Anteroposterior Components Research Articles

Unraveling stroke gait deviations with movement analytics, more than meets the eye: a case control study.

This study aimed to identify and quantify the kinematic and kinetic gait deviations in post-stroke hemiplegic patients with matched healthy controls using Statistical Parametric Mapping (SPM). Fifteen chronic stroke patients [4 females, 11 males; age 53.7 (standard deviation 12.2) years; body mass 65.4 (10.4) kg; standing height 168.5 (9.6) cm] and 15 matched healthy controls [4 females, 11 males; age 52.9 (11.7) years; body weight 66.5 (10.7) years; standing height 168.3 (8.8) cm] were recruited. In a 10-m walking task, joint angles, ground reaction forces (GRF), and joint moments were collected, analyzed, and compared using SPM for an entire gait cycle. Generally, when comparing the stroke patients' affected (hemiplegic) and less-affected (contralateral) limbs with the control group, SPM identified significant differences in the late stance phase and early swing phase in the joint angles and moments in bilateral limbs (all p < 0.005). In addition, the vertical and anteroposterior components of GRF were significantly different in various periods of the stance phase (all p < 0.005), while the mediolateral component showed no differences between the two groups. SPM was able to detect abnormal gait patterns in both the affected and less-affected limbs of stroke patients with significant differences when compared with matched controls. The findings draw attention to significant quantifiable gait deviations in the less-affected post-stroke limb with the potential impact to inform gait retraining strategies for clinicians and physiotherapists.

Investigation of joint contact forces during walking in the subjects with toe in gait due to increasing in femoral head anteversion angle.

Toe-in gait is a pathology in which the child walks and turns the foot inward instead of pointing straight ahead. The alignment of the lower limb structure changes in this disease, increasing the incidence of knee and hip osteoarthritis. This study aimed to determine the kinematic and joint loading in subjects walking with a toe-in gait pattern. This study selected two groups of subjects: normal subjects and those with toe-in gait due to an increased femoral head anteversion angle (each group consisted of 15 subjects). A Qualisys motion analysis system and a Kistler force plate were used to record the motions and forces applied to the leg while walking. OpenSim software (version 3.3) was used to analyze the range of motion, moments, muscle forces, and joint contact forces in both groups of subjects. The mean values of stride length for normal subjects (1.1 ± 0.141 m) and those with toe-in gait (0.94 ± 0.183 m) differed significantly. The mediolateral component of the ground reaction force decreased significantly in the toe-in gait group compared to normal subjects (p-value = 0.05). The peak force of most of the hip joint muscles increased significantly in those with toe-in gait compared to normal subjects (p-value < 0.05). The results of this study showed that those with toe-in gait, due to an increase in femoral head anteversion angle, only had a change in rotation of the pelvic and hip joint. There was no significant difference between walking speed and most ground reaction force components between normal subjects and those with toe-in gait. As the peaks of most of the hip joint muscles increased significantly in the toe-in gait group, this increased joint contact forces (especially the anteroposterior component of the hip joint and the mediolateral component of the knee joint), which may ultimately increase the incidence of hip and knee joint osteoarthritis.

Right ventricular contraction patterns in healthy children using three-dimensional echocardiography.

The right ventricle (RV) has complex geometry and function, with motion along three separate axes-longitudinal, radial, and anteroposterior. Quantitative assessment of RV function by two-dimension echocardiography (2DE) has been limited as a consequence of this complexity, whereas newer three dimensional (3D) analysis offers the potential for more comprehensive assessment of the contributors to RV function. The aims of this study were to quantify the longitudinal, radial and anteroposterior components of global RV function using 3D echocardiography in a cohort of healthy children and to examine maturational changes in these parameters. Three-dimensional contours of the RV were generated from a cohort of healthy pediatric patients with structurally normal hearts at two centers. Traditional 2D and 3D echo characteristics were recorded. Using offline analysis of 3D datasets, RV motion was decomposed into three components, and ejection fractions (EF) were calculated (longitudinal-LEF; radial-REF; and anteroposterior-AEF). The individual decomposed EF values were indexed against the global RVEF. Strain values were calculated as well. Data from 166 subjects were included in the analysis; median age was 13.5 years (range 0 to 17.4 years). Overall, AEF was greater than REF and LEF (29.2 ± 6.2% vs. 25.1 ± 7.2% and 25.7 ± 6.0%, respectively; p < 0.001). This remained true when indexed to overall EF (49.8 ± 8.7% vs. 43.3 ± 11.6% and 44.4 ± 10%, respectively; p < 0.001). Age-related differences were present for global RVEF, REF, and all components of RV strain. In healthy children, anteroposterior shortening is the dominant component of RV contraction. Evaluation of 3D parameters of the RV in children is feasible and enhances the overall understanding of RV function, which may allow improvements in recognition of dysfunction and assessment of treatment effects in the future.

