Analysis of Rollover Shape and Energy Storage and Return in Cantilever Beam-Type Prosthetic Feet

This paper presents an analysis of the rollover shape and energy storage and return in a prosthetic foot made from a compliant cantilevered beam. The rollover shape of a prosthetic foot is defined as the path of the center of pressure along the bottom of the foot during stance phase of gait, from heel strike to toe off. This path is rotated into the reference frame of the ankle-knee segment of the leg, which is held fixed. In order to achieve correct limb loading and gait kinematics, it is important that a prosthetic foot both mimic the physiological rollover shape and maximize energy storage and return. The majority of prosthetic feet available on the market are cantilever beam-type feet that emulate ankle dorsiflexion through beam bending. In this study, we show analytically that a prosthetic foot consisting of a beam with constant or monotonically decreasing cross-section cannot replicate physiological rollover shape; the foot is either too stiff when the ground reaction force (GRF) acts near the ankle, or too compliant when the GRF acts near the toe. A rigid constraint is required to prevent the foot from over-deflecting. Using finite element analysis (FEA), we investigated how closely a cantilever beam with constrained maximum deflection could mimic physiological rollover shape and energy storage/return during stance phase. A constrained beam with constant cross-section is able to replicate physiological rollover shape with R[superscript 2] = 0.86. The ratio of the strain energy stored and returned by the beam compared to the ideal energy storage and return is 0.504. This paper determines that there is a trade off between rollover shape and energy storage and return in cantilever beam-type prosthetic feet. The method and results presented in this paper demonstrate a useful tool in early stage prosthetic foot design that can be used to predict the rollover shape and energy storage of any type of prosthetic foot.MIT Tata Center for Technology and DesignMassachusetts Institute of Technology. Department of Mechanical EngineeringMIT International Science and Technology Initiatives (India Innovation Fund

Design and Preliminary Testing of a Prototype for Evaluating Lower Leg Trajectory Error as an Optimization Metric for Prosthetic Feet

This work presents the design and preliminary testing of a prosthetic foot prototype intended for evaluating a novel design objective for passive prosthetic feet, the Lower Leg Trajectory Error (LLTE). Thus far, all work regarding LLTE has been purely theoretical. The next step is to perform extensive clinical testing. An initial prototype consisting of rotational ankle and metatarsal joints with constant rotational stiffness was optimized and built, but at 2 kg it proved too heavy to use in clinical testing. A new conceptual foot architecture intended to reduce the weight of the final prototype is presented and optimized for LLTE. This foot consists of a rotational ankle joint with constant stiffness of 6.1 N·m/deg, a rigid structure extending 0.08 m from the ankle-knee axis, and a cantilever beam forefoot with bending stiffness 5.4 N·m2. A prototype was built using machined delrin for the rigid structure, three parallel extension springs offset along a constant radius cam from a pin joint ankle, and machined nylon as the beam forefoot. In preliminary testing, it was determined that, despite efforts to minimize weight and size, this particular design was still too heavy and bulky as a result of the extension springs to be used in extensive clinical testing. Future work will focus on reducing the weight further by replacing linear extension springs with flexural elements before commencing with the clinical study.Massachusetts Institute of Technology. Tata Center for Technology and DesignMassachusetts Institute of Technology. Department of Mechanical Engineerin

Passive Prosthetic Foot Shape and Size Optimization Using Lower Leg Trajectory Error

