常用動作時間測量敏捷性，而變向動作則有採用生物力學研究方法的量化分析探討其動作特徵。但是，這些動作時程較長的單一測驗結果，卻也夾雜了衝刺能力、無氧代謝能力等因素。方向變換逆差 (change of direction deficit, CODD) 參數的發展，乃是通過數學的扣除方法，結合了純粹衝刺與變向衝刺等二項測驗的結果，能夠更精準地獲得敏捷能力的指標。本文整合了敏捷測驗、變向技能個別差異與生物力學特徵的過去相關文獻，提供教練員、肌力與體能訓練專家、運動員、體育教師在運動現場監控敏捷表現的資訊，也提醒方向變換逆差的參數是國際正發展評估敏捷能力具高靈敏度及準確度的指標，其信度與效度議題則有發展及探索的價值。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;Change of direction (COD) is an essential ability for athletes to perform multi-directional locomotion. COD can be enhanced through specific training, agility training, and technique development in order to successfully achieve the tactics of defense and offense within sport activities. Previous studies have developed many COD and agility tests, such as shuttle runs, 505 agility tests, and pro-agility tests. These field tests are used to assess agility by measuring movement time. There has been quantitative analysis of COD movements through a biomechanical approach to identify movement characteristics. However, using single outcome measures with long movement duration can blend the factors of sprint ability and anaerobic capacity. The development of the parameter of change-of-direction deficit (CODD) is a subtractive method in mathematics that combines two measurements to evaluate the index of agility precisely. This article summarizes previously published material on individual differences and biomechanical characteristics of COD skills to provide sport instructors, strength and conditioning specialists, athletes, or physical educators with information to monitor agility performance in the field. CODD is a sensitive and precise indicator for assessing agility. It is worth developing and exploring the issues of reliability and validity.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

The Functional Limits of the Aneurysmal Aortic Root: A Unique Pressure Testing Apparatus

The aortic root has unique embryological development and is a highly sophisticated and complex structure. In studies that report on the biomechanical characteristics of the thoracic aorta, distinction between the aortic root and ascending aorta regions is non-existent. This study aimed to determine the maximal pressures at which dissection or tissue failure occur in both the aneurysmal aortic root and ascending aorta and to analyse any differences. This may help guide preoperative monitoring, diagnosis, and the decision for operative intervention for aortic root aneurysms in normal and susceptible populations.

The elbow is the load-bearing joint during arm swing

Background: Arm swing plays a role in gait by accommodating forward movement through trunk balance. This study evaluates the biomechanical characteristics of arm swing during gait.Methods: The study performed computational musculoskeletal modeling based on motion tracking in 15 participants without musculoskeletal or gait disorder. A three-dimensional (3D) motion tracking system using three Azure Kinect (Microsoft) modules was used to obtain information in the 3D location of shoulder and elbow joints. Computational modeling using AnyBody Modeling System was performed to calculate the joint moment and range of motion (ROM) during arm swing.Results: The mean ROM of the dominant elbow was 29.7°±10.2° and 14.2°±3.2° in flexion–extension and pronation–supination, respectively. The mean joint moment of the dominant elbow was 56.4±12.7 Nm, 25.6±5.2 Nm, and 19.8±4.6 Nm in flexion–extension, rotation, and abduction–adduction, respectively. Conclusions: The elbow bears the load created by gravity and muscle contracture in dynamic arm swing movement.

Swallowing biomechanics in tracheostomised critically ill patients compared to age- and gender-matched healthy controls

