Disclosure
“Flappe” is a term from the 16th century denoting something that hangs broad and loose, attached by only one side. The evolution of the flap courses tortuously over the centuries, illustrating the intense drive for humans to reconstruct deficient anatomy and create form where originally absent. As such, flaps premiered long before the comfort and convenience of anesthesia. In India in 600 BC, Sushruta Samita described operations for nasal reconstruction—a necessity during the pre-Christian era since amputation of the nose (an organ of “respect and reputation”) was common as criminal punishment. As years passed, many advances regarding flap use arose, including extensive facial flaps and the first cross-leg flap. However, the first muscle flap of recorded history debuted in 1906. Louis Ombredanne of Paris described the use of the pectoralis minor muscle for breast reconstruction following mastectomy. That same year, Tanzini introduced the latissimus dorsi muscle flap for postmastectomy breast reconstruction. As breast surgery became more radical, the human drive toward reconstruction created and stimulated the appearance of the first musculocutaneous flap (ie, muscle in addition to overlying skin and subcutaneous tissue). In 1912, Professor Stefano d'Este introduced this technique. He used the latissimus dorsi muscle and the skin of that same area to reconstruct the chest wall after mastectomy. Developments in anesthesia, antibiotics, hematology, and wound healing brought about routine use of flaps with good postoperative results.
Often the concepts of a flap and a graft are confused. In an effort to sort between the two terms, their definitions are listed below.
Many types of flaps are available, including cutaneous (local), muscle, musculocutaneous, fasciocutaneous, and free. Containing all layers of the skin plus superficial fascia, the local skin flap restores the wound integrity of areas with smaller defects. The muscle flap uses only muscle for defect coverage. It is used primarily to provide a vascularized surface for the defect. Commonly, the muscle flap is used to eradicate infection and to revascularize bone. Additionally, the musculocutaneous flap encompasses skin, subcutaneous tissues, and muscle for composite coverage as previously mentioned. The musculocutaneous flap is a regional pedicle flap that allows for rotation of a greater distance into a nearby area of defect than the local cutaneous flap, which requires elevation in close proximity to the defect. Because a skin paddle is provided, the musculocutaneous flap generally is preferred to the muscle flap alone due to its ability to provide a combined replacement of deficient tissue. Chronic skin ulcers, such as pressure sores, that are refractory to conventional local wound therapies are good examples of potential beneficiaries of the musculocutaneous flap. The exception to the myocutaneous preference is in lower extremity defects in which a muscle flap and a skin graft provide a better result than the all-in-one musculocutaneous tissue transfer. Breast reconstruction and treatment of irradiated wounds are the most effective uses of the musculocutaneous flap. Recent reports from the Instituto Nacional de Cancerologia in Mexico City suggest pedicled, musculocutaneous flaps are "excellent" regarding breast cancer reconstruction patients with advanced disease, recurrent disease, and radiation complications. The fasciocutaneous flap entails skin, fascia, and subcutaneous tissue. It is noted to be an appropriate flap in areas where not as much bulk is needed as for the musculocutaneous flap, and it should be in close proximity to the defect. Studies boast that fasciocutaneous flaps are easy to mobilize and very reliable. However, all elements being equal, in a potential infection the musculocutaneous flap appears superior because of better ingrowth into the contaminated area. Briefly, the free flap (more precisely, the free tissue transfer flap) is an "en bloc" transfer of tissues from a carefully selected donor site of meticulous flap design to a distant (even remote) recipient site. The nature of this reconstructive technique requires complete division of donor segment blood supply with reanastomosis (microvascular) at the recipient site vasculature. This technically demanding procedure is often an option when local or regional flaps are not feasible, such as in defects resulting from severe traumatic injury. Degloving injuries of the extremities is a good example for free flap reconstruction. The flap algorithm can act as a general guide to aid in the decision of flap choice (se below). Of note, more recently the "perforator" flap, evolving from the musculocutaneous flap, is coming into favor. The flap's blood supply originates from a single perforating arterial branch in contrast to the multiple vascular patterns of the musculocutaneous flap (see Anatomy). A group of hand surgeons in Germany find the perforating flap allows for increased individuality in flap design.
See Image 6 for a flap algorithm to aid in choosing the appropriate flap. |
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Muscle and musculocutaneous flaps are characterized by their vascular patterns. They have a dominant vascular pedicle that supplies the named muscle and the overlying skin secondary to perforating branches of the dominant vessel. The 5 different vascular patterns of the muscle and musculocutaneous flaps are as follows:
II. Dominant vascular pedicle and minor vascular pedicle (eg, gracilis; see Image 2) III. Two dominant pedicles (eg, gluteus maximus; see Image 3) IV. Segmental vascular pedicles (eg, sartorius; see Image 4) V. Single dominant vascular pedicle and secondary segmental pedicles (eg, latissimus dorsi; see Image 5)
Flaps work because of eventual vascular connections between the flap with its nutrient vessels and the recipient site. Approximately 4 weeks are required before homeostasis returns after a tissue transfer. Below are chronologic changes of a flap and the recipient site after elevation and transfer.
