MULTIMODAL BIOMECHANICAL FOOT ASSESSMENT ON AGING, OBESITY AND DIABETES

Indian Institute of Technology Delhi (IITD), New Delhi, 2014

MULTIMODAL BIOMECHANICAL FOOT ASSESSMENT ON AGING, OBESITY AND DIABETES by R PERIYASAMY Centre for Biomedical Engineering Submitted In fulfilment of the requirements of the degree of DOCTOR OF PHILOSOPHY to the INDIAN INSTITUTE OF TECHNOLOGY DELHI December 2014 ii

Dedicated to my beloved Parents for giving me the Precious gift of education

CERTIFICATE This is to certify that the thesis entitled MULTIMODAL BIOMECHANICAL FOOT ASSESSMENT ON AGING, OBESITY AND DIABETES being submitted by R Periyasamy to the Indian Institute of Technology Delhi, India for the award of the degree of Doctor of Philosophy in Biomedical Engineering, is a record of bonafide research work carried out by him under our supervision and guidance. To the best of our knowledge the thesis has reached the requisite standard. The results presented in this thesis have not been submitted in part or in full to any other University or Institute for the award of any degree or diploma. (Sneh Anand, Ph.D.) Professor Centre for Biomedical Engineering Indian Institute of Technology, Delhi New Delhi 110016, INDIA (Ashutosh Mishra, Ph.D.) Assistant Professor Biomedical Engineering & Applied Sciences Division Indian Institute of Information Technology, Allahabad Allahabad 211012 (U.P), INDIA iii

ACKNOWLEDGEMENTS Before I express my heart-felt gratitude towards all my mentors, first and foremost, I would like to thank my greatest teacher and of course of all: God. He has given me the power to believe in myself and my passion to pursue this study. I could never have done this without His blessings. I would like to express my deep and sincere gratitude to my supervisor Professor Sneh Anand for her untiring support and guidance in different stages of this work. Her leadership, support, attention to detail, and hard work have set an example I hope to match someday. I am deeply grateful to my supervisor, Dr. Ashutosh Mishra, for providing detailed and constructive comments, as well as supporting me in all situations during the dissertation. I would like to express my warm and sincere thanks to Dr. A.C. Ammini, Head, Department of Endocrinology and metabolism, AIIMS, New Delhi, who introduced me to the clinical aspects of present research work. Her ideas and concepts have had a remarkable influence on my entire career in the field of foot biomechanics. I am thankful to Dr. Jyotsna, who gave me valuable advice and friendly help, during my difficult moments. Also I thank my well-wisher Dr. Nivedita for her timely guidance whenever required during my research. My sincere thanks to Dr. VB Narayana Murthy Plastic surgeon and diabetic foot surgeon Sundaram medical Foundation, Chennai for his extensive discussions around my work and interesting explorations during data interpretation have been very helpful for this study. Also I would like to take this opportunity to thank all the subjects participated in the study. I am grateful to my seniors Dr. Nanda Kumar selvaraj, Dr. Tamalika and my fellow researchers Dr.Deepak joshi, Dr.Tapan, Dr. Sanjeev, Dr. Vijay, Dr. Pahuja and Dr. Yogeswarao for giving me the guidelines towards publishing the manuscripts and writing the thesis. Apart, their friendly guidance made me to keep myself cool during my tough time. iv

I thank my fellow lab colleagues and friends Sonal, Nagananda, Jean, and Chhaya for the stimulating discussions, and for all the fun and fight we have had in the last four years. I enjoyed the atmosphere, their friendship, and their support. Special thanks to all my juniors lab colleagues, helping me out with all possible ways during my frustration period. I am particularly grateful to Mrs. Sumita who shared friendly moments and care, and for helping me in all the logistic issues during my research tenure at IIT Delhi. Also I thank Mr. Rajesh, Mr. Anil Pandey and CBME office staff for sharing the funny moments and making my stay comfortable at IIT Delhi. I am thankful to my parents for instilling in me confidence and a drive for pursuing my PhD and supporting me spiritually throughout my life. I am thankful to my wife (Nandini) and my son (Harish) and daughter (Vidya) for supporting and motivating me whenever I showed signs of losing my patience. I would like to thank the authors of the literature I have gone through without which it would have been impossible for me to carry out this exciting research. Although I have tried to express my gratitude to every person who contributed in this work directly or indirectly, there may still be someone hiding behind the veils of my forgetful part of memory. Last but not the least; I would like to thank all such souls. (R Periyasamy)

