Differences In Biomechanical Parameters Research Articles

From Biomechanical Properties to Morphological Variations: Exploring the Interplay between Aortic Valve Cuspidity and Ascending Aortic Aneurysm.

Background: This research explores the biomechanical and structural characteristics of ascending thoracic aortic aneurysms (ATAAs), focusing on the differences between bicuspid aortic valve aneurysms (BAV-As) and tricuspid aortic valve aneurysms (TAV-As) with non-dilated aortas to identify specific traits of ATAAs. Methods: Clinical characteristics, laboratory indices, and imaging data from 26 adult patients operated on for aneurysms (BAV-A: n = 12; TAV-A: n = 14) and 13 controls were analyzed. Biomechanical parameters (maximal aortic diameter, strain, and stress) and structural analyses (collagen fiber organization, density, fragmentation, adipocyte deposits, and immune cell infiltration) were assessed. Results: Significant differences in biomechanical parameters were observed. Median maximal strain was 40.0% (control), 63.4% (BAV-A), and 45.3% (TAV-A); median maximal stress was 0.59 MPa (control), 0.78 MPa (BAV-A), and 0.48 MPa (TAV-A). BAV-A showed higher tangential modulus and smaller diameter, with substantial collagen fragmentation (p < 0.001 vs. TAV and controls). TAV-A exhibited increased collagen density (p = 0.025), thickening between media and adventitia layers, and disorganized fibers (p = 0.036). BAV-A patients had elevated adipocyte deposits and immune cell infiltration. Conclusions: This study highlights distinct pathological profiles associated with different valve anatomies. BAV-A is characterized by smaller diameters, higher biomechanical stress, and significant collagen deterioration, underscoring the necessity for tailored clinical strategies for effective management of thoracic aortic aneurysm.

Characterization of rabbit corneal biomechanical properties after corneal refractive surgery based on rapid loading-unloading uniaxial tensile test

In order to understand how the biomechanical properties of rabbit cornea change over time after corneal ablation, 21 healthy adult rabbits were used in this study, with the left eye as experimental side and the right eye as the control side. Firstly, a lamellar knife was used to remove a portion of the anterior corneal surface tissue (30%~50% of the original corneal thickness) from the left eye of each rabbit, as an animal model simulating corneal refractive surgery. Secondly, postoperative experimental rabbits were kept for one, three, or six months until being euthanized. Strip specimens were produced using their corneas in vitro to perform a uniaxial tensile test with an average loading-unloading rate of approximately 0.16 mm/s. Finally, the visco-hyperelastic material constitutive model was used to fit the data. The results showed that there was a significant difference in the viscoelastic parameters of the corneas between the experimental and the control eyes at the first and third postoperative months. There was a difference in tangential modulus between the experimental and the control eyes at strain levels of 0.02 and 0.05 at the third postoperative month. There was no significant difference in biomechanical parameters between the experimental and the control eyes at the sixth postoperative month. These results indicate that compared with the control eyes, the biomechanical properties of the experimental eyes vary over postoperative time. At the third postoperative month, the ratio of corneal tangential modulus between the experimental and the control eyes significantly increased, and then decreased. This work lays a preliminary foundation for understanding the biomechanical properties of the cornea after corneal refractive surgery based on rapid testing data obtained clinically.

Anatomical and biomechanical characteristics of plantaris tendon and its application in ligament reconstruction

