Flexible Foot Research Articles

Using Remotely Operated Suction Irrigation System in da Vinci SP Submucosal Dissection.

Submucosal dissection using the da Vinci SP® system (Intuitive Surgical, Sunnyvale, CA, USA) is an emerging approach for treating premalignant lesions in the colon and rectum. The endoluminal space is tight and small, and during the procedure, this tight space is accessed by the 40 mm GelPOINT® Path transanal platform (Applied Medical, Rancho Santa Margarita, CA, USA). Most of the trocar space is occupied by the 25 mm port of the da Vinci SP® system. There is limited space for an additional trocar, and the full mobility of this trocar is restricted; hence there is a need for an effective suction irrigator during these procedures. Although the da Vinci SP® system has four instrument capabilities, it does not have a suction irrigation instrument. To address this issue, we tested a Remotely Operated Suction Irrigation System (ROSI™) (VTI, Nashua, NH, USA) in three patients undergoing da Vinci SP® submucosal dissection. The impact of innovation is the evaluation of a flexible suction irrigator during endorobotic submucosal dissection (ERSD), addressing space constraints and enhancing surgical precision. This was a single-center retrospective observational study involving three patients who underwent ERSD, between February 2023 and May 2023. ROSI™ was used selectively for rectal lesions. The first patient was a 67-year-old male with a 30 mm tubulovillous adenoma found in the rectum at 4 cm. The second patient was a 49-year-old female, referred after a screening colonoscopy, with a 40 mm rectal mass 12 cm from the anal verge. A biopsy revealed a tubular adenoma without dysplasia. The last patient was a 66-year-old male with a 25 mm tubulovillous adenoma with a focal high-grade dysplasia at 10 cm. There was no evidence of invasive carcinoma or lymph node metastasis on MRI in any of the patients. The patients were placed in a modified lithotomy position, and the GelPOINT® Path was inserted. A silk suture was attached at the proximal end of ROSI™ to facilitate tubing manipulation. ROSI™ was freely passed into the endoluminal space through the gel using a surgical clamp. Any bleeding during the operation was aspirated and irrigated using ROSI™ with the assistance of bipolar forceps. All surgeries were completed without complications and the patients were discharged on the same day. ROSI™ is a flexible foot pedal-controlled suction irrigator that can facilitate da Vinci SP® submucosal dissection. The flexibility and controllability of ROSI in the surgeon's hand may qualify it as an essential tool for performing ERSD and possibly other TAMIS procedures.

Individuals with asymptomatic hallux valgus exhibit altered foot kinematics during gait regardless of their foot posture

BackgroundA flatfoot has been believed to be closely associated with the development of hallux valgus; however, the association is still controversial. Abnormal foot kinematics has been identified as a possible risk factor for the development of hallux valgus, but it remains unclear whether foot posture contributes to abnormal foot kinematics. This is the first study to investigate the differences in foot kinematics during gait between individuals with and without hallux valgus, while controlling for foot posture. MethodsTwenty-five females with hallux valgus and 25 healthy females aged 18 to 22 were recruited. Foot posture was measured using normalized navicular height truncated and the leg-heel angle. Foot kinematic and kinetic data during gait were recorded by a three-dimensional motion capture system. To investigate the characteristics of foot kinematics in individuals with hallux valgus while controlling for foot posture, we used a propensity score matching method. The matching was obtained by using the 1:1 nearest-neighbor procedure and a caliper width of 0.2. FindingsTwelve pairs were matched. Individuals with hallux valgus had significantly increased midfoot dorsiflexion from 56% to 80% during stance phase, rearfoot eversion from 53% to 71%, and forefoot abduction from 5% to 29% compared with control. InterpretationIndividuals with hallux valgus have a flexible foot that cannot suppress the dynamic deformation of the rearfoot and midfoot during gait. To suppress the development of hallux valgus, interventions that aim to prevent dynamic deformations of the rearfoot and midfoot during gait may be necessary, regardless of their static foot posture.

Efficacy of hinged and carbon fiber ankle-foot orthoses in children with unilateral spastic cerebral palsy and drop-foot gait pattern.

