When the Foot Hits the Ground the Wound Changes

Bijan Najafi, PhDProfessor of Surgery

Director of Clinical Research, Division of Vascular Surgery and Endovascular Therapy

Director of Interdisciplinary Consortium on Advanced Motion Performance (iCAMP)

Michael E. DeBakey Department of Surgery

Baylor College of Medicine

Speaker’s Bureau:

• None

Honorarium:

• None

Consultant:

• Biosensics LLC

• Hamad Medical Co- Doha-Qatar

Disclosures

Stockholder:

• None

Grant/Research Support:

• Biosensics LLC

• Eden Medical

• EO2 Concept

• AVEX

• OHI

• LifeNet

• AVAZZIA

Medical/Scientific Boards:

• None

3

objectives

1. Understand the age-related changes in foot Biomechanics in

people with diabetes

2. Discuss current and future technologies and strategies to

improve biomechanics of lower extremities.

Over 51 million age 65+ (16%)2019

Over 12 million (25%) older

adults have diabetes2015

Over $ 300

billion2017

Demographic shift: Population Aging More than 25% of the U.S. population aged ≥65 years have diabetes

Kirkman et al (2012), Diabetes Care

The Road to Ulceration

Armstrong et al (2017), NEJM

Age-related changes in Biomechanics of lower extremities

SkinSoft Tissue

Joint RoM

Foot Function

OldYoung

Wrobel & Najafi (2010), J. of Diabetes Sci. & Tech; Menz (2015), Gerontology

Decreased sweating→ Dry skin

High pressure→ Joint deformityPain & Poor sensationRigidity & Fall

Diabetic peripheral neuropathy and

poor balance

• High risk of fall in the diabetic peripheral

neuropathy (DPN) population, with an overall

incidence of 1.25 fall/person-year1 5+ folds

higher than age-matched controls2

• Strong association between poor postural

balance and prospective falls in particular

among frail and pre-frail older adults3

• Increase in plantar numbness is associated

with increase in gait unsteadiness and increase

in risk of falling 4,5

1: Wallace et al (2002), Diabetes Care; 2:Richardson et al (1995), J. Gerontol; 3. Mohler et al (2015), Gerontology4: Najafi et al (2013), JAPMA, Kelly et al (2013), JAPMA

8

Why should we care?

Biomechanical Abnormalities

Lazzarini, Crews,…, and Najafi (2019), JDST

How does offloading work?

❑ By locking ankle joint transferring pressures to forefoot are avoided.

❑ Cast offloads by transferring weight bearing to the leg itself

❑ By accommodated offloading, pressure under regions of interest are removed.

IWGDF Recommendation 1

Offloading the Diabetic Foot

a. In a person with diabetes and a

neuropathic plantar forefoot or

midfoot ulcer, use a non-removable

knee-high offloading device with

an appropriate foot-device

interface as the first-choice of

offloading treatment to promote

healing of the ulcer. (GRADE

strength of recommendation:

Strong; Quality of evidence: High)

IWGDF Recommendation 2

In a person with diabetes and a

neuropathic plantar forefoot or midfoot

ulcer for whom a non-removable knee-

high offloading device is contraindicated

or not tolerated, consider using a

removable knee-high offloading

device with an appropriate foot-device

interface as the second choice of

offloading treatment to promote healing

of the ulcer. Additionally, encourage the

patient to consistently wear the device.

(Weak; Low)

The International Working Group on the Diabetic Foot (IWGDF), 2019

12

Poor adherence to knee-high offloading

Only 28% of total daily activity recorded

while patients were wearing their RCW

Armstrong et al (2003), Diabetes Care

13

Negative impact of offloading on gait

N=80

Ling, …, Najafi, Clinical Biomechanics, Under Review

14

Factors affecting adherence to offloading

Crews et al (2016), Diabetes Care

Key results: Foot pain and postural instability are significant predictors of adherence to offloading

Study Design: 79 DFU (46 from UK and 33 from US) and wound healing was documented over 6-weeks

15Crews,…, Najafi(2012), Clinical Biomechanics

❑ Ankle-high walker provides 25% better balance during walking

Shall we choose different strut height for older adults with poor mobility?