As described briefly in the definition section, the muscle and myocutaneous flaps should be primary considerations when presented with a large and/or deep anatomic defect. This defect can be a surgically planned deficiency such as a postmastectomy wound or the result of trauma or chronic infection. A wound worrisome for infection is a candidate for a muscle or musculocutaneous flap primarily because of its ability to decontaminate. Three important questions relating to a successful flap outcome must be asked prior to flap selection.
Preoperative assessment of the wound's ability to heal is key. Assess nutritional status, vascular supply, infection, and potential causes for a nonhealing wound. Potential patient comorbidities that affect wound healing include radiation history, nutritional deficits, tobacco use, diabetes, connective tissue diseases, peripheral vascular disease, and obesity. Recipes for jeopardized blood supply and increased infection risk should headline a preoperative checklist. Researchers at the University of Texas MD Anderson Cancer Center found that obese patients undergoing free transverse rectus abdominis myocutaneous flaps have significantly higher incidence of flap reconstruction complications, such as fat necrosis, flap loss, and donor-site infection. Factors that challenge the principles of wound healing should be addressed in the patient prior to flap design. On occasion, a patient may need an imaging study before undergoing an operation. For example, a preoperative angiogram may be obtained in a patient with a chronic open wound who, at the time of original injury, sustained a crush fracture to the distal lower extremity. If lower extremity pulses are weakened, the arterial study helps map vascular anatomy to the potential donor sites for wound coverage. However, if the planned flap provides accurate coverage, maintains form at both the donor and recipient site, and does not compromise function at the donor site, the workup for a potentially successful muscular flap is complete. As with all operative intervention, thorough informed consent is a must to obtain. Of specific importance with regard to tissue transfer techniques, the patient must be aware of the risks ranging from pain and scar to deformity and compromise/loss of normal function of the involved tissues. The price for reconstruction is not always solely paid for with currency.
Errors in judgment, technique, and patient treatment foster complication in muscle and musculocutaneous flap survival. Poor flap design is often a source of flap demise. For example, failure to recognize posttransfer tension and failure to recognize compromised flap blood supply after tissue elevation and transfer can risk flap viability. Both tension on a wound and impaired tissue perfusion represent general flap ischemia. With "reverse planning" (ie, preceding operative intervention with a mock transfer using a piece of fabric and rotating it from the donor site to the recipient site as would be done during the procedure), some technical complications can be intercepted. Improper flap design (eg, failure to factor nutrition, obesity) leads to seroma formation, hematoma formation, superficial skin necrosis, and wound separation with eventual partial and/or complete flap loss. Seromas generally can be treated with a continuous pressure dressing to promote reabsorption. Conversely, dependent on surgeon preference, the fluid pocket can be actively aspirated with a needle or passively aspirated with a closed suction drainage system. Intraoperative examination of the flap provides an early opportunity to optimize flap survival. At the time of surgery, the presence of a brisk, bright red blood flow from the distal edge of the flap is the only anatomic test helpful in determining flap viability. Again, the flap must provide adequate coverage under no tension. Keeping the skin edges moist to decrease depth of tissue loss and keeping the flap warm to prevent the vasoconstriction of hypothermia are techniques that can increase the chance of flap survival. The primary cause of flap demise is not inadequate arterial inflow but rather venous insufficiency (ie, compromise of venous outflow). During venous congestion necrosis requires several days for definitive demarcation. Areas of concern are those that are bluish in color and that demonstrate a sluggish circulation. Because necrosis is a slow phenomenon, often the elapsed time allows for some revascularization from peripheral tissues at the recipient site. Therefore, instead of complete flap death there will be loss of tissue centrally where the revascularization is most challenged. If the warnings of imminent flap death are identified early, then simple maneuvers like taking out sutures/staples at areas of tension and freeing congestion with periodic needle sticks may curb necrosis. Frequently, partial flap salvage is possible. If there is definitive loss of tissue in an area of the flap, then the affected region requires sharp debridement with subsequent local wound care. Complications such as hematoma formation and complete flap loss may require second-look operative intervention, particularly if persistent bleeding and signs of infection appear, respectively. Complete flap loss is rare and proper flap design and planning are the keys to successful muscle flap transfer. Korean researchers at the Wonju College of Medicine conclude, based on rodent models, that prostaglandin E1 may increase flap survival. Pending further in vivo success, prostaglandin E1 use could be part of a future musculocutaneous flap protocol.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
){kind=small}
View Full Size Image