In children with unilateral spastic cerebral palsy (USCP), ankle-foot orthoses (AFOs) are widely used to correct common gait deviations such as a drop-foot pattern. Most studies on this topic have investigated specific time points while omitting other parts of the gait cycle. This study investigated the separate effects of prefabricated carbon fiber AFOs and custom-made hinged AFOs compared with barefoot walking in children with USCP with a drop-foot gait pattern using statistical parametric mapping. Retrospective, cross-sectional, repeated measures study. Twenty ambulatory children (9.9 ± 2.5 years) with USCP and a drop-foot gait pattern were included. Kinematics, kinetics, and spatiotemporal parameters assessed during 3-dimensional gait analysis were compared between barefoot and AFO walking. Statistical parametric mapping was used to compare joint angles and moment waveforms. Kinematics, kinetics and spatiotemporal parameters assessed during 3-dimensional gait analysis were compared between barefoot and AFO walking for each AFO type but not between the 2 AFO types. Compared with barefoot walking, there was a steeper sole angle at initial contact, corresponding to a heel strike pattern, and an increased ankle dorsiflexion in swing with the use of both AFOs. The ankle plantar flexion moment during loading response increased. Ankle power generation during pre-swing decreased in the carbon fiber AFO group when walking with AFOs. Both AFOs were beneficial for improving a drop-foot gait pattern in these small patient groups and can, therefore, be recommended to treat this gait deviation in patients with unilateral cerebral palsy. However, the reduction in ankle power generation during push-off and additional goals targeted by AFOs, such as correction of structural or flexible foot deformities, should be considered for prescription.

Evaluation of Hindfoot Alignment on Lateral Weightbearing x-rays: A Novel Prospective In Vivo Study

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: In clinical practice and research, there are several scenarios when a hindfoot alignment view weightbearing XR is not obtained whether as a result of a lack of resources, technology, in retrospective studies when a hindfoot view was not obtained, as well as in many practices where a hindfoot view XR is not considered a routine examination for foot and ankle disorders. A lateral weightbearing radiograph however is almost routinely obtained, and the goal of this study was to correlate the hindfoot alignment angle with measurements on lateral weightbearing images. Methods: Four volunteers (8 feet) with flexible feet and ankles and no symptoms, nor significant trauma & surgical history in their lower limbs were recruited for this study. A portable fluoroscopy machine (Smart C, Turner Imaging, Salt Lake City, USA) was used for imaging. The participant was asked to stand on different custom wooden wedges with the angle changed every 5 degrees from 30 degrees of varus to 30 degrees of valgus and a weightbearing lateral image was taken for each position. The hindfoot alignment was measured using a skin marker which had been drawn prior to initiation of the imaging, and the angular changes of the hindfoot was measured with the placement of each wedge placed. All standardized measurements of the midfoot and hindfoot were obtained on the lateral images. Results: With the hindfoot positional changes between 30o of varus to 30o of valgus, there was a gradual measurable change in the subtalar joint, with corresponding changes in the midfoot and hindfoot. There was a significant linear correlation between the hindfoot alignment angle and all radiographic parameters on lateral images. When the hindfoot alignment angle increased by 1 degree in the valgus direction, there was 0.49o decrease in the pitch angle, 0.58o of decrease in the middle vs posterior facet angle, 0.06o of decrease in the proximal cuneiform/cuboid height, 0.40o of decrease in the proximal cuneiform/5th Metatarsal height, 0.40o of increase in the fifth metatarsal/cuboid height, 0.009o of increase in the sinus tarsi/lateral process height, and 0.015o increase in Cuboid/Anterior Process Height. (Figure 1) Conclusion: The lateral weightbearing XR can be used to predict the status of the hindfoot alignment, and this study has proven that this can be none not only qualitatively but also quantitatively. This novel research can provide our colleagues with linear regression equations to correlate the lateral imaging metrics with the hindfoot alignment angle. Further study with a larger sample size and participants with different types of hindfoot deformities is needed to help develop an algorithm that would help both clinical practice and research.

