CAD/CAE of Jaipur foot for standardized and contemporary manufacturing

Abstract

Objective: Despite immense popularity of Jaipur foot as low cost prosthetic, not much work has been reported on its design for manufacturing standardization. Without manufacturing standardization, it cannot be mass produced using contemporary manufacturing technologies. The objective of this work is to carry out its computer aided design (CAD) followed by computer aided engineering (CAE) based on the material properties obtained from the previous work [1 Rachel HT, Kristine MF, Benjamin BW, et al. Assessment of the compressive and tensile mechanical properties of materials used in the Jaipur foot prosthesis. Prosthet Orthot Int. 2018;42:511–517.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] of the authors. This may lead to the possible use of modern manufacturing processes for the Jaipur foot design.

Design: After modelling using CAD tool including its organic surfaces, the designed foot was analysed using a CAE tool for balanced standing load conditions to determine maximum stresses and deformation in its various parts. The bending analysis was done to check the dorsiflexion movement so that the strained sections could be identified for more reliable and durable prosthetic foot. For the static load analysis, base of the foot was constrained and 300–500 N load was applied through the bolt whereas for bending, the part near the bolt was fixed and pressure was applied at junction of front foot and toes.

Results: The results show that the maximum stress and deformation occur at the bolt, while the skin undergoes maximum strain. CAE analysis also proves the robustness of the Jaipur foot design and a well manufactured Jaipur foot as per standardized design should be able to withstand the real life conditions without failure. The CAD model is also used for FDM based printing for a nonfunctional prototype of Jaipur foot.

• Implications for rehabilitation

• The results of this study will serve as an important guideline for further research regarding equivalent material replacement, material optimization and obtaining an optimized design after studying the foot for dynamic analysis.

     

Randomised trial of the effects of four weeks of daily stretch on extensibility of hamstring muscles in people with spinal cord injuries

The aim of this assessor-blind randomised controlled trial was to determine the effect of four weeks of 30 minute stretches each weekday on extensibility of the hamstring muscles in people with recent spinal cord injuries. A consecutive sample of 16 spinal cord-injured patients with no or minimal voluntary motor power in the lower limbs and insufficient hamstring muscle extensibility to enable optimal long sitting were recruited. Subjects' legs were randomly allocated to experimental and control conditions. The hamstring muscles of the experimental leg of each subject were stretched with a 30 Nm torque at the hip for 30 minutes each weekday for four weeks. The hamstring muscles of the contralateral leg were not stretched during this period. Extensibility of the hamstring muscles (hip flexion range of motion with knee extended, measured with a 48 Nm torque at the hip) of both legs was measured by a blinded assessor at the commencement of the study and one day after the completion of the four-week stretch period. Changes in hamstring muscle extensibility from initial to final measurements were calculated. The effect of stretching was expressed as the mean difference in these changes between stretched and non-stretched legs. The mean effect of stretching was 1 degree (95% CI -2 to 5 degrees). Four weeks of 30 minute stretches each weekday does not affect the extensibility of the hamstring muscle in people with spinal cord injuries.     

Shielding islets with human amniotic epithelial cells enhances islet engraftment and revascularization in a murine diabetes model

Hypoxia is a major cause of considerable islet loss during the early posttransplant period. Here, we investigate whether shielding islets with human amniotic epithelial cells (hAECs), which possess anti‐inflammatory and regenerative properties, improves islet engraftment and survival. Shielded islets were generated on agarose microwells by mixing rat islets (RIs) or human islets (HI) and hAECs (100 hAECs/IEQ). Islet secretory function and viability were assessed after culture in hypoxia (1% O₂) or normoxia (21% O₂) in vitro. In vivo function was evaluated after transplant under the kidney capsule of diabetic immunodeficient mice. Graft morphology and vascularization were evaluated by immunohistochemistry. Both shielded RIs and HIs show higher viability and increased glucose‐stimulated insulin secretion after exposure to hypoxia in vitro compared with control islets. Transplant of shielded islets results in considerably earlier normoglycemia and vascularization, an enhanced glucose tolerance, and a higher β cell mass. Our results show that hAECs have a clear cytoprotective effect against hypoxic damages in vitro. This strategy improves β cell mass engraftment and islet revascularization, leading to an improved capacity of islets to reverse hyperglycemia, and could be rapidly applicable in the clinical situation seeing that the modification to HIs are minor.     

The patient’s pathway for breast cancer in the COVID‐19 era: An Italian single‐center experience

COVID‐19 has been declared a pandemic by the World Health Organization. As of April 1, 2020, Italy was the country with the second highest number of cases in the world. The spread of COVID‐19 has required a rapid reorganization of health service delivery in face of the pandemic. Breast cancer units have reprioritized their workload to guarantee the health of oncologic patients at the highest risk and regular screening activities. However, at the end of the pandemic emergency, many benign and reconstructive cases will return to our attention and their surgical treatment will be necessary as soon as possible.     

Framework for prioritizing head and neck surgery during the COVID‐19 pandemic

The COVID‐19 pandemic has placed an extraordinary demand on the United States health care system. Many institutions have canceled elective and non‐urgent procedures to conserve resources and limit exposure. While operational definitions of elective and urgent categories exist, there is a degree of surgeon judgment in designation. In the present commentary, we provide a framework for prioritizing head and neck surgery during the pandemic. Unique considerations for the head and neck patient are examined including risk to the oncology patient, outcomes following delay in head and neck cancer therapy, and risk of transmission during otolaryngologic surgery. Our case prioritization criteria consist of four categories: urgent—proceed with surgery, less urgent—consider postpone > 30 days, less urgent—consider postpone 30 to 90 days, and case‐by‐case basis. Finally, we discuss our preoperative clinical pathway for transmission mitigation including defining low‐risk and high‐risk surgery for transmission and role of preoperative COVID‐19 testing.