Mechanical adaptation of the right ventricle to increased volume overload associated with secondary tricuspid regurgitation

Abstract Funding Acknowledgements Type of funding sources: None. Background Right ventricular (RV) function is strongly associated with the prognosis of patients with secondary tricuspid regurgitation (STR). However, the mechanical adaptations (contraction pattern) of the RV to volume overload associated with STR remain to be clarified. Purpose To investigate the changes in RV contraction pattern associated with the increase in severity of STR and to analyse whether the assessment of each RV motion component of RV ejection fraction (RVEF) (longitudinal, radial, and anteroposterior) adds prognostic value in patients with STR. Methods Consecutive patients with STR who underwent clinically indicated transthoracic echocardiography were enrolled in a multi-center prospective observational study. The primary outcome was defined as heart failure hospitalization or cardiac death. 3-dimensional echocardiography studies were performed at baseline and the ReVISION software package (Argus Cognitive, Inc, Lebanon, NH) was used to quantify the contribution of the longitudinal, radial, and anteroposterior motion components to total RVEF (Figure). Results We enrolled 172 patients (43% men, age: 75±15 years), followed for a median of 9 months. The patients were divided in two groups by STR severity (non-severe n=125, severe n=47). The characteristics of patients with massive/torrential STR (n=12) vs. "only" severe STR (n=35) were also assessed. RV end-diastolic volume index (r=0.33, p&amp;lt;0.001) and the longitudinal component of RVEF demonstrated significant correlation with STR severity (r=-0.22, p&amp;lt;0.01), while total RVEF did not (r=0.14; p = NS). The anteroposterior component of RVEF was the only parameter showing relatively strong correlation with left ventricular ejection fraction (r=0.39; p&amp;lt;0.001). RVEF was comparable between non-severe and severe patients (49±10 vs. 49±11%, p = NS). In patients with severe STR, the radial and also anteroposterior component of RVEF were comparable to non-severe STR patients, while the longitudinal component was significantly lower in severe STR (19±6 vs.17±7%, p&amp;lt;0.05; shown on Figure). Notably, in patients with massive/torrential STR, the radial contribution markedly decreased (27±8 vs. 20±9%, p&amp;lt;0.05), with consequently reduced global RVEF (52±9 vs. 41±12%, p&amp;lt;0.01) (Figure). In a multivariable Cox regression, using parameters proved to be significant in the univariable analysis, longitudinal component of total RVEF was a significant and independent predictor of outcome (hazard ratio, 0.947 [CI, 0.903–0.992], P= 0.022). Conclusions Patients with severe STR demonstrate significant morphological and functional RV remodeling with chamber enlargement and maintained RVEF, but a significant decrease in the longitudinal component of RVEF. In patients with massive/torrential STR, the radial mechanism markedly deteriorates, leading to decreased global RVEF. The longitudinal component of RV motion demonstrated independent prognostic value in patients with STR.

Predicting vertical and shear ground reaction forces during walking and jogging using wearable plantar pressure insoles

BackgroundThe development of plantar pressure insoles has made them a potential replacement for force plates. These wearable devices can measure multiple steps and might be used outside of the lab environment for rehabilitation and evaluation of sport performance. However, they can only measure the vertical force which does not completely represent the vertical ground reaction force. In addition, they are not able to measure shear forces which play an import role in the dynamic performance of individuals. Indirect approaches might be implemented to improve the accuracy of the force estimated by plantar pressure systems. Research questionThe aim of this study was to predict the vertical and shear components of ground reaction force from plantar pressure data using recurrent neural networks. MethodsGround reaction force and plantar pressure data were collected from 16 healthy individuals during 10 trials of walking and five trials of jogging using Bertec force plates at 1000 Hz and FScan plantar pressure insoles at 100 Hz. A long short-term memory neural network was built to consider the time dependency of pressure and force data in predictions. The data were split into three subsets of train, to train the model, evaluate, to optimize the model hyperparameters, and test sets, to assess the accuracy of the model predictions. ResultsThe results of this study showed that our long short-term memory model could accurately predict the shear and vertical force components during walking and jogging. The predictions were more accurate during walking compared to jogging. In addition, the predictions of mediolateral force had higher error and lower correlation compared to vertical and anteroposterior components. SignificanceThe long short-term memory model developed in this study may be an acceptable option for accurate estimation of ground reaction force during outdoor activities which can have significant impacts in rehabilitation, sport performance, and gaming.

