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Pedicle Flaps

- Discussion:
    - pedicle flaps can incorporate a variety of tissues, ranging from skin and subQ fat to essentially a complete finger;
    - used to provide coverage in areas where tendon (denuded of epitenon), bone (denuded of periosteum), or joints are exposed;
    - areas that must support tendon grafting or transfers are best covered w/ pedicle flap;
    - periosteal surfaces can be skin grafted, but flap coverage provides more durable surface that is less prone to traumatic breakdown;
    - pedicle flaps can be used to provide sensation or specialized tissues
    - blood supply to pedicle flaps is thru intact base, stalk, or pedicle;
    - donor site is closed primarily or is skin grafted;
    - local flaps are obtained within the area of the defect and mobilized to fill the defect;
    - regional flaps are further removed from the defect but raised on the same extremity;
    - most regional and all distant pedicle flaps coverage requires at least two stages;
           - in the first stage the flap is inset at the recipient site;
           - more complete the inset at primary stage, more extensive vascular ingrowth into the flap;
           - vascular supply of either local or distant pedicle flap can be enhanced by the staged division of a portion of its vascular supply 
                  (delay maneuver), thereby encouraging a more efficienct circulation;
                  - this permits its use of a greater length to width ratio than would otherwise be possible;
    - after flap has established sufficient vascular connections w/ recipient site, the second stage, pedicle transection and inset completion, is performed;

- Axial Pedicle Flaps:
    - classified as either peninsular or island
    - peninsular flaps maintain tissue continuity across the length of to the donor area;
    - island flaps consist of an island of skin, muscle, fascia, or subQ tissue maintained on a debulked or skeletonized pedicle;
    - flaps are often designed of greater dimension than initially estimated to avoid tension, since undue tension will initially impair venous return;
         - tension associated with a single suture can produce a white line across a flap, resulting in distal necrosis;
         - thick flaps are less pliable and compensations for their inelasticity must be made;
         - pallor reflects inadequate arterial supply, while cyanosis indicates venous congestion;
         - mottling, cyanosis, and and edema herald impending necrosis, and violet discoloration signals established tissue necrosis;
         - hematoma or seroma between the flap and recipient bed will impair healing and predispose to infection and flap necrosis;
              - hematoma can also reduce vascular flow thru direct pressure;

- Innervated Pedicle Flaps:
    - innervated flaps are used primarily to provide coverage of the working (opposable) surfaces of the hand;
    - this includes the ulnovolar surfaces of the thumb pad and the radio-volar surfaces of the finger pads;
    - these flaps can be developed from local or regional tissues

- References:
Wound tension and blood flow in skin flaps.
Complications of 100 Consecutive Local Fasciocutaneous Flaps.
An Anatomic Review of the Delay Phenomenon: II. Clinical Applications.
Classification of the vascular anatomy of muscles: experimental and clinical correlation.
Muscle flap transposition with function preservation: technical and clinical considerations.
When does a random flap die?
Tissue oxygen measurements in delayed skin flaps: a reconsideration of the mechanisms of the delay phenomenon.
Enhanced capillary blood flow in rapidly expanded random pattern flaps.
Augmentation of blood flow in delayed random skin flaps in the pig: effect of length of delay period and angiogenesis.