To improve the clinical utility of the plantaris tendon mainly by summarizing its anatomical characteristics, biomechanical properties, harvesting methods, and its applications in ligament reconstruction. The relevant literature from domestic and international databases regarding the anatomical and biomechanical characteristics of the plantaris tendon and its applications in ligament reconstruction was comprehensively reviewed and systematically summarized. The plantaris tendons have an absence. The majority of plantaris tendon forms a fan-shape on the anterior and medial sides of the Achilles tendon and terminates at the calcaneal tuberosity. There are significant differences in biomechanical parameters between plantaris tendon with different numbers of strands, and multi strand plantaris tendon have significant advantages over single strand tendon. The plantaris tendon can be harvested through proximal and distal approaches, and it is necessary to ensure that there are no obvious anatomical variations or adhesions in the surrounding area before harvesting. The plantaris tendon is commonly utilized in ligament reconstruction around the ankle joint or suture reinforcement for Achilles tendon rupture, with satisfactory effectiveness. There is limited research on the use of plantar tendon in the reconstruction of upper limb and knee joint ligaments. The plantaris tendon is relatively superficial, easy to be harvested, and has less impact on local function. The plantaris tendon is commonly utilized in ligaments reconstruction around the ankle joint or suture reinforcement for Achilles tendon rupture. The study on the plantaris tendon for upper limbs and knee joints ligament reconstruction is rarely and require further research.

Biomechanical profile of varying suture button constructs in cadaveric specimens: a systematic review and meta-analysis.

Suture button fixation of syndesmotic injuries allows for more physiologic motion of the ankle joint while maintaining adequate reduction and may avoid the need for additional surgeries, given the lower risk of syndesmotic diastasis and implant failure. Few studies have examined the optimal number and configuration of suture buttons for syndesmotic disruption. The purpose of this systematic review and meta-analysis is to compare different suture button configurations from the cadaveric literature and to assess their relative effect on the stability of the syndesmotic reduction and functional movement of the ankle. A literature search in the databases MEDLINE via PubMed, Embase via Elsevier, Scopus via Elsevier, and SPORTDiscus via EBSCO were searched through December 2022 to identify studies related to cadaveric modeling of the syndesmosis. Only cadaveric studies with suture button fixation and studies in English were included. The quality of cadaveric studies was assessed using the Quality Assessment for Cadaveric Studies (QUACS) tool. Revman 5.3 software was used to perform the meta-analysis. The meta-analysis included 5 studies and 86 limbs. The systematic review included 15 studies. When comparing single and double suture button configurations, no difference was found between groups with regard to fibular rotation (MD =-0.9; 95% CI: -2.09 to 0.27; I2=79%; P=0.13) and both groups had similar rotational stability. The double suture button technique did demonstrate less sagittal fibular translation compared to the single suture button (MD =0.48; 95% CI: 0.02-0.94; I2=66%; P=0.04). When comparing two suture buttons in parallel and divergent configurations, studies did not find any differences with regard to strength or stability. There were no significant differences in biomechanical parameters when comparing single and double suture button constructs. While single button suture constructs result in minimal fibular rotation, double suture button constructs minimize fibular translation. This review may serve as a guide for clinicians when approaching these injuries.

A spatiotemporal analysis of the left coronary artery biomechanics using fluid-structure interaction models.

Biomechanics plays a critical role in coronary artery disease development. FSI simulation is commonly used to understand the hemodynamics and mechanical environment associated with atherosclerosis pathology. To provide a comprehensive characterization of patient-specific coronary biomechanics, an analysis of FSI simulation in the spatial and temporal domains was performed. In the current study, a three-dimensional FSI model of the LAD coronary artery was built based on a patient-specific geometry using COMSOL Multiphysics. The effect of myocardial bridging was simulated. Wall shear stress and its derivatives including time-averaged wall shear stress, wall shear stress gradient, and OSI were calculated across the cardiac cycle in multiple locations. Arterial wall strain (radial, circumferential, and longitudinal) and von Mises stress were calculated. To assess perfusion, vFFR was calculated. The results demonstrated the FSI model could identify regional and transient differences in biomechanical parameters within the coronary artery. The addition of myocardial bridging caused a notable change in von Mises stress and an increase in arterial strain during systole. The analysis performed in this manner takes greater advantage of the information provided in the space and time domains and can potentially assist clinical evaluation.

Biomechanics of the lead straight punch and related indexes between sanda fighters and boxers from the perspective of cross-border talent transfer.

