Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

C H A P T E R 93

BELOW-KNEE AMPUTATION

Arthur P. Sanford

STEP 1: SURGICAL ANATOMY

Cross-sectional anatomy of the lower leg is shown in Figure 93-1, A.

STEP 2: PREOPERATIVE CONSIDERATIONS

Selection of level for amputation depends on the underlying pathology and the need to ascertain efficient wound healing of the amputation stump.

Below-knee amputation stumps do not rely on a symmetrical flap closure, but rather the posterior flap with extensive musculature is to be brought anteriorly.

Use of a tourniquet is at the discretion of the surgeon.

STEP 3: OPERATIVE STEPS

1.INCISION

Planning the level of incision begins by determining the bony structures to preserve, typically 2 to 3 fingerbreadths below the tibial tuberosity (Figure 93-1, B).

From this landmark, skin flaps are developed, typically the midpoint of the leg in an anterior to posterior plane is identified, just below this level.

The anterior flap is incised anteriorly.

The posterior flap is incised as a semicircle, at its apex with a length equal to the distance to reach the anterior margin of the wound.

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2. DISSECTION

Divide the anterior compartment with an amputation knife, down to the interosseous membrane, taking care to ligate the anterior tibial artery (Figure 93-2).

Expose minimal lengths of tibia and fibula with periosteal elevation, because this compromises the blood supply to bony segments.

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Divide the tibia and fibula using a bone saw and beveling the anterior surface, taking the fibula more proximally, because this will not be a weight-bearing component of the amputation stump (Figures 93-3 through 93-6).

Fibula cleared of adjacent tissue and periosteum with elevator and divided 1-2 cm proximal from division line of tibia

FIGURE 93–3

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Final inspection for hemostasis

of marrow cavity

FIGURE 93–6

C H A P T E R 93 • Below-Knee Amputation 1037

Identify and ligate posterior compartment vessels short of the wound (Figure 93-7).

Similarly, identify and strip nerves short, and allow retraction to prevent neuromas in the closed wound.

Posterior tibial vessels are

ligated individually between clamps

FIGURE 93–7