ObjectiveThe mechanistic effects of a tracheostomy on swallowing are unclear. Pharyngeal high-resolution manometry with impedance (P-HRM-I) is a novel swallow assessment tool providing quantifiable metrics. This study aimed to characterise swallowing biomechanics in tracheostomised critically ill (non-neurological) patients. DesignCohort study. SettingAustralian tertiary hospital intensive care unit. ParticipantsTracheostomised adults, planned for decannulation. Main outcome measuresSwallowing assessment using P-HRM-I, compared to healthy age- and gender-matched controls. ResultsIn this tracheostomised cohort (n = 10), the Swallow Risk Index, a global measure of swallow function, was significantly elevated (p < 0.001). At the upper oesophageal sphincter (UOS), hypopharyngeal intrabolus pressure and UOS integrated relaxation pressure were significantly elevated (control 0.65 mmHg [-1.02, 2.33] v tracheostomy 13.7 mmHg [10.4, 16.9], P < 0.001; control −4.28 mmHg [-5.87, 2.69] v tracheostomy 12.2 mmHg [8.83, 15.6], P < 0.001, respectively). Furthermore, UOS opening extent and relaxation time were reduced (control 4.83 mS [4.60, 5.07] v tracheostomy 4.33 mS [3.97, 4.69], P = 0.002; control 0.52 s [0.49, 0.55] v tracheostomy 0.41 s [0.37, 0.45], P < 0.001, respectively). Total pharyngeal contractility (PhCI) measuring pharyngeal pressure generation was significantly elevated (control 199.5 mmHg cm.s [177.4, 221.6] v tracheostomy 326.5 mmHg cm.s [253.3, 399.7]; P = 0.001). ConclusionIn a critically ill tracheostomised cohort, UOS dysfunction was the prevalent biomechanical feature, with elevated pharyngeal pressures. Pharyngeal weakness is not contributing to dysphagia in this cohort. Instead, elevated pharyngeal pressures may represent a compensatory mechanism to overcome the UOS dysfunction. Further studies to extend these findings may inform the development of timely and targeted rehabilitation.

What makes vertical femoral neck fracture with posterior inferior comminution different? An analysis of biomechanical features and optimal internal fixation strategy

Background and purposeFracture comminution occurs in 83.9%-94% of vertical femoral neck fractures (VFNFs), the majority of which were located in posterior-inferior region, and poses a clinical challenge in fixation stability. We conducted a subject-specific finite element analysis to determine the biomechanical features and optimal fixation selection for treating VFNF with posterior-inferior comminution. Patients and methodsEighteen models with three fracture types (VFNF without comminution [NCOM], with comminution [COM], with comminution + osteoporosis [COMOP]) and six internal fixation types (alpha [G-ALP], buttress [G-BUT], rhomboid [G-RHO], dynamic hip screw [G-DHS], invert triangle [G-ITR], femoral neck system (G-FNS)) were created based on the computed tomography data. By using the subject-specific finite element analysis method, stiffness, implant stress, yielding rate (YR) were compared. Additionally, in order to elucidate distinct biomechanical characters of different fracture types and fixation strategies, we calculated interfragmentary movement (IFM), detached interfragmentary movement (DIM), shear interfragmentary movement (SIM) of all fracture surface nodes. ResultsGenerally, in comparison with NCOM, COM showed a 30.6% reduction of stiffness and 1.46-times higher mean interfragmentary movement. Besides, COM had a 4.66-times (p = 0.002) higher DIM at the superior-middle position, but similar SIM across fracture line, which presented as varus deformation. In COM and COMOP, among all six fixation strategies, G-ALP had significantly the lowest IFM (p<0.001) and SIM (p<0.001). Although G-FNS had significantly highest IFM and SIM (p<0.001), it had the highest stiffness and lowest DIM (p<0.001). In COMOP, YR was the lowest in G-FNS (2.67%). ConclusionsPosterior-inferior comminution primarily increases superior-middle detached interfragmentary movement in VFNF, which results in varus deformation. For comminuted VFNF with or without osteoporosis, alpha fixation has the best interfragmentary stability and anti-shear property among six current mainstream fixation strategies, but a relatively weaker stiffness and anti-varus property compared to fixed-angle devices. FNS is advantageous owing to stiffness, anti-varus property and bone yielding rate in osteoporosis cases, but is insufficient in anti-shear property.

EEG Reveals Alterations in Motor Imagery in People With Amnestic Mild Cognitive Impairment.

Motor imagery has been used to investigate the cognitive mechanism of motor control. Although behavioral and electrophysiological changes in motor imagery in people with amnestic mild cognitive impairment (aMCI) have been reported, deficits in different types of imagery remain unclear. To explore this question, we used electroencephalography (EEG) to study neural correlates of visual imagery (VI) and kinesthetic imagery (KI) and their relationship to cognitive function in people with aMCI. A hand laterality judgment task was used to induce implicit motor imagery in 29 people with aMCI and 40 healthy controls during EEG recording. Mass univariate and multivariate EEG analysis was applied to explore group differences in a data-driven manner. Modulation of stimuli orientation to event-related potential (ERP) amplitudes differed significantly between groups at 2 clusters located in the posterior-parietal and frontal areas. Multivariate decoding revealed sufficient representation of VI-related orientation features in both groups. Relative to healthy controls, the aMCI group lacked accurate representation of KI-related biomechanical features, suggesting deficits in automatic activation of KI strategy. Electrophysiological correlates were associated with episodic memory, visuospatial function, and executive function. Higher decoding accuracy of biomechanical features predicted better executive function via longer response time in the imagery task in the aMCI group. These findings reveal electrophysiological correlates related to motor imagery deficits in aMCI, including local ERP amplitudes and large-scale activity patterns. Alterations in EEG activity are related to cognitive function in multiple domains, including episodic memory, suggesting the potential of these EEG indices as biomarkers of cognitive impairment.

