Normal Motion Research Articles

Complete Closed Rupture of the Medial Bundle of the Flexor Hallucis Brevis Tendon Off the Medial Sesamoid Insertion

Category: Midfoot/Forefoot; Basic Sciences/Biologics; Sports; Trauma Introduction/Purpose: Flexor tendon injuries of the hallux are uncommon overall but when they happen, the flexor hallucis longus (FHL) tendon is the most frequent one affected. The rupture of FHL usually results from open injuries and deep cuts in the sole at the base of the toe;4 complete subcutaneous ruptures are extremely rare.5 There are around 36 cases reported of complete or partial closed ruptures of the FHL tendon along its entire course6 and the majority of the partial ruptures correspond to dancers and athletes.7 As far as FHB, we found a few reports of calcific tendinitis of the medial bundle and cases of calcifying tendinitis.8 To the best of our knowledge, this is the only case report of isolated closed rupture of the FHB tendon. Methods: A 33-year-old man, amateur soccer player, presented with mild swelling, ecchymosis, and increasing pain in the left hallux triggered by movement and palpation, relieved by rest. He sustained a direct axial blow and blunt force trauma with a soccer ball plus hyperextension. Standard bilateral weightbearing feet radiographs were normal. Physical exam revealed the left hallux normally aligned but with limited painful motion of 20° each way and no obvious instability. Palpation of the left first metatarsophalangeal joint was tender but not particularly over the sesamoids. MRI revealed an avulsion of the flexor Hallucis Brevis tendon off the proximal aspect of the medial sesamoid accompanied by fluid and edema, effusion in the first MTP joint and bone contusions in the first metatarsal head and dorsal base of the first proximal phalanx. Treatment with a toe spacer and postop sandal with the toe straight with an extension block was decided. Results: Tendon's blood flow around the sesamoids is limited making it susceptible to degenerative rupture. The most common mechanism of complete tendon rupture is direct open injury. Closed rupture is very rare and complete rupture in closed injury is even more. We did not find reports on third degree type of injuries, neither for any kind of isolated rupture of FHB. In our patient's case, dorsiflexion stretched all plantar soft tissue around the first MTP but he was able to do active movement of the great toe probably due to the FHL and lateral FHB insertion integrity. We found few reports of second-degree strain injury of FHL and FHB in a chronic setting, all treated conservatively with partial immobilization and strapping of the hallux to prevent extension. After conservative treatment at 3 months follow-up, our patient presented with no subjective complains, normal motion, stability and alignment of the hallux. Conclusion: Despite an extensive literature search, we did not find a similar injury, and this is probably the first time it is described. As found in our research, the most common injury related to the flexor tendons of the hallux are in soccer players and involve the FHL or both.23 These findings made us conclude that these injuries are either under-diagnosed or exceptional.

The Role of the Plantar Fascia, Flexor Hallucis Longus, and Fiberosseous Tunnel in Functional Hallux Rigidus