Objective: To bridge the technical gaps in reserve athletes in China's national boxing program and to rapidly improve the overall level of boxing, the Wushu Sports Administration Center of the General Administration of Sports of China has sent outstanding Sanda players to boxing events through cross-border talent transfer. This was done to widely improve the strengths and resources in various fields to prepare for the Tokyo Olympic Games. In view of this, we analyzed and compared differences in biomechanical parameters of the lead straight punch and index of force developments of the lower extremities between Sanda and boxing. The results provide information and insights to bridge the technical gaps in cross-border talent transfer from Sanda to boxing. Methods: We employed a Vicon infrared 3D motion capture system, two Kistler platforms, a Kistler target, and a synchronous instrument. Eleven boxers and sixteen Sanda athletes were recruited, and their lead straight punch techniques were compared and analyzed. Three indexes of punch velocity, six indexes of strength measurement, and four indexes of lower extremity strength were analyzed. Results: Significant differences in the peak punch velocity and contact velocity were found between the two groups. Furthermore, significant differences were noted in the peak impulse, peak strength, relative strength, and the rate of force development (RFD). Among the kinetics indexes of lower limbs, the front leg strength index was higher in the boxing group than in the Sanda group, namely the RFD index and RFD/body mass. Conclusion: Based on the disparity in the effects of the lead straight punch and biomechanical parameters of both lower extremities, we can conclude that, compared to the boxers, most Sanda athletes lack standard punching technique. Therefore, it is advised that coaches and practitioners carefully consider selecting Sanda athletes with higher technical standards of punching.

Analysis of Functional Arch Support Insoles on the Biomechanics and Performance in Right-Forward Lunging Step of Badminton Players.

The purpose of this study was to examine the differences in biomechanical parameters and sports-specific performance of lower limbs between arch support insoles (ASI) and flat insoles (FLI) when performing net strides. After installing the MVN IMU system, 18 college badminton team members were asked to take the following tests: (1) Consecutive net stride tests; (2) Six-point footwork tests; (3) Retrieve/stroke the ball at the left and right net; (4) Smash and retrieve/stroke the ball at the net; (5) Smash at the front and back crossover step. The joint angle of the lower limbs and ground reaction force during the support phase was collected. The results demonstrated that the peak right hip flexion angle was significantly greater with ASI than FLI (63.09 ± 10.70; 60.08 ± 13.82; p = 0.028), while the peak right foot inversion angle was significantly smaller with ASI than FLI (20.68 ± 7.87; 23.85 ± 8.11; p = 0.013). The principal conclusion was that the arch support insole avoids the decrease in the hip flexion angle and the increase in the foot inversion angle during the net stride tests.

Trihydroxyethyl Rutin Provides Neuroprotection in Rats With Cervical Spinal Cord Hemi-Contusion.

Objective: To investigate the neuroprotective effects of trihydroxyethyl rutin in rats with cervical spinal cord hemi-contusion.Methods: Adult male Sprague–Dawley rats were subjected to hemi-contusion at a stroke depth of 1.2 mm, and then intraperitoneally injected with 50 or 100 mg/kg trihydroxyethyl rutin per day for 12 weeks (T50 and T100 groups, respectively). Changes in somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs), and behavior were continuously monitored. At 12 weeks post-injury, immunohistochemical staining was performed to assess changes in cervical spinal cord microvascular morphology. Magnetic resonance imaging (MRI) scans were performed to examine end-stage injury in the cervical spinal cord, and Eriochrome cyanine-stained slices of spinal cord tissue were evaluated for injury.Results: There were no significant differences in biomechanical parameters among the spinal cord injury, T50 and T100 rat groups. At 3 days-post-injury, there was a significant decrease in grip strength. At 12 weeks post-injury, grip strength recovery was significantly better in the T50 and T100 groups than in the injury group. Compared with the injury group, the total limb placement frequency was significantly higher in the T50 group at 2, 4, 6, 10, and 12 weeks post-injury and in the T100 group at 2, 6, 8, and 10 weeks post-injury. Ipsilateral SEPs and MEPs were dynamic, increasing in latency and decreasing in amplitude in the injury compared with sham group. MRI scanning demonstrated that the coronal, sagittal, and transversal lesion areas were smaller in the T50 and T100 groups than in the injury group. Microvascular density showed a greater reduction in the injury group compared with the T50 and T100 groups. Eriochrome cyanine staining showed that the ipsilateral side, residual parenchyma, and gray matter areas were larger in the T50 and T100 groups than in the injury group.Conclusion: Trihydroxyethyl rutin exhibits robust neuroprotective effects, improving limb motor function and nerve electrophysiological parameters after spinal cord injury, maintaining microvascular density, and reducing the area of injury and degree of demyelination.

