Principle design of an energy efficient transfemoral prosthesis

In the pursuit of realizing an energy efficient transfemoral prosthetic, in this paper we present a preliminary study on a principle design. In particular, the design is based on the idea that the efficiency of the system can be realized by energetically coupling the knee and the ankle joints. In order to allow the energy transfer during the normal walking, we propose to introduce continuous controllable springs, which basically act as passive actuators

Temperature changes in serial casting in the treatment of clubfoot

INTRODUCTION: Idiopathic clubfoot (talipes equinovarus) is a congenital deformity of the foot. The common treatment consists of serial manipulation and casting, known as the Ponseti method, which is started in the first week after birth. After an average of five cast changes and often a percutaneous Achilles tenotomy the deformity is corrected [1]. An abduction orthosis is worn for several years to prevent relapse. The application of plaster cast includes soaking the roll in lukewarm water which starts the exothermic curing reaction. After the plaster has cured the surplus water evaporates, which is an endothermic process. Heat is drawn from the surrounding but also from the patient. One case study describes observed hypothermia after the application of a plaster jacket for immobilization of the cervical spine [2]. In a survey among parents (unreported, 49 respondents) a number of parents mentioned that their child seemed to feel cold the first hours after a new cast had been applied. The aim of current study is to investigate the temperature changes underneath the cast in the treatment of clubfoot with the Ponseti method. METHODS: A 1-wire DS1825 digital thermometer (Maxim Integrated, San Jose, CA, USA) was used to measure the temperature underneath the cast. The sensor was placed underneath the sole of the foot and attached to a custom made data logger which stored time and temperature data every 10 minutes for a full week. Dip duration was calculated as the time from the moment the first maximum was reached until the temperature reached the mean value of the last 6 days. T-Tests were used to test the temperature difference for statistical significance.According to the Medical ethical evaluation committee of the UMCG the study does not fall under the Medical Research Involving Human Subjects act. RESULTS AND DISCUSSION: Preliminary results of the first seven measurements in four subjects (age 2-30d, all boys, 2 bilateral) are presented in Figure 1. Figure 1: Typical measurement of the temperature underneath the cast during the first 24 hours after casting.After an initial temperature increase after the application of the plaster cast, a decrease was visible in all measurements (p < 0.000). This dip reached a minimum of 23-33°C and lasted 5.9-16h before reaching a relatively stable 34-37°C. During the ISB2017 the additional results of the remaining scheduled measurements will be presented. CONCLUSIONSA considerable decrease in skin temperature was observed after the application of long leg casts in the treatment of clubfoot. Especially in bilateral cases this might cause discomfort or even hypothermia. ACKNOWLEDGEMENTS: This study has been supported by the Dutch Technology Foundation

Conceptual design of an energy efficient transfemoral prosthesis

In this study, we present the conceptual design of a fully-passive transfemoral prosthesis. The design is inspired by the power flow in human gait in order to have an energy efficient device. The working principle of the conceptual mechanism is based on three storage elements, which are responsible of the energetic coupling between the knee and the ankle joints. Design parameters of the prosthesis have been determined according to the energy absorption intervals of the human gait. Simulation results shows that the power flow of the system is comparable with human data. Finally, an initial prototype is presented as proof of concept

The Modular Socket System as Rural Solution in Indonesia

INTRODUCTION: The majority of the people in low-income countries, who need assistive technology do not have access to prosthetic devices [1]. Instead of these people having to make a long journey to one of the few prosthetic workshops, solutions like the Modular Socket System (MSS, Össur®) may be useful, because potentially they could be delivered and manufactured on site, at the location of the person [2]. This could make it suitable for application in a Community Based Rehabilitation (CBR) setting.The aim of this study was to evaluate the technical feasibility of the MSS for implementation in a CBR setting in terms of required tools, skills and required production time. METHODS: The study was performed at the Department of Prosthetics & Orthotics of the Jakarta I Polytechnic School of Health Science (JSPO). Four JSPO students received a three days training in manufacturing of the MSS. Lower limb amputees were recruited to participate in this study from the region of Jakarta (n = 5) and Bali (n = 10). A set of standardized instruments including the two minutes’ walking test (2MWT) and Prosthesis Evaluation Questionnaire (PEQ) were used to measure performance and satisfaction with the prosthesis. Production and maintenance logbooks were filled out by the involved prosthetists to evaluate the technical feasibility of the MSS. RESULTS AND DISCUSSION: Performance (2MWT) and satisfaction (PEQ) scores were comparable to that of similar studies with other lower leg prostheses [3,4]. Both measures did not decrease significantly over time (Figure 1). This suggest that the JSPO students were able to reach sufficient quality.It took the prosthetists 3.5 to 10.5 hours to fit an amputee with a MSS prosthesis. Mean socket production time was 2.0±0.6 hours and mean prosthesis assembly and fitting time was 4.1±2.6 hours. The only non-portable machine needed for the production of the prosthesis was a grinding machine (router). Smaller portable machines used were a cast cutter/jigsaw, Icecast® Compact and resin injection tool. If in the future the grinding machine will be replaced by a handheld tool, production of the MSS could be performed on site, making it suitable for use in a rural setting. Figure 1: The results of the 2MWT at the moment of fitting (t0), at 1-3 months post fitting (t1), and at the end evaluation at 4-6 months post fitting (t2). CONCLUSIONS: Patients who normally have to travel long distances to access prosthetic services were only required to make one visit to the health facility in order to receive a prosthesis. From a technical and quality perspective the method seems feasible, although, high costs remain an issue.ACKNOWLEDGEMENTSMaterials and training for the production of all prostheses were sponsored by Össur®. REFERENCES: 1.Borg J, et al. Assistive Technology for Children with Disabilities: Creating Opportunities for Education, Inclusion and Participation - a discussion paper. 20152.Normann E, et al., Prosthetics and orthotics international. 35(1):76-80, 20113.Boonstra AM, et al. Prosthetics and orthotics international. 17(2):78-82, 19934.Zidarov D, et al. Archives of Physical Medicine and Rehabilitation. 90(4):634-645, 200