Category: Midfoot/Forefoot Introduction/Purpose: Functional hallux rigidus is characterized by limited first metatarsophalangeal (MTP) dorsiflexion during weight bearing conditions, but normal motion when the metatarsal is allowed to plantarflex. This phenomenon alters the mechanics of the foot, potentially leading to lateral column overloading and dynamic cavovarus. Furthermore, it is suspected that the abnormal forces across the first MTP alters its biomechanics, leading to cartilage destruction and eventual structural hallux rigidus. The purpose of this study is to assess the role of the flexor hallucis longus (FHL) and plantar fascia in functional hallux rigidus and to determine the best surgical treatment. Methods: Six cadaveric lower limbs disarticulated at the hip were analyzed. The feet were positioned manually in the same manner that would be used in a clinical exam of patients. The examiner's thumb was used to stabilize the first metatarsal head and prevent plantarflexion to simulate the closed-chain kinetics of weight bearing. The same hand was used to hold the ankle neutrally aligned to the leg. The other hand was used to maximally dorsiflex the great toe. X-ray was used to obtain images of the feet. The plantar fascia was transected with a Z cut, shortened approximately 5 mm, then repaired. The fiberosseous tunnel was released. The FHL was transected with a Z cut then shortened approximately 5 mm. Great toe dorsiflexion was assessed and X-rays taken after each of the manipulations. Range of motion of the first MTP was measured on Xrays and analyzed using Student's T-test. Results: Average passive dorsiflexion of the first MTP is 29.8° (range 17-46°) prior to manipulation. Shortening the plantar fascia and FHL did not decrease the MTP dorsiflexion significantly beyond baseline (P = 0.08, 0.09 respectively). Transecting the plantar fascia increased the dorsiflexion by 14° (standard deviation (SD) 9.5) and transecting the FHL increased dorsiflexion by 13.7° (SD 4.0). Dorsiflexion increased significantly beyond baseline with both these methods (P = 0.02 and P < 0.001 respectively), but the difference between the two methods was not significant (P = 0.93). Releasing the fiberosseous tunnel alone increased the dorsiflexion 8.8° (SD 5.7). Increased dorsiflexion beyond baseline was significant (P = 0.03). The increase in dorsiflexion with fiberosseous tunnel release was not significantly different than transecting the plantar fascia or the FHL (P = 0.40 and 0.42 respectively). Conclusion: By definition, functional hallux rigidus is diagnosed when first MTP dorsiflexion cannot reach 60°. Its prevalence may be more widespread than previously identified. Both the FHL and plantar fascia are implicated in functional hallux rigidus, as transection of either improves the dorsiflexion of the great toe. However, accessing the plantar fascia comes with significant risks and complete transection of the FHL is not feasible. As an alternative, releasing the fiberosseous tunnel is a simple, minimally morbid procedure that can also significantly improve functional hallux rigidus to a similar degree.

Ultrasound Imaging and Prevalence of Intrasheath Peroneal Tendon Subluxation in Asymptomatic Volunteers

Category: Ankle; Other Introduction/Purpose: Intrasheath peroneal tendon subluxation is typically an incidental finding in athletes with sports-related injuries and is characterized by a temporary reversal in the anteroposterior positions of the peroneus longus (pL) and peroneus brevis (pB) tendons within their common tendon sheath. It is currently unclear whether intrasheath subluxation represents normal physiologic or pathologic tendon motion. This study aims to determine the normal variation in motion of supramalleolar pB and pL tendons in multiple ankle positions and to determine the overall prevalence of intrasheath tendon subluxation in asymptomatic volunteers. Methods: Static sonographic images of the peroneal tendons in 22 asymptomatic volunteers were collected in the neutral position, in eight fixed ankle positions (active and passive pronation, dorsiflexion, supination, and plantarflexion), and during dynamic ankle circumduction. The center of each tendon in relation to the lateral fibular cortex and in relation to each other was measured in each position and used to calculate absolute and percentage displacement. Two-way ANOVA was used to determine the significance of passive versus active motion and two-tailed paired sample t-test was used to compare the mean displacement of pL and pB in active and passive positions. Results: Intrasheath subluxation was not visualized in any static position but was visualized in 33% of patients during active ankle circumduction, regardless of direction or laterality. Percent displacement was greatest in active ankle plantarflexion (55%) for pB and in active pronation (34%) for pL. A statistically significant difference in the tendon positions in relation to each other was found in the anteroposterior direction (p=0.026), but there were no statistically significant differences between active and passive motions or with ankle positioning. A non-painful ankle 'snap' was palpated by the sonographer in all cases of intrasheath subluxation. Conclusion: Intrasheath subluxation is a fairly common occurrence seen in one third of our volunteers. Our results suggest that a snapping ankle in otherwise asymptomatic patients is highly suggestive of intrasheath peroneal tendon subluxation and can be well-documented with dynamic ultrasound. Establishing the normal ranges of motion of supramalleolar peroneal tendons may assist in the evaluation of patients with lateral ankle pain.

