Amputation Principles

Indications for Amputation:

1. Peripheral vascular disease

2. Trauma

   1. Insensate limb distally

   2. Facilities

   3. MESS score

3. Infection

4. Tumours

5. Nerve injury (trophic ulceration)

6. Congenital anomalies

Aims:

• Return Patient to maximum level of independent function

• Ablation of diseased tissue

• Reduce morbidity & mortality

• Considered first part of a Reconstruction to produce a physiological end organ

• Requires a Multidisciplinary approach

Pre-operative Evaluation

1. Tissue
   1. Clinical - feel pulses, skin temperature, level of dependent rubor
   2. Doppler - Ankle/ Brachial index more than .45 = 90% healing; inaccurate with calcified vessels
   3. Toe systolic BP - 55 mm Hg min for distal healing
   4. Transcutaneous PO ₂ min 35 for assured healing
   5. Arteriogram
   6. Other:
      1. Skin blood flow (Xe 133 clearance)
      2. thermography
      3. thallium scanning
2. Immune Competence
   1. serum albumin at least 3g/dl
   2. WCC more than 1500/ mL
3. Systemic
   1. control diabetes
   2. evaluate cardiac, renal + cerebral circulation
   3. Preop TPN in malnourished pt
4. Psychological
   1. early plan for return to function
   2. preop counselling
   3. amputee support groups
5. Preop Pain Control
   1. Pain clinic review
   2. Spinal anaesthesia
      

Surgical Principles

• Level [ Diagram below ]

Amputation Levels (for prosthesis fitting):	Optimum	Shortest	Longest
Transradial (forearm)	junction prox 2/3 & distal 1/3	3cm below biceps insertion	5cm above wrist joint
Transhumeral	middle third	4cm below axillary fold	10cm above olecranon
Transfemoral	middle third	8cm below pubic ramus	15cm above medial joint line of knee
Transtibial	8cm for every metre of height	7.5cm below medial joint line of knee	level at which myoplasty can be done

• Skin flaps

  • Use defined flaps electively with the apex of the fish mouth at the level of the bony resection

  • Use any available flaps in trauma to preserve length

  • Tailor flaps at least as long as the diameter of the stump

• Muscles

  • Divide ~5 cm distal to level of bone resection
  • Bevelling or contouring may be required for good stump shape
  • Stabilisation of muscle mass
  • provides stump padding
  • prevents atrophy
  • counterbalances deforming forces
  • improves function
  • prevents bursa formation
  • Myoplasty = involves suture of flexors to the extensors over bony stump
  • Myodesis = direct suture of muscle to bone - most useful in AK, AE and disarticulations

• Nerves

  • Divide cleanly under gentle tension proximal to bone ends - allow to retract

  • Large nerves eg sciatic - ligate due to large contained vessels

• Blood vessels

  • Large arteries & veins should be doubly ligated and haemostasis achieved prior to closure

• Bone

  • Avoid excessive periosteal stripping (prevent spur formation)

  • Bevel & smooth bone

• Closure

  • Do not close under tension

  • Interrupted sutures preferably

• Drains

  • are necessary

• metabolic costs

  • higher with more proximal amputations (incr. O ₂ consumption)

Children

• Usually for congenital limb deficiencies

• Try to retain limb if possible

• Preserve length

• Disarticulate if possible to preserve growth potential rather than trans-diaphyseal amputation (-> bony overgrowth)

Aftercare

• Rigid vs soft dressing

• Compression -Avoid proximal compression

• PAM Aid

• Prevent contracture

• Early prosthetic fitting

Complications

1. Haematoma

2. Infection

3. Necrosis

4. Contractures

5. Neuroma

6. Phantom pain

7. Terminal overgrowth (children)