Clinical Biomechanics and its Implications on Diabetic Foot

By Animesh Hazari and G. Arun Maiya

This book presents essential information on biomechanical features of the diabetic foot, which could help to minimize the risk of future diabetic foot problems. 

India has recently been classified as the ‘diabetic capital’ of the world. Type 2 diabetes mellitus has become a serious concern for Indian society, where the prevalence rate is increasing exponentially. Similarly, the comorbidities and foot complications of type 2 diabetes mellitus are worsening day by day. Of all complications, diabetes peripheral neuropathy is the most common, and leads to foot deformities, pain, altered sensation, loss of foot arch, etc. The ultimate fate can even be gangrene and amputation. Accordingly, foot complications of diabetes represent a pressing medical issue. 

Sharing insights into diabetic foot syndrome, its causative factors, prevention and management, this book offers a valuable resource for medical and paramedical students, researchers, podiatrists, surgeons, and physicians alike. 

• Language: English
• Publisher: Springer
• Release date: Jun 19, 2020
• ISBN: 9789811536816

Book preview

© Springer Nature Singapore Pte Ltd. 2020

A. Hazari, G. A. MaiyaClinical Biomechanics and its Implications on Diabetic Foothttps://doi.org/10.1007/978-981-15-3681-6_1

1. Introduction and Understanding of the Diabetic Foot Syndrome

Animesh Hazari¹   and G. Arun Maiya²  

(1)

LFAMS, Lovely Professional University, Jalandhar, Punjab, India

(2)

Centre for Diabetic Foot Care and Research, MAHE, Manipal, Karnataka, India

Animesh Hazari (Corresponding author)

Email: [e-mail]

G. Arun Maiya

Foot is an essential body part for efficient weight distribution and locomotion. Foot complications are very commonly seen but often ignored by people with diabetes mellitus until recent past where diabetic foot syndrome (DFS) has become a serious concern. It is now well accepted that DFS has a serious impact on the morbidity and mortality of diabetes mellitus population leading to multiple foot complications. Among all, foot ulceration is the most dangerous which leads to amputation frequently. The data from the Netherland, reported by Bakker et al. (2005), confirmed that a lower limb was lost every 30 s among diabetes mellitus population. As per the recent trends, the number has increased drastically across the globe, and Indians may have suffered to the highest extent due to lack of awareness, management resources, and economic constraints. Before we go into much detail, let us try to understand the term diabetic foot syndrome.

All complications of the foot due to diabetes were previously described under the umbrella of Diabetic Foot. In the recent past, the term diabetic foot has been replaced with diabetic foot syndrome. The diabetic foot syndrome as defined by the World Health Organization is an ulceration of the foot (distally from the ankle and including the ankle) associated with neuropathy and different grades of ischemia and infection (Tuttolomondo et al. 2015). In other words, diabetic foot syndrome could be considered as a clinical triad of neurological, vascular, and musculoskeletal changes in the foot of a diabetes mellitus individual. In this book, we shall refer diabetic foot syndrome to any complications, deformity, or spectrum of disorders in the foot of diabetes mellitus people unless stated otherwise. Thus, DFS consists of all possible changes in the foot of diabetic population. It has been found that there is a foot lesion associated out of every four diabetes mellitus individual worldwide, which suggests that diabetic foot syndrome is relatively very common and should be addressed well.

Among the most common clinical presentation of diabetic foot syndrome, diabetes peripheral neuropathy accounts for the highest. Many studies have reported that diabetes peripheral neuropathy (DPN) is one the most serious complications of diabetes that accounts for significant morbidity in terms of foot ulceration and amputation (Sawacha et al. 2012). DPN refers to the presentation of sign and symptoms for peripheral neuropathy among people with diabetes mellitus when other causes for neuropathy have been excluded. Among all types of DPN, 75% present with symmetrical distal neuropathy. We shall discuss DPN in more detail in the upcoming chapters.