ABSTRACT Keywords: Foot biomechanics, foot arch, joint mobility, neuropathy, obesity, optimal plantar pressure distribution, pedopowergraph, sole hardness, type II diabetes, computational analysis A multidimensional study has been conducted to evaluate plantar foot biomechanical structure dynamics during standing and walking which leads to pathological and anatomical problems. Foot problems have been reported more often in females than males because of the anatomical and physiological differences. Foot patho-mechanics multifactorial risks could be associated with obesity and diabetes. Structural characteristics of foot directly affect dynamics which alters musculoskeletal pathology and neural feedback sensation. Decreased range of movements in the joints of foot and ankle are related to elevated plantar pressure in diabetes. High plantar foot pressure is not the only parameter that causes plantar ulceration. In addition foot sole hardness due to altered plantar pressure distribution results in ulceration. Despite the multifactorial pathophysiology of diabetic foot risk, diabetic peripheral neuropathy within 10 to 15 years duration plays a vital role in ulcer formation. The detection of diabetic neuropathy in type II diabetic patients is a crucial test would require monofilament test, vibration perception, thermal conduction, which are highly subjective. The present study has been validated on gender, aging, obesity, foot type and diabetes subjects by assessing multimodal foot biomechanical parameters viz Loss of Protective Sensation (LOPS), Power Ratio (PR), sole Hardness (H), Joint mobility (JM) and Computational analysis to understand the foot injury / ulcer formation. The study was conducted after approval from the All India Institute of Medical Science (AIIMS) hospital v

ethics committee along with the written consent from volunteer /patients. The study was conducted on three different groups of healthy volunteers (groups I, II and III), as well as on type II diabetic patients (group IV). The neuropathy status was confirmed by testing the loss of protective sensation (LOPS) using 10gm Semen s Weinstein Monofilament (SWMF) in eight foot sole areas. Static foot pressure intensity image was recorded by using optical PedoPowerGraph. The acquired foot pressure intensity image was analyzed to obtain accurate power ratio (PR, defined as ratio of high frequency power to total power in the foot pressure intensity image) value in seven clinically identified areas. Foot arch type was assessed by analysing the foot pressure intensity image. Sole hardness assessment was performed in eight sole areas using Shore meter (ASTM-D 2240 standards). Limited joint mobility (LJM) was assessed at the subtalar joint (ankle) and hallux, using manual plastic goniometer. PR data, sole hardness and joint mobility parameter data were analyzed statistically and correlated with aging, BMI, and foot type on normal subjects and compared with diabetic mellitus subjects data collected on neural characteristics based on disease duration. Statistical comparison test by ANOVA shows significant changes in foot biomechanical parameters and linear regression analysis confirms significant positive correlation with joint mobility parameters. Linear discriminant analysis (LDA) aided optimum threshold classifier was used for classification of foot arch type in normal subjects with the help of Arch index-mid foot pressure distribution ratio data. Software algorithm based on feed forward back-propagation Artificial Neural Network (ANN) was implemented to classify neuropathy from PR and sole hardness data in diabetes mellitus patients. The results showed high classification accuracy of 94.5% with reference to existing computational system. vi

The concept can be extended to predict the reference values in the control population based on degree of exercise, flooring, footwear type and barefoot walking affect sole hardness, muscle activity and standing plantar pressure distribution. Appropriate therapeutic intervention including the use of grounding the foot, foot orthoses and foot wear insole with optimal hardness design to prevent existing risk factors. Further the system developed and validated by monitoring the blood flow and its relationship between foot biomechanical parameters will benefit the millions of global population to prevent several existing multifactorial risk factors. vii

