Gautham Gopalakrishna

Development of Polyurethane-Based Sheets by Coagulation Method and Study of Mechanical and Cushion Properties for Therapeutic Footwear Applications

Abstract Many foams and viscoelastic materials are used in shoes as insoles to replace the shock-absorbing and pressure distributing functions of natural fat pad beneath the foot that was lost due to some conditions such as diabetes, arthritis, age or overuse. In the present work, porous polyurethane sheets of 3–10 mm thickness based on segmented polyetherurethanes and polyesterurethane were developed by coagulation method. Sheets of different density, hardness and thickness were developed and tested for their mechanical and cushioning properties. The effect of concentration and composition of polymer and volume of solvent were studied and the required density, hardness and thickness of the sheets for application in therapeutic footwear were optimized from the test results.

PU viscoelastic memory foam for application as cushion insole/insock in shoes

Polymer elastomers and foams are widely used to meet the material properties of the insole and insock. Among various polymers, ethylene vinyl acetate (EVA), polyurethane (PU) and rubber based materials are widely used in footwear. PU foams and elastomers are proved as the most effective materials for shock absorption in footwear (Pratt et al. 1986, Pratt 1988). Though these materials are effective when new, the softer foam materials tend to deteriorate rapidly with use. Very compliant foams tend to ‘bottom out’ at moderate loads, unless a considerable thickness is used, which is seldom practical (Ersfeld 2001). Therefore there is a need for new material which can be used as inserts in shoes in 3 to 4 mm thickness and will retain the original properties throughout the life of shoes.

Standardization of Foot Sizes of Patients with Diabetic Foot Ulcer through Anthropometric Survey

ABSTRACT Plantar pressure off-loading at ulcer site is one of the therapeutic interventions for healing diabetic foot ulcer (DFU). Due to peripheral neuropathy and vascular disease, the foot anatomy of patients with diabetes is significantly different from that of normal persons. Presently, the therapeutic footwear or other off-loading devices for patients with DFU are customized which will ultimately delay the treatment intervention. The objective of the present paper is to derive standardized foot anthropometric data for patients with DFU to use as a reference for developing pressure off-loading devices. The measurement of foot dimensions for 100 patients with DFU and 52 age matched control subjects were recorded using 3D laser foot scanner and statistically analysed using SPSS software. By regression analysis, the significant difference and correlation between normal and patients with DFU were studied. By using cluster analysis, 3 average sizes for male and 3 average sizes for female that can accommodate seventy percent of patients with DFU had been derived. Development of pressure off-loading devices based on the derived sizes and trial with patients are on-going projects of this study.

Plantar Pressure Analysis on Polyurethane Foam Materials in Footwear Exclusive for Overweight/Obese

The overweight/obese individuals, in general, develop varied foot consequences during walk of life. The body weight and the prevalence of flat foot on the plantar surface are the primary indicators for the discomfort in respect of high BMI individuals. The body weight has been implicated as a factor in plantar heel [4, 11, 12]. The role of PU foam materials is of greater importance to render therapeutic advantages in footwear. The PU foam materials are widely used as varied elements in footwear and the consumers’ gain benefits and sense of satisfaction on comfort parameters. The main objective of research is to scientifically investigate the characteristics PU foam materials and explore these materials for plantar pressure analysis using In-shoe pressure measurement device on footwear designed and developed exclusively for overweight/obese individuals. The foot or thoses are commonly used in the conservative treatment of plantar fasciitis and are helpful to reduce the symptoms of strain during standing and ambulation [1,5,6,7].The investigation on PU foam materials and their efficacy as footwear inserts to provide therapeutic solutions especially for high BMI individuals has been not scientifically attempted in the domain of footwear research. Hence, the investigation on choosing ideal material thereby minimising the foot related problems being experienced by high BMI individuals is aimed at using plantar pressure analysis in this paper. The polyurethane foam materials possessing uniform substance of 4mm with varied densities such as D55, D75, D95 and D120 have been assessed on a range of physical characteristics such as Density, Hardness, Compression set followed Resiliency and cushioning behaviours. These materials are employed as foot inserts in footwear specifically designed and developed for overweight/obese individuals and the pressure analysis has been carried out using In-shoe pressure measurement method in the phase of human locomotion. Based on the results obtained on pressure analysis experiments, the ideal material aid in alleviating foot problems of high BMI individuals has been scientifically revealed and recommended to the beneficiaries.

Improved design and development of a functional moulded prosthetic foot.

Abstract Purpose: In the Indian scenario, the Jaipur foot is a low-cost breakthrough that enabled the disabled person to adapt to the Indian environment. The aim of this study is to modify the present foot in terms of ankle support design and method of fabrication, foot moulds profile and the inner core material in order to improve the performance and durability. Method: The optimized design of ankle support and flat foot profile moulds suitable for both left and right foot were developed through CAD/CAM and prosthetic feet were fabricated using ethylene vinyl acetate (EVA) foam as an appropriate alternative core material for microcellular rubber (MCR). The developed prosthetic feet were tested for rigidity by load-deflection analysis in universal testing machine. Result: EVA foot had shown better rigidity than conventional MCR foot, which will help in weight transfer during walking and increase the durability. The CAD modeled ankle support and single block EVA had made the manufacturing process easy and reduced the weight of foot and improved Gait to the person fitted with it due to improved flat foot profile. Conclusion: The new artificial foot had proven to be efficacious technically as well as functionally, which is clearly borne out from the extremely positive feedback given by the amputees. Implications of Rehabilitation Persons with below knee amputation are usually provided with transtibial prosthesis, which allows for easier ambulation and helps them to get back to their normal life. Transtibial prosthesis is an artificial limb that replaces a lower limb that is amputated below the knee. In our study, a new prosthetic foot with a modified ankle support and flat foot profile using better inner-core material than the conventional Jaipur foot was developed and the process was also optimized for mass production. The developed prosthetic foot can be fitted with both above and below knee exoskeleton type of prosthesis.

Improving the design of therapeutic footwear using QFD and TRIZ

Footwear has been used as one of the therapeutic interventions for treating diabetic foot ulcers (Hampton 1979, White 1994, Mueller 1997). Generally, patient compliance on using any therapeutic product requires higher product quality. The quality of therapeutic footwear (TFW) is composed of many aspects such as satisfaction, effectiveness, efficiency, attractiveness, maintainability and ease of use. It was found that the patients with diabetes buy this footwear on a doctor’s recommendation but will not use it; or though they buy and use it, they do not use it regularly or discontinue using it after some period of time (Williams and Meacher 2001). The proper design and customisation of TFW based on patients’ as well as physicians’ needs is important to increase the patients’ compliance of using TFW. Therefore those issues that prevent the patients from using this footwear need to be identified and focused on during the designing and development of TFW.

MANUFACTURING ALGORITHMS FOR APPROPRIATE DIABETIC FOOTWEAR FOR VARIOUS RISK CATEGORIES

INTRODUCTION This paper aims at characterizing the diabetic foot complications into various risk categories. The parameters of the diabetic foot with respect to each risk category are identified. Algorithms facilitating the manufacture of specific diabetic footwear unique to each risk category with respect to Materials, Fit and Design unique to each Risk Category are suggested. Footwear best suited to tackle the problems associated with each risk category are manufactured and their efficacy in minimizing complications studied.