Comparison of 5 Normalization Methods for Knee Joint Moments in the Single-Leg Squat.

Ratio scaling is the most common magnitude normalization approach for net joint moment (NJM) data. Generally, researchers compute a ratio between NJM and (some combination of) physical body characteristics (eg,mass, height, limb length, etc). However, 3 assumptions must be verified when normalizing NJM data this way. First, the regression line between NJM and the characteristic(s) used passes through the origin. Second, normalizing NJM eliminates its correlation with the characteristic(s). Third, the statistical interpretations following normalization are consistent with adjusted linear models. The study purpose was to assess these assumptions using data collected from 16 males and 16 females who performed a single-leg squat. Standard inverse dynamics analyses were conducted, and ratios were computed between the mediolateral and anteroposterior components of the knee NJM and participant mass, height, leg length, mass × height, and mass × leg length. Normalizing NJM-mediolateral by mass × height and mass × leg length satisfied all 3 assumptions. Normalizing NJM-anteroposterior by height and leg length satisfied all 3 assumptions. Therefore, if normalization of the knee NJM is deemed necessary to address a given research question, it can neither be assumed that using (any combination of) participant mass, height, or leg length as the denominator is appropriate nor consistent across joint axes.

Contraction patterns of the systemic right ventricle: a three-dimensional echocardiography study.

To investigate contraction patterns of the systemic right ventricle (SRV) in patients with transposition of great arteries (TGA) post-atrial switch operation and with congenitally corrected transposition of great arteries (ccTGA). Right ventricular (RV) volumes and ejection fraction (EF) were measured by three-dimensional echocardiography in 38 patients with the SRV (24 TGA and 14 ccTGA; mean age 45 ± 12 years, 63% male), and in 38 healthy volunteers. The RV contraction was decomposed along the longitudinal, radial, and anteroposterior directions providing longitudinal, radial, and anteroposterior EF (LEF, REF, and AEF, respectively) and their contributions to total right ventricular ejection fraction (LEFi, REFi, and AEFi, respectvely). SRV was significantly larger with lower systolic function compared with healthy controls. SRV EF and four-chamber longitudinal strain strongly correlated with B-type natriuretic peptide (BNP) level (Rho -0.73, P < 0.0001 and 0.70, P < 0.0001, respectively). In patients with TGA, anteroposterior component was significantly higher than longitudinal and radial components (AEF 17 ± 4.5% vs. REF 13 ± 4.9% vs. LEF 10 ± 3.3%, P < 0.0001; AEFi 0.48 ± 0.09 vs. REFi 0.38 ± 0.1 vs. LEFi 0.29 ± 0.08, P < 0.0001). In patients with ccTGA, there was no significant difference between three SRV components. AEFi was significantly higher in TGA subgroup compared with ccTGA (0.48 ± 0.09 vs. 0.36 ± 0.08, P = 0.0002). Contraction patterns of the SRV are different in TGA and ccTGA. Anteroposterior component is dominant in TGA providing compensation for impaired longitudinal and radial components, while in ccTGA all components contribute equally to the total EF. SRV EF and longitudinal strain demonstrate strong correlation with BNP level and should be a part of routine echocardiographic assessment of the SRV.