A markerless pipeline to analyze spontaneous movements of preterm infants

Background and Objective: The analysis of spontaneous movements of preterm infants is important because anomalous motion patterns can be a sign of neurological disorders caused by lesions in the developing brain. A diagnosis in the first weeks of child’s life is crucial to plan timely and appropriate rehabilitative interventions. An accurate visual assessment of infants’ spontaneous movements requires highly specialized personnel, not always available, and it is operator dependent. Motion capture systems, markers and wearable sensors are commonly used for human motion analysis, but they can be cumbersome, limiting their use in the study of infants’ movements.Methods: In this paper we propose a computer-aided pipeline to characterize and classify infants’ motion from 2D video recordings. The final goal is detecting anomalous motion patterns. The implemented pipeline is based on computer vision and machine learning algorithms and includes a specific step to increase the interpretability of the results. Specifically, it can be summarized by the following steps: (i) body keypoints detection: we rely on a deep learning-based semantic features detector to localize the positions of meaningful landmark points on infants’ bodies; (ii) parameters extraction: starting from the trajectories of the detected landmark points, we extract quantitative parameters describing infants motion patterns; (iii) classification: we implement different classifiers (Support Vector Machines, Random Forest, fully connected Neural Network, Long Short Term Memory) that, starting from the motion parameters, classify between normal or abnormal motion patterns.Results: We tested the proposed pipeline on a dataset, recorded at the 40th gestational week, of 142 infants, 59 with evidence of neuromotor disorders according to a medical assessment carried out a posteriori. Our procedure successfully discriminates normal and anomalous motion patterns with a maximum accuracy of 85.7%.Conclusions: In conclusion, our pipeline has the potential to be adopted as a tool to support the early detection of abnormal motion patterns in preterm infants.

Experimental and performance analysis of the combined damping system with a TMD and a multiple unidirectional single-particle damper

Although the tuned mass damper (TMD) is characterized by simple construction, a definite damping mechanism, and a strong damping effect, a narrow damping frequency band, a detuning effect, and large occupied space limit its application in practical engineering. Particle dampers have the advantages of damping frequency bandwidth and small space, but the damping effect is unsatisfactory. Therefore, a new combined damping system (CTP) containing a TMD and a multiple unidirectional single-particle damper (MUSPD) was developed. A series of shaking table tests for a controlled and uncontrolled structure were conducted to investigate the performance of the system, and the damping effects of a TMD, MUSPD and CTP subjected to harmonic excitation, normal ground motions, rock ground motions, and soft ground motions were compared and analyzed. Finally, a mechanical model of the CTP and corresponding numerical simulation method were developed based on its damping mechanism. The results indicate that a CTP can effectively integrate the advantages of a TMD and MUSPD, and exhibits a better damping effect, wider damping frequency band, and stronger robustness. The shaking table test demonstrates the rationality and feasibility of a simulation method for a CTP.

A Novel Compensatory Motion Detection Method Using Multiple Signals and Machine Learning

Harmful compensatory motion will seriously influence the upper limb rehabilitation effect of stroke patients. Existing compensatory motion pattern detection methods, which are mainly based on accelerometers, inertial measurement units (IMUs), and vision, have problems such as high installation requirements, calibration difficulty, object occlusion, and complex operations. To solve these problems, by analyzing the principle of compensatory motion, this paper designs a trunk restraint belt, compensation motion mode detection system that is composed of a force sensor (F-S), angular displacement sensor (AD-S), and surface electromyography (sEMG). Fifteen healthy subjects without dyskinesia completed normal motion and simulated compensatory movement modes (trunk rotation, trunk forward tilt, and scapular elevation) based on the system. Machine learning (ML) methods are used to classify three compensated motion and normal motion (NM). Among them, the support vector machine (SVM) classifier shows good classification performance for trunk forward tilt (F1-score = 0.9256), shoulder blade elevation (F1-score = 0.9190), trunk rotation (F1-score = 0.8262) and normal motion (F1-score = 0.9758). This method is a new compensation detection method with obvious advantages: it is easy to wear, and without considering the problems of calibration and target occlusion, it can not only identify the patient motion mode but also limit the large range of compensatory motion.