Biomechanical analysis of a novel Y-plate designed for the treatment of extraarticular distal humerus fractures

Adult distal humerus fractures are infrequent, yet they account for one-third of all humerus fractures. For the treatment of comminuted and osteoporotic fractures, locking plates are claimed to be biomechanically superior to alternative internal fixing techniques. Treatment remains difficult despite recent advancements and the use of locking plates due to frequent comminution, low bone quality, and limited healing ability in osteoporotic bone. An optimal design of the newly constructed plate and the control model were selected. The biomechanical characteristics of non-osteoporotic and osteoporotic synthetic bone were compared on six models. The biomechanical properties of the new plate were tested and compared on 54 osteoporotic synthetic humerus models. The control models were reconstructive and parallel LCPs. The tests were carried out under static and dynamic axial, lateral and bending loads. Fracture displacements were measured by optical measuring system Aramis. The test model is significantly stiffer for lateral load (p = 0.0007) and for bending load at the moment of model failure (p = 0.0002), while for axial load the LCP model showed greater stiffness (p = 0.0017). During lateral dynamic loading, all three LCP models broke and there was a significant difference compared to the test model (p = 0.0125). The LCP model is dynamically significantly more durable under axial load, while the largest displacements were recorded with the test model (p = 0.029). The displacements induced by all three loads are within the limits that fulfil the parameters of appropriate biomechanical stability. A novel locking plate for extra-articular distal humerus fractures may provide an alternative to the traditional two-plate.

Phenotypic and Biomechanical Characteristics of Human Fetal Neural Progenitor Cells Exposed to Pesticide Compounds

Various forms of pesticides have been reported to be among the environmental toxicants, which are detrimental to human health. The active ingredients of these formulations can enter the human body through air, food, or water. Epidemiological studies suggest that these compounds strongly affect the developing brain in fetal and infant stages due to their ability to breach the underdeveloped blood–brain barrier. Since neural progenitor stem cells (NPCs) in the developing brain are the most vulnerable to these compounds, the mechanisms by which NPCs experience toxicity upon exposure to these chemicals must be investigated. Here, we assessed the viability of human fetal NPCs in 2D cultures in the presence of the active ingredients of six widely used pesticides using Live/Dead® and Hoechst staining. The IC50 values ranged from 4.1–201 μM. A significant drop in cell viability with increasing toxicant concentration (p &lt; 0.01) was noted, with the order of toxicity being malathion &lt; 4-aminopyridine &lt; methoprene &lt; prallethrin &lt; temephos &lt; pyriproxyfen. Changes in cellular biomechanical characteristics (Young’s modulus, tether force, membrane tension, and tether radius) were quantified using atomic force microscopy, whereas cell migration was elucidated over 48 h using a customized wound-healing assay. The Young’s modulus of fetal NPCs exposed to IC50/2 doses of these compounds was reduced by 38–70% and that of those exposed to IC50 doses was reduced by 71–80% (p &lt; 0.001 vs. controls for both; p &lt; 0.01 for IC50 vs. IC50/2 for each compound). Similar patterns were noted for tether forces and membrane tension in fetal NPCs. NPC migration was found to be compound type- and dose-dependent. These results attest to the significant detrimental effects of these compounds on various aspects of the human fetal NPC phenotype, and the utility of cell mechanics as a marker to assess developmental neurotoxicity.