Effects of walking speed on magnitude and symmetry of ground reaction forces in individuals with transfemoral prosthesis

Individuals with unilateral transfemoral amputation (uTFA) walk asymmetrically. Investigating gait symmetry in ground reaction force (GRF) is critical because asymmetric loading on the residual limb can result in injury. The aim of this study was to investigate the GRF of individuals with uTFA by systematically controlling their walking at eight speeds(2.0–5.5 km/h with increments of 0.5 km/h) on a treadmill. Forty-eight individuals participated in this study, which included 24 individuals with uTFA (K3 and K4) and 24 individuals without amputation. GRFs (anteroposterior, mediolateral, and vertical) of the prosthetic and intact limb steps were collected for the individuals with uTFA and those of the right limb were collected for the control group. Peak force values of the GRF components, temporal parameters, impulses, and their asymmetry ratios were investigated and statistically analyzed. With an increasing walking speed, the magnitude of GRF changed gradually; individuals with uTFA exhibited increased GRF asymmetry in the vertical and mediolateral components, while that of the anteroposterior component remained constant. uTFA individuals typically maintained a constant asymmetry ratio in the mediolateral and anteroposterior (braking and propulsive) GRF impulses across a wide range of walking speeds. This result suggests that individuals with uTFA may cope with various walking speeds by maintaining symmetric mediolateral and anteroposterior impulses. The data provided in this study can serve as normative data for the GRF and its symmetry across a range of walking speeds in individuals with uTFA.

Contraction Patterns of the Right Ventricle Associated with Different Degrees of Left Ventricular Systolic Dysfunction

The functional adaptation of the right ventricle (RV) to the different degrees of left ventricular (LV) dysfunction remains to be clarified. We sought to (1) assess the changes in RV contraction pattern associated with the reduction of LV ejection fraction (EF) and (2) analyze whether the assessment of RV longitudinal, radial, and anteroposterior motion components of total RVEF adds prognostic value. Consecutive patients with left-sided heart disease who underwent clinically indicated transthoracic echocardiography were enrolled in a single-center prospective observational study. Adverse outcome was defined as heart failure hospitalization or cardiac death. Cross-sectional analysis using the baseline 3-dimensional echocardiography studies was performed to quantify the relative contribution of the longitudinal, radial, and anteroposterior motion components to total RVEF. We studied 292 patients and followed them for 6.7±2.2 years. In patients with mildly and moderately reduced LVEF, the longitudinal and the anteroposterior components of RVEF decreased significantly, while the radial component increased resulting in preserved total RVEF (RVEF: 50% [46%-54%] versus 47% [44%-52%] versus 46% [42%-49%] in patients with no, mild, or moderate LV dysfunction, respectively; data presented as median and interquartile range). In patients with severe LV systolic dysfunction (n=34), a reduction in all 3 RV motion components led to a significant drop in RVEF (30% [25%-39%], P<0.001). In patients with normal RVEF (>45%), the anteroposterior component of total RVEF was a significant and independent predictor of outcome (hazard ratio, 0.960 [CI, 0.925-0.997], P<0.001). In patients with left-sided heart disease, there is a significant remodeling of the RV associated with preservation of the RVEF in patients with mild or moderate LV dysfunction. In patients with normal RVEF, the measurement of the anteroposterior component of RV motion provided independent prognostic value.

Ratio of forces during sprint acceleration: A comparison of different calculation methods

The orientation of the ground reaction force (GRF) vector is a key determinant of human sprint acceleration performance and has been described using ratio of forces (RF) which quantifies the ratio of the antero-posterior component to the resultant GRF. Different methods have previously been used to calculate step-averaged RF, and this study therefore aimed to compare the effects of three calculation methods on two key “technical” ability measures: decline in ratio of forces (DRF) and theoretical maximal RF at null velocity (RF0). Twenty-four male sprinters completed maximal effort 60 m sprints from block and standing starts on a fully instrumented track (force platforms in series). RF-horizontal velocity profiles were determined from the measured GRFs over the entire acceleration phase using three different calculation methods for obtaining an RF value for each step: A) the mean of instantaneous RF during stance, B) the step-averaged antero-posterior component divided by the step-averaged resultant GRF, C) the step-averaged antero-posterior component divided by the resultant of the step-averaged antero-posterior and vertical components. Method A led to significantly greater RF0 and shallower DRF slopes than Methods B and C. These differences were very large (Effect size Cohen’s d = 2.06 – 4.04) and varied between individuals due to differences in the GRF profiles, particularly during late stance as the acceleration phase progressed. Method B provides RF values which most closely approximate the mechanical reality of step averaged accelerations progressively approaching zero and it is recommended for future analyses although it should be considered a ratio of impulses.

