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Most important technical consideration at the time of doing below knee amputation is :
A. posterior flap should be longer than anterior flap
B. anterior flap should be longer than posterior flap
C. stump should be short
D. stump should be large

Explanation  :

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)

By Dr. Tushar Mehta

MBBS , DNB (Ortho), MNAMS, PGDCR, http://www.facebook.com/orthopaedicsplus.in

6 thoughts on “MCQ”
  1. This is the first time I am seeing this MCQ.
    I appreciate your details reg amputation which will be of immense help to the students.
    Have you mentioned anywhere what is the correct answer for the question posted. According to me “anterior flap should be longer than the posterior flap” is the correct answer. Comment.

    1. Thanks Dr. V M Iyer for the appreciation. As far as this MCQ is concerned , the correct answer is A . The posterior flap is always kept longer than the anterior flap so as to give a correct stump in which the suture line lies anterior to coronal stump and does not come in the line of exact weight bearing .

  2. Thanks sir , for such a nice presentation .
    i knew the answer somehow , but not the reason .

    thanks for that .

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