A Doppler-exclusive non-invasive computational diagnostic framework for personalized transcatheter aortic valve replacement

Given the associated risks with transcatheter aortic valve replacement (TAVR), it is crucial to determine how the implant will affect the valve dynamics and cardiac function, and if TAVR will improve or worsen the outcome of the patient. Effective treatment strategies, indeed, rely heavily on the complete understanding of the valve dynamics. We developed an innovative Doppler-exclusive non-invasive computational framework that can function as a diagnostic tool to assess valve dynamics in patients with aortic stenosis in both pre- and post-TAVR status. Clinical Doppler pressure was reduced by TAVR (52.2 ± 20.4 vs. 17.3 ± 13.8 [mmHg], p < 0.001), but it was not always accompanied by improvements in valve dynamics and left ventricle (LV) hemodynamics metrics. TAVR had no effect on LV workload in 4 patients, and LV workload post-TAVR significantly rose in 4 other patients. Despite the group level improvements in maximum LV pressure (166.4 ± 32.2 vs 131.4 ± 16.9 [mmHg], p < 0.05), only 5 of the 12 patients (41%) had a decrease in LV pressure. Moreover, TAVR did not always improve valve dynamics. TAVR did not necessarily result in a decrease (in 9 out of 12 patients investigated in this study) in major principal stress on the aortic valve leaflets which is one of the main contributors in valve degeneration and, consequently, failure of heart valves. Diastolic stresses increased significantly post-TAVR (34%, 109% and 81%, p < 0.001) for each left, right and non-coronary leaflets respectively. Moreover, we quantified the stiffness and material properties of aortic valve leaflets which correspond with the reduced calcified region average stiffness among leaflets (66%, 74% and 62%; p < 0.001; N = 12). Valve dynamics post-intervention should be quantified and monitored to ensure the improvement of patient conditions and prevent any further complications. Improper evaluation of biomechanical valve features pre-intervention as well as post-intervention may result in harmful effects post-TAVR in patients including paravalvular leaks, valve degeneration, failure of TAVR and heart failure.

The Biomechanical Influence of Defected Cartilage on the Progression of Osteochondral Lesions of the Talus: A Three‐dimensional Finite Element Analysis

Osteochondral lesions of the talus (OLTs) are common injuries in the general population. Abnormal mechanical conditions applied to defected cartilage are believed to be the culprits to deteriorating OLTs. This study aims to investigate the biomechanical effects of defect size of talar cartilage on OLTs during ankle movements. A finite element model of the ankle joint was created based on the computed tomography images of a healthy male volunteer. Different defect sizes (S = 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, and 2.0 cm2 ) of talar cartilage were modeled to simulate the progression of OLTs. Mechanical moments were applied to the model to generate different ankle movements, including dorsiflexion, plantarflexion, inversion, and eversion. The effects of varying defect sizes on peak stress and its location were evaluated. The maximum stress on the talar cartilage increased as the area of the defect enlarged. Additionally, as the defect size of OLTs increased, the areas with peak stress on talar cartilage tended to move closer to where the injury was located. High stresses were present in the medial and lateral areas of the talus at the neutral position of the ankle joint. The concentrated stresses were mainly located in the anterior and posterior defect areas. The peak stress in the medial region was higher than on the lateral side. The order of peak stress from highest to lowest was dorsiflexion, internal rotation, inversion, external rotation, plantar flexion, and eversion. Osteochondral defect size and ankle joint movements significantly modulate the biomechanical features of the articular cartilage in osteochondral lesions of the talus. The progression of osteochondral lesions in a talus deteriorates the biomechanical well-being of the bone tissues of the talus.

Numerical study on the blocking effect of skin on Flash-Ball Impact and damage assessment

To explore the response law of non-lethal large-size kinetic energy projectiles to blunt attack on skin tissue, and to evaluate the skin injury characteristics of the attacked personnel and the use safety of kinetic energy projectiles. Based on the LS-DYNA simulation software, a three-layer skin simulation model and a Flash-Ball rubber bullet model are established, and the force-time and deformation-time biomechanical corridors of the Flash-Ball rubber bullet impacting human skin tissue are obtained. The corridor curve and the energy transfer and diffusion are analyzed and compared. The safety evaluation of the damage caused by the rubber bullet shooting a human body at different distances is carried out using the empirical formula of the penetration limit. Finally, the safe shooting distance is obtained. The results show that the model used in the simulation has a good correlation with the experimental data, its biomechanical corridor characteristics are different from those of conventional vehicle impact and small-size projectile response characteristics. The energy transfer and action time of medium and low-speed impact may cause greater damage. The fat layer is the largest energy absorption unit. The minimum safe shooting distance to ensure skin tissue from penetrating damage is 15.8 m, and the limit specific kinetic energy of skin damage is 7.88 J/cm2. This study can be extended to the study of biomechanical response law and safety evaluation under the impact of the same type of large kinetic energy projectile, which provides an important theoretical reference for the police to use large kinetic energy projectiles to conduct safe shooting in peacekeeping operations.