Comparing Hip Contact Pressures Between Acetabulum Labral Repair vs. Total Labral Reconstruction

To biomechanically compare the contact area, contact pressures, and peak forces of primary labral repair versus labral reconstruction. A cadaveric study was performed using 8 frozen hemi-pelvises with cam-type deformities (alpha angle >55°) with an intact labrum. Intraarticular pressure maps were produced for each specimen under the following conditions: 1) intact labrum, 2) labral repair, and 3) labral reconstruction using iliotibial band (ITB) allograft. Specimens were examined at neutral, 20° of extension and 60° of flexion to simulate the complete arc of the natural hip range of motion during normal gait on a level surface and during stair climbing. Each specimen was placed in a custom-designed jig in the MTS electromechanical test system to create pressure and area map measurements. In each condition, contact pressure, contact area, and peak force within a region-of-interest (ROI) were obtained. Repeated measures ANOVA was used to identify differences in biomechanical parameters among the three conditions with post-hoc analysis using pairwise comparison with Bonferroni correction to analyze the differences within each condition. Analysis of contact pressures between labral repair and labral reconstruction were normalized to the pressures measured in the intact labrum. Repeated measures ANOVA for contact area in neutral, extension, and flexion demonstrated statistically significant differences between study states (p<0.05). Post-hoc analysis for each consistently demonstrated significantly larger contact areas measured in labral repair specimens compared labral reconstruction specimens. In addition, paired-T test analysis demonstrated significantly higher contact areas (33.3+-7.9 vs 27.4+-6.9; p=0.009) and significantly lower contact pressures (2.5+-0.3 vs 2.7+-0.4; p=0.038) in labral repair specimens compared to labral reconstruction specimens. Finally, there was no statistically significant difference in peak forces measured between specimens (p<0.05 for all). Primary labral repair may result in lower intra-articular hip contact pressures and higher contact area compared to primary complete labral reconstruction.

Comparison of Suction Seal and Contact Pressures Between 270° Labral Reconstruction, Labral Repair, and the Intact Labrum

To biomechanically compare the suction seal, contact area, contact pressures, and peak forces of the intact native labrum, torn labrum, 12- to 3-o'clock labral repair, and 270° labral reconstruction in the hip. A cadaveric study was performed using 8 fresh-frozen hemipelvises with intact labra and without osteoarthritis. Intra-articular pressure maps were produced for each specimen using an electromechanical testing system under the following conditions: (1) intact labrum, (2) labral tear, (3) labral repair between the 12- and 3-o'clock positions, and (4)270° labral reconstruction using iliotibial band allograft. Specimens were examined in neutral position, 20° of extension, and 60° of flexion. In each condition, contact pressure, contact area, and peak force were obtained. Repeated-measures analysis of variance was used to identify differences in biomechanical parameters among the 3 conditions. Qualitative differences in suction seal were compared between labral repair and labral reconstruction using the Fisher exact test. Repeated-measures analysis of variance for contact area in neutral position, extension, and flexion showed statistically significant differences between the normalized study states (P < .05). Post hoc analysis showed significantly larger contact areas measured in labral repair specimens than in labral reconstruction specimens in the extension and flexion positions. Region-of-interest analysis for the normalized contact area in the extension and flexion positions, as well as normalized contact pressures in neutral position, showed statistically significant differences between the labral states (P < .05). Finally, 8 labral repairs (100%) versus only 1 labral reconstruction (12.5%) retained the manually tested suction seal (P < .001). In this invitro biomechanical model, 270° labral reconstruction resulted in decreased intra-articular contact area and loss of suction seal when compared with labral repair. Clinically, labral reconstruction may not restore the biomechanical characteristics of the native labrum as compared with labral repair. Labral reconstruction may result in lower intra-articular hip contact area and loss of suction seal, affecting the native biomechanical function of the acetabular labrum. Further biomechanical studies and clinical studies are necessary to determine whether there are any long-term consequences of 270° labral reconstruction.