Apart from neuropathy, the vascular changes consist of a complex interaction between inflammatory, metabolic, and procoagulant variables. The vascular complications also have a close relationship with insulin resistance, obesity, hypertension which creates an adipo-vascular axis predisposing to the higher risk of diabetic foot syndrome. Thus peripheral artery disease could be seen due to direct damage to the nerves and blood vessels. The diabetic vascular disease has three main components like arteritis, neuropathy, and large vessel atherosclerosis.

Although the neuropathy and vascular mechanism of DFS are well documented, the role of musculoskeletal and biomechanical alteration cannot be ignored. It has been seen that lower levels of plasma adiponectin and higher interleukin-6 lead to musculoskeletal foot changes, thus causing foot ulceration. If not treated well, it may progress to gangrene and require amputation. It is evident that a diabetic foot syndrome could have multiple presentations depending upon the pathogenic pathway consisting of neuropathy, vascular, autonomic, musculoskeletal, and biomechanical changes. Thus to understand the presentation of a diabetic foot syndrome, an established classification system could be beneficial which has been discussed below.

1.1 Classification of Diabetic Foot

The presentation and outcomes of a diabetic foot syndrome are diverse, thus many classifications prevail. The most widely used classification includes Wagner’s, University of Texas (Armstrong), PEDIS, and SINDBAD. All these classifications have provided a better understanding of diabetic foot syndrome. These classification systems are easily accessible for academic purpose, and we shall discuss about each briefly here.

1.1.1 Wagner’s Classification

The Wagner’s classification of diabetic foot was introduced by Wagner in 1981 for clinical description, diagnosis, and treatment of diabetic foot syndrome. It was validated by Smith (2003). It basically grades the diabetic foot ulcers ranging from Grade 0 to Grade V where Grade I, II, and III are non-gangrenous and Grade IV and V are gangrenous as shown in Table 1.1.

Table 1.1

DFS classification suggested by Wagner

According to Wagner Grade I classification, localized and superficial ulcer may be present and could be treated by antibiotics and glycemic control. An example of such diabetic foot syndrome can be seen in Fig. 1.1.

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Fig. 1.1

Diabetic foot ulcer classified as Grade I as per Wagner’s system. (Source: Diabetic Foot Centre, KH, Manipal, India)

Similarly, Fig. 1.2 depicts Grade II, Fig. 1.3 Grade III, Fig. 1.4 Grade IV, and Fig. 1.5 Grade V as per the classification system given by Wagner.

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Fig. 1.2

Diabetic foot ulcer classified as Grade II as per Wagner’s system. (Source: Diabetic Foot Centre, KH, Manipal, India)

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Fig. 1.3

Diabetic foot ulcer classified as Grade III as per Wagner’s system. (Source: Diabetic Foot Centre, KH, Manipal, India)

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Fig. 1.4

Diabetic foot ulcer classified as Grade IV as per Wagner’s system. (Source: Indian Podiatry Association)

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Fig. 1.5

Diabetic foot ulcer classified as Grade V as per Wagner’s system. (Source: Indian Podiatry Association)

The classification given by Wagner could be very useful in identifying the gangrenous nature of diabetic foot along with possible treatment approaches. However, it does not identify the extent of infection and ischemia (Oyibo et al. 2001). Thus, further classification was required.

1.1.2 University of Texas (Armstrong)

The University of Texas classification of diabetic foot ulcer was given in 1996 (Lavery et al. 1996) and validated by Armstrong and his colleagues in 1998 (Armstrong et al. 1998). The classification has four stages (Stage A, B, C, and D) with grade ranging from 0 to III. This classification could be helpful in determining the outcome with specific features on the depth, infection, and ischemia for risk of amputation in diabetic foot as shown in Table 1.2.

Table 1.2

DFS classification given by Armstrong

The diabetic foot ulcers shown in Fig. 1.6 could be better classified by grading given by Armstrong in comparison to Wagner as infection, and greater extent of ischemia can be seen.