A method is presented to optimize the shape and size of a passive prosthetic foot using the Lower Leg Trajectory Error (LLTE) as the design objective. The LLTE is defined as the root-mean-square error between the lower leg trajectory calculated for a given prosthetic foot by finding the deformed shape of the foot under typical ground reaction forces and a target physiological lower leg trajectory obtained from published gait data for able-bodied walking. In previous work, the design of simple two degree-of-freedom analytical models consisting of rigid structures, rotational joints with constant stiffness, and uniform cantilevered beams, have been optimized for LLTE. However, prototypes built to replicate these simple models were large, heavy, and overly complex. In this work, the size and shape of a singlepart compliant prosthetic foot keel made out of nylon 6/6 was optimized for LLTE to produce a light weight, low cost, and easily manufacturable prosthetic foot design. The shape of the keel was parameterized as a wide Bézier curve, with constraints ensuring that only physically meaningful shapes were considered. The LLTE value for each design was evaluated using a custom MATLAB script, which ran ADINA finite element analysis software to find the deformed shape of the prosthetic keel under multiple loading scenarios. The optimization was performed by MATLAB's built-in genetic algorithm. After the optimal design for the keel was found, a heel was added to structure, sized such that when the user's full weight acted on the heel, the structure had a factor of safety of two. The resulting optimal design has a lower LLTE value than the two degree-of-freedom analytical models, at 0.154 compared to 0.172, 0.187, and 0.269 for the two degree-of-freedom models. At 412 g, the optimal wide curve foot is nearly half the mass of the lightest prototype built from the previous models, which was 980 g. The design found through this compliant mechanism optimization method is thus far superior to the two degree-of-freedom models previously considered.Massachusetts Institute of Technology. Tata Center for Technology and Desig

Design and Testing of a Prosthetic Foot Prototype With Interchangeable Custom Rotational Springs to Adjust Ankle Stiffness for Evaluating Lower Leg Trajectory Error, an Optimization Metric for Prosthetic Feet

A prosthetic foot prototype intended for evaluating a novel design objective for passive prosthetic feet, the Lower Leg Trajectory Error (LLTE), is presented. This metric enables the optimization of prosthetic feet by modeling the trajectory of the lower leg segment throughout a step for a given prosthetic foot and selecting design variables to minimize the error between this trajectory and target physiological lower leg kinematics. Thus far, previous work on the LLTE has mainly focused on optimizing conceptual foot architectures. To further study this metric, extensive clinical testing on prototypes optimized using this method has to be performed. Initial prototypes replicating the LLTE-optimal designs in previous work were optimized and built, but at 1.3 to 2.1 kg they proved too heavy and bulky to be considered for testing. A new, fully-characterized foot design reducing the weight of the final prototype while enabling ankle stiffness to be varied is presented and optimized for LLTE. The novel merits of this foot are that it can replicate a similar quasi-stiffness and range of motion of a physiological ankle, and be tested with variable ankle stiffnesses to test their effect on LLTE. The foot consists of a rotational ankle joint with interchangeable U-shaped constant stiffness springs ranging from 1.5 Nm/deg to 16 Nm/deg, a rigid structure extending 0.093 m from the ankle-knee axis, and a cantilever beam forefoot with a bending stiffness of 16 Nm2. The prototype was built using machined acetal resin for the rigid structure, custom nylon springs for the ankle, and a nylon beam forefoot. In preliminary testing, this design performed as predicted and its modularity allowed us to rapidly change the springs to vary the ankle stiffness of the foot. Qualitative feedback from preliminary testing showed that this design is ready to be used in larger-scale studies. In future work, extensive clinical studies with testing different ankle stiffnesses will be conducted to validate the optimization method using the LLTE as a design objective.Massachusetts Institute of Technology. Tata Center for Technology and DesignMassachusetts Institute of Technology. Department of Mechanical Engineerin

Internet-based cognitive behavioural therapy programme as an intervention for people diagnosed with adult-onset, focal, isolated, idiopathic cervical dystonia: a feasibility study protocol

