mechanism foot injury and ulcer formation

1. Overview of Mechanisms
causing Diabetic Foot Ulcers
Arun Bal
Raheja Hospital, Mumbai

6. Fig
Charcot’s
Foot with
Acute Stage
of
Destruction

7. Fig Bilateral Charcot’s Foot in Acute Stage of Destruction

8. Diabetic Foot Wounds Are Like
ICEBERG

9. How Does Foot Injury Occur ?
• Tissue ischemia
• Rupture of micro & macro anatomic
structures
• Irregular interaction between vertical &
shear stress ie pressure differentials
• Cellular mechanisms
• Neuropathy, trauma, infection

10. Mechanical Factors
• Repetitive moderate force as in walking
• Inflammation
• Erythema and warmth
• Collection of exudate
• Blister formation
• Breakdown of skin ie ulcer

11. Biomechanical Aspects Of
Ulcer Formation and Healing
• Structural alteration
• Structure & function relationship
• Tissue properties
• Limited joint mobility
• Plantar callus
• Fractures

12. Biomechanical Aspects Of
Ulcer Formation and Healing
• Weakness of muscles
• Prior ulceration
• Shear stress
• Body weight
• Abnormal posture
• Footwear

13. Biomechanical Aspect Of
Ulcer Formation and Healing
• Foot ulceration is mainly a breakdown of
skin under pressure beyond the tolerance
of skin.
• Other factors may vitiate the progress
• Often ulcers occur from within out,
• Infection is not really the cause of ulcers,
but a consequence

14. Biomechanical Aspect Of
Ulcer Formation and Healing
• The pressures on foot are evenly distributed on
the fore foot lateral longitudinal arch and heel.
• Conditions under which the pressures go
beyond tolerance are
• Faster the gait
• Longer the stride
• Foot deformities - disturb the even distribution
and create areas of abnormal pressures where
breakdown occurs

15. Biomechanical Aspect Of
Ulcer Formation and Healing
The break down pressure is between
• 500 TO 700 kilo Pascals
• Healing thus will occur if we reduce the
pressure below this level
• Deformities cause excessive pressures and
callosities.
• Callosities in turn raise pressures 30 times
more

16. Vascular Phenomena
• Peak plantar pressure generated while
walking is 600 kilo Pascals
• Systolic blood pressure of 120mm of Hg
can be obliterated by 15 kilo Pascals
• Capillary pressure by 6 kilo Pascals
• Causes delayed recovery from ischemia
• Leading to delayed restoration of normal
tissue oxygen concentration

17. Neuropathy and development of ulcer
• Sensory Neuropathy leads to
Loss of pain, heat and cold sensation,
The insensate foot, leads to ignorance of
repeated or damaging trauma of
Painful foreign bodies, surfaces that are hot
or cold, leading to the development of ulcer

18. Neuropathy and development of ulcer
• Motor – Intrinsic small muscle imbalance,
foot deformity, abnormal areas of plantar
pressures, ulcer
• Autonomic neuropathy – combines tissue
ischemia and gross deformities

19. Component causes of foot ulcers
• Peripheral neuropathy 78%
• Minor trauma 77%
• Deformity 63%
• Edema 37%
• Peripheral ischemia 35%
• Callus 30%
• Infection 01%

20. RISK FACTORS
DIABETIC NEUROPATHY
• MODIFIABLE
• Hyperglycemia
• Hypertension
• Increased cholesterol
• Smoking
• Alcohol use
• NON MODIFIABLE
• Old age
• Long duration of
diabetes
• HLA DR 3/4 genotype
• Greater height

21. ETIOLOGY OF DIFFUSE
NEUROPATHY
• Hyperglycemia
• Vasa nervorum closure
• Abnormal fatty acid metabolism
• Myoinositol deficiency

22. Tissue properties
• Advanced glycated end products cause either
ligamental laxity or hardening
• This results in deformities like Hallux rigidus,
loosing elasticity, becomes susceptible to
trauma
• Laxity will cause collapse of the arches and
raised mid foot pressures
• Displacement of metatarsal cushion distally

23. Other factors
• Vibration and position sense is carried by
same fibers and lost together, results in
altered gait
• Foot lands on the walking surface in
abnormal or uneven position, pressures get
irregularly distributed with high pressure
zones leading to ulceration

24. Psychological Problems Associated
With Diabetic Foot
On the rise
• Depression
• Divorce rate
• Alcohol abuse
• Disruption in
social,domestic
environment
• Negative attitude
On decline
• Diabetic self care
• Psychological
adjustment to illness
• Social/family support
• Self esteem
• Quality of life
• Satisfaction with
treatment

25. Preventing ulcer formation
• Many common sense advise can be given to
prevent ulcer formation
• Careful clinical examination should reveal
conditions of foot predisposing it to the
ulceration
• That decides what advise is needed

26. Contraindicated Exercises
• Insensate, deformed foot with
previous ulceration
or present ulcer contraindicates
• Treadmill, jogging, Stairmaster
• Prolonged, fast and long stride walking

27. Common Sense Advise
• Educate patients to look at their feet, wash
daily with warm water, soft soap, dry in the
interspaces, cut nails square,
• Wide toe box, extra depth shoes
• Insole wing pad, enhances ulcer healing rate
to 90%
• “Always shoe” policy
• Socks – keep feet most