Biomechanical, histologic, and molecular characteristics of graft-tunnel healing in a murine modified ACL reconstruction model.

SummaryPurposeThe purpose of our study was to introduce and validate a metal-free, reproducible and reliable mouse model of anterior cruciate ligament (ACL) reconstruction (ACLR) surgery as an effective tool for a better understanding of molecular mechanisms of graft-tunnel healing after ACLR.MethodsA total of 150 C57BL/6 mice were randomly allocated into five Groups: Group 1 (mice with intact ACL), Group 2–4 (mice underwent modified ACLR surgery and sacrificed 1-, 2-, and 4-weeks after surgery), and Group 5 (mice underwent unmodified ACLR surgery and sacrificed 4 weeks after surgery). Micro-computed tomography (CT), biomechanical histological as well as immunohistochemical (IHC) analyses were performed to characterize the modified ACLR.ResultsMicro-CT analysis demonstrated there is a non-significant increase in BV/TV and BMD of the bone tunnel during the tendon-to-bone healing following ACLR. Biomechanical tests showed that the mean load-to-failure forces of Group 3 and 4 are equal to 31.7% and 46.0% of that in Group 1, while the stiffness was 33.1% and 57.2% of that of Group 1, respectively. And no obvious difference in biomechanical parameters was found between Group 4 and 5. Histological analysis demonstrated that formation of fibrovascular tissue in the tibial tunnel and aperture in Groups 4 and 5 and direct junction appeared between tendon graft and tunnel both in Groups 4 and 5. IHC results showed that there are gradually enhanced expression of Patched1, Smoothened and Gli2 concomitant with decreased Gli3 protein in the tendon-bone interface during the tendon-bone healing process.ConclusionWe introduced a metal-free, reproducible and reliable mouse model of ACLR compared to the unmodified ACLR procedure, and characterized the expression pattern of key molecules in Ihh signaling during the graft healing process.The translational potential of this articleIn the present study we introduced and validated, for the first time, a metal-free, reproducible and reliable ACLR mouse model, which could be used to investigate the detailed molecular mechanisms of graft-tunnel healing after ACLR. We also explored new strategies to promote the healing of tendon-to-bone integration.

Does the presence of self-reported walking difficulty influence gait mechanics and muscular activations in individuals with knee osteoarthritis?

Does the presence of self-reported walking difficulty influence gait mechanics and muscular activations in individuals with knee osteoarthritis?

Learning spinal manipulation: Gender and expertise differences in biomechanical parameters, accuracy, and variability.

The purpose of this study was to investigate gender differences and expertise effects on biomechanical parameters as well as force accuracy and variability for students learning spinal manipulation. A total of 137 fourth- and fifth-year students were recruited for the study. Biomechanical parameters (preload, time to peak force, peak force, rate of force), as well as accuracy and variability of thoracic spine manipulation performance, were evaluated during 5 consecutive trials using a force-sensing table and a target force of 450 N. Gender, expertise differences on biomechanical parameters, as well as constant, variable, and absolute error were assessed using 2-way analysis of variance. Analyses showed significant gender differences for several biomechanical parameters, as well as significant gender differences in accuracy and variability. Although women showed lower time to peak force and rate of force values, they were more precise and showed less variability than men when performing thoracic spine manipulations. Students with clinical expertise (fifth-year students) used less force and were more precise. Our results showed that gender differences in spinal manipulation performance exist and that these differences seem to be mainly explained by alternative motor strategies. To develop gender-specific teaching methods, future studies should explore why men and women approach spinal manipulation tasks differently.