Background Dystonia is one of the most common forms of movement disorder, caused by the co-contraction of antagonistic muscles, leading to abnormal postures and considerable disability. Non-motor symptoms, notably psychiatric disorders, are well recognised comorbid features of the disorder. However, there is no standardised model for the management of these symptoms in dystonia, with them frequently going undiagnosed and untreated. An internet-based cognitive behavioural therapy programme may provide a future model of care that also maximises available resources. Methods This study represents a two-armed randomised feasibility trail, aiming to recruit a total of 20 participants with a diagnosis of adult-onset primary focal cervical dystonia. Participants will be recruited from the Global Myoclonus Dystonia Registry and Dystonia Non-Motor Symptom Study (conducted at Cardiff University) based on presence of moderate symptoms of anxiety/depression as indicated by standardised questionnaires. All participants will undergo assessment at baseline, 3 and 6 months, with this including questionnaires for assessment of non-motor symptoms and clinical assessment of motor symptom severity. Participants will be randomised to either the control (n = 10) or treatment (n = 10) groups. The treatment group will be asked to complete one session of the online CBT program a week, for 8 weeks. The primary outcome measure will be the engagement of participants with the programme, with secondary outcomes of non-motor and motor symptom scores. Discussion Promising results have been shown using face-to-face cognitive behavioural therapy to reduce levels of anxiety and depression in individuals with a diagnosis of dystonia. However, no studies to date have sought to determine the feasibility of an internet-delivered cognitive behavioural therapy programme. A number of effective internet-based programmes have been developed that combat anxiety and depression in the general population, suggesting the potential for its effectiveness in cervical dystonia patients. Success with this study would significantly impact the clinical care delivery for patients with cervical dystonia, as well as widening potential access to effective treatment

The Valuation of Wetlands

This Article asserts that an understanding of wetland valuation requires consideration of many disciplines, including biology, chemistry, social sciences, economics, and state and federal law. The authors explain that wetland valuation is dependent upon the definition of wetland in the area under study and the surrounding situation, and conclude that if practitioners understand the major points of wetland appraisal, they will be able to present hearing officers and judges with relatively sophisticated, comprehensive, and accurate information upon which rulings can be based

Internet-based cognitive behavioural therapy as a feasible treatment of adult-onset, focal, isolated, idiopathic cervical dystonia

Introduction Psychiatric symptoms are well recognised co-morbid traits in adult-onset idiopathic, isolated, focal cervical dystonia (AOIFCD), although few studies have sought to address their management. Internet-based cognitive behavioural therapy (iCBT) may provide an accessible solution. Here, we determine the feasibility of using iCBT in the management of non-motor symptoms for individuals with AOIFCD. Methods Participants were randomised to receive an 8-week iCBT programme (n=10) or not (n=10), both alongside routine clinical care. All participants underwent assessments at baseline, 3-, and 6- months for anxiety, depression, quality of life and motor symptoms, and engagement with iCBT was recorded. Group differences over time were determined using two-way mixed ANOVA, and simple statistics evaluated change on an individual participant level. Results Over half of participants receiving iCBT (6/10) showed high engagement, with feedback indicating most participants found iCBT useful (6/8), would continue to use it (7/8), and try it again if offered (7/8). Although no between-group significant differences were observed (e.g. Beck’s Depression Inventory p=0.067) anxiety and depression levels showed trends towards improvement at 3-months in those receiving iCBT. Individual level analysis also indicated higher percentage level improvements in these symptoms, with this sustained in 86% participants. Conclusion iCBT represents a feasible therapeutic option in the management of co-morbid anxiety and depression in AOIFCD. Further work is needed to replicate these findings in a larger cohort, identify those most likely to benefit from this form of therapy and overcome barriers hindering those less likely to engage with this form of treatment

Development of a Passive and Slope Adaptable Prosthetic Foot

Historically, users of prosthetic ankles have relied on actively operated systems to provide effective slope adaptability. However, there are many drawbacks to these systems. This research builds upon work previously completed by Hansen et al. as it develops a passive, hydraulically operated prosthetic ankle with the capability of adapting to varying terrain in every step. Using gait cycle data and an analysis of ground reaction forces, the team determined that weight activation was the most effective way to activate the hydraulic circuit. Evaluations of the system pressure and energy showed that although the spring damper system results in a loss of 9J of energy to the user, the footplate stores 34J more than a standard prosthesis. Therefore, the hydraulic prosthetic provides a 54% increase in stored energy when compared to a standard prosthesis. The hydraulic circuit manifold prototype was manufactured and tested. Through proof of concept testing, the prototype proved to be slope adaptable by successfully achieving a plantarflexion angle of 16 degrees greater than a standard prosthetic foot currently available on the market.Massachusetts Institute of Technology. Tata Center for Technology and Desig

NRG Oncology-Radiation Therapy Oncology Group Study 1014: 1-Year Toxicity Report From a Phase 2 Study of Repeat Breast-Preserving Surgery and 3-Dimensional Conformal Partial-Breast Reirradiation for In-Breast Recurrence.