25%

3. IWGDF Recommendation

Offloading the Diabetic Foot

In a person with diabetes and a neuropathic plantar

forefoot or midfoot ulcer for whom a knee-high

offloading device is contraindicated or not tolerated,

use a removable ankle-high offloading device as the

third-choice of offloading treatment to promote healing

of the ulcer. Additionally, encourage the patient to

consistently wear the device. (GRADE strength ofrecommendation: Strong; Quality of evidence: Low)

The International Working Group on the Diabetic Foot (IWGDF), 2019

17

Frail Patients FootUlcer

Woundhealing

ProlongedImmobilizationwith offloading

Slow MuscleRecovery

Recurrence

Prolonged immobilization of foot could lead to frailty

Najafi et et al (2019), ISDF Meeting

Rahemi, .. Najafi(2018), Sensors

Alteration in Gait Alteration in Propulsion Performance

Lower extremity muscle loss affects propulsion performance

58% longer HO phase

N=161, age 65+70% frail or pre-frail

45% weaker Power 31% slower Gait

Tissue Stress on forefoot pressure is maximum during heel-off (HO) phase

HO Phase

Heel –off Phase

𝑃 =𝐺𝑅𝐹

𝐴𝑟𝑒𝑎 𝑜𝑓 𝐶𝑜𝑛𝑡𝑎𝑐𝑡

Does prolonged offloading increase risk of ulcer recurrence?

Prolonged offloading → poor propulsion performance →increased peak pressure

Frailty induced by offloading

Initial Swing(acceleration)

Mid Swing

Co

ntr

ols

Pat

ien

ts Co

ntr

ols

Pat

ien

ts

Co

ntr

ols P

atie

nts

Najafi et et al (2019), ISDF

Alteration in Propulsive Function Plantar Pressure

Frailty induced by offloading may increase plantar pressure

Propulsion

𝑃 =𝐺𝑅𝐹

𝐴𝑟𝑒𝑎 𝑜𝑓 𝐶𝑜𝑛𝑡𝑎𝑐𝑡

Najafi et et al (2019), ISDF

23

What can we do about it?

Balance

control

Development of DPNBalducci et al., 2006

DPN symptomsKluding et al., 2012

Balance controlRichardson et al., 2001

Allet et al., 2010

Grewal et al. 2015

Gait speedAllet et al., 2010

Balance

control Wang et al., 2018

Step

widthRichardson et al., 2004

DPN

symptoms

Najafi et al., 2017

Gait

speed

Improving lower extremity biomechanics to reduce recurrence of ulcers (?)

DPN

symptoms

Kang et al., 2019

Balance

control

Gait

speed

Lower Extremity Exercise Assistive footwear/Exoskelton Plantar Stimulation

GaitRoser et al., 2017

Risk of falling

Wang et al.,

2018

There is evidence that foot and ankle exercise could address some of the Age-Related Biomechanics factors including:

• Foot strength • Lower extremity range of motion• Balance• Gait• Falls

Schwenk, …, Najafi (2013), JAPMA

Exe

rgam

e

Stu

dy

De

sign

75 HD, RCTIG: 41 (Exergame); CG:34 (similar exercise without technology)

4 weeks therapy Re

sult

s

Gait Balance

0

0.2

0.4

0.6

0.8

CG IG

Gai

t sp

ee

d, m

/s

BL 4W

Najafi et al, Unpublished

Gamification - ExergamingBenefit of technology to personalize foot and ankle exercise

body & mind exercise

Sensor

Outcomes

12%*

0

0.1

0.2

0.3

0.4

0.5

0.6

CG IGBo

dy

sway

, cm

2

BL 4W

-31.2%**

Daily plantar mechanical stimulation Potential solution to reduce risk of recurrence of ulcerA

ctiv

e In

sole

s w

ith

emb

edd

ed m

ech

anic

al c

om

pre

ssio

n p

um

p

Stu

dy

De

sign

30 DPNSingle arm

4 weeks therapy

Re

sult

s

0

10

20

30

40

50

VP

T,

Vo

lts

16%*

0

0.6

1.2

1.8

EyesOpen

EyesClosed

19 %* 25 %

Numbness

(VPT) Balance

BL WK 4

Ba

lan

ce

Kang, …, Najafi, JDST (2019)

Outcomes

28

Najafi et al (2017), Journal of diabetes science and technology

Gamification – Digital Health

29

Smar

t In

sole

s

Stu

dy

De

sign

90 with history of DFUsRCT-doubled blinded

18 months FU58 completed

26 CG & 32 IG

8,638 person-days in CG

11,835 person-days in IG

Re

sult

s 71% reduction in ulcer recurrence!

IRR=0.29, p=0.037

10 DFUs in CG

4 DFUs in IG

Digital Health - WearablesEffectiveness of Interactive Smart Insoles to Prevent Ulcer

Recurrence

Abbott, .., and Reeves (2019), Lancet Digital Health

❑ Aging impacts biomechanics of lower extremities➢ Skin➢ Soft tissue➢ Joint range of motion➢ Arch collapse and foot deformity ➢ Poor gait & poor balance

❑ Alteration in biomechanics of lower extremity because of aging could affect diabetic foot management ➢ Poor adherence ➢ High rate of recurrence of ulcers

❑ There is an urgent need to tailor diabetic foot management in older adults❑ Compromised offloading ❑ Lower extremity exercise❑ Plantar stimulation❑ Smart wearables & Gamification

Summary

31

www.bcm.edu/icamp

Credit : My son, Ryan Najafi ☺