30. Influence of toggling on pullout force and screw diameter increase in spine fixation

<h3>BACKGROUND CONTEXT</h3> Pedicle screw fixation provides spinal stabilization and maintains normal vertebral motions in degenerative spondylolisthesis and scoliosis. Pedicle screw fixation requires several parameters to be optimized at the screw-bone interface to minimize clinical and biomechanical failure, including screw trajectory, bone density and screw sizing. Although prior studies have demonstrated screw loosening as an effect of toggling, they ultimately focus on the magnitude of the pullout force after cyclic loading rather than screw-bone interface throughout cycling. <h3>PURPOSE</h3> A stiffness decay model may help to better predict stability and investigate the effects of pedicle screw diameter to pedicle width ratio on overall screw stability following cyclic loading in the thoracolumbar spine. <h3>OUTCOME MEASURES</h3> Pullout force, toggling forces, decay functions. <h3>METHODS</h3> Thoracolumbar vertebrae (T1-L5) were harvested from two cadaveric spines. Pedicle screws were placed using a standard surgical technique. Five-hundred cycles toggle testing was conducted with a uniaxial load frame followed by axial pullout tests. Exponential decay models with a stiffness coefficient were computed to examine toggling force over the number of toggle cycles for each screw. Linear regression modeling and Pearson's correlation tests were used to compare the decay coefficient with the ratio of the screw diameter to the pedicle diameter, the pullout strength, and pedicle loosening. Subgroup analysis was performed between under-sized (70% pedicle diameter) screws. <h3>RESULTS</h3> Sixty-eight pedicles were harvested. Of the 44 viable pedicles, 33 (75%) were from the thoracic spine and 11 (25%) were from the lumbar spine. There were 23 pedicle screws in the undersized group and 21 pedicle screws in the normal-sized group. The average screw diameter was 53% (SD 5%) of the pedicle diameter in the undersized group and 77% (SD 8%) of the pedicle diameter in the normal-sized group (p < 0.001). A significant association was found between the screw to pedicle diameter ratio and the natural log of the stiffness decay coefficient (p = 0.035). The average pullout force was 170 N (SD 75) in the under-sized pedicle group and 194 N (SD 109) in the normal-sized group (p=0.40). Higher pullout force was associated with a lower stiffness decay coefficient (p = 0.005). Both pullout force and the natural log of the stiffness decay coefficients were associated with the drop in maximum toggling force after 500 cycles (p = 0.026 and p < 0.001, respectively). Utilizing the stiffness decay coefficient provided a better fit model for the predicted drop in maximum toggling force with a lower Akaike information criterion. <h3>CONCLUSIONS</h3> Pedicle screws with a high stiffness decay coefficient during toggle testing had lower pullout strengths. While higher pedicle screw to bone diameter ratios were associated with increased stiffness decay coefficient, there was no relationship between pedicle screw size and pullout strength. In subgroup analysis, however, increasing pedicle screw to bone diameter ratios were associated with lower pullout strength in the normal-sized group. Clinically, selecting a screw size that maximizes the pedicle diameter-screw ratio may not always lead to better fixation in all spine levels or regions. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

A small-amplitude hunting motion recognition method based on transfer learning

The hunting motion of the vehicle increases the wear of the wheel tracks and affects the lateral stability of the vehicle system and safety, so the hunting motion of the vehicle needs to be recognized. However, the existing recognition methods ignore the small-amplitude hunting motion that precedes the onset of the running motion. In addition, due to the scarcity of real hunting data of high-speed trains, there is a problem of underfitting when training with traditional deep learning methods. In this paper, first, the dynamics model of a high-speed train is established, and the normal, small-amplitude hunting and hunting motions of high-speed trains in the process are simulated. Second, this paper proposes a transfer learning-based method for high-speed train hunting motion recognition. The method uses easily collected normal data samples in the training process, does not use real data samples of small-amplitude hunting and hunting motions, and completes the high-speed train running motions recognition task by transferring from simulation data (source domain) to real data (target domain). Finally, the validation is carried out using the real data, which proves that the method-related approach has some engineering application value in the intelligent monitoring of high-speed trains.

Traction Tenolysis for Flexor Tendon Adhesions: Outcomes in 97 Patients

Traction tenolysis is an alternative, less invasive way of performing flexor tendon tenolysis by winding affected tendons around a surgical instrument. This study assessed outcomes and complications in a cohort of patients who underwent traction tenolysis to determine its effectiveness. We retrospectively reviewed 97 patients who underwent traction tenolysis performed by 4 fellowship-trained hand surgeons from 2010 to 2019. We collected data on preoperative and postoperative ranges of motion, the number and type of prior ipsilateral hand surgeries, and the duration of therapy and follow-up. Cases of traditional open tenosynovectomy tenolysis were excluded. Approximately two-thirds of the patients achieved more than 75% of the normal total active motion, and 80% achieved at least 50% of the normal total active motion. The mean total active flexion increased significantly by 42° and passive flexion by 25°. The differences in active and passive flexion significantly decreased from 28° before the surgery to 9° after the surgery. The active and passive flexion of the distal interphalangeal and proximal interphalangeal joints improved similarly, at approximately 20° and 10°, respectively. The average duration of follow-up was 11 ± 8 weeks. The complication rate was 5%: 1 case of intraoperative flexor digitorum superficialis tendon rupture, 1 case of postoperative infection, and 3 reoperations because of failure to progress. Traction tenolysis is an alternative to traditional open tenolysis surgery in selected patients. Therapeutic IV.