The Variation Between Unilateral and Bilateral Weight Bearing in Hindfoot Alignment Evaluation. Part I: A Prospective In Vivo Radiographic Study

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: When weight bearing radiographs are taken, the patient is frequently asked to stand on the foot being examined with the other foot lifted off the floor. We have found however that alignments of the hind and midfoot change when bearing weight switches from bilateral to unilateral standing. This study investigated the possible differences in hindfoot alignments between unilateral and bilateral weight bearing using radiographical evaluation. Methods: Eight flexible feet without symptoms symptoms, nor significant trauma & surgical history in their lower limbs were recruited for this study. A portable fluoroscopy machine (Smart C, Turner Imaging, Salt Lake City, USA) was used to take weightbearing lateral views. The patient first stood on both feet with the non-examined foot standing outside of the collimator but bearing weight evenly (Figure 1), and then lifted the non-examined foot off the floor when the lateral XR image was taken for the examined foot. Hindfoot alignment in both positions was reflected by measuring the angle between the long axes of the proximal and distal portions of the Achilles tendon on the skin using the subtalar joint line as the intersection. On lateral XRs, various parameters were measured to reflect the subtalar joint alignment, the position of the calcaneus with inversion and eversion of the hindfoot, and the lateral and medial arch heights. Results: From bearing weight on two feet (bilaterally) to one foot (unilaterally), the Hindfoot Alignment Angle (Achilles) increased (6.23 to 11.21 degrees), the Calcaneal Pitch Angle decreased (22.06 to 19.22 degrees), the Middle vs Posterior Facets Angle decreased (166.46 to 160.74 degrees), and the 5th metatarsal/cuboid height decreased (0.73 to 0.67) all significant changes (p < 0.05). All of these represented a pronation movement in the mid and hindfoot, ie, valgus tilt/eversion of the calcaneus, decreased sinus tarsi opening, and reduced lateral arch height. In this small cohort, these differences were more obvious in the feet that were either slightly flat or cavus shaped (Figure 1, Table 1, and 2) than in feet with a more neutral alignment. Conclusion: The hindfoot and midfoot are more pronated in unilateral weightbearing than in bilateral weightbearing which may mask the severity of the deformity in a flexible cavovarus foot, but increase that in a flexible flatfoot. Modification of the traditionally used unilateral weightbearing position in obtaining clinical radiographs should be considered. Bilateral WBCT scans may be a better alternative, taking advantage of allowing both feet to stand in the most natural position without one foot blocking the other during the radiographic imaging.

Split transfer of tibialis anterior for equinovarus foot deformity in cerebral palsy

: Foot deformities in children with cerebral palsy are common. The various foot deformities are equinus, planovalgus, equinovarus, equinovalgus. Treatment for the flexible foot deformity should be with orthotics and manual therapy initially and then with tendon lengthening. Equinovarus deformity of the foot is a result of the muscle imbalance in which invertors of the foot, posterior and anterior tibialis muscle, overpower evertors. Untreated spastic equinovarus deformity may cause severe fixed foot deformity and painful callosities under metatarsal heads and on the lateral side of foot. To evaluate the effectiveness of split transfer of tibialis anterior for equinovarus foot deformity in spastic cerebral palsy children.40 spastic cerebral palsy (13 diplegic and 27 hemiplegic) children between the age of 5-15 years with equinovarus foot deformity were selected. The procedure adopted in all the cases was tendoachilles lengthening and split anterior tibialis tendon transfer to cuboid. The result was graded as good, fair and poor. In 28 of the cases varus deformity of the forefoot and midfoot got corrected with plantigrade foot, in 10 of the cases forefoot and midfoot supination was corrected but heel was in varus and in 2 of the cases there was no improvement.: Spastic T.A. is most often the cause of varus of forefoot. Split transfer utilises the spastic nature of the muscle to counter balance the deformity caused by the original muscle. Hence, it is better solution to the problem. However accurate diagnosis of deforming muscle, i.e, T.A or T.P. is essential to produce good result.

Design of Flexible Feet for Legged Robots

Due to its unique body structure and movement mode, the legged robot has strong terrain adaptability and can move in many complex environments. However, the robot's feet will frequently contact with the ground during the movement, and will be subject to greater ground impact. The flexible foot structure can effectively reduce the ground impact. The leg and foot structures, and locomotor characteristics of cats and insects were analyzed based on bionic principles. Combined with the structural characteristics of the small-legged robot, the structure and function of the flexible foot end is analyzed.

A Neural Coordination Strategy for Attachment and Detachment of a Climbing Robot Inspired by Gecko Locomotion.