Global and regional right ventricular mechanics in repaired tetralogy of Fallot with chronic severe pulmonary regurgitation: a three-dimensional echocardiography study

BackgroundData about the right ventricular (RV) mechanics adaptation to volume overload in patients with repaired tetralogy of Fallot (rToF) are limited. Accordingly, we sought to assess the mechanics of the functional remodeling occurring in the RV of rToF with severe pulmonary regurgitation.MethodsWe used three-dimensional transthoracic echocardiography (3DTE) to obtain RV data sets from 33 rToF patients and 30 age- and sex- matched controls. A 3D mesh model of the RV was generated, and RV global and regional longitudinal (LS) and circumferential (CS) strain components, and the relative contribution of longitudinal (LEF), radial (REF) and anteroposterior (AEF) wall motion to global RV ejection fraction (RVEF) were computed using the ReVISION method.ResultsCorresponding to decreased global RVEF (45 ± 6% vs 55 ± 5%, p < 0.0001), rToF patients demonstrated lower absolute values of LEF (17 ± 4 vs 28 ± 4), REF (20 ± 5 vs 25 ± 4) and AEF (17 ± 5 vs 21 ± 4) than controls (p < 0.01). However, only the relative contribution of LEF to global RVEF (0.39 ± 0.09 vs 0.52 ± 0.05, p < 0.0001) was significantly decreased in rToF, whereas the contribution of REF (0.45 ± 0.08 vs 0.46 ± 0.04, p > 0.05) and AEF (0.38 ± 0.09 vs 0.39 ± 0.04, p > 0.05) to global RVEF was similar to controls. Accordingly, rToF patients showed lower 3D RV global LS (-16.94 ± 2.9 vs -23.22 ± 2.9, p < 0.0001) and CS (-19.79 ± 3.3 vs -22.81 ± 3.5, p < 0.01) than controls. However, looking at the regional RV deformation, the 3D CS was lower in rToF than in controls only in the basal RV free-wall segment (p < 0.01). 3D RV LS was reduced in all RV free-wall segments in rToF (p < 0.0001), but similar to controls in the septum (p > 0.05).Conclusions3DTE allows a quantitative evaluation of the mechanics of global RVEF. In rToF with chronic volume overload, the relative contribution of the longitudinal shortening to global RVEF is affected more than either the radial or the anteroposterior components.

Postural stability assessment in flatfoot subjects trough lyapunov exponent analysis

Abstract Background Flatfoot subjects presents an increase plantar foot area related to a plantar pressure feedback impairment. The Lyapunov Exponent is considered a nonlinear parameter used to characterize a signal chaotic behavior measuring the information rate loss from time series, i.e., for the Center of Pressure data. This exponent is used to quantify and measure the capability and resistance of subjects to several perturbations. The study purpose was to investigate the postural stability differences among foot posture condition through the Lyapunov Exponent analysis. Methods The sample of the observation descriptive study consisted of 31 participants (23.26 yo ± 4.43 SD) comprising a total of 62 feet, where 15 integrated into the experimental group with bilateral flatfoot condition and the remaining 16 in the control group with the bilateral neutral foot condition. Subjects were screened, before posture analysis, using the Navicular Drop Test and Resting Calcaneal Stance Position test, to characterize each group. All participants were subjected to a bipedal weight-bearing stance posture stability analysis a force platform, both in eyes-open and closed condition. The Lyapunov Exponent was calculated using the Matlab-R2020b (MathWorks Inc., USA) software. Results Regarding the Center of Pressure outcomes, only the Lyapunov Exponent value upon the Antero-Posterior component regarding groups in the eyes closed condition (diff = 3.09°, p = .016) presented a significant result. Conclusion Flatfoot subjects present a significant difference compared to neutral foot participants, in bipedal weight-bearing stance, in the eyes closed condition regarding the Lyapunov Exponent. This relates to increase variability and decrease stability regarding the Antero-Posterior component.

Anteroposterior Contraction of the Systemic Right Ventricle: Underrecognized Component of the Global Systolic Function

Accurate echocardiographic evaluation of the systemic right ventricle is challenging because of its specific morphology and contraction patterns. We present a detailed multimodality assessment of the systemic right ventricle, analyze the relative contribution of the longitudinal, radial, and anteroposterior components of systolic function, and identify reasons for a potential discrepancy among imaging modalities. (Level of Difficulty: Intermediate.)