PURPOSE: To determine the associated toxicity, tolerance, and safety of partial-breast reirradiation. METHODS AND MATERIALS: Eligibility criteria included in-breast recurrence occurring \u3e1 year after whole-breast irradiation, \u3c3 \u3ecm, unifocal, and resected with negative margins. Partial-breast reirradiation was targeted to the surgical cavity plus 1.5 cm; a prescription dose of 45 Gy in 1.5 Gy twice daily for 30 treatments was used. The primary objective was to evaluate the rate of grade ≥3 treatment-related skin, fibrosis, and/or breast pain adverse events (AEs), occurring ≤1 year from re-treatment completion. A rate of ≥13% for these AEs in a cohort of 55 patients was determined to be unacceptable (86% power, 1-sided α = 0.07). RESULTS: Between 2010 and 2013, 65 patients were accrued, and the first 55 eligible and with 1 year follow-up were analyzed. Median age was 68 years. Twenty-two patients had ductal carcinoma in situ, and 33 had invasive disease: 19 ≤1 cm, 13 \u3e1 to ≤2 cm, and 1 \u3e2 cm. All patients were clinically node negative. Systemic therapy was delivered in 51%. All treatment plans underwent quality review for contouring accuracy and dosimetric compliance. All treatment plans scored acceptable for tumor volume contouring and tumor volume dose-volume analysis. Only 4 (7%) scored unacceptable for organs at risk contouring and organs at risk dose-volume analysis. Treatment-related skin, fibrosis, and/or breast pain AEs were recorded as grade 1 in 64% and grade 2 in 7%, with only 1 ( CONCLUSION: Partial-breast reirradiation with 3-dimensional conformal radiation therapy after second lumpectomy for patients experiencing in-breast failures after whole-breast irradiation is safe and feasible, with acceptable treatment quality achieved. Skin, fibrosis, and breast pain toxicity was acceptable, and grade 3 toxicity was rare

Weekly paclitaxel, gemcitabine, and external irradiation followed by randomized farnesyl transferase inhibitor R115777 for locally advanced pancreatic cancer.

PURPOSE: The Radiation Therapy Oncology Group (RTOG) multi-institutional Phase II study 98-12, evaluating paclitaxel and concurrent radiation (RT) for locally advanced pancreatic cancer, demonstrated a median survival of 11.3 months and a 1-year survival of 43%. The purpose of the randomized Phase II study by RTOG 0020 was to evaluate the addition of weekly low- dose gemcitabine with concurrent paclitaxel/RT and to evaluate the efficacy and safety of the farnesyl transferase inhibitor R115777 following chemoradiation. PATIENTS AND METHODS: Patients with unresectable, nonmetastatic adenocarcinoma of the pancreas were eligible. Patients in Arm 1 received gemcitabine, 75 mg/m(2)/week, and paclitaxel, 40 mg/m(2)/week, for 6 weeks, with 50.4 Gy radiation (CXRT). Patients in Arm 2 received an identical chemoradiation regimen but then received maintenance R115777, 300 mg twice a day for 21 days every 28 days (CXRT+R115777), until disease progression or unacceptable toxicity. RESULTS: One hundred ninety-five patients were entered into this study, and 184 were analyzable. Grade 4 nonhematologic toxicities occurred in less than 5% of CXRT patients. The most common grade 3/4 toxicity from R115777 was myelosuppression; however, grade 3/4 hepatic, metabolic, musculoskeletal, and neurologic toxicities were also reported. The median survival time was 11.5 months and 8.9 months for the CXRT and CXRT+R115777 arms, respectively. CONCLUSIONS: The CXRT arm achieved a median survival of almost 1-year, supporting chemoradiation as an important therapeutic modality for locally advanced pancreatic cancer. Maintenance R115777 is not effective and is associated with a broad range of toxicities. These findings provide clinical evidence that inhibition of farnesylation affects many metabolic pathways, underscoring the challenge of developing an effective K-ras inhibitor