Progress in diagnosis and hip arthroscopic treatment of borderline developmental dysplasia of hip with Cam-type femoroacetabular impingement

To summarize the biomechanical characteristics, diagnosis, and hip arthroscopic treatment of borderline developmental dysplasia of hip (BDDH) with Cam-type femoroacetabular impingement (Cam FAI). The literature on BDDH with Cam FAI at home and abroad in recent years was extensively reviewed and analyzed. In patients with BDDH and Cam FAI, the femoral neck anteversion angle and femoral neck shaft angle increase, the pelvis tilts, and the acetabulum rotates, resulting in instability of the hip joint. In order to maintain the stability of the hip joint, the direction of biomechanical action of the hip joint has changed, which further affects the anatomical structures such as the proximal femur and acetabular morphology. BDDH with Cam FAI can be diagnosed clinically by combining lateral center edge angle, anterior center edge angle, and acetabular index. BDDH with Cam FAI can be effectively treated through arthroscopic polishing of the edges of the acetabular proliferative bone, excision of Cam malformations, and minimally invasive repair of the glenoid lip and cartilage of the hip joint. Currently, there is no unified standard for the diagnosis and treatment of BDDH with Cam FAI. Minimally invasive treatment of the hip under arthroscopy can achieve good early- and medium-term effectiveness, and has certain advantages in repairing and maintaining the integrity of the glenoid lip and suturing/compression joint capsule. However, the long-term effectiveness needs to be further followed up to determine. The timing of surgery, intraoperative bone edge depth polishing, and joint capsule suturing/compression techniques also need to be further explored.

The choice of IOP measurement method for assessing the effectiveness of glaucoma surgery

Purpose of this study — to compare the results of different tonometry methods before surgical treatment of glaucoma and in the early postoperative period.The study was conducted on a group of 50 patients (50 eyes) aged 55 to 80 years with uncompensated primary open-angle glaucoma, who were admitted to in-patient department for glaucoma surgery. Patients were examined using bidirectional applanation tonometry of the cornea performed on Ocular Response Analyzer, pneumotonometry on Canon TX-20P device, and with Icare tonometer. These studies were carried out on the day before the surgery, the next day, and 2 weeks after the operation.Significant differences in tonometry readings were revealed between all tested devices at high intraocular pressure (IOP) levels (before glaucoma surgery). Significant differences were also found in IOP values obtained with Icare tonometer in the central zone of the cornea and in the middle periphery in the nasal and temporal sectors. A significant difference between the indicators remained on the next day after surgery, except for the Icare readings. After two weeks, the tonometric parameters did not differ significantly from each other.Corneal compensated IOP (IOPcc) is the most important tonometric indicator in clinical practice because it takes into account the individual biomechanical characteristics of the patient’s cornea. When examining patients with glaucoma, the IOPcc indicator significantly differed in uncompensated IOP, which is important for determining the correct treatment tactics. When assessing the level of IOP after surgery this trend persisted, indicating a systematic underestimation of IOP level (overestimation of the effect of glaucoma surgery). The reliability of the study is confirmed by the results of measurements on unoperated fellow eyes (control).

A new approach of using organ-on-a-chip and fluid-structure interaction modeling to investigate biomechanical characteristics in tissue-engineered blood vessels.

The tissue-engineered blood vessel (TEBV) has been developed and used in cardiovascular disease modeling, preclinical drug screening, and for replacement of native diseased arteries. Increasing attention has been paid to biomechanical cues in TEBV and other tissue-engineered organs to better recapitulate the functional properties of the native organs. Currently, computational fluid dynamics models were employed to reveal the hydrodynamics in TEBV-on-a-chip. However, the biomechanical wall stress/strain conditions in the TEBV wall have never been investigated. In this paper, a straight cylindrical TEBV was placed into a polydimethylsiloxane-made microfluidic device to construct the TEBV-on-a-chip. The chip was then perfused with cell culture media flow driven by a peristaltic pump. A three-dimensional fluid-structure interaction (FSI) model was generated to simulate the biomechanical conditions in TEBV and mimic both the dynamic TEBV movement and pulsatile fluid flow. The material stiffness of the TEBV wall was determined by uniaxial tensile testing, while the viscosity of cell culture media was measured using a rheometer. Comparison analysis between the perfusion experiment and FSI model results showed that the average relative error in diameter expansion of TEBV from both approaches was 10.0% in one period. For fluid flow, the average flow velocity over a period was 2.52cm/s from the FSI model, 10.5% higher than the average velocity of the observed cell clusters (2.28mm/s) in the experiment. These results demonstrated the facility to apply the FSI modeling approach in TEBV to obtain more comprehensive biomechanical results for investigating mechanical mechanisms of cardiovascular disease development.

