The Functionality Verification through Pilot Human Subject Testing of MyFlex-δ: An ESR Foot Prosthesis with Spherical Ankle Joint

Most biomechanical research has focused on level-ground walking giving less attention to other conditions. As a result, most lower limb prosthesis studies have focused on sagittal plane movements. In this paper, an ESR foot is presented, of which five different stiffnesses were optimized for as many weight categories of users. It is characterized by a spherical ankle joint, with which, combined with the elastic elements, the authors wanted to create a prosthesis that gives the desired stiffness in the sagittal plane but at the same time, gives flexibility in the other planes to allow the adaptation of the foot prosthesis to the ground conditions. The ESR foot was preliminarily tested by participants with transfemoral amputation. After a brief familiarization with the device, each participant was asked to wear markers and to walk on a sensorized treadmill to measure their kinematics and kinetics. Then, each participant was asked to leave feedback via an evaluation questionnaire. The measurements and feedback allowed us to evaluate the performance of the prosthesis quantitatively and qualitatively. Although there were no significant improvements on the symmetry of the gait, due also to very limited familiarization time, the participants perceived an improvement brought by the spherical ankle joint

The Functionality Verification through Pilot Human Subject Testing of MyFlex-δ: An ESR Foot Prosthesis with Spherical Ankle Joint

Most biomechanical research has focused on level-ground walking giving less attention to other conditions. As a result, most lower limb prosthesis studies have focused on sagittal plane movements. In this paper, an ESR foot is presented, of which five different stiffnesses were optimized for as many weight categories of users. It is characterized by a spherical ankle joint, with which, combined with the elastic elements, the authors wanted to create a prosthesis that gives the desired stiffness in the sagittal plane but at the same time, gives flexibility in the other planes to allow the adaptation of the foot prosthesis to the ground conditions. The ESR foot was preliminarily tested by participants with transfemoral amputation. After a brief familiarization with the device, each participant was asked to wear markers and to walk on a sensorized treadmill to measure their kinematics and kinetics. Then, each participant was asked to leave feedback via an evaluation questionnaire. The measurements and feedback allowed us to evaluate the performance of the prosthesis quantitatively and qualitatively. Although there were no significant improvements on the symmetry of the gait, due also to very limited familiarization time, the participants perceived an improvement brought by the spherical ankle joint

In vitro study of the aortic interleaflet triangle reshaping

Aortic interleaflet triangle reshaping (AITR) is a surgical approach to aortic valve incontinence that involves placing three stitches at half of the interleaflet triangles height. In this work, the relationship between the actual stitch height and valve functioning, and the safety margin that the surgeon can rely on in applying the stitches were systematically investigated in vitro. AITR surgery was applied to six swine aortic roots placing the stitches empirically at 50%, 60% and 75% of the triangle heights. Then the actual stitch heights were measured and the hydrodynamic performances were evaluated with a pulsatile hydrodynamic mock loop. Actual stitch heights were 45\ub12%, 61\ub14% and 79\ub16%. As compared to untreated conditions, the 50% configuration induced a significant variation in the effective orifice area. With stitches placed at 60%, the mean systolic pressure drop increased significantly with respect to the untreated case, but no significant changes were recorded with respect to the 50% configuration. At 75%, all the hydrodynamic parameters of systolic valve functioning worsened significantly. Summarizing, the AITR technique, when performed in a conservative manner did not induce significant alterations in the hydrodynamics of the aortic root in vitro, while more aggressive configurations did. The absence of a statistically significant difference between the 50% and 60% configurations suggests that there is a reasonably limited risk of inducing valve stenosis in the post-op scenario due to stitch misplacement

Aortic interleaflet triangles reshaping : hydrodynamic, kinematic and morphological effects in in-vitro analysis

BACKGROUND AND AIM OF THE STUDY: Subcommissural triangles reshaping is a reparative technique used to remodel the ventriculo-aortic junction. The study aim was to evaluate, by means of in-vitro testing, the effects of this technique on hemodynamics, leaflet kinematics and aortic root functional unit morphology. METHODS: Twenty-one porcine aortic roots were tested in a pulsatile mock loop under basal conditions and after subcommissural triangles reshaping performed at 50% of the interleaflet triangles height. During each test, hydrodynamic quantities, high-speed digital videos and echocardiographic images were recorded. RESULTS: The comparison between pre- and post-surgery data showed a statistically significant increase in coaptation height (p < 0.01) and length (p < 0.01). Significant reductions were found in the virtual basal ring diameter (p < 0.01), sinus of Valsalva diameters (p < 0.01), maximum leaflet opening (p < 0.01), leaflet opening before rapid valve closing time (p < 0.01) and maximum opening area (p < 0.01). An opened valve time reduction (p <0.01) was observed due to an opening time reduction (p < 0.01), offset by a closed valve time increase (p < 0.01). A slow closing period increase (p < 0.07) and a rapid closing phase reduction (p < 0.01), were also highlighted without influence on the total closing time. A statistical, but not clinically significant, increase in pressure drop across the valve (p < 0.01) and an effective orifice area reduction (p < 0.01) were observed. CONCLUSION: Subcommissural triangles reshaping performed at 50% of the interleaflet triangles' height determines an increase in leaflet coaptation by remodeling the ventriculo-aortic junction. Some hydrodynamic and kinematic changes also occur, without any acute clinically threatening alterations