TITLE CERTIFICATE TABLE OF CONTENTS Page ii iii ACKNOWLEDGEMENTS ABSTRACT TABLE OF CONTENTS LIST OF FIGURES LIST OF TABLES iv v viii xiv xix CHAPTER I: INTRODUCTION AND LITERATURE SURVEY 1.1 BACKGROUND 1 1.2 OVERVIEW 2 1.2.1 Anatomy of the foot and ankle 2 1.2.2 Biomechanics of the foot 5 1.3 BIOMECHANICAL FOOT ASSESSMENT 6 1.3.1 Plantar pressure measurements in foot biomechanics 7 1.3.1.1 Plantar pressure measurement system 8 1.3.2 Sole hardness measurement 15 1.3.2.1 Methods to assess hardness of the sole 15 1.4 PATHOPHYSIOLOGY OF FOOT INJURY/ ULCERATION 18 1.4.1 Pathways for foot sole injury and falls risk in normal subjects 18 1.4.2 Pathways for foot sole ulceration in diabetic subjects 20 1.5 MULTIMODAL COMPREHENSIVE FOOT RISK ASSESSMENT 23 1.5.1 Factors known to influence biomechanical parameters in normal foot 24 1.5.1.1 Effect of Gender on standing plantar pressure distribution 24 1.5.1.2 Influence of body composition and foot arch type on standing 25 viii

plantar pressure distribution 1.5.1.2.1 Influence of BMI 25 1.5.1.2.2 Effect of foot arch type 26 1.5.1.3 Effect of aging on biomechanical foot parameters 27 1.5.1.3.1 Effect of aging on sole hardness 27 1.5.1.3.2 Influence of aging on standing plantar pressure 28 distribution 1.5.2 Factors known to influence biomechanical parameters in Diabetic foot 29 1.5.2.1 Influence of neuropathy on biomechanical foot parameters 29 1.5.2.1.1 Standing plantar pressure distribution variation and its 29 relationship with duration of diabetes in diabetes mellitus subjects 1.5.2.1.2 Foot sole hardness variation in patients with diabetes 31 mellitus 1.5.2.1.3 Joint mobility parameter variation and its relationship 33 with plantar hardness in diabetes mellitus subjects 1.6 COMPUTATION METHODS FOR SCREENING FOOT AT RISK FOR 34 INJURY/ULCERATION 1.6.1 Foot type classification using standing plantar pressure distribution data and 35 Arch index 1.6.2 Computational tool for Neuropathy classification using biomechanical foot 37 parameters 1.7 RESEARCH AIM AND OBJECTIVES 40 1.8 OVERVIEW OF THE THESIS 41 ix

CHAPTER II: RESEARCH METHODOLOGY AND PROTOCOLS 2.1 FOOT BIOMECHANICAL PARAMETERS RECORDING 43 2.1.1 Subjects selection 43 2.2 METHODOLOGY 44 2.2.1 Body composition 45 2.2.2 Foot biomechanical parameter measurement 47 2.2.2.1 Neuropathy 47 2.2.2.2 Measurement of biomechanical properties of foot sole skin 48 2.2.2.3 Standing plantar pressure distribution 50 2.2.2.4 Foot and ankle limited joint mobility 53 2.3 EXPERIMENTAL PROTOCOL 54 2.3.1 STUDY ON HEALTHY VOLUNTEER GROUPS 54 2.3.1.1 Group I - Gender difference in standing foot pressure distribution 54 2.3.1.2 Group II Standing plantar pressure distribution variation in 55 pre-obese subjects 2.3.1.3 Group III - Age related difference in biomechanical parameters 55 of foot sole 2.3.1.4 Effect of foot arch type on standing foot pressure distribution 56 2.3.1.5 Development of a robust system for foot arch type classification 57 using foot pressure distribution data and arch index 2.3.2 STUDY ON DIABETIC PATIENTS GROUPS 57 2.3.2.1 Group IV- Association of foot sole biomechanical parameter 57 variation with joint mobility parameters in Diabetes mellitus patients to understand ulcer formation 2.3.2.2 A screening computational tool to classify diabetic neuropathy 60 x

and non-neuropathy from type 2 diabetes subjects using Power ratio and foot sole hardness CHAPTER III: BIOMECHANICAL DATA ANALYSIS AND ALGORITHM DEVELOPMENT FOR CLASSIFICATION OF FOOT ARCH AND DIABETIC NEUROPATHY 3.1 STATISTICAL FOOT BIOMECHANICAL PARAMETER DATA ANALYSIS 61 AND ALGORITHM DEVELOPMENT 3.1.1 Reduction of Bias 61 3.1.2 Softwares 62 3.1.3 FOOT PRESSURE INTENSITY IMAGE ANALYSIS 62 3.1.3.1 Repeatability of PedoPowerGraph PR value 66 3.1.3.2 Fore foot to hind foot pressure distribution ratio (F/H) 67 3.1.3.3 Big toe to fore foot pressure distribution ratio (B/F) 67 3.1.3.4 Percentage Medial Impulse (PMI) 67 3.2 PARAMETER ANALYSIS ON HEALTHY VOLUNTEER GROUPS 68 3.2.1 DATA ANALYSIS OF STANDING PLANTAR PRESSURE 68 DISTRIBUTION FOR GENDER VARIATION, BMI VARIATION, AGING AND FOOT ARCH TYPE SUBJECTS 3.2.1.1 Analysis of standing plantar pressure distribution between 68 men and women 3.2.1.2 Analysis of standing plantar pressure distribution variation in 68 pre-obese subject 3.2.1.3 Analysis of foot sole hardness and standing plantar pressure 69 distribution between young adult and older subject 3.2.1.4 Analysis of standing plantar pressure distribution for different foot 70 xi

arch type subjects 3.2.1.5 Classification of foot arch type from plantar pressure distribution 70 and arch index using Linear Discriminant Analysis 3.3 PARAMETER ANALYSIS ON DIABETIC PATIENTS GROUPS 3.3.1 DATA ANALYSIS OF FOOT BIOMECHANICAL DIABETES 74 PARAMETER IN MELLITUS PATIENTS AND ALGORITHM DEVELOPMENT TO CLASSIFY DIABETIC NEUROPATHY 3.3.1.1 Analysis of standing plantar pressure distribution, sole hardness 74 and its correlation with joint mobility in diabetes mellitus patients 3.3.1.2 Detection of neuropathy and non-neuropathy using ANN technique 76 CHAPTER IV: RESULTS AND DISCUSSIONS 4.1 GENDER, BMI, AGING AND FOOT ARCH TYPE IN FOOT 84 BIOMECHANICAL PARAMETERS 4.1.1 Gender difference in standing foot pressure distribution 84 4.1.2 Standing plantar pressure distribution variation in pre-obese subject 85 4.1.3 Effect of Aging on biomechanical parameters of foot sole skin 90 4.1.4 Effect of foot arch on standing plantar pressure distribution 99 4.1.5 Develop a robust system to classify foot arch type from plantar pressure 103 distribution and arch index data using linear discriminant analysis 4.2 FOOT BIOMECHANICAL PARAMETERS VARIATION AND ITS 109 ASSOCIATION WITH JOINT MOBILITY IN DIABETES MELLITUS PATIENTS 4.2.1 Biomechanical parameters of foot sole variation in north Indian diabetes 109 mellitus subjects 4.2.2 Association of limited joint mobility and increased plantar hardness in north 121 Indian diabetes mellitus subject xii

4.2.3 Develop a screening computational tool for detection of diabetic neuropathy 127 and non-neuropathy in type-2 diabetes subjects CHAPTER V: CONCLUSION AND FUTURE SCOPE 5.1 IMPORTANT FINDINGS 133 5.1.1 GENDER, AGE, OBESITY, FOOT ARCH CLASSIFIER 133 USING BIOMECHANICAL PARAMETERS 5.1.2 CORRELATION BETWEEN DIABETIC NEUROPATHY AND 135 JOINT MOBILITY 5.2 IMPLICATIONS OF THE PROPOSED TECHNIQUE 137 5.2.1 FLEXIBILITY TO PODIATRY 137 5.3 LIMITATIONS AND FUTURE SCOPE 137 5.3.1 LIMITATIONS 137 5.3.2 FUTURE SCOPE 138 REFERENCES 139 LIST OF AWARDS/PUBLICATIONS BASED ON THE THESIS 176 BIODATA 180 xiii