Local upregulation of interleukin-1 beta in aortic dissecting aneurysm: correlation with matrix metalloproteinase-2, 9 expression and biomechanical decrease

Our goal was to examine whether interleukin-1 beta (IL-1β) originates locally and its possible relationship with matrix metalloproteinases (MMPs), apoptosis, elastin fibres and biomechanics in aortic dissecting aneurysms (DAs). Aortic DAs were induced in 24 rats with β-aminopropionitrile (BAPN); another 12 rats without BAPN were designated as controls. Then IL-1β levels were measured both in the circulation and in local aortic specimens. The expression of MMP-2 and MMP-9 and Victoria blue and TUNEL staining were also detected. Biomechanical parameters such as the elasticity modulus were used to detect the biomechanical changes in the aortic wall. The correlation of IL-1β, MMP-2, MMP-9, apoptosis and biomechanical properties was analysed. Seventeen rats (17/24, 71%) in the BAPN-treated group died of DA rupture. IL-1β levels were dramatically increased in the DA specimens but not in the circulation. Victoria blue staining confirmed the formation of the DA and the reduction of elastin content after induction by BAPN. The extent of apoptosis in the aortic media was dramatically higher in rats with BAPN-induced DA than that in the control group and that in rats treated with BAPN but without DA. MMP-2 and MMP-9 levels were significantly increased in BAPN-treated rats compared to the controls, but no statistical significance was found between rats with and without DA. There were significant differences in biomechanical parameters, such as the elasticity modulus. Among the 3 groups, IL-1β was positively correlated with MMP-2 and MMP-9 levels and with the elasticity modulus but not with apoptosis. Local IL-1β might participate in the formation of aortic DA through the upregulation of MMP-2 and MMP-9 and the breakage of elastin fibres, which finally weakens the biomechanical properties of the aortic wall.

Continuous sweep versus discrete step protocols for studying effects of wearable robot assistance magnitude

BackgroundDifferent groups developed wearable robots for walking assistance, but there is still a need for methods to quickly tune actuation parameters for each robot and population or sometimes even for individual users. Protocols where parameters are held constant for multiple minutes have traditionally been used for evaluating responses to parameter changes such as metabolic rate or walking symmetry. However, these discrete protocols are time-consuming. Recently, protocols have been proposed where a parameter is changed in a continuous way. The aim of the present study was to compare effects of continuously varying assistance magnitude with a soft exosuit against discrete step conditions.MethodsSeven participants walked on a treadmill wearing a soft exosuit that assists plantarflexion and hip flexion. In Continuous-up, peak exosuit ankle moment linearly increased from approximately 0 to 38% of biological moment over 10 min. Continuous-down was the opposite. In Discrete, participants underwent five periods of 5 min with steady peak moment levels distributed over the same range as Continuous-up and Continuous-down. We calculated metabolic rate for the entire Continuous-up and Continuous-down conditions and the last 2 min of each Discrete force level. We compared kinematics, kinetics and metabolic rate between conditions by curve fitting versus peak moment.ResultsReduction in metabolic rate compared to Powered-off was smaller in Continuous-up than in Continuous-down at most peak moment levels, due to physiological dynamics causing metabolic measurements in Continuous-up and Continuous-down to lag behind the values expected during steady-state testing. When evaluating the average slope of metabolic reduction over the entire peak moment range there was no significant difference between Continuous-down and Discrete. Attempting to correct the lag in metabolics by taking the average of Continuous-up and Continuous-down removed all significant differences versus Discrete. For kinematic and kinetic parameters, there were no differences between all conditions.ConclusionsThe finding that there were no differences in biomechanical parameters between all conditions suggests that biomechanical parameters can be recorded with the shortest protocol condition (i.e. single Continuous directions). The shorter time and higher resolution data of continuous sweep protocols hold promise for the future study of human interaction with wearable robots.

