Radial Forearm Tissue Transfer Treatment & Management

An informed consent is obtained.

A two-team approach may be used and is ideal for minimizing time under anesthesia for the patient. The skin paddle is marked centered on the palpable radial artery and designed to fit the estimated defect size. The cephalic vein is also marked because it usually decompresses with tourniquet inflation and may be difficult to visualize. The arm is exsanguinated with an elastic wrap, and the tourniquet is inflated to 250 mm Hg.

A number 15 blade is used to incise the periphery of the flap, beginning on the medial (ulnar) aspect of the flap and extending in a curvilinear fashion into the proximal forearm (as seen below). The dissection is carried down medially to the flexor carpi radialis in a subfascial dissection to expose the intermuscular septum. The flexor carpi radialis is followed back into the proximal arm, and the pedicle is identified proximally and dissected free. The lateral (radial) aspect of the skin incision is then carried down through the skin and subcutaneous tissue to the BR.

A subfascial dissection is then performed on the BR, with the superficial branch of the radial nerve, which lies on the lateral aspect of the BR muscle, identified and preserved. It is important to stay on the muscle. The intermuscular septum containing the pedicle is then dissected off of the BR. If there is no concern for ulnar artery viability, the distal pedicle can be divided at this point. The cephalic vein is identified proximally and either harvested with the flap or left intact. The LABC nerve is identified in proximity and harvested if required for neural anastomosis.

Tiny perforating vessels that provide the blood supply to the radius are identified and cauterized or clipped; otherwise, they will bleed when tourniquet pressure is released. If bone harvest is planned, these distal perforators are preserved and followed to the radius. The bone is cut obliquely (keel shaped) so as not to overcut and weaken the radius. It is safe to take 40% of the diameter of the radius. Care is taken not to shear the vessels from the bone during harvest.

The skin paddle and the pedicle are then dissected free from all surrounding subcutaneous tissue. The pedicle is identified to one artery and one vein if possible. If it is not possible to identify the venous pedicle to one vessel, two venous anastomoses can be done or, if the venae comitantes are of adequate caliber, venous drainage can be based on only one branch. The tourniquet is then released, and the vessels are further cleaned of their adventitia under loupe visualization.

At an appropriate time, the pedicle is ligated proximally, and the flap is inset in the defect. If bone was harvested, it is our practice to have an orthopedic surgeon plate the remaining radius. The donor site defect is minimized using a purse-string suture of 3-0 Vicryl. The donor site is carefully closed with acellular dermis and a split-thickness skin graft that covers any tendon denuded of paratenon with nearby muscle prior to skin grafting. A skin graft that has been pie crusted by hand rather than run through a mesher has a better cosmetic appearance.

Suitable recipient vessels in the neck should previously have been identified. The vessels are cleaned of adventitia under the binocular microscope. Using microvascular techniques, the anastomoses are then performed. The authors use a 9-0 nylon suture for the arterial anastomosis and either 9-0 nylon or a venous anastomotic device for the venous anastomosis or anastomoses. The vascular clamps are removed from the vessels, and flow is reestablished and verified. Papaverine is placed on the pedicle, and closure is completed. Suction drains are carefully placed in the neck and secured with sutures to avoid direct contact with the pedicle. It is the authors' practice to place an implantable Doppler device on the arterial anastomosis for postoperative monitoring.

The arm is dressed with Xeroform and a bolster and loosely wrapped with Kerlix. A splint is placed, as is a feeding tube, if necessary, and the patient is transferred to the recovery room. An intensive-care bed may be necessary, depending on the experience of the nursing personnel.

Postoperative care is similar to that for any free tissue transfer, although details may vary from institution to institution. Patients are closely monitored in the hospital, and the transplanted forearm skin is frequently evaluated for signs of vascular compromise.