World Federation of Athletic Training and Therapy World Congress 2022 Peer-Reviewed Track Abstracts, May 5–7, 2022, Winnipeg, Manitoba, Canada

World Federation of Athletic Training and Therapy World Congress 2022 Peer-Reviewed Track Abstracts, May 5–7, 2022, Winnipeg, Manitoba, Canada

Regional Cardiac Motion Scoring With Multi-Scale Motion-Based Spatial Attention.

Regional cardiac motion scoring aims to classify the motion status of each myocardium segment into one of the four categories (normal, hypokinetic, akinetic, and dyskinetic) from multiple short-axis MR sequences. It is essential for prognosis and early diagnosis for various cardiac diseases. However, the complex motion procedure of the myocardium and the invisible pattern differences pose great challenges, leading to low performance for automatic methods. Most existing works mitigate the task by differentiating the normal motion patterns from the abnormal ones, without fine-grained motion scoring. We propose an effective method for the task of cardiac motion scoring by connecting a bottom-up and another top-down branch with a novel motion-based spatial attention module in multi-scale space. Specifically, we use the convolution blocks for low-level feature extraction that acts as a bottom-up mechanism, and the task of optical flow for explicit motion extraction that acts as a top-down mechanism for high-level allocation of spatial attention. To this end, a newly designed Multi-scale Motion-based Spatial Attention (MMSA) module is used as the pivot connecting the bottom-up part and the top-down part, and adaptively weight the low-level features according to the motion information. Experimental results on a newly constructed dataset of 1440 myocardium segments from 90 subjects demonstrate that the proposed MMSA can accurately analyze the regional myocardium motion, with accuracies of 79.3% for 4-way motion scoring, 89.0% for abnormality detection, and correlation of 0.943 for estimation of motion score index. This work has great potential for practical assessmentof cardiac motion function.

Human-Gait-Based Tracking Control for Lower Limb Exoskeleton Robot

Research shows that it is practical for the normal human movement mechanism to assist the patients with stroke in robot-assisted gait rehabilitation. In passive training, the effect of rehabilitation training for patients can be improved by imitating normal human walking. To make the lower limb exoskeleton robot (LLER) move like a normal human, a tracking control scheme based on human gait data is proposed in this paper. The real human gait data is obtained from healthy subjects using a three-dimensional motion capture platform (3DMCP). Furthermore, the normal human motion characteristics are adopted to enhance the scientificity and effectiveness of assistant rehabilitation training using LLER. An adaptive radial basis function network (ARBFN) controller based on feed-forward control is presented to improve the trajectory tracking accuracy and tracking performance of the control system, where the ARBFN controller is deployed to predict the uncertain model parameters. The feed-forward controller based on the tracking errors is used to compensate for the input torque of LLER. The effectiveness of the presented control scheme is confirmed by simulation results based on experimental data.

Smart Phone-Based Motion Capture and Analysis: Importance of Operating Envelope Definition and Application to Clinical Use

Human movement is vital for life, with active engagement affording function, limiting disease, and improving quality; with loss resulting in disability; and the treatment and training leading to restoration and enhancement. To foster these endeavors a need exists for a simple and reliable method for the quantitation of movement, favorable for widespread user availability. We developed a Mobile Motion Capture system (MO2CA) employing a smart-phone and colored markers (2, 5, 10 mm) and here define its operating envelope in terms of: (1) the functional distance of marker detection (range), (2) the inter-target resolution and discrimination, (3) the mobile target detection, and (4) the impact of ambient illumination intensity. MO2CA was able to detect and discriminate: (1) single targets over a range of 1 to 18 ft, (2) multiple targets from 1 ft to 11 ft, with inter-target discrimination improving with an increasing target size, (3) moving targets, with minimal errors from 2 ft to 8 ft, and (4) targets within 1 to 18 ft, with an illumination of 100–300 lux. We then evaluated the utility of motion capture in quantitating regional-finger abduction/adduction and whole body–lateral flex motion, demonstrating a quantitative discrimination between normal and abnormal motion. Overall, our results demonstrate that MO2CA has a wide operating envelope with utility for the detection of human movements large and small, encompassing the whole body, body region, and extremity and digit movements. The definition of the effective operating envelope and utility of smart phone-based motion capture as described herein will afford accuracy and appropriate use for future application studies and serve as a general approach for defining the operational bounds of future video capture technologies that arise for potential clinical use.

