A Guide To Using Bilobed Flaps In Lower Extremity Surgery

Peter A. Blume, DPM, FACFAS

   Closure of the bilobed flap can occur with suturing of the primary lobe to the first frenulum and suturing the secondary lobe to the second frenulum with circumferential sutures in the periphery of each lobe. One would suture these lobes with 4.0 nylon in a simple interrupted suture mattress. Corner stitches and deep sutures are not recommended as they can lead to necrosis and dehiscence of the flap. Closure of the adjacent lobes with respect to the defect can lead to a small dog ear formation, which one should not back cut or excise as this can compromise the base of the flap and lead to necrosis. The dog ear formation typically resolves spontaneously over several weeks without resection or risk to the flap.

   There are numerous advantages of the bilobed flap for closure of defects of the lower extremity. This flap allows for recruitment of large amounts of tissues, which rotate from different areas in a tangential design. The bilobed flap allows for preservation of tissue, reduction of scar formation, mobility of tension lines and the ability to close defects in a variety of anatomic locations.

How To Create a Bilobed Flap

The technique for creating a bilobed flap includes an initial excision of the lesion with a number 15 blade. One would completely excise the lesion’s full thickness through the subcutaneous tissue to the level of the deeper structures. After fully excising the lesion, assess the lines of maximal extensibility and the relaxed skin tension lines. The pinch test allows one to determine how supple the tissue is within the region, which will ultimately determine the rotation of the axis from mobility to immobility.

   Design the flaps after completing the excision of the lesion. Carefully dissect the flaps utilizing skin hooks and atraumatic techniques. Rotate the flap and elevate it from the deeper levels in order to allow for subcutaneous adipose tissue to remain within the flap. Utilizing dissecting scissors, one can carefully undermine the peripheral region from which each of the flaps had been elevated. Undermining this region will produce laxity within the region. Rotate the primary lobe into the adjacent defect and then inset the second lobe into the primary flap site. Tourniquet use can be acceptable based upon assessment of the patient. When it comes to tourniquet use, it should be deflated and one should achieve appropriate hemostasis. A Colorado tip and a bipolar cautery can prevent collateral damage as these flaps are extremely delicate.

   The bilobed flap can provide coverage for a diabetic foot wound but surgeons must take many additional steps prior to considering this flap for closure of a defect. As with many indications for this flap with respect to pigmented lesions and soft tissue mass excisions, one must excise the defect as the initial step. More often than not, a diabetic foot wound requires some form of bone realignment, bone debridement or bone resection.8 These wounds are considered contaminated and one should treat them as such. One should excise the wound’s full thickness including any underlying subcutaneous tissue, possible bursa and bone in the region. Creation and mobilization of the bilobed flap can occur at the same point.

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