The ideal technique by which a flap can be assessed is only theoretical and practically varies depending on the flap, the patient, available equipment, and other factors. Based on individual preference, cost, and familiarity with monitoring techniques, various monitors are available. Direct visualization and assessment of capillary refill, with or without needle prick, is very reliable in trained hands.

The use of an implantable Doppler device is an excellent tool for the well-trained surgeon, as well as the ancillary staff and family involved in the care of these patients. This technology is routinely used in our practice; it has been proven to increase the detection of immediate/incipient vascular problems with a sensitivity of 87% and a specificity of 99%. ^[4] Arterial problems usually manifest within 24 hours; venous congestion often develops 48-72 hours postoperatively. Frequent evaluation and careful monitoring allow for early identification of problems.

Fluid balance and overall patient condition are monitored as well. The authors use prophylactic antibiotics for 24 hours, although many routinely use prophylactic antibiotics for much longer periods. We do not routinely heparinize or give preoperative or postoperative aspirin to these patients. (A literature review by Swartz et al indicated that anticoagulant drugs studied in the report—aspirin, low–molecular weight dextran, unfractionated heparin, low–molecular weight heparin, and prostaglandin-E1—do not improve the survival of or lower the complication rate for radial forearm free flaps used in head and neck reconstruction. ^[5] )

The arm splint is changed on the fifth postoperative day, and the skin graft is evaluated. The patient continues to wear a splint until the skin graft site has healed completely. Active physiotherapy is instituted to ensure recovery of wrist and hand function.

It is not our practice to routinely discharge patients on anticoagulation. The first postoperative visit generally occurs 1-2 weeks after release from the hospital. Flap and skin graft viability are assessed, any remaining sutures are removed, and the recipient site is evaluated for complications. If not already initiated preoperatively or on an inpatient basis, physical therapy is instituted to restore function when the donor site has healed. Removal of the feeding tube and/or tracheotomy tube, if still present, is considered. A speech pathologist, a physical therapist, and other specialists also evaluate the patient as needed.

Patients generally resume an oral diet approximately 2-3 weeks following discharge if no complications arise. Continuing dental/oral surgical evaluation and management allows for placement of dentures or implants at an appropriate time.

The primary problem with the radial forearm free flap is the cosmetic outcome of the donor site. The surgical defect almost always requires skin grafting. Aggressive attempts at primary closure can result in compartment syndrome, a dreaded complication that can compromise the limb. Methods to decrease the defect size have been reported and may improve cosmetic outcome. Meticulous attention to closure is the most reliable technique for optimizing the cosmetic result the donor site. ^{[6, 7]}

Tendon exposure with delayed wound healing has been reported in up to 40% of patients, but basing the flap more on the radial side and covering the tendons with proximal muscle has drastically reduced the frequency of this complication, to less than 10% of cases. ^[8]

Reports on the use of cadaveric dermis on the wound have been presented. This technique provides a better cosmetic result but may take up to 3 months to heal. A full-thickness skin graft alone has not been shown to increase cosmetic or functional outcome. In our experience, we find that the use of AlloDerm with a split-thickness skin graft over it can provide thicker coverage of the forearm defect, with minimal donor site morbidity and superior cosmetic results compared with a split-thickness skin graft alone (see the image below). ^[9] Problems with the skin graft donor site are rare, but infection and delayed healing have been documented.

The development of donor site infection or hematomas is possible but rare. The authors do not routinely place drains in the arm, although many surgeons rely on closed-suction drains to evacuate any blood from the midforearm and proximal forearm.

Compartment syndrome is a rare, but serious, problem. The arm should not be closed under significant tension in an effort to avoid a skin graft.

Patients treated with radial forearm free flaps do not usually notice a subjective loss of range of motion or function in the arm. However, an objective decrease in absolute strength can often be measured. Radial forearm osteocutaneous flaps (see the image below) may result in fracture of the radius. Prophylactic intraoperative plating and postoperative casting are of benefit and have minimized this complication.