Design and Implementation of Human Motion Monitoring System on Account of Intelligent Computing of Internet of Things

The era of big data network represented mainly by the Internet of Things is limited by various factors such as various environments, volumes, and calculations. This paper proposes and studies a human motion detection system based on the intelligent computing of the Internet of Things, which can effectively detect the daily motion of the human body. In the era of the Internet of Things, this paper designs and develops a human motion detection system based on the Internet of Things technology and intelligent computing and explores the law of normal human motion. This paper also analyzes the design ideas and technical advantages of the human motion detection system from many aspects. This research is a human motion detection system designed and developed under the comprehensive use of Internet of Things technology and intelligent computing technology, which can effectively detect the actual situation of the human body in the state of motion. Experimental results show that the overall accuracy of the system for monitoring and recognizing human walking is 96.91%, and the overall accuracy of monitoring and recognizing human jogging is 97.18%. It monitors and recognizes human jogging with an overall accuracy rate of 97.96%. It has great practical significance.

Biomechanical effect of C5-C6 intervertebral disc degeneration on the human lower cervical spine (C3-C7): a finite element study

The biomechanical effects of intervertebral discs and facet joints degeneration on the cervical spine are essential to understanding the mechanisms of spinal disorders to improve pathological and clinical treatment. In this study, the biomechanical effects of a progressively degenerated C5-C6 segment on the human lower cervical spine are determined by a detailed simulation of intervertebral disc degeneration. A detailed asymmetric three-dimension intact finite element model was developed using computed tomography scan data of the human lower cervical spine (C3-C7). The intact finite element model was then modified at the C5-C6 segment to build three degenerated models, such as mild, moderate, and severe degeneration. The physiological compressive load 73.6 N, and moment 1 Nm were applied at the superior endplate of the vertebra C3, and the inferior endplate of the C7 vertebra was a constraint for all degrees of freedom. Range of motion, maximum von Mises stress in the annulus, intradiscal pressure, and facet joint force of the degenerated models were computed. With progressive degeneration in the C5-C6 segment, the range of motion of degenerated and normal segments decreases in all postures. Intradiscal pressure of the degenerated segment decreases but increases in normal segments of degenerated segment C5-C6, and facet joint forces increase at both degenerated and normal segments. This study emphasizes that the degenerated disc alters the degenerated and normal segments' motion and loading patterns. The abnormal increase in facet joint force in the degenerated models threatened to accelerate the degeneration in the normal segments.

Intraoperative Management of the Recurrent Laryngeal Nerve Transected or Invaded by Thyroid Cancer.

Thyroid cancer often invades the recurrent laryngeal nerve (RLN), causing vocal cord paralysis. In such patients, the invaded portion of the RLN usually needs to be resected through curative surgery. We attempt to preserve the nerve by performing sharp dissection in such cases. During nerve dissection, an intraoperative nerve monitoring system helps identify the course of the RLN in the fibrous tissue around the tumor or even within the tumor, and also helps evaluate the nerve integrity. Because of extensive dissection, the preserved RLN may become much thinner than its original thickness. We refer to this procedure as “partial layer resection” of the RLN. In our cases, although the dissected RLNs became thinner, we found that vocal cord function recovered in most patients. If the RLN is fully involved by thyroid cancer or response of the vocal cord against electric stimulation to the RLN is lost, we resect the portion of the RLN together with the tumor and repair it using one of the reconstruction techniques. When a unilateral RLN is resected, the vocal cord on that side is paralyzed. Symptoms include hoarseness, mis-swallowing, and short phonation. RLN reconstruction using one of the reconstruction techniques leads to the recovery of phonatory and swallowing function, although the normal motion of the vocal cord on the side of the anastomosis is not restored. We used direct anastomosis, free nerve grafting, ansa cervicalis-RLN anastomosis, and vagus-RLN anastomosis to reconstruct the RLN. Thyroid cancer often invades the RLN near the Berry’s ligament. In such patients, surgeons might assume that reconstruction of the RLN may not be possible because the peripheral stump of the RLN cannot be observed. However, if we divide the inferior pharyngeal constrictor muscles along the lateral edge of the thyroid cartilage, the peripheral RLN can be identified, and nerve reconstruction can be performed. We refer to this procedure as “laryngeal approach”.In summary, of the patients with thyroid cancer who required resection of the RLN, RLN reconstruction led to the recovery of phonatory function. We suggest that all thyroid surgeons familiarize themselves with these reconstruction techniques.

