Upper Limb Amputation Principles

Background

Causes of UL amputation:

  • Trauma (>80%)
  • Malignancy
  • Infection
  • Vascular disease/ischaemia
  • Deformity (congenital/contracture)

UE accounts for 1/3 of amputations — 8% proximal to wrist

Trauma Amputation Indications

  • Irreparable loss of blood supply
    • Prolonged ischaemia time
  • Severe soft tissue compromise
    • Severely crushed/mangled/contaminated parts
    • Traumatic amputation at multiple levels
  • Too unwell for reimplantation/reconstruction

Amputation vs Reconstruction

Mangled Extremity Severity Score (Johansen et al. 1990)

  • Most widely utilised score for UE/LE injuries — only a guide
  • Score based on:
    • Degree of soft tissue injury
    • Perfusion and limb ischaemia time
    • Presented in shock or not
    • Patient’s age
  • Actually based on lower extremity injuries but widely used for UL these days
  • MESS < 7 = good predictor for not requiring amputation (Prichayudh et al, 2009)
  • Previously MESS > 7 = 100% predictive of requiring amputation, but this is a poor predictor in upper limb trauma

Ischaemic time

  • Varies with extremity part and whether its cold or warm ischaemia time
  • Proximal to carpus – 6hrs warm, 12hrs cold ischaemia time max

General Principles

Functional outcomes significantly lower in UE vs LE amputations

  • Prosthesis rejection 44% UE vs 16% LE (Reichle et al. 2008)
  • All efforts should be made to salvage upper extremity limbs — always consider replantation as it has much better success rates than lower extremity

Preserve as much length as possible

  • Length increases lever arm to reduce amount of energy expenditure
  • Function of stump reduces with each higher level of amp and dexterity is related to the number of functional joints left on the stump
  • Prosthesis rejection also increases the higher the amp due to increased pressures placed on the soft tissues
  • Nerve repair and reconstruction more successful in UE and prostheses have more difficulty with replicating native dexterity and sensory feedback in UE

Traction neurectomy to prevent neuroma

Osteoplasty (smoothing/contouring underlying bone within stump) – prevent painful pressure areas

Adequate padding at amputation site

  • Skin for fingers
  • Myodesis — suturing muscle to bone
  • Myoplasty — suturing muscle to muscle = more complications (no bony fixation point = risk of developing painful bursa between sutured muscle ends and underlying bone)

2hr max tourniquet time, and not for malignancy/infection

  • Can re-inflate after 5mins for each 30mins up
    • e.g. after 20mins for 2hr previous use

Soft tissue coverage (in order of preference):

  • Local tissue flaps ideal if available
  • Skin grafting if sufficient muscle/subcut tissue coverage
  • Free tissue transfer
  • More proximal amputation to achieve tissue flap

Prostheses

Passive (cosmetic)

  • Limited to basic tasks such as pulling and pushing

Body powered

  • Make use of cables, pulleys and hooks and are affixed to patients to allow control by the remaining motility of the limb stump

Externally powered

  • Controlled via EMG signals from muscles around the stump site
  • The patient sends the specific signal to the device to perform the desired movement

Targeted muscle reinnervation

  • Invasive procedure where large nerves that would otherwise be amputated are attached to motor nerves of remaining muscles
  • E.g. a prosthesis can be designed to pick up EMG signals from a pec major that has been reinnervated by the median nerve to trigger a hand prosthesis to close, just like the action of the finger flexors

Complications

Wound breakdown — especially in peripheral vascular disease and diabetes

Oedema — minimise with pressure dressings

Pain

  • Phantom limb pain
    • Occurs in approximately 10% of patients, but up to 100% of traumatic amputations
    • Usually settles 4-6 weeks post-op
  • CRPS
    • Prevention is better than cure
    • Peri-operative epidural or post-op intra-neural anaesthesia
  • Neuroma
    • Can be prevented in most cases with gentle nerve traction before sectioning
  • Mechanical causes
    • Sharp bone ends
    • Poor soft tissue coverage
    • Skin breakdown
    • Poor fitting prosthesis
  • Osteoarthritis of proximal joint

Contractures — prevent with early aggressive mobilisation and positioning

HO and bony overgrowth

  • Most common in paediatric patients who undergo transosseus amputations
  • Disarticulation procedures are often preferred to prevent this

Achieving Good Outcomes

Patient involvement/explanation during process

Early team involvement — prosthetics, rehab

  • Appropriate prosthesis prescription and early fitting
  • Physiotherapy and occupational therapy based rehabilitation

Good surgical technique — optimal length, residual joints & soft tissue coverage

Other Radical Treatment Options

Ossteointegration

Forearm transplant — varied success and need for lifelong immunosuppression

Author Contributions

Page written by Dr James Drummond