Biomechanical characteristics of silver enriched diamond-like carbon coatings for medical applications

Silver enriched diamond-like carbon (Ag/DLC) coatings are gaining a reputation for medical applications as Ag doping improves the intrinsic biocompatibility and antimicrobial features of DLC, and higher Ag amounts improve its hemocompatibility and growth inhabitation of tumours etc. However, higher Ag amounts in DLC coatings can also lead to increased cytotoxic effects. This work presents the co-sputter deposition of Ag-enriched DLC coatings with 17, 40, and 65 at% Ag in a DLC matrix. The structural and mechanical properties of the coatings are studied with field emission scanning electron microscopy, electron dispersive X-ray, X-ray diffraction, contact surface profiler, and nanoindentation. The biocompatibility of 72 h and 168 h leached extracts of Ag/DLC coatings are assessed through Ag ion release rates in Dulbecco’s modified eagle medium using inductively coupled plasma optical emission spectroscopy and their corresponding biocompatibility profiles are mapped against the L929 mouse fibroblast cell line. EDX mapping shows a throughout distribution of Ag in DLC matrix instead of localization distributions and clustering. The XRD diffraction peaks reflect the amorphous-like behaviour of 17 at% Ag/DLC and prominent Ag crystallinity for 40 and 65 at% Ag/DLC coatings. The leached Ag ions concentration of 8 ppm demonstrated by the 65 at% Ag/DLC coating completely diminishes its biocompatibility. The results suggest that 17 at% Ag enriched DLC coatings are a safe candidate for biomedical application and retain biocompatibility when treated with extracts prepared over prolonged ion leaching periods of 168 h, when compared to 40 and 65 at% Ag/DLC coatings. Similarly, the 17 at% Ag/DLC coatings show less compromise on mechanical properties, which decline by over 50% for 40 and 65 at% Ag/DLC coatings. This work has extended the typical range of Ag for depositing safe and biocompatible DLC coatings for medical applications.

Abdominal aortic aneurysm volume and relative intraluminal thrombus volume might be auxiliary predictors of rupture-an observational cross-sectional study.

The study aimed to identify differences and compare anatomical and biomechanical features between elective and ruptured abdominal aortic aneurysms (AAAs). Data (clinical, anatomical, and biomechanical) of 98 patients with AAA, 75 (76.53%) asymptomatic (Group aAAA) and 23 (23.46%) ruptured AAA (Group rAAA), were prospectively collected and analyzed. Anatomical, morphological, and biomechanical imaging markers like peak wall stress (PWS) and rupture risk equivalent diameter (RRED), comorbid conditions, and demographics were compared between the groups. Biomechanical features were assessed by analysis of Digital Imaging and Communication in Medicine images by A4clinics (Vascops), and anatomical features were assessed by 3Surgery (Trimensio). Binary and multiple logistic regression analysis were used and adjusted for confounders. Accuracy was assessed using receiving operative characteristic (ROC) curve analysis. In a multivariable model, including gender and age as confounder variables, maximal aneurysm diameter [MAD, odds ratio (OR) = 1.063], relative intraluminal thrombus (rILT, OR = 1.039), and total aneurysm volume (TAV, OR = 1.006) continued to be significant predictors of AAA rupture with PWS (OR = 1.010) and RRED (OR = 1.031). Area under the ROC curve values and correct classification (cc) for the same parameters and the model that combines MAD, TAV, and rILT were measured: MAD (0.790, cc = 75%), PWS (0.713, cc = 73%), RRED (0.717, cc = 55%), TAV (0.756, cc = 79%), rILT (0.656, cc = 60%), and MAD + TAV + rILT (0.797, cc = 82%). Based on our results, in addition to MAD, other important predictors of rupture that might be used during aneurysm surveillance are TAV and rILT. Biomechanical parameters (PWS, RRED) as valuable predictors should be assessed in prospective clinical trials. Similar studies on AAA smaller than 55 mm in diameter, even difficult to organize, would be of even greater clinical value.