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Above the Knee Amputation

 

Figure 4

Above the Knee Amputation 1

Above the Knee Amputation 2

(see also: AKA Prosthesis, Amputations in the Diabetic Patient

Discussion

  • average AK amputee walks 43% slower and expends 89% more kcal/min than the normal person;
  • if proximal circulation is adequate, a longer anterior muscle flap may be left and the combination myodesis-
    • myoplasty technique is used;
  • ability to ambulate with a prosthesis depends heavily on the fitness of the patient;

Technique

  • tourniquet is routinely used;
  • level of the bone transection 4 to 6 inches proximal to the knee joint line;
  • fish mouth incision is made distal to the level of bone transection;
    • anterior flap is created so that the scar will be posterior;
    • the surgeon can create a full thickness flap upto the superior pole of the patella;

adductor musculature

  • preservation of the adductor magnus helps balance out the forces generated by the abductors;
  • ensure that adductor musculolature and the iliotibial band are not dissected with the fish mouth, but rather, are dissected 4-5 cm distal to the the skin incision;
  • create a long adductor muscle flap;
  • at the end of the case, the adductor flap can be sutured to and across the end of the femur;
  • by creating an adductor myodesis to the femur, the femur will be prevented from moving to a flexion-abduction position (which is otherwise common);

anterior musculature

  • anterior musculature is transected sharply with a large scalpel blade or a sharp amputation knife, allowing the muscle to retract to the level of the intended bone transection;

femoral transection

  • transection of the femur early in the case allows subsequent easy access to neurovascular bundle;
  • knife is used to elevate the periosteum off the femur;
  • femur is transected, and retracted anteriorly and laterally with a large bone hook;

neurovascular bundle

  • profunda femoris lies just posterior to the femur, and the SFA lies just posterior to the vastus medialis muscle;
  • posteromedial & posterior muscle can then be systemically transected and the major vessels identified, clamped, and doubly ligated;
  • sicatic nerve is placed on gentle stretch & ligated w/ slow cautery;

posterior musculature

  • posterior musculature is freed from femur w/ periosteal elevator and periosteum is cut circumferentially at level at which anterior musculature has retracted, ie. the level of bone transection;

adductor myodesis

  • drill holes (7/64 inch) are placed are placed thru the cortex of cut end of femur approximately 3/8 inch above distal end;
  • adductor flap is sutured to and across the end of the femur (utilizing the drill holes) with care taken to keep the femur in maximum adduction as the adductors are tied down;
  • this prevents the musculture from hanging and retracting and removes tension from the anterior myocutaneous flap;

quadriceps myodesis

  • the quadriceps can be secured to either the adductor flap or to the posterior femur;
  • in either case, the femur should be in full extension as the quadriceps is secured inorder to avoid hip flexion contracture;

Knee Disaarticulations

Hindquater Amputation

References