Climbing behavior is a superior motion skill that animals have evolved to obtain a more beneficial position in complex natural environments. Compared to animals, current bionic climbing robots are less agile, stable, and energy-efficient. Further, they locomote at a low speed and have poor adaptation to the substrate. One of the key elements that can improve their locomotion efficiency is the active and flexible feet or toes observed in climbing animals. Inspired by the active attachment-detachment behavior of geckos, a hybrid pneumatic-electric-driven climbing robot with active attachment-detachment bionic flexible feet (toes) was developed. Although the introduction of bionic flexible toes can effectively improve the robot's adaptability to the environment, it also poses control challenges, specifically, the realization of attachment-detachment behavior by the mechanics of the feet, the realization of hybrid drive control with different response characteristics, and the interlimb collaboration and limb-foot coordination with a hysteresis effect. Through the analysis of geckos' limbs and foot kinematic behavior during climbing, rhythmic attachment-detachment strategies and coordination behavior between toes and limbs at different inclines were identified. To enable the robot to achieve similar foot attachment-detachment behavior for climbing ability enhancement, we propose a modular neural control framework comprising a central pattern generator module, a post-processing central pattern generation module, a hysteresis delay line module, and an actuator signal conditioning module. Among them, the hysteresis adaptation module helps the bionic flexible toes to achieve variable phase relationships with the motorized joint, thus enabling proper limb-to-foot coordination and interlimb collaboration. The experiments demonstrated that the robot with neural control achieved proper coordination, resulting in a foot with a 285% larger adhesion area than that of a conventional algorithm. In addition, in the plane/arc climbing scenario, the robot with coordination behavior increased by as much as 150%, compared to the incoordinated one owing to its higher adhesion reliability.

A stick-slip piezoelectric actuator with high assembly interchangeability

The stick-slip piezoelectric actuator with simple driving signal and structure is a very promising type for achieving the high resolution and large stroke. However, as a typical actuator working by the friction-inertia principle, the contact between the stator and mover requires precise adjustment, which brings difficulty for the assembly of the actuator. Excessive assembly errors may even cause the piezoelectric actuator to fail to work. Accordingly, to decrease the effects of assembly factors on the output performances and enhance the assembly interchangeability of stick-slip piezoelectric actuators, a method of low stiffness contact was proposed in this study, which used the flexible foot to replace the generally employed rigid foot with high stiffness. By comparing with the rigid foot actuator, the feasibility of the proposed method was theoretically analyzed first. Then, the effects of preload deformation and three potential assembly errors (deflection, overturning and pitching) on the output performances were characterized. Finally, a highly interchangeable actuator with compact structure was designed, and its abilities for quick disassembly and assembly, interchangeability of the stator and large-stroke stable motion were tested. Experimental results indicated that the proposed actuator can achieve good motion stability and high interchangeability. The strategy of low stiffness contact can significantly decrease the assembly requirement, which is beneficial to the practical production and application of stick-slip piezoelectric actuators.

Leg lengthening and deformity correction in fibular hemimelia using ring external fixator

Background: The treatment of fibular hemimelia aims to achieve a functional limb nearly equal in length to the normal limb at maturity, with a plantigrade, stable and flexible foot. The aim of this work was to evaluate the functional results of reconstructive lengthening and deformity correction in fibular hemimelia using the ring external fixator. Methods: This observational study was carried out on 41 patients with fibular hemimelia. The cases either prospectively gathered (sixteen cases, 39 %) to start their management plan or retrospectively collected (twenty-five cases, 61 %) and followed up. Foot reconstruction surgery was done in 22 cases while lengthening surgery applied all cases. All patients were subjected to: history taking, clinical examination (local (lower limb), foot and knee), general examination and imaging. Results: regarding overall results, at the end of follow-up with an average period of 2 years, 4 patients had excellent results (9.76%), 21 patients (51.2%) had good results, 12 patients (29.28%) had fair results and 4 patients (9.76%) had poor result. Regarding subjective functional assessment, out of 41 patients, 20 of them (48.8%) were from 75 to 100% subjectively satisfied, 11 patients (26.8%) from 50 to 74% and 10 patients (24.4%) from 0 to 49% satisfied.

