Diabetic Foot Ulcers
Etiology
Intrinsic factors
1. impaired blood supply
2. neuropathy
3. impaired defences against infection
Extrinsic factors
1. trauma
2. Charcot joints
3. thick callous
4. previous foot ulcer
5. improper footwear,
6. unobtainable or low-quality podiatry service
Secondary risk factors include
1. poor metabolic control
2. psychological factors
3. tobacco smoking
4. old age
5. low socioeconomic status.
Neuropathy
 Diabetic neuropathy may be the most important
 Motor neuropathy leads to muscle atrophy, foot deformity (figure), altered
biomechanics of walking, and redistribution of foot pressures during standing and
walking
 Abundant callus formation on pressure points, together with thinning of the submetatarsal head fat-pads, additionally increases the force of plantar pressure and
ultimately results in foot ulceration
 Autonomic neuropathy results in loss of sweating, which leaves the skin dry and
vulnerable to cracks and fissures, and altered neurogenic regulation of cutaneous
blood flow
 Sensory neuropathy can substantially impair the patient's perception of touch, deep
pressure, temperature, and joint position. Leads to loss of protective sensations
and altered foot mechanics during ambulation on uneven surfaces
 DPN affects the sensory neurons, with small-fiber sensory loss resulting initially in
loss of pain, light touch, and temperature sensation, followed by loss of
vibratory sensation as degeneration of the large myelinated fibers advances.
 Foot ulcers will develop in about 15% of patients with diabetes, and 25% of those
will require amputation
Vasculopathy
 2-3-fold excess risk of accelerated atherosclerosis
 characteristically affects vessels between the knee and the ankle
Trauma
 direct trauma, thermal injury
 mechanical stress that is repetitive (walking barefoot or in improper footwear) or
continuously applied (extended unperceived pressure).
 Susceptibility increased with restricted joint mobility, poor foot care, and foot
deformity resulting in bony prominences
Classification
 neuropathic, ischaemic, or neuroischaemic
 International Working Group on the Diabetic Foot has proposed the PEDIS
classification - grades the wound on the basis of five features:
1. perfusion (arterial supply)
2. extent (area)
3. depth
4. infection
5. sensation.
Management
1. Perfusion
a. reduce the risk of atherosclerotic vascular disease - smoking cessation, diet
improvement, and medication prescription when needed to reach target
concentrations of total and LDL cholesterol;
b. establish the extent of any neuropathy
c. establish presence of vascular disease, which includes
i. palpating for foot pulses,
ii. measuring the ankle-brachial pressure index (ABPI) and toe pressures,
iii. colour-flow duplex ultrasonography
iv. transcutaneous oxygen measurement,
d. Magnetic resonance angiography (MRA) or conventional intra-arterial digital
subtraction angiography if planning vascular reconstruction
2. Infection
a. Most diabetic foot infections do not produce systemic manifestations, such
as fever or leucocytosis, but when these signs are present, they typically
suggest that any accompanying infection is severe
b. most important pathogens causing diabetic foot infections are aerobic grampositive cocci (GPC), especially S aureus, but also β-haemolytic streptococci
(especially group B) and coagulase-negative staphylococci.
c. These GPCs often cause monomicrobial infections, but patients with chronic
ulcers, or those who have recently received antibiotic treatment, often have a
polymicrobial mix of aerobic gram-negative bacilli with GPCs
d. old standard test for osteomyelitis is a bone biopsy sample processed for
culture and histology
3. Wound dressings
a. New treatments for diabetic foot ulcers continue to be introduced, yet few are
subjected to controlled or comparative studies of their efficacy.
b. Routine debridement of devitalised tissue at follow-up visits is widely
recommended, but evidence showing that it accelerates healing is scarce
c. Studies show that advancement of >0.7mm per week is 80% sensitive and
specific for eventual wound closure
d. Recent developments include the use of
i. bone-marrow-derived stem cells
ii. negative pressure dressings
1. randomized controlled trial (Armstrong, Lancet Nov 2005)
shows a higher proportion of healed wounds, faster time to
wound closure, a more rapid and robust granulation tissue
response, and a potential trend towards reduced risk for a
second amputation than control treatment.
iii. bioengineered skin equivalents
1. Apligraf – 56% vs 38% wound closure at 12 weeks
2. Dermagraft – 30% vs 18% wound closure at 12 weeks
iv. growth-factor therapy
1. PDGF-BB - 15% increased incidence of wound closure at 20
weejs
v. Hyperbaric oxygen treatment seems to reduce the risk of major
amputation, but not the time to ulcer healing or the rate of minor
amputation.
vi. Maggot (larval) biotherapy seems to be effective for debridement and
acceleration of healing, and perhaps also in reducing antibiotic use and
risk of amputation
4. Mechanical load relief
a. should be counselled never to walk in the same shoes that could have
contributed to a foot ulcer.
b. Pressure relief on ulcers, commonly referred to as off-loading, should always
be a part of the treatment plan.
c. The most compelling evidence that off-loading accelerates ulcer healing
comes from studies using a total contact cast for healing non-infected
neuropathic ulcers.
d. Neuropathic ulcers that have resisted healing for many months or years
typically heal in about 6 weeks in a total contact cast.
e. Pressure between the foot and ground at a plantar prominence can exceed
1000 kPa, whereas pressure between a correctly applied total contact cast and
a potential ulcer site is less than 100 kPa
f. Total contact casts are successful when properly applied and changed at least
weekly, partly because patients cannot remove them easily.
g. Crutches, bedrest, wheelchairs, and assistive ambulatory devices are probably
not effective for off-loading without direct intervention at the foot, because of
poor patient compliance.
5. Surgery
a. Prevention
i. Percutaneous lengthening of the Achilles tendon (ulcers due to
limited ankle dorsiflexion) temporarily reduces pressure under the
metatarsal heads, but carries an additional risk of secondary heel ulcers
resulting from an altered gait.
ii. Percutaneous tenotomy of the toe extensors reduces toe deformity
and can hasten ulcer healing and prevent recurrence.
iii. metatarsal osteotomy and resection of prominent metatarsal heads,
either prophylactically or at the time of ulceration but this procedure
poses a risk of secondary ulceration or other complications.
b. Reconstruction
Diabetic Foot Reconstruction
Traditional views were pessimistic:
Karp NS; Microvascular free-flap salvage of the diabetic foot: a 5-year experience.
Plast Reconstr Surg. 1994 Nov
 21 microvascular free flaps to the diabetic foot in 19 patients over a 65-month
period.
 Twenty of the flaps survived.
 The operations required a long, costly hospitalization with frequent
recipient- and donor-site complications.
 All patients eventually ambulated on their flaps.
 Five patients(20%) came to proximal amputation from 6 to 37 months after
surgery. Only one amputation was for flap breakdown.
 Increasing literature on the reliability of flap coverage in diabetic foot ulcers
 Multistaged multidisciplinary approach
 In the presence of nonpalpable foot pulses – revascularisation, if possible
performed first
 initial debridement where deep cultures taken and bone sent for pathologic
evaluation
 serial debridement until wound clean
 Bone was debrided until normal bleeding bone was reached (Paprika sign).
 wounds observed until all signs of infection had resolved and soft-tissue
regeneration was present
Attinger C; Relative roles of aggressive wound care versus revascularization in
salvage of the threatened lower extremity in the renal failure diabetic patient. Plast
Reconstr Surg. 2002 Apr
 overall 43 percent complication rate.
 mean follow-up of over 3 years, 79 percent of wounds healed, 89
percent of all limbs were salvaged, and 49%of patients survived
Blume, P, Attinger, C; Single-Stage Surgical Treatment of Noninfected Diabetic Foot
Ulcers. PRS Feb 2002
 single-stage approach consisted of total excision of the ulcer with broad
exposure, correction of the underlying osseous deformity, and immediate
primary closure using a local random flap
 selection – well perfused non infected diabetic foot
Attinger, C; The Role of Intrinsic Muscle Flaps of the Foot for Bone Coverage in Foot
and Ankle Defects in Diabetic and Nondiabetic Patients. PRS Sep 2002
 Five different pedicled muscle flaps were used:
o workhorse flap (abductor digiti minimi) is particularly useful for lateral
ankle and calcaneal defects.
o abductor hallucis flap is useful for medial midfoot, heel, and ankle
defects.
o flexor digitorum brevis flap is useful for plantar heel defects.
o extensor digitorum brevis flap is useful for anterior ankle defects.
 26% complication rate
 complete pedicled muscle flap failure rate 3%
Ozkan O. Reliability of free-flap coverage in diabetic foot ulcers. Microsurgery. 2005
 ultimate limb salvage rate was 83%
 should be considered a useful reconstructive option for serious defects in wellselected cases
 During the follow-up period of 8 months to 2 years, no ulcer recurrence was
noted
Rainer; Microsurgical management of the diabetic foot. J Reconstr Microsurg. 2003
Nov
 10 microvascular free muscle flaps in nine patients over a mean follow-up
period of 44 months.
 one flap loss, and nine flaps were transferred successfully.
 Seven of eight patients whose flaps survived had complications related to the
free-flap recipient site.
 These seven patients underwent 20 secondary surgical procedures due to
arterial and venous thrombosis, partial necrosis of the skin grafts, minor local
infections, and gangrene or necrosis of the remaining toes.
 In three patients, progressive ischemic necrosis of the remaining toes, with
total survival of the flap, was attributed to a microvascular steal
phenomenon.
 However, all eight patients whose flaps survived subsequently ambulated on
their flaps.
Summary
 Well selected patients
 Adequate debridement
 Free flap success high
 Perioperative complications high
 Prolonged hospital stay
 Free flaps can be done successfully in diabetic patients and will lead to limb
salvage and ambulation in the intermediate term