Investigating the effect of innovative storing-restoring hybrid passive ankle-foot orthosis on braking and propulsion impulse of walking in drop-foot patients: a prospective cohort study

Background: Drop foot is a disorder that is characterized by reduction in speed and the patients’ inability to propel the paretic side, which disrupts the walking patterns. Ankle-foot orthoses (AFO) are widely prescribed in these patients in order to facilitate their leg propulsion and foot clearance during the swing phase. The purpose of this study was to use the correlation between effect of innovative AFO on braking and propulsion impulse and speed, in order to interpret the innovative AFO’s influence on the paretic and nonparetic side in drop-foot patients. Methods: Ten participants with drop foot walked at their self-selected speed, in order to collect the kinetic and kinematic data. The anteroposterior ground reaction force (GRF) components were extracted from the decomposition method with an innovative storing-restoring hybrid passive AFO and compared with baseline shoes only for both paretic and nonparetic sides. Results: There is a strong correlation between the innovative AFO speed and the anteroposterior component of GRF. After that, correlation was found between anteroposterior GRF and the storing-restoring hybrid passive AFO in comparison with baseline shoes only in both the paretic and nonparetic sides. Conclusions: This study demonstrated a strong correlation during walking between speed and the propulsion and braking impulses of the anteroposterior component of GRF on both sides. Level of Evidence: Level II.

Functional adaptation of the right ventricle to different degrees of the left ventricular systolic dysfunction in patients with left-sided heart disease: a three-dimensional echocardiography study

Abstract Funding Acknowledgements Type of funding sources: None. Background. Right ventricular (RV) systolic dysfunction in patients with left-sided heart disease is known adverse factor. However, the RV adaptation at the different degrees of left ventricular (LV) dysfunction remains to be clarified. Purpose to assess the change in RV contraction pattern in relation to LV ejection fraction (EF) in patients with left-sided heart disease. Methods. LV and RV volumes and EF were measured by 3D-echocardiography in 295 patients with left-sided heart disease (59 ± 17years, 69% male). The 3D meshmodel of the RV was postprocessed by the ReVISION software and its contraction pattern was decomposed along the longitudinal, radial and anteroposterior directions (Fig. A) providing longitudinal, radial and anteroposterior EF (LEF, REF, AEF). Relative contribution of each component to the RV systolic function was measured as the ratio between LEF, REF and AEF and global RVEF (LEFi, REFi, AEFi). Results. Patients with LV systolic dysfunction also had reduced RVEF. Relative contribution of the longitudinal and anteroposterior components decreased, while radial component increased in patients with reduced LVEF (Table). RV LEF and AEF significantly correlated with the LVEF (Rho 0.50 and 0.51, p &amp;lt; 0.0001), while the correlation between REF and LVEF was weak (Rho 0.22, p = 0.0002). There was a significant drop in LEF and AEF (Fig. B) and their relative contribution to the total RVEF (Fig. C) starting from the earlier stages of LV dysfunction. However, it was effectively compensated by significant increase in the radial RV component resulting in preservation of total RVEF in those with normal, mildly and moderately reduced LVEF (50 [46;54] vs 47 [44;52] vs 46 [42;49]%), whereas total RVEF dropped significantly only in severe LV dysfunction (30 [25;39]%; p &amp;lt; 0.0001) (Fig. D). Conclusions. The longitudinal and anteroposterior RV contraction was related to the LVEF and decreased from early stages of the LV systolic dysfunction. Increase in the radial component compensated for the loss of longitudinal and anteroposterior RV components in mild and moderate LV dysfunction to maintain total RVEF. Drop in all three components resulted in significant reduction of total RVEF in severe LV dysfunction. Characteristics of study population Overall (N = 295) LVEF≥50% (N = 166) LVEF &amp;lt; 50% (N = 129) LV EF, % 49.6 ± 14.3 59.9 ± 5.6 36.4 ± 10.9* RV EF, % 46.5 ± 9.2 49.8 ± 6.9 42.3 ± 10.0* RV LEFi 0.42 ± 0.09 0.45 ± 0.09 0.38 ± 0.09* RV REFi 0.47 ± 0.1 0.45 ± 0.1 0.50 ± 0.09* RV AEFi 0.39 ± 0.08 0.41 ± 0.08 0.37 ± 0.07* *p &amp;lt; 0.0001 Abstract Figure.