The effects of calf muscles fatigue on dynamic plantar pressure distribution in normal foot posture and flexible flatfoot: A case-control study

Flexible flatfoot is associated with altered plantar pressure distribution, but it is not clear how muscle fatigue affects plantar pressure characteristics in flexible flatfoot and normal foot. To investigate the effects of calf muscles fatigue on plantar pressure variables in flexible flatfoot and normal foot. Twenty-five people with flexible flatfoot and twenty-five people with normal foot were included. The unilateral heel-rise test was used to induce calf muscles fatigue. Plantar pressure variables were collected during preferred walking immediately before and after fatigue. The two-way mixed-design ANOVA was used to determine the main effect of fatigue and the interaction between foot posture and fatigue. Fatigue caused medialization of the contact area under the forefoot and the maximum force under the heel and forefoot (p< 0.05). When examining the differences in the effects of fatigue between groups, the contact area under the medial heel increased with fatigue in flexible flatfoot but decreased in normal foot; moreover, the contact area and maximum force under the midfoot and the maximum force under the third metatarsal decreased with fatigue in flexible flatfoot but increased in normal foot (p< 0.05). Calf muscles fatigue caused medialization of the maximum force and contact area. Especially the midfoot was affected differently by fatigue in flexible flatfoot and normal foot.

Humanoids’ Feet: State-of-the-Art &amp; Future Directions

Robotic feet play a fundamental role in the walking performance of a biped robot. Feet are essential to maintain dynamic stability and to propel the body during walking. They may ensure stability on uneven terrains. Yet, complex feet are seldom used on humanoids. This paper surveys 36 types of robotic feet we found in the literature. We classified them according to strategy, capabilities, structure, number of degrees of freedom, actuation method of ankle and foot, type of actuator, sensorization and type of control. Subsequently, we analyzed the dynamic and static models of flexible feet. We discussed considerations on foot dynamics or kinematics in the robot’s whole body control system. We analyzed both active joints control for feet including actuated joints, and control for feet with elastic elements (for example, a rubber layer in the sole). Finally, we present some limitations of robotic feet and possible future developments.

Effect of 3D printed foot orthoses stiffness on muscle activity and plantar pressures in individuals with flexible flatfeet: A statistical non-parametric mapping study

BackgroundThe 3D printing technology allows to produce custom shapes and add functionalities to foot orthoses which offers better options for the treatment of flatfeet. This study aimed to assess the effect of 3D printed foot orthoses stiffness and/or a newly design posting on muscle activity, plantar pressures, and center of pressure displacement in individuals with flatfeet. MethodsNineteen individuals with flatfeet took part in this study. Two pairs of foot orthoses with different stiffness were designed for each participant and 3D printed. In addition, the flexible foot orthoses could feature an innovative rearfoot posting. Muscle activity, plantar pressures, and center of pressure displacement were recorded during walking. FindingsWalking with foot orthoses did not alter muscle activity time histories. Regarding plantar pressures, the most notable changes were observed in the midfoot area, where peak pressures, mean pressures and contact area increased significantly during walking with foot orthoses. The latter was reinforced by increasing the stiffness. Concerning the center of pressure displacement, foot orthoses shifted the center of pressure forward and medially at early stance. At the end of the stance phase, a transition of the center of pressure in posterior direction was observed during the posting condition. No effect of stiffness was observed on center of pressure displacement. InterpretationThe foot orthoses stiffness and the addition of posting influenced plantar pressures during walking. The foot orthoses stiffness mainly altered the plantar pressures under the midfoot area. However, posting mainly acted on peak and mean pressures under the rearfoot area.

Tracking control of an uncertain heavy load robot based on super twisting sliding mode control and fuzzy compensator

AbstractThis paper presents a new combined strategy to control an uncertain heavy load robot with position disturbance caused by flexible foot, and the control strategy is realized only by position feedback. Firstly, deformation during motion is analyzed, and the position transformation generated by this deformation is treated as periodic position disturbance and non‐periodic position disturbance. Then, a control method combined by computed torque controller (CTC), super twisting sliding mode (STSM) controller, and fuzzy compensator is designed for the robot dynamic system to track ideal trajectory. Meanwhile, a proportional–integral–derivative (PID) controller based on CTC is designed as a comparison to verify the trajectory tracking performance and robustness of the combined strategy under external disturbances. Finally, simulation results show that CTC‐STSM is clearly found to converge faster and to show stronger ability to suppress interference than CTC‐PID. The addition of fuzzy compensator (CTC‐STSM‐Fuzzy) can further reduce the sliding mode chattering effect and improve the performance.