A study by Emanuelli et al indicated that preoperative physical exam and ultrasonographic findings do not predict donor-site morbidity following the harvesting of radial forearm flaps. Using the modified Cold Intolerance Symptom Severity and Quick Disabilities of the Arm, Shoulder and Hand questionnaires, the investigators found that 20% of donor arms were positive for cold intolerance and that 76% of patients reported extremity-related disability. In neither case did the preoperative results of an Allen test or ultrasonographic evaluation correlate with the outcome. ^[10]

As with any microvascular surgery, free flap failure is a risk. Flap salvage following venous or arterial thrombosis is possible if early identification of vascular compromise leads to early (urgent) operative intervention. If thrombosis is identified and appropriately managed or if pedicle geometry is optimized after twisting has occurred, the flap may be saved. Thrombectomy and revision of thrombosed vessel(s) are performed if required; occasionally, this necessitates vein grafting.

For flaps with venous congestion, if the patient cannot be returned to the operating room immediately, leeches may be used to temporarily relieve the congestion. (However, this technique should not be considered first line.) Leeches remove the engorged blood from the flap and thereafter allow an artificial venous outflow through the bite they have made in the patient's flap skin. Blood flow through the bite is enhanced by an enzyme, hirudin, found in leech saliva. This enzyme is a powerful anticoagulant and, together with removal of the tiny clot that forms at the bite site, allows flaps to slowly bleed for hours.

Leeches can transmit Aeromonas hydrophila, a gram-negative rod, so patients should prophylactically receive an antibiotic that covers beta lactamase–resistant organisms if leech therapy is used. Blood loss in leech therapy can be significant, and the patient's hemoglobin should be carefully monitored. Leeches are placed directly on the flap at intervals throughout the day. When they are sated, they fall off the flap and are discarded as medical waste.

If one or all of the veins are thrombosed, the arterial anastomosis may be allowed to remain intact at the discretion of the surgeon. The vein can be transected, with venous drainage occurring through the unattached vein. The authors irrigate the artery with Alteplase, which then flows though the flap and out of the unattached vein. Systemic heparin should generally be started in the operating room and continued in the postoperative period for 7 days. Hematomas may develop as a result of anticoagulation. Drains should be placed carefully in the operating room and not removed until the heparin has been discontinued.

The radial forearm flap is extremely reliable. The overall flap success rate of microvascular free tissue transfer in larger series is 90-98%. Nevertheless, all microvascular procedures are dependent on the experience of the surgeon and various patient factors. A take-back rate of 10% is expected, and about half of these flaps are successfully salvaged.

A literature review by Markiewicz et al indicated that there is no difference in flap survival at the recipient site between a variety of microvascular free flaps commonly used for mandibular reconstruction, with the exception of the deep circumflex iliac artery (DCIA) flap. Compared with the radial forearm free flap, according to the study, the DCIA flap has a seven-fold greater chance of failure. ^[11]

The reliability of the flap and the ability to reinnervate the flap via the MABC or LABC nerves have been well established. ^[12] The functional implications of such reinnervation have yet to be determined. Techniques for improving donor site morbidity are also being evaluated. Improving cosmesis through different grafting materials and suture techniques will ultimately make this flap even more appealing.

A study by Brinkman et al indicated that in patients who have extensive composite defects due to resection of locally advanced head and neck cancer, acceptable long-term survival and functional outcomes can be achieved with the simultaneous use of two free flaps, including a fibula free flap combined with a radial forearm free flap. Most of the study’s 42 patients underwent double-flap treatment with a combination of either fibula and anterolateral thigh flaps (22 patients) or fibula and radial forearm flaps (14 patients). The postoperative mean 10-item Eating Assessment Tool score was 8.4, while the Intelligibility Rating Scale demonstrated moderate to good speech intelligibility in 90% of patients. Nineteen patients remained alive at mean 55-month follow-up. The complete flap survival rate was 95%. ^[13]