Mechanical contraction patterns of the systemic right ventricle: a 3D echocardiography study

Abstract Funding Acknowledgements Type of funding sources: None. Background. In patients with transposition of great arteries (TGA) post atrial switch operation or with congenitally corrected TGA (ccTGA), the morphologically right ventricle (RV) has to adapt to the chronically increased systemic pressure. Purpose. To investigate the functional adaptation of the systemic RV in patients with TGA post Mustard repair or ccTGA. Methods. RV volumes and EF were measured by 3D echocardiography in 33 patients with the systemic RV (21 TGA and 12 ccTGA; 45 ± 13y, 61% male), and in 33 healthy volunteers (44 ± 13y, 61% male). The 3D RV model was postprocessed by the ReVISION software and its contraction was decomposed along the longitudinal, radial and anteroposterior directions (Fig.A, Systemic RV in TGA) providing longitudinal, radial and anteroposterior EF (LEF, REF and AEF). Relative contribution of each component was measured as the ratio between LEF, REF and AEF to the global RVEF (LEFi, REFi and AEFi). Results. Systemic RV was significantly larger with reduced function compared to controls (Tab). 3D RVEF demonstrated stronger correlation with BNP (Rho -0.76, p &amp;lt; 0.0001) compared to other parameters of RV function (free wall strain 0.55, p = 0.0083; FAC -0.47, p = 0.024; S’ -0.39 and TAPSE 0.06, p &amp;gt; 0.05). While in healthy volunteers, all 3 components of RV systolic function contributed equally to the global RV EF, in patients with TGA the relative contribution of the anteroposterior component was dominant and differed significantly from longitudinal and radial components (AEFi 0.48 ± 0.06 vs LEFi 0.31 ± 0.07 vs REFi 0.36 ± 0.09, p &amp;lt; 0.0001)(Fig. B,C). In patients with ccTGA the longitudinal component was dominant and provided a relative compensation for the reduced anteroposterior and radial components (LEFi 0.47 ± 0.07 vs AEFi 0.34 ± 0.07, p = 0.0002 and vs REFi 0.36 ± 0.09, p = 0.0023)(Fig. B,C). Relative contribution of the radial contraction was significantly reduced in all systemic RV patients. Conclusions. Systemic RV contraction patterns change significantly with anteroposterior contraction being dominant in patients with TGA post Mustard repair and longitudinal component being dominant in ccTGA. 3DE should be a part of routine assessment of the systemic RV, especially in TGA since no conventional echo parameters take into account anteroposterior RV contraction. Parameters of RV systolic function Parameter Control group (N = 33) All SRV patients (N = 33) TGA (N = 21) ccTGA (N = 12) 3D EF, % 60 ± 3.8 36 ± 8.6* 34 ± 7.3* 38 ± 10* FAC, % 41.4 ± 3.7 25.9 ± 9.3* 25.1 ± 9.2* 27.1 ± 9.9* TAPSE, mm 24.6 ± 4.2 11.9 ± 3.9* 11.1 ± 2.9* 13.2 ± 5.1* RV free wall strain, % -32.5 ± 4.2 -14.5 ± 3.5* -14.5 ± 2.9* -15.5 ± 3.5* * p &amp;lt; 0.0001 Abstract Figure.

INFLUENCE OF DIABETIC NEUROPATHY ON GAIT COMPLEXITY

ABSTRACT Introduction: Human gait is a complex movement dependent on multilevel neural control, which allows a consistent, regular and complex periodic pattern, properties that characterize it as a nonlinear system. Sensory and motor deficits, with diminished proprioceptive responses, may reduce the adaptive capacity of the system, as demonstrated in Parkinson's, Alzheimer's and Huntington's diseases. However, little is known about the effect of peripheral diabetic neuropathy on these responses. Objectives: To analyze the influence of peripheral diabetic neuropathy on entropy in different gait environments. Methods: Ten elderly patients, with and without a diagnosis of peripheral diabetic neuropathy, walked on a treadmill (initial speed of 3 km/h, with 0.5 km/h increments every 5 minutes up to the speed of 5 km/h) to record center of mass acceleration in the vertical, mediolateral and anteroposterior components throughout the test. The sample entropy of the three vectors was calculated for each test speed. Results: The vertical component did not show any statistically significant differences. The mediolateral component showed statistically significant difference for the factors group, speed, and interaction between factors (group and speed). The anteroposterior component showed statistically significant differences for the group factor, but not for speed and interaction between factors (group and speed). Effect sizes classified as large were found in all the comparisons. Conclusions: Peripheral diabetic neuropathy produced changes in the ability to adapt to changes in the environment during gait, probably due to changes in the complexity of the multilevel neural control system, which depends on motor and sensory feedback, known to be affected by peripheral diabetic neuropathy. Level of Evidence II; Diagnostic studies - Investigating a diagnostic test.