Split anterior tibialis tendon transfer to peroneus brevis for spastic equinovarus in children with hemiplegia.

PurposeThe aim of this study is to report the safety and eff-cacy of soft-tissue surgery incorporating split transfer of tibi-alis anterior to peroneus brevis (SPLATT-PB) for children with hemiplegic spastic equinovarus.MethodsThis was a retrospective case series of children and adolescents with spastic hemiplegia who had a novel combination of SPLATT-TB, intramuscular tenotomy of tibialis posterior and either spasticity management or gastrocsole-us lengthening as the index surgery. The principal outcome measures were changes in pain and difficulty with shoe wear and radiological parameters obtained from weight-bearing anteroposterior and lateral radiographs of the affected foot before and after surgery.ResultsA total of 63 patients with symptomatic spastic equinovarus met the inclusion criteria. Mean age at surgery was 9.8 years (6 to 18) and the mean follow-up was seven years (range 3 to 10 years). Foot pain and problems with shoe wear improved after surgery. Seven radiological criteria showed a clinically and statistically significant improvement at follow-up, the majority being in the normal range. There were 11 surgical adverse events, all classified as Modified Cla-vien-Dindo Grade II. Three patients required further surgery for recurrent equinus, eight patients required further surgery for valgus deformities and four patients required bony surgery for residual varus deformities.ConclusionSoft-tissue surgery for spastic equinovarus was successful in the majority of children with spastic hemiplegia, particularly between ages eight and 12 years, resulting in a plantigrade, flexible foot with minimal pain or limitations in shoe-wear. Children younger than 8 years at index surgery were more prone to overcorrection into valgus. Children older than 12 years had persistent varus deformities requiring bony surgery.Level of evidenceLevel IV, retrospective case series

The Custom Total Contact Cast to Offload Foot Ulcers in the Presence of Biomechanical Deformities: A Case Report

Although offloading foot ulcers with a total contact cast (TCC) remains the cornerstone of managing these wounds, the TCC is underutilized. Patient intolerance and potential iatrogenic complications due to TCCs' general lack of customizability and the inability to address flexible biomechanical deformities that are not in the sagittal plane may be one of the reasons patients with foot ulcers do not receive this crucial component of care. To describe the use of a novel approach to the standard TCC technique that uses strategic padding to potentially increase patient compliance and comfort while decreasing the likelihood of iatrogenic ulceration, as well as to correct flexible frontal plane biomechanical deformities with casting tape that is pulled medial to lateral, or lateral to medial, to bring the plantar surface of the foot to neutral position. The custom total contact cast (C-TCC) was used in a 54-year-old woman who had diabetes, obesity, and a flexible cavovarus foot type with a recurring plantar fifth metatarsal base wound. Weekly debridement followed by silver dressings and C-TCC application were performed. The latter included strategic padding, 2 forms of plaster of paris with contouring, fiberglass, and medial-to-lateral positioning of the foot during application. This case study describes two (2) treatment episodes, with a focus on the second episode. At initial presentation, the ulcer took 5 weeks to heal. During the second treatment, a 48.7% reduction in wound volume was noted after 1 week. By the fourth week of treatment, a 98.7% wound volume reduction was achieved. By the ninth week, the ulcer epithelialized completely. At 1-month and 12-month follow-ups, the site remained fully epithelialized. No iatrogenic ulcerations, cast discomfort, or ambulatory dysfunction were reported by the patient. In this case, the C-TCC helped address flexible frontal plane deformities and facilitated healing. Randomized, controlled clinical studies to evaluate the safety and effectiveness of different TCC methods are needed to guide care and improve the utilization of optimal offloading methods for the management of plantar foot ulcers.

Dynamic analysis and decoupled control of a heavy-duty walking robot with flexible feet based on super twisting algorithm

In this paper, the dynamics and control strategies of a biped robot with 6-DOF parallel leg mechanism are studied. Firstly, the multi-body kinematic model and dynamic model of the robot are established. Secondly, the insufficient stiffness of robot’s feet and the coupling effect between the kinematic chains are considered in dynamics modeling, and the rigid-flexible coupling model is established by using ADAMS and finite element method. Finally, aiming at the position deviation and system vibration caused by the flexible foot, a strategy based on the combination of a computed torque controller (CTC) and a second-order sliding-mode super twisting algorithm (STA) is designed. At the same time, the control strategy based on CTC and PID and the control strategy based on CTC and sliding mode control (SMC) are designed to compare with CTC-STA. The results show that CTC-STA has faster regulation ability and stronger robustness than CTC-SMC and CTC-PID.