Biomechanical Parameters in Plantar Fasciitis Measured by Gait Analysis System With Pressure Sensor.

ObjectiveTo investigate the differences in biomechanical parameters measured by gait analysis systems between healthy subjects and subjects with plantar fasciitis (PF), and to compare biomechanical parameters between ‘normal, barefooted’ gait and arch building gait in the participants.MethodsThe researchers evaluated 15 subjects (30 feet) with bilateral foot pain and 15 subjects (15 feet) with unilateral foot pain who had a clinical diagnosis of PF. Additionally, 17 subjects (34 feet) who had no heel pain were recruited. Subjects were excluded if they had a traumatic event, prior surgery or fractures of the lower limbs, a leg length discrepancy of 1 cm or greater, a body mass index greater than 35 kg/m2, or had musculoskeletal disorders. The participants were asked to walk with an arch building gait on a treadmill at 2.3 km/hr for 5 minutes. Various gait parameters were measured.ResultsWith the arch building gait, the PF group proved that gait line length and single support line were significantly decreased, and lateral symmetry of the PF group was increased compared to that of the control group. The subjects with bilateral PF displayed significantly increased maximum pressure over the heel and the forefoot during arch building gait. In addition, the subjects with unilateral PF showed significantly increased maximum pressure over the forefoot with arch building gait.ConclusionThe researchers show that various biomechanical differences exist between healthy subjects and those with PF. Employing an arch building gait in patients with PF could be helpful in changing gait patterns to normal biomechanics.

The biomechanical characteristics of the pharynx in patients with aspiration after radiotherapy for nasopharyngeal carcinoma

Objective To explore the biomechanical characteristics of the pharynx in patients with aspiration after radiotherapy for nasopharyngeal carcinoma (NPC). Methods Clinical data on NPC patients with dysphagia admitted between July 2011 and June 2015 were retrospectively analyzed. Twenty-three patients were found who had received videofluoroscopic swallowing studies (VFSSs) and whose pharyngeal pressure and upper esophageal sphincter (UES) relaxing were tested using high-resolution solid-state manometry (HRM). The cases were divided into an aspiration group and a non-aspiration group according to the VFSS results. Differences in biomechanical parameters between the 2 groups when taking food of different viscosity were compared. Results Patients with aspiration had significantly higher UES residual pressure when taking thick liquids (20.1±14.3 mmHg) and paste (18.0±14.3 mmHg) than patients not aspirating (9.3±9.2 mmHg and 7.2±8.9 mmHg for thick liquid and paste respectively). But no significant difference in average pharyngeal pressure between the two groups was observed. Conclusion Aspiration after radiotherapy may be correlated with increased UES residual pressure. Key words: Dysphagia; Aspiration; Nasopharyngeal carcinoma; Radiotherapy

A New Fracture Model for “Terrible Triad” Injuries of the Elbow

The purpose of this study was to evaluate the influence of forearm rotation on failure patterns of the elbow under axial loads. Fourteen upper extremities were resected mid-humerus and mounted on a custom apparatus, which allowed rotation of the ulna, radius, and humerus about a fixed wrist while loading in axial compression. Seven specimens were loaded to failure with the forearm in pronation and 7 in supination. Six of the 7 elbows axially loaded in pronation resulted in fractures of the radial head and coronoid with posterior dislocation (terrible triad). Six of the 7 elbows loaded in supination dislocated without fracture. One of the 7 elbows tested in supination had a terrible triad-type elbow injury. Five of the 6 specimens with ulna external rotation had damage to the lateral ligaments; all 8 specimens with internal rotation had damage to the medial ligaments. There were no significant differences in biomechanical parameters between pronation and supination. The forearm position during axial load was the primary determinant of fracture-dislocation pattern. When the forearm was pronated, a terrible triad injury pattern most often occurred. When the forearm was supinated, a dislocation without fracture most often occurred. In both forearm rotation positions, when the ulna internally rotated during failure, the medial structures were the first to be disrupted. When the ulna externally rotated, the lateral structures were the first to be disrupted. Understanding the pathomechanics of elbow dislocation may improve diagnosis and treatment of these injuries.