Evaluation of a Functional Brace in ACL-Deficient Subjects Measuring Ground Reaction Forces and Contact Pressure: A Pilot Study

ABSTRACT Introduction An ideal functional brace for anterior cruciate ligament-deficient (ACLD) patients should control anterior movement of the tibia and simultaneously decrease the effects of ground reaction shearing force. The current study was aimed to compare the interface pressure between the anterior shell of a functional brace and proximal of tibia in both sound and ACLD limbs, and to assess the effect of using functional brace on the symmetry of vertical and anteroposterior components of ground reaction force and impulse of ground reaction force during level walking. Methods Seven unilateral ACLD men participated in this study. The interface pressure between the anterior shell and proximal of the tibia and ground reaction force was recorded by means of Novel Pliance X and Kistler force platform, respectively. Wilcoxon ranked-sign test and factor analysis repeated measure analysis of variance were used to analyze data. Results The use of functional brace had no significant effect on interface pressure and peak points of the ground reaction force. By use of a functional brace, the valley and the impulse of the vertical component of ground reaction force on ACLD limb increased significantly (P &lt; 0.05) and also improved limb symmetry of all parameters. The interface pressure was greater at distal contact points of the shell, which are at the middle level of the tibia crest. Conclusions The results suggest that functional brace could not apply force on proximal tibia especially at ACLD limb and therefore could not normalize vertical component of ground reaction force during level walking.

Effects of age-related changes in step length and step width on the required coefficient of friction during straight walking

BackgroundSlipping is one of the leading causes of falls among older adults. Older adults are considered to walk with a small anteroposterior (AP) component and a large mediolateral (ML) component of the required coefficient of friction (RCOF) owing to a short step length and a wide step width, respectively. However, limited information is available. Research questionWhat are the effects of aging on the resultant RCOF (RCOFres) and its ML (RCOFML) and AP (RCOFAP) components during straight walking? MethodsWe used the kinetic and kinematic data of 188 participants aged 20–77 years from a publicly available database (National Institute of Advanced Industrial Science and Technology Gait Database 2015). The participants were divided into the following three groups: young group (n = 56; age range, 20–34 years), middle-aged group (n = 50; age range, 35–64 years), and old group (n = 82; age range, 65–77 years). ResultsThe RCOFres and RCOFAP were lower in the old group than in the other groups, indicating a lower slip risk in this group. However, the RCOFML was higher and the step width was greater in the old group than in the other groups. The higher RCOFML and lower RCOFAP in the old group might be associated with slips in a more lateral direction. SignificanceOur findings suggest that older adults have a high risk of slipping in a more lateral direction. Shoes with high-slip resistance in the lateral direction are recommended to prevent hazardous lateral slips among older adults.

Eye Movements in Frogs and Salamanders-Testing the Palatal Buccal Pump Hypothesis.

SynopsisIn frogs and salamanders, movements of the eyeballs in association with an open palate have often been proposed to play a functional role in lung breathing. In this “palatal buccal pump,” the eyeballs are elevated during the lowering of the buccal floor to suck air in through the nares, and the eyeballs are lowered during elevation of the buccal floor to help press air into the lungs. Here, we used X-Ray Reconstruction of Moving Morphology to investigate eye movements during lung breathing and feeding in bullfrogs and axolotls. Our data do not show eye movements that would be in accordance with the palatal buccal pump. On the contrary, there is a small passive elevation of the eyeballs when the buccal floor is raised. Inward drawing of the eyeballs occurs only during body motion and for prey transport in bullfrogs, but this was not observed in axolotls. Each eye movement in bullfrogs has a vertical, a mediolateral, and an anteroposterior component. Considering the surprisingly weak posterior motion component of the eyeballs, their main role in prey transport might be fixing the prey by pressing it against the buccal floor. The retraction of the buccal floor would then contribute to the posterior push of the prey. Because our study provides no evidence for a palatal buccal pump in frogs and salamanders, there is also no experimental support for the idea of a palatal buccal pump in extinct temnospondyl amphibians, in contrast to earlier suggestions.