Rapid development of application-specific flexible MRI receive coils

Over the last 30 years, there have been dramatic changes in phased array coil technology leading to increasing channel density and parallel imaging functionality. Current receiver array coils are rigid and often mismatched to patient’s size. Recently there has been a move towards flexible coil technology, which is more conformal to the human anatomy. Despite the advances of so-called flexible surface coil arrays, these coils are still relatively rigid and limited in terms of design conformability, compromising signal-to-noise ratio (SNR) for flexibility, and are not designed for optimum parallel imaging performance. The purpose of this study is to report on the development and characterization of a 15-channel flexible foot and ankle coil, rapidly designed and constructed using highly decoupled radio-frequency (RF) coil elements. Coil performance was evaluated by performing SNR and g-factor measurements. In vivo testing was performed in a healthy volunteer using both the 15-channel coil and a commercially available 8-channel foot coil. The highly decoupled elements used in this design allow for extremely rapid development and prototyping of application-specific coils for different patient sizes (adult vs child) with minimal additional design consideration in terms of coil overlap and geometry. Image quality was comparable to a commercially available RF coil.

Ponseti method in the treatment of post-operative relapsed idiopathic clubfoot after posteromedial release. A short term functional study

BackgroundRelapsed clubfeet deformity after surgical treatment by posteromedial release are frequently encountered in pediatric orthopedic practice and further revision surgery may be needed. As surgery adds more fibrosis and scaring, complication may be devastating and treatment is challenging. Ponseti method, the gold standard technique for treatment of clubfoot may be of a value in the management of postoperative relapses. Aim of the studyDetermine the effectiveness of Ponseti casting Method in treatment of relapsed idiopathic clubfoot in children after being treated with surgical posteromedial release. Materials and methodsProspective interventional study of 17 patients (25 feet) presented with a relapsed idiopathic clubfoot deformity after previous surgical posteromedial release. The patients were reviewed using Pirani and Dimeglio score. Ponseti method was done to obtain supple, flexible foot rather than a fully corrected foot, the residual deformity were treated by, heel cord lengthening or tenotomy, tibialis anterior transfer, follow up was for a minimum of 12 months. Result17 Patients (25 feet) their age ranging from 1 to 10 years were evaluated and treated. Casts were applied until the only deformities remaining were either hindfoot equinus and/or dynamic supination.22 feet required a heel cord procedure for equinus and 13 required tibialis anterior transfer for dynamic supination. The follow up (average 56.1 months) was for a minimum of one year. 4 feet had persistent heel varus deformity which required Calcaneal osteotomy later. Three feet didn’t need more casting and 2 feet were resistant cases that required further Ilizarov procedure, 4 needed lateral arch shortening and other 4 needed posterior capsulotomy. Improvement in the Pirani and Dimeglio scores was highly statistically significant. ConclusionPonseti method for treatment of relapsed clubfeet after a previous posteromedial soft tissue surgical release is an effective, non invasive, with excellent results.

Design and Research of a Flexible Foot for a Multi-Foot Bionic Robot

To solve the problems of large landing impact, vibration, and poor adaptability to complex ground surfaces in the motion of a foot-type robot, a two-degree-of-freedom flexible foot-end structure was proposed and designed in this study. The effects of flexible materials, flexible parameters, and structural forms on the performance of the foot end have been discussed. Through simulation and experimentation, the parameter analysis and mechanical calibration of the foot end were completed, and a motion experiment of the flexible foot robot was designed. The simulation and experimental results showed that the flexible foot-end structure has uniform and reliable force and can effectively reduce the foot impact. Compared with the rigid foot, the foot-end force of the flexible foot was only 1/3 of the contact force, the peak foot pressure decreased by 59%, the motion stability increased by 37.4%, and the error of force perception was controlled at 11%. The flexible foot structure improved the stability of the robot motion process, reduced the vibration, provided the robot with good terrain adaptability, and achieved omnidirectional motion of the robot.