Avaliação das alterações biomecânicas da córnea antes e após lasik em pacientes míopes e hipermetrópes utilizando Moriá® Sub-Bowman's Keratomileusis (SBK)

PURPOSE: To evaluate biomechanical changes measured with the ORA (Ocular Response Analyzer®; Reichert Ophthalmic Instruments, Buffalo, New York, USA) after Lasik with the Moria One Use Plus and to compare the biomechanics changes after myopic and hyperopic ablations. METHODS: Fourteeneyes for hyperopia (H) and 19 eyes for myopia (M) were evaluated with the ORA preoperatively and 1 month after Lasik with thin flap (100 microns) using SBK-OUP (Sub-Bowman Keratomileusis - One Use Plus, Moria®).CH (Corneal Hysteresis), CRF (Corneal Resistance Factor), IOPg (gold-standard, Goldmann correlated Intraocular pressure), IOPcc (Corneal compensated Intraocular pressure) and more 38 variables derived from the corneal biomechanical response signal of the ORA were analyzed. The Wilcoxon test was used to assess differences between the variables before and after surgery for each group and the differences between the pre and postoperative (1 month) myopic eyes were compared with those obtained in hyperopic eyes, using the Mann-Whitney test. RESULTS: There was a significant difference before and after Lasik in myopic and hyperopic eyes in IOPg (Wilcoxon, p <0.05), but not in IOPcc. Only myopic eyes showed a significant difference in CH and CRF measurements before and after LASIK, as well as 9 other biomechanical parameters (aspect1, h1, dive1, path1, p1area1, W11, H11, and w2 path11; Wilcoxon, p <0, 05), 8 of these being related to the first sign of flattening.Five parameters related to the sign of the second applanation showed significant variation only in the eyes before and after hyperopic Lasik (aspect2, h2, dive2, mslew2 and H21; Wilcoxon, p<0,05).There was a difference in both myopic and hyperopic on three parameters related to the applanation signal areas (p1area, and p2area p2area1; Wilcoxon, p <0.05). Differences in IOPg and p1area, before and after surgery were significantly higher in myopic eyes than in hyperopic eyes (Mann-Whitey, p <0.05). CONCLUSION: There are several significant differences in biomechanical parameters after Lasik with Moria OUP_SBK. Overall, the impact of myopic LASIK on corneal biomechanics is higher than of hyperopic Lasik. The parameters derived from the first sign of the ORA are more affected in myopic LASIK, whereas parameters derived from the second applanation are more affected in hyperopic LASIK.

Methodology for biomechanical testing of fresh anterior wall vaginal samples from postmenopausal women undergoing cystocele repair

To explore the methodological challenges of biomechanical testing of freshly harvested human anterior vaginal wall (HAVW) samples. Longitudinal full-thickness samples of HAVW were excised during cystocele repair in postmenopausal women and age-matched controls. Two methods of tissue storage during transport were compared. All samples were prepared for uniaxial testing within 2 hr of harvest and loaded at a rate of 0.5 mm/sec, until irreversible deformation was observed. Young's modulus and other parameters were extracted from the tensile stress-strain curves. Samples were obtained over 2 years from 42 patients. Significant differences in biomechanical parameters were noted based on the degree of hydration of the tissue, suggesting that the wetter samples were mechanically weaker. This study reports on a new method for testing the biomechanical properties of freshly harvested HAVW tissues and the impact of tissue hydration during transport between the operating room and the testing lab.