C33 PERCUTANEOUS CLOSURE OF MITRAL PARAVALVULAR LEAK (PVL): WHEN REVERSAL MAKES ALL THE DIFFERENCE

Abstract PVL is a complication associated with the implantation of a prosthetic valve. Since surgical re–intervention has a high operative risk, percutaneous closure (PC) has emerged due to its reduced invasiveness and the development of dedicated materials. We describe the case of a 66–year–old man with a mechanical oscillating disc mitral prosthesis who was admitted for acute heart failure. An echo showed a left ventricle with normal motion and a postero–medial mitral PVL with significant regurgitation. A transoesophageal echo confirmed the PVL in the 5 o’clock viewing portal with severe regurgitation. After optimising the medical therapy and with no change in echo findings, a cardiac catheterisation showed persistent post–capillary pulmonary hypertension, and therefore PC of the PVL was scheduled. Given the postero–medial location of the PVL, a transseptal puncture was performed using a 8.5 Fr Agilis introducer (Terumo) with telescoping system of a 6 r. JR4 catheter. The PVL was passed through with a Terumo 0.035 J–shaped guide, but without managing to advance the catheter beyond the leak. The guide was therefore advanced into the abdominal aorta and an arteriovenous circuit was created, which allowed the catheter to be advanced beyond the PVL and a closure device (AVPIII 14/5,Abbott St.Jude) was positioned with anterograde placement, with a distal disc on the ventricular side. Obliteration of the PVL, interference with the prosthetic disc and high transprosthetic gradients were observed despite several attempts to relocate the AVP, which was therefore removed. A second procedure was performed at a distance, creating a similar arteriovenous circuit by using a long introducer (110cm–Cook) which was advanced from the femoral artery beyond the leak in the opposite direction. An AVPIII (12/5) with a distal disc on the atrial side was positioned, this time with retrograde placement, with effective closure of the PVL and minimal residual regurgitation, without interference with the prosthesis. The course was free of complications; after one month the echo confirmed the result. Transcatheter closure of the PVL is a complex procedure, but relatively safe in experienced hands. This case is of particular interest due to the difficulty presented by the location of the PVL, which required measures of high technical complexity and because it describes a possible complication of the procedure, which was resolved by the simple reversal of the placement of the device.

C14 A PROMISING SURGICAL TECHNIQUE IN PATIENTS WITH ATRIAL FUNCTIONAL MITRAL REGURGITATION: HYPER–DOWN–SIZING ANNULOPLASTY

Abstract Objective Atrial functional mitral valve regurgitation is a less common form of functional mitral regurgitation with normal leaflet motion and morphology, preserved dimension and function of left ventricle, associated with atrial fibrillation ad/or left atrial dilatation. Several factors are involved into the etiology, such as mitral annular dilation and insufficient leaflet remodeling, atriogenic leaflet tethering, loss of annular saddle shape and contractility, changes in heart rate. Methods Eleven consecutive patients with atrial functional mitral regurgitation, mean age 65 ± 12 years, normal left ventricle dimension and ejection fraction greater than 50% underwent mitral valve repair via right mini–thoracotomy in case of isolated mitral and tricuspid valve surgery or via median sternotomy in case of combined procedures. Concomitant procedures include tricuspid valve repair in 1 patient and coronary artery bypass in 5 patients. All patients presented an increased dimension of left atrium (mean left atrial volume: 90 ± 23 ml); mitral annular dimension was investigated with trans–esophageal echocardiography before operation. In all patients was implanted a downsized complete rigid annuloplasty ring with asymmetrical design of two sizes smaller respect to measured intercommissural distance. Clinical outcomes of patients and echocardiographic findings related to mitral regurgitation recurrence and left ventricle function were followed in the time. Results At discharge, any patient present a residual mitral regurgitation greater than mild, mean trans–mitral gradient was 2.5 ±2.1 mmHg. During the follow–up period of 24 ± 5 months, the New York Heart Association functional class significantly improved from 2.5 ± 0.4 to 1.5 ± 2.1. In three patients occurred cardiac rhythm disturbances requiring hospital stay, only one patient developed a greater than mild mitral regurgitation, reoperation was not becessary in any case. Left atrial volume decreased from 90 ± 23 ml to 58 ± 30 ml. Conclusions Mitral annuloplasty with downsized ring is a safe and effective procedure in patient with atrial functional mitral regurgitation in the same way of patient with functional mitral regurgitation due to ventricular dilation and tethering. The comforting clinical and echocardiographic outcome in our small group of patient encourage future studies in this particular group of patients.

P305 ACUTE MYOPERICARDITIS IN 2021: COVID19 RELATED?

The term myopericarditis is used when there are primarily pericarditis symptoms with myocardium involvement as evidenced by cardiac biomarker elevation or imaging studies revealing normal wall motion. We report a case of a young 23–years old man, who presented to the Emergency Department with fever and diarrhea lasting 5 days followed by acute chest pain, modified by trunk position. The electrocardiogram (ECG) showed diffuse inferior and anterolateral ST–segment elevation. No signs of hemodynamic instability were detected. Laboratory tests showed WBC 8840/mmc, CRP 53,2 mg/L, TnT 986 ng/L, a mildly altered liver function with AST 92 UI/L, ALT 88 UI/L, GGT 82 UI/L and an altered pancreatic function with amylase 190 UI/L, lipase 267 UI/L. Naso–pharyngeal swab was negative. The patient received COVID–19 mRNA vaccination 4 months before symptoms, with high immune response, detected with IgG dosage (465 BAU/ml). Ecocardiography showed a left ventricle with normal size, function, and segmental contractility. Valvular apparatus in normal range. Hyper–refraction of the posterior pericardium with minimal effusion. The diagnosis of acute myopericarditis was glaring and we treated the patient with high dosage of non–steroidal anti–inflammatory drugs, colchicine and ACE Inhibitors, based on the increased troponin levels (nadir 1439 nl/L), in order to prevent the possible cardiovascular remodeling. On laboratory testing, the deepening of the main causes of viral or autoimmune myopericarditis did not clarify the etiopathogenesis. No arrhythmias occurred on ECG monitoring. Cardiac MRI showed multiple areas of altered signal (T2) and altered uptake in lateral and inferior ventricular segments and in adjacent pericardium. The pain was gone in two days and left ventricle function was still preserved upon discharge. In conclusion we report a successful treatment of acute myopericarditis of unknown pathogenesis, in a healthy young man. As there are described cases of myopericarditis and myositis associated with COVID–19 in the absence of respiratory symptoms, and others related to SARSCoV2 mRNA vaccination, we dutifully excluded both.

Opposite motion of the Central Helices of efflux pump KmrA is important for its export efficiency

Efflux pump of Major Facilitator Superfamily (MFS) is widely distributed in bacteria, while its role in regulating antibiotic resistance of nosocomial pathogen Klebsiella pneumoniae remains unclear. Herein we analyzed the effect of amino acid substitution of MFS efflux pump KmrA on its export efficiency via molecular biology and molecular dynamics (MD). After searching across the 804 sequenced K. pneumoniae isolates, we identified four major variants of KmrA, while one of them KmrA-A was demonstrated an inactive one in MIC and ethidium bromide efflux assays. Subsequently, MD simulations of KmrA and its variants were conducted and the opposite motion of the central helices were observed for the active variants, while it was not found for KmrA-A. To further identify the importance of the opposite motion to the conformational transition, we calculated their differences in volume of binding pocket, salt bridge and hydrophilic interaction with water based on the rocker-switch model. Our results indicated that the opposite motion of KmrA conferred a larger binding pocket and stronger hydrogen bond with water at inward-facing conformation. An unusual substitution S374A of KmrA-A disrupted the normal motion of central helices by enhancing hydrophobic interactions between them, resulting into the altered positions and strengths of salt bridge, which was deduced to affect the conformational transition. Overall our data provided detailed information on the regular of KmrA's moving trajectory, demonstrating the importance of opposite motion of central helices to KmrA's export efficiency.