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Fig. 1.6

Diabetic foot ulcer classified as Stage D, Grade III, and II as per Armstrong system. (Source: Indian Podiatry Association, India)

1.1.3 PEDIS Classification of Diabetic Foot

This classification system was introduced by the International Working group of the Diabetic Foot (IWGDF) in 2003 (Gandhi et al. 2019; Schaper et al. 2003). The PEDIS classification stands for Perfusion, Extent/Size, Depth/Tissue Loss, Infection and Sensation. The grading system is based on scientific literature and expert opinion to identify the severity of diabetic foot syndrome. It could be more user friendly, objective, and applicable to research. A PEDIS score of 7.5 can predict the outcome of diabetic foot ulcer with 100% sensitivity (Gandhi et al. 2019). The details on the classification criteria of PEDIS could be seen explained as below:

1.1.3.1 Perfusion

Grade I—No signs or symptoms of peripheral artery disease (PAD) in the affected foot, in combination with:

Palpable dorsalis pedal or posterior tibial artery or

Ankle brachial index 0.9–1.1 or

Toe brachial index >0.6 or

Transcutaneous oxygen pressure (TcPO2) >60 mmHg

Grade II—Presence of signs and symptoms of PAD, but not of critical limb ischemia (CLI).

Presence of intermittent claudication

Ankle brachial index <0.9, but with ankle pressure >50 mmHg or

Toe brachial index <0.6, but systolic blood pressure >30 mmHg or

TcPO2 30–60 mmHg or

Other abnormalities on noninvasive testing, compatible with PAD but not with CLI

Grade III—Critical limb ischemia, as defined by:

Systolic ankle blood pressure <50 mmHg or

Systolic toe blood pressure <30 mmHg or

TcPO2 <30 mmHg

1.1.3.2 Wound Extent/Size

It is measured in square centimeters preferably after wound debridement. The surface area is calculated by multiplying the largest diameter by the perpendicular and the second largest diameter.

1.1.3.3 Depth/Tissue Loss

Grade I—Superficial full-thickness ulcer, not penetrating any structure deeper than dermis.

Grade II—Deep ulcer, penetrating deeper than dermis to subcutaneous structures, involving fascia, muscle, or tendon.

Grade III—All subsequent layers of the foot are involved including bone and/or joint (exposed bone, probing to bone).

1.1.3.4 Infection

Invasion and multiplication of microorganism into the body tissues of foot causing tissues destruction.

Grade I—No symptoms or signs of infection.

Grade II—Infection of the skin and subcutaneous tissue meeting at least two of the following criteria:

Local swelling or indurations

Erythema >0.5–2 cm around the ulcer

Local tenderness or pain

Local warmth and/or

Purulent discharge

Grade III—Erythema >2 cm plus one of the items suggested above or infections deeper than skin and subcutaneous tissues such as abscess, osteomyelitis, fasciitis with no systemic inflammatory signs.

Grade IV—Infections with signs of two or more systemic inflammatory response syndrome (SIRS) as described below:

Temperature >38 or <36 °C

Heart rate >90 beats/min

Respiratory rate >20 breaths/min

PaCO2 <32 mmHg

White blood cells >12,000 or <4000 /mm³ and/or

10% Immature (band) forms

1.1.3.5 Sensation

Detects the presence or absence of protective sensation in the affected foot.

Grade I—No loss of protective sensation on the affected foot, defined by tools as discussed below.

Grade II—Loss of protective sensation on the affected foot is defined as the absence of perception for one of the following tests:

Absent pressure sensation on 10 g monofilament, in two out of three testing sites.

Absent vibration sensation using 128 Hz tuning fork or vibration pressure threshold >25 V tested on plantar aspect of the hallux.

It could be seen that the PEDIS could be a very useful classification for objective evaluation of diabetic foot ulcers. However, this system could not be used for classifying patients for polyneuropathy, and further, more investigation may be