Surgical Aspects of the Diabetic Foot

Reviewed by

Dr Nathan White
MBBS | Unaccredited Orthopaedic Registrar

Introduction

  • Diabetes epidemic in Western Melbourne
  • Ardeer: 1 in 3 over 55
  • Sharp rise in 16 – 39 with T2DM
  • High cost of treatment

Presentation

  • 2 broad types of presentation
    • Complications of diabetes: ulcers, infection, charcot
    • Injury / other conditions in a diabetic patient

Aetiology of diabetic foot disease

  • Neuropathy ± Vascular disease = Diabetic foot disease

Peripheral neuropathy

  • Common: 30% of diabetics in hospital
  • Ischaemic insult to vasa nervorum
  • Multi modality: Sensory, Autonomic, Motor
    • Sensory
      • Negative symptoms:
        • sensory loss: insidious, progressive, worse distally
      • Positive symptoms:
        • burning pain, paraesthesia: less than other neuropathies
    • Autonomic skin changes
      • Stiff / dry,
      • Inflexible,
      • Cracked,
      • Portal for infection
    • Motor
      • Intrinsic wasting
      • Claw & hammer toes
  • Mononeuritis
    • Uncommon: peroneal nerve
  • Neurological examination
    • Combination of proprioception, vibration:
      • 128Hz,
    • touch:
      • 10g Semmes–Weinstein monofilament

Vasculopathy

  • 45% at 20 years
  • Commonly involves vessels below knee
  • Occlusive lesions more diffuse
  • Circumferential calcification of the tunica media: lead pipe appearance
  • Small vessel abnormailities
  • Vascular assessment
    • Clinical history
    • Pulses
      • Pulses present, symptoms absent: 96% NPV
      • Absent pulses: 71% peripheral vascular disease
    • Ankle brachial index
      • unreliable due to poorly compressed arteries, falsely elevated

Imaging the diabetic foot

Most important question: is there infection?

  • Xray
    • Standing xray
      • osteomyelitis
        • detection sensitivity: 70%
      • Diabetic osteolysis
        • (pencilling of distal MTs, phalangeal loss)
        • non infective, thought due to hyperaemia
        • Changes rarely due to infection in absence of wound
  • Imaging beyond plain films often unhelpful
  • Nuclear medicine
    • Tc
      • Sensitivity 70-95%, Specificity 43-89%
      • Charcot joint +ve also
    • Indium
      • sensitivity and specificity 79%
    • Combined sensitivity 93%, specificity 83%
    • Difficult to distinguish bone and soft tissue
  • MRI
    • Can’t differentiate infective & Charcot oedema
    • Low false –ve rate

Ulceration

  • The most common cause of infection leading to amputation
  • Primarily due to excessive pressure in an insensate foot
  • Exacerbated by poor vascularity & deformity
  • Repetitive blunt trauma has a cumulative effect

Treatment

  • Optimise general condition
  • Treat infection
  • Obtain deep sample
  • Often polymicrobial
  • Consider vascular reconstruction
  • Further treatment guided by Brodsky classification

Osteomyelitis

Depends on infection location

  • Forefoot OM
    • usually compatible with foot salvage
    • ray amputation
    • Principle: skin flaps maximised, aim for primary closure
  • Midfoot OM
    • Chopart (talonavicular-calcaneocuboid)
    • Syme’s (ankle disarticulation)
  • Hindfoot OM
    • Heel salvage key issue for foot retention
    • Partial calcanectomy

Charcot

aetiology

  • Neurotraumatic pathway
    • Repetitive microtrauma & degeneration
  • Sympathetic hyperaemia → osteoclastic resorption and bone fragmentation
    • Ankle & forefoot (resorptive) vs midfoot (degenerative) patterns

natural history

  • Fragmentation / destruction
    • Swollen, warm, inflamed: 6 – 12 months
    • DDx infection: rare if skin intact
    • MRI & bone scan often unhelpful
  • Coalescence
    • Destruction slows
    • Evidence of healing, less swelling & heat
  • Consolidation
    • Healing but often with deformity / instability

management

  • Goals:
    • Plantigrade foot
    • Allows weight bearing
    • Shoeable
  • Non-operative treatment mainstay
    • Total contact cast
    • Maintain position while healing occurs
    • wean to shoe & insert: as T drops & xray healing
  • Type 1: (70%)
    • least likely to require stabilisation
    • Most common cause of deformity: rocker bottom
    • Subsequent plantar ulceration
    • Ostectomy targeted to prominence
    • Occasional arthrodesis
  • Type 2 (20%) & 3a
    • More likely to cause instability requiring brace or reconstruction
    • Bracing, AFO
    • Pantalar arthrodesis
    • Once consolidation underway
  • Type 3b
    • Avulsion TA insertion : nonoperative Mx

Foot & ankle fracture in diabetic patient

  • No absolute distinction between Charcot and traumatic fracture in presence of neuropathy
  • Peripheral neuropathy and vascular disease complicate treatment
  • 10/12 patients with absent pulses developed complications

Recommendations

  • Sever compromise
    • Consider immediate vascular reconstruction if severe compromise
      • If not possible nonoperative treatment mandatory
      • Increased immobilisation time
  • ORIF
    • Advocate internal fixation if no vascular compromise and unstable fracture pattern
    • Low threshold for ORIF:
      • 4/6 in one series became infected in BKPOP with reduced sensation and prolonged immobilisation

Webpage Last Modified: 12 July, 2010