· diabetic foot problems are responsible for
· 50% of admissions of diabetics
· 50% of nontraumatic lower limb amputations
· problems may be caused by
· soft tissue neuropathic changes
· neuropathic arthropathy
· ischaemia
· main problem is diabetic ulcer
· prophylaxis is important aspect
· neuropathy is most common cause of diabetic foot problems
· ischaemia is usually only underlying or aggravating factor
Sensory
· stocking distribution
· worse distally
· tissue trauma caused by loss of protective sensation with
· repetitive pressure
· unrecognised injury
· most sensitive method of assessment is Semmes-Weinstein filaments
· graded nylon filaments
· smallest filament felt by patient recorded
Autonomic
· leads to loss of normal sweating
· skin becomes dry and stiff
· leads to cracking with infection
· calluses become hard
Motor
· causes intrinsic dysfunction
· leads to toe clawing
· deformity leads to
· increased pressure under MT head
· prominence of dorsum of IP jt
· both can lead to ulceration
· due to combination of sensory and autonomic neuropathy
· repetitive microtrauma in bones and joints that lack protective sensation (pain and proprioception)
· vasodilatation with increased blood flow and osteoporosis
· diabetics have problems with large and small vessels
· large vessel disease (artherosclerosis) primarily responsible for ischaemia in diabetic foot
· small vessel disease (microangiopathy) primarily responsible for retinopathy and nephropathy
· have typical iliac and femoral occlusive disease
· have particularly severe arterial involvement distal to knee
· painful foot usually due to ischaemia
· no increased susceptibility to infection
· do not handle infection as well once established
· usually polymicrobial
· gram positive cocci
· gram negative enteric rods
· anaerobes
· usually require broad-spectrum treatment
· ulceration usually requires both
· insensitivity (sensory neuropathy)
· pressure over bony prominence
· bony prominence produced by deformity
· claw toes
· Charcot midfoot or hindfoot
· healing of ulceration relies on reduction of pressure
· external (nonoperative)
· internal (operative)
· insufficiency should be suspected in
· painful ulcers
· ulcers that will not heal
· heel ulcers
Evaluation
· traditionally evaluated by ABI
· arm-brachial index
· use Doppler ultrasound and BP cuff
· determine systolic pressure at ankle and arm
· ABI = ankle SBP / brachial SBP
· normal is 1.0
· healing said to be possible if index > 0.45
· falsely elevated by rigid arteries
· Doppler studies more accurate
· pressures and waveforms obtained
· pressure > 40 mm Hg in toe predictive for healing
· triphasic waveforms indicate resilience of arterial wall
· other methods
· transcutaneous oxygen measurement
· xenon clearance
· fluorescein angiography
Reconstruction
· techniques include
· proximal bypass graft
· distal bypass graft
· angioplasty
· reconstruction should precede orthopaedic treatment
· accurate specimens should be collected
· surface swabs inaccurate
· intraoperative deep pus or tissue better
· broad spectrum initial coverage indicated
· third-generation cephalosporin
· ciprofloxacin
· augmentin
· adjusted according to cultures
· should consult with ID specialist
· good control of BSL improves wound healing
· control can only be obtained when infection eliminated
· nutritional factors affect wound healing
· predictive nutritional indices
· total protein > 60
· albumin > 35
· WCC > 1500
· pressure causes ulcers
· ischaemia causes gangrene
· original classification has been modified
Wagner (Ranchos Los Amigos)
· grade 0
· intact skin
· grade I
· superficial ulcer
· skin or subcutaneous tissue only
· grade II
· deep ulcer
· to tendon, bone or joint capsule
· grade III
· infected deep ulcer
· with abscess, osteomyelitis or septic arthritis
· grade IV
· local ischaemia
· gangrene of toes or distal forefoot
· grade V
· extensive ischaemia
· gangrene of midfoot or hindfoot
Depth-Ischaemia (Brodsky)
Depth
· grade 0
· at risk
· previous ulcer, or deformity with neuropathy
· grade 1
· superficial ulceration
· not infected
· grade 2
· deep ulceration
· exposed tendon or joint
· +/- superficial infection
· grade 3
· extensive ulceration
· exposed bone AND/OR
· deep infection (osteomyelitis or abscess)
Ischaemia
· grade A
· not ischaemic
· grade B
· ischaemia without gangrene
· grade C
· partial (forefoot) gangrene
· grade D
· complete foot gangrene
· ulcer is
· painless
· rimmed by hard callus
· may be present for years
· most commonly plantar
· usually under metatarsal heads
· may also be due to trauma to sole
· may be dorsal
· over IP joints
· usually associated with claw toes from intrinsic weakness
According to classification
· grade 0
· education
· appropriate shoewear
· grade 1
· external pressure relief
· grade 2
· surgical debridement
· wound care
· prn antibiotics
· pressure relief if convert to grade 1
· grade 3
· surgical debridement
· partial amputation
· IV antibiotics
· pressure relief if convert to grade 1
· grade A
· nil
· grade B
· vascular evaluation
· vascular reconstruction if required
· grade C
· vascular evaluation
· vascular reconstruction if required
· partial foot amputation
· grade D
· vascular evaluation
· BKA
· possible proximal vascular reconstruction
External pressure relief
· 1st step is modified shoewear
· stiff-soled surgical shoe
· open-toe sandal for dorsal ulcers
· if fails, total contact cast
· redistributes pressure across larger area
· provides structural protection for Charcot joint
· firm-fitting minimally padded short leg cast
Wound care
· callus carefully pared away
· removes hard edge
· wet-to-dry saline packs most effective dressings
· debride wound
· stimulate granulation and epithelialisation
Shoewear
· wide-toe shoe
· custom-moulded insole
· Plastazote with soft top layer, firmer bottom layer
· alternative is jogger
Correction of bony deformity
Ostectomy
· resection of prominent bone
· ideally performed after ulcer healed
· approach usually through ulcer
Osteotomy
· most commonly of metatarsal neck
· internal fixation preferable
· problems with
· transfer metatarsalgia
· delayed union
Debridement
· in the form of
· drainage of pus
· debridement of osteomyelitis
· amputation of toe or ray
· most common deformity is claw toe
· from intrinsic weakness
· next most common deformity pes planovalgus
· due to Charcot joint
· initial treatment is
· external relief of pressure
· external support
· prophylactic surgery to correct deformity not indicated
· usually present with moderate onset of red hot swollen foot
· may be diagnosed as infection or gout
· most common deformity is pes planovalgus
· sensory-motor deficit
· bounding pulse
Laboratory
· WCC and ESR not significantly elevated
Plain x-ray
· osteopaenia
· periarticular bone fragmentation
· new bone formation
· joint subluxation
· fracture
Doppler ultrasound
· increased blood flow
Nonoperative
· protection from weight bearing
· minimises deformity
· crutches and padded cast or polypropylene splint
· continued 3-6 mths until
· radiographic evidence of healing
· clinical reduction of redness and swelling
· then extra-depth shoe with double upright patellar tendon-bearing brace for 1 yr
Operative
· for unbraceable deformity
· arthrodesis in corrected position
· prolonged non weight-bearing required
· deep infection almost always associated with open wound
· haematogenous spread very uncommon
· hot red swollen foot usually Charcot joint rather than cellulitis
· avoid incision and drainage
· diagnostic dilemna when ulcer present
· x-ray changes can be similar
· infection suggested by raised temperature, WCC and ESR
· MRI may be useful
· not within realms of orthopaedics
· associated with
· claudication
· rest pain
· faint or absent pulses
· dependent rubror
· skin changes
· daily inspection of feet by patient or relative
· hourly inspection of feet with new shoes
· daily washing, drying and lubrication of feet
· thick woollen socks with no seam
· inspection of shoes by hand before wearing
· never barefoot
· avoidance of long walks and uneven ground
· avoid
· high heels
· toe crowding
· standard oxford lace-up shoe with moulded insert if no deformity
· custom extra-depth shoe if deformity present
· rocker bottom sole or steel shank if metatarsal heads prominent
· regular podiatry for nail, corn and callus care
· regular outpatient review to assess deformity
· aim to preserve foot
· BKA leads to contralateral BKA in 50% within 5 yrs
· aim to select ‘biological amputation level’
· most distal functional amputation level with reasonable potential for wound healing
· determined by
· location of ulcer
· grade of ulcer
· adequacy of vascular inflow
· tissue nutrition
· immunocompetence
· through foot or ankle
Indications
1. no pus or cellulitis at level of amputation
2. satisfactory arterial inflow
3. satisfactory tissue nutrition and immunocompetence
4. heel pad free of open lesions
5. potential to walk after surgery
Principles
· vascular reconstruction first
· broad spectrum antibiotic cover
· do not use tourniquet
· treat skin edges very carefully
· save all viable tissue
· do not include inflamed skin
· make longer plantar flap if possible
· do not leave sharp corners on bone
· remove cartilage if possible
· avoid any tension on flaps
· many small sutures
· do not use constricting dressings
· leave stitches in 6-8 weeks
· delay weight bearing and prosthetic fitting
Toe
· amputation usually for infection complicating gangrene
· all infected and necrotic tissue must be removed
· wound healing often unpredictable
Ray
· should only be performed for 1st or 5th ray
· central ray resection
· takes a long time to heal if wound left open
· is difficult to treat orthotically
Midfoot
· through
· metatarsal shafts
· tarsometatarsal joints (Lisfranc)
· midtarsal joints (Chopart)
· Lisfranc and Chopart amputation may be complicated by late equinovarus
· addressed by tendo Achilles lengthening at the time of surgery
· may require lateral transfer of tibialis anterior tendon
· usually require
· AFO
· toe filler
Hindfoot
· occasionally used in children
· performs poorly in adults
Ankle
· Syme’s ankle disarticulation
· two-stage procedure advised